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Laser Therapy

Laser

The Word laser is an acronym (from the Creek, aero, which means; tip, extremity; nomos means law).

Acronym by definition means, word formed by the initial of each successive segment of a locution, Houaiss, (2001). It’s an acronym of English language origin that means: Light Amplification by Stimulated Emission of Radiation. This radiation is of non-ionizing electromagnetic type, being a luminous source with very specific characteristics.

And it’s just the special characteristics of this kind of light that grants important therapeutic properties and allows it to be used in surgeries with advantages in relation to the conventional scalpel.

The optical radiations produced by different kinds of lasers basically have the same characteristics, for they are generated through the same principle, however, it is possible to work with laser, aiming to obtain very specific clinical results, for what determines its interaction with biological tissue is the optical potency density of the system, and its wavelength.

In the beginning the lasers were classified according to the kind of device that was available in the market. Nowadays, we suggest a classification based on the laser’s interaction with target tissue involved. The cell has a survival threshold, based on the kind of tissue where it is located and its physiological condition. When we work with the laser respecting the threshold, we offer the cell a low intensity of energy, and we work with the laser operating in low density of potency (Figure 1). That is why we use the terms Low Potency Laser or Laser of low intensity of energy. Internationally, up to the 90’s decade, the utilization of this kind of laser was known as Low Power Laser (LPL), Low Energy-Level Laser Therapy (LLLT) and Low Intensity Laser Therapy (LILT).

However, with the same laser, we can work in two very distinct ways, searching for very specific tissue interactions. The first of them is when we offer low density of energy, but sufficiently high so that the target cell uses it in a way to stimulate its membrane, or its organelles.

This way, we will be inducing the cell’s bio modulation, that is, it will try to re-establish the normal conditions of the affected area. From 1996, Ohshiro and Calderhead, started to call this kind of therapy with laser the Laser Therapy, which began to be accepted as an international terminology for this kind of treatment with laser. Also in Brazil, the first publications adopting the terminology Laser Therapy started to appear (Almeida-Lopes, 1997, 1999), and the laser employed for that purpose (low intensity laser), began to be known as therapeutic laser.

Its main indications are all pathological conditions where a better quality and a greater speed in the reparation process are intended (post operation conditions, soft tissue reparation, nervous or bony), Established Edema conditions (where a medication of the inflammatory process is desired), or in pain conditions (chronic and acute).

We can still work with the laser operating at a so low intensity level that the stimulation of the organelles or cell membranes does not take place (Figure 2). The emitted potency would be compared to that one of a laser pointer, used in classrooms. The purpose of this kind of device would be the diagnosis utilization of incipient cavities and tumor cells, among other lesions. This laser is not capable of either producing therapeutic effects, or microscopically changing the tissue, so we know it simply as Diagnosis Laser (DiagnoDent – Kavo’s trademark)

When, on the other hand, we apply such a high density of energy, so that thermal damages are caused and surpassing the survival threshold of the cell, causing it to come to a lise, and thus its death, we will be using a laser with a surgical finality. This laser will be operating at either a high intensity of energy or high density of potency (Figure 2).

With this type of device, we can destroy the tissue, removing cavities, making incisions, excisions or vaporizations. This is what we call Laser Surgery, and for that, we use several kinds of Surgical Lasers

(Laser of CO2, Nd:YAG, Er:YAG, diode, argon, among others).

In this work, we will discuss only the utilization and effects of Therapeutic Lasers. The word has already been included to the Portuguese vocabulary and its present in all its dictionaries. As a substantive in Portuguese, ended in es. Therefore, the plural of laser becomes laseres, as all the other substantives ended in that way. If we adopt the plural in English, lasers, we have to write it always in italics, pattern adopted in our language when it has written a foreign word.

Figure 1 – Interaction of the laser with the biological tissue.

 

Figure 2 – Different types of laser actions with biological tissue.

Physical Principles

Light, Laser and its basic principles

The light can be described as an electromagnetic emission, and because of that, it has some characteristics that identify it completely. These emissions are generically known as, radiations or electromagnetic waves, and are contained in a great band or track, which is subdivided according to some peculiar physical characteristics. There are those ones that we cannot see, such as sound waves emitted by someone who speaks or sings and the AM and FM radio waves (Figure 3), and there are those ones that we can see, such as luminous ones, formed by photons, like the light emitted by the lamps of a house’s chandeliers.

The emissions are organized following what is called Electromagnetic Radiations Spectrum, based on a particular characteristic: The wavelength (Figure 4). This spectrum is formed by infrared radiations, visible radiations, ultraviolet radiations, non-ionizing radiations (x-ray and gamma ray), besides other types of radiation which are not related to this work. The lasers for medical, odontological and veterinarian treatment (what we call Life Sciences) emit radiations that are located in the range of visible radiations, infrared and ultraviolet and those ones that are ionizing.

In order to identify in which part of the spectrum is classified a certain radiation, we need to know its wave-length, which is nothing more than the measured distance between two consecutive peaks of a waving trajectory (wake like) (Figure 5). The used unit to express this greatness is a meter’s fraction, normally the nanometer, which is equivalent to 0.000000001 meters (or 10-9).

A very simple way of understanding the spectrum concept is to observe the rainbow (Figure 4). This natural phenomenon is formed by the decomposition of the white light in seven basic colors. These seven colors, which we can see, are part of the spectrum of the electromagnetic radiations, are defined by their wavelength and when they are mixed they generate the white color. Each emitted color has got its own wavelength, and that happens with other colors that we cannot see, but whose effects can be felt.

Figure 3 – Oscillations, radiations or electromagnetic waves, are expressions that can be synonym.

 

Figure 4 – Electromagnetic radiations spectrum.

 

Figure 5 – Mensuration of length of an electromagnetic wave.

In the scale of wavelength, below the range of emissions of what we call visible, we have the ultraviolet, which is a very broad range. The ultraviolet emission is responsible for the darkening of our skin when we are exposed to the sun.

Above this range of emissions we call visible, we have the infrared, which is also a very broad er range than the broad we can see. This type of emission is responsible for the heating we observe in the light generated by the photopolymerizers that use halogen light source, and which is commonly called heat.

The Laser is nothing more than light, and thus it has the light behavior, that is it can be reflected, absorbed or transmitted, suffering or not the spreading in the process (Figure 6). However, it is a light with very special characteristics, such as, unidirectionality, coherence and monochromaticity.

Figure 6 – The laser has the light behavior.

The light can be understood as small packages of energy (photons) traveling according to a wavy trajectory.

The laser is a type of light whose photons are identical and they propagate over parallel trajectories, differently from the common light, where the photons with different wavelength are emitted and they propagate in a chaotic way, in all directions (Figure 7). It is still a coherent light, where the peaks and valleys of all wave like trajectories of photons that form it, coincide in terms of direction and sense, amplitude, length and phase. These aspects are the ones that make it different from the common light, where there is no synchronicity in the emitted photons (Figure 8). Like all the photons emitted by a laser device, the patterns are identical, they propagate according to identical trajectories, direction, sense, amplitude and phase. They are device capable of emitting light with unique and defined wavelength. Then we can say that these photons are of pure color (Figure 9).

Figure 7 – The laser is a passible light to suffer collimation, this is, walks in a parallel way different than the common light that gets lost in time and space.

Figure 8 – The laser is a coherent light.

 

Figure 9 – The laser is a monochromatic light.

For a laser production, some special conditions are necessary. Firstly an Active Means is needed, formed by (gaseous, liquid, solid or yet by their associations) substances that generate light when they are excited by an external light source. This excitement process is called Pumping and its function is to transform the active means into a radiation amplifier means, since it causes in this phenomenon called inversion of population, that is, the electrons of the valence layer of the means absorb the Dumped energy and they jump to a more external level of energy. Since this second level is more distant from the core influence, its level of energy is greater. We call this situation Meta stable state. When the first electron goes down, returning to the level with less energy (Original energy), the liberation of the small package of highly concentrated energy takes place, and we call it Photon (Figure 10). This photon ends up exciting the going down of the remaining atoms that already were in excited state (meta stable). This generates a waterfall process and with a growth in geometrical progression, which results in the stimulated emission of radiation (Bagnato, 2001).

The active means must be contained in a reservatory called Resounding Cavity. In the internal extremities of this cavity there must be mirrors, being one of them of total reflection and the other of partial reflection. This will assure that the system formed by optical reaction and active means be the seat of a laser oscillation. Since the laser cavity is formed by mirrors in its extremities, this radiation is amplified, that is, the photons emitted by stimulation go into phase (all photons take up the same direction) and make it possible to occur an increment in each trip (multiple reflections) that is completed in the cavity.

There are a lot of types of laser, but, the basic principle to produce a laser bundle is the same for all of them, no matter if it is surgical, therapeutic or diagnosis laser.

Figure 10 – Photon formation.

 

Figure 11 – Diagram of the resonant cavity of a generic laser.

For the identification of the laser, we need to know its generating source (characterized by the active means that will generate the laser light) and its intensity (characterized by the density of the optical potency produced or energy generated by the laser). The same way the domestic lamps are identified by their potency, normally expressed in Watts, we also use this measuring unit (or a fraction of it), to identify the lasers potency (mW = miliWatt = 0,001 W).

The last relevant characteristic of the lasers is related to their functioning process, that is, there are those ones that when they are activated, they remain turned on continuously until they are turned off (Continuous Lasers, CW) and there are other types that work in a pulsating or switched form (Figure 12), that is, they are part of the time turned on and part of the time off. Most of the Therapeutic Lasers operate in a continuous mode.

Figure 12 – Different types of emissions of a laser diode.

Laser of semiconductor

The lasers of semiconductor are the emitters of the smallest dimensions that exist and they can be produced in large quantities. Thanks to their effectiveness and the small size they are especially adequate to be used in Dentistry Clinics.

The simplest active means is formed by a diode (P-N junction) with high concentration of donating impurities (doping) in the N zone and receiving ones in the P zone, and for which the base material is the same for both zones (for example GaAs or InP).

This type of arrangement is known by the name of homo junction. The basic configuration of this type of diode is indicated in the Figure 13 A.

When an electrical tension V is applied, directly polarizing this union, a very narrow area is created around it, where the inversion of population is produced. It happens when there is a greater probability of electrons to be in the conduction band, than in the valence band. The direct polarization produces an electrical current, which is translated into a passage of electrons to the Pe Zone, and blanks to the N zone. The luminous radiation is produced by a recombination of electrons and blanks in the junction zone.

The wavelength of the transition depends on the energetic leap between the Valence and the conduction bands. The potential energy needed for an electron to leap from the valence band to the conduction band is equal to the photon’s energy that is produced after its recombination.
Normally the commercial diode lasers are of the hetero junction type (Figure 13 B), that is, they are formed by the union of two distinct materials (for instance GaAs e AIGaAs). This type of structure presents some technical advantages in relation to the homo junction and that is why it is more routinely used. In order to obtain the laser action, two faces of the semiconductor element are cut and polished in parallel (to function as mirrors), being that in the two other faces it is necessary to have a rugous working, as to avoid that the laser phenomenon be produced between them. Frequently, the two polished surfaces are not covered with anti reflexive coatings, since a semiconductor’s level of refraction is high, and there is enough reflexivity (around 35%) on the surface between the semiconductor and the air to produce the acceptable optical feeding.

The active region where the laser energy circulates has got a rectangular section, with typical dimensions of 0,5 :m x 10 :m in the hetero junction lasers. The output laser beam has got an elliptical section, with different divergences in the plan parallel to the union and in the perpendicular plan (Figure 1 3 B). With proper optical systems, this section can be converted to circular, more convenient for a further focalization.
The Diode lasers applications are very diversified, but above all those in the medical – odontological area, communication by optical fiber field, dimensional recognition, Bar codes reading, compact disk reading, Office printers, and sharpener among others.

Figure 13A – Basic configuration of a diode laser.

Figure 13B – Basic configuration of a diode laser of double heterojunction.

Laser’s Historical Aspects

The application of light as photo-therapeutic treatment is a very procedure. In 1903, Finsen received the Nobel Prize for the advances in the Vulgar Lupus’ treatment using an ultraviolet light source. Specifically for lasers, everything started with Einstein, who has postulated the theoretical basis about the controlled manipulation of light waves, and has published his ideas in 1917. This theory was checked by Landberg in 1928, but only between 1933 and 1934 Townes and Weber for the first time talked about micro waves amplification. At the same time there was a great advance in the development of the optical fibers and material in a general way. The theory about the amplification of stimulated emission was patented in 1951 by Fabrikant (a Russian Physicist) and his team, however it remained unpublished until 1959.

The first device that has used stimulated emission has been named MASER (another English acronym formed from Microwave Amplification by Stimulated Emission of Radiation), built by Townes in 1952.

Weber proposed in the same year the MASER amplification, theory that was published in 1953.

Theodore Maiman, an American Scientist in the United States, constructed the first laser in history in 1960. This first laser was developed from a synthetic ruby bar, which produced a short-lived light, and with high density of energy, operating in 694,3 nm when an intense common light fell upon it. It was developed in the Hughes Aircraft Research Laboratory in Malibu, and on this date presented to the press. In 1961, Gould obtained the application’s patent, which caused a great confusion about who its inventor would be. He published the biomedical indications of the high-density energy laser light. The first application was performed in the Ophthalmology field, and it was where the first clinical complication was observed. In 1962, Dulberger published a work about the lesions produced by focusing of the light over the retina and thus causing vision loss.

In 1961, Leon Goldman, in the University of Cincinnati, founded the first laser laboratory for medical applications, where the first in-vivo experiments were performed.

In 1962, Patel developed the first laser, which, later on would be used with therapeutic objective, a device whose active means was a mixture of the Helium and Neon gases (He-Ne), generating a laser light bundle with a wavelength of 632,8 nm (Pontinen, 1992).

In the ancient Soviet Union, different scientists have simultaneously worked on the laser development. Basov and Prokhorov have made great progress in this area, and together with Townes they won the Nobel Prize in 1964.

In 1966, the first clinical applications with laser operating in low potency were reported by Endre Mester from Budapest, Hungary, when the first reports of clinical cases about Laser Bio stimulation of chronic ulcers of the lower members using ruby and argon lasers were presented (Mester, 1966). He produced a great volume of scientific, clinic and experimental works, having the He-Ne Laser as the central subject.

The most used therapeutic Lasers in the 70’s and 80’s decades were the He-Ne lasers, with emission in the red region (632,8 nm). In this region of the electromagnetic spectrum, the laser radiation presents little penetration in the biological tissues, which limited its utilization. For the application of this kind of laser in deeper lesions, it would be necessary an optical fiber to conduct the light to the inner part of the body oncontextmenu=”return false” onselectstart=”return false” onmousedown=”return false” , thus limiting and counter indicating many times this type of therapy, for being such an invasive technique. Another Limitation of the He-Ne lasers was its great physical dimension and the fact that its active means was in glass ampoules that could easily break. The helium gas itself, formed by very small atoms, quickly migrates through the ampoule’s walls drastically reducing the work life of these devices.

In 1973, following the same line of Mester, Heinrich Plogg from Fort Coulombe, Canada, presented a work about the The use of laser in needleless acupuncture, for pain relief (Baxter, 1994).

From the end this decade, diode lasers started to be developed, originating this way the first diode laser operating in the infrared region next to (<img src=”lambida.jpg” width=”20″ height=”20″> = 904 nm), constituted by a crystal of gallium arsenate (As-Ga). The main advantages of this laser over the He-Ne laser are smaller dimensions and greater penetration in the biological tissues. Another advantage is that this device can operate in either a continuous or a pulsating mode, while the He-Ne laser can only operate in the continuous mode. The bio stimulation effect using the pulsating laser has been the subject of different works, but Morrone et al., in 1998, demonstrated that for in-vivo applications the continuous radiation shows better results than the pulsating radiation, what Almeida-Lopes confirmed in 2003, although this fact is only true exclusively for the soft tissues’ cicatrisation, but not for the osseous cicatrisation or for the pain treatment.

In 1981, the first report of the clinical application of a As-Ca-AI diode laser appeared, published by Glen Calderhead, from Japan, who compared the pain relief that a diode laser promoted to the Nd:YAG laser, (Yttrium and Aluminum, doped with Neodymium), 1064 nm.

In the same year the Nobel Prize was granted to Schawlow, Bloemberger and Siegmahn, for their studies about spectroscopy applied to the laser technology.

From the 90’s different dopers (doping agents = impurity that alters a pure substance’s properties) were introduced aiming to obtain different diode lasers, which were capable of generating different wavelengths. With the availability of this technology, nowadays we can count on small apparatus, easily handled and transported, with high durability and low cost.

 

Theoretical Aspects: Therapeutic laser, irradiance concept, flux and deposited energy and wavelength.

Therapeutic Lasers

The therapeutic lasers of low intensity maybe are the most widely studied in the world, and for sure they are already part of the daily routine of a large number of clinics in countries such as Spain, Russia, Japan. Germany and Brazil. One of the reasons of the popularity of this kind of laser is related to the effectiveness and low cost of the equipment, besides the objectivity and simplicity of the therapeutic and clinical procedures tomwhich it is directed.

The first studied therapeutic lasers, as we’ve said before, were the lasers in which the active means were a gaseous mixture of Helium and Neon (He-Ne), with potency varying between 5 and 30 mW, and wavelength of 632,8 nm, which is located within the visible range of the light spectrum, more precisely in the red color region.

It was formed by a glass reservatory (tube) filled with the mentioned gas, which was activated by a generating source of high tension electrical feeding. The light conduction up to the application point occurred through a flexible optical fiber cable of a bundle type (similar to the cables used in the photopolymerizers of the first generation), which would give a low optical yield to the system, that is, very little light reached the application point.

Along with the characteristics of the low optical yield, there is also the fact that this wavelength is highly absorbed by soft tissue, what compromises extremely the penetrability of the light.

These technical limitations have imposed the necessity of searching for low cost, with higher potency levels and with wavelengths that could go through soft tissues, without however, compromising the integrity of these tissues. That has been possible with the appearing of diode lasers, which according to what has been previously discussed , are relatively simple and low cost electronic devices.

The most used diode laser s in Dentistry have as an active means a compound of GaAIAs, with wavelength ranging between 760 and 850 nm (currently the most used is the one of 830 nm).

Which is located out of the visible range of the light spectrum, more precisely in the range of the near infrared, with potencies varying between 20 and 1000 mW.

Another type of active means used if the InGaAlP compound that produces light with wavelength varying between 635 and 690 nm, which is located within the visible range of the light spectrum, more specifically in the red color region, with potencies varying between 1 and 250 mW.

The generated light by this type of emitter has the same characteristics described for the He-Ne emitter and, thus, the same limitations in terms of penetrability.

 

Irradiance concept, fluency and energy deposited

Irradiance is the term that the photo biologists use as a synonym for potency density (PD), which is defined as being the laser’s working optical potency, expressed in Watts (W), divided by the irradiated area, expressed in squared centimeters (cm²). It is through an irradiance control that the surgeon can cut, vaporize, coagulate or weld the tissue, when surgical lasers are used. The proper potency density can also create the photo activation from a laser of low intensity of energy (therapeutic laser).

Fluency is the tern used to describe the energy rate that is being applied in the biological tissue.

When we multiply the irradiance (expressed in Watts) by squared centimeters (W/cm²), by the exposition time (expressed in seconds) we obtain the fluency or density of the energy or yet the energy dosage (ED) expressed in Joules by squared centimeter (J/cm²).

Energy is a physical greatness that, in the laser therapy case, represents the amount of laser light that is being deposited in the tissue, and it is defined multiplying the working optical potency of the laser device (expressed in Watts) by the exposition time (expressed in seconds).

The obtained result has as a representation the Joule unit (J).

The discussion about the mathematical aspects will be retaken in the further topics, because in this stage, the question that really matters for the professionals of the dentistry area is what these greatnesses mean, and how they relate to each other. We believe that through examples we can make these important concepts clear:

1. For a given potency, variations in the irradiance can produce effects on the biological tissue that clearly differentiated. For example, a laser with an output potency of 10 W, irradiating an area of 10 cm², will present irradiance equal to 1 W/cm². If the same laser is focused on an area of 1 cm², the irradiance will be increased ten times, probably generating thermal damages to the biological tissue, depending on the exposition time.

Conclusion: In fact, in order to define if the laser device can cause thermal damages, we should assess the generated irradiance, and not the working optical potency of the laser device in discussion.

2 – For a given amount of energy to be deposited, variations of the fluency can produce effects over the biological tissue that is clearly differentiated.

For example, let’s suppose that we should apply a total dosage of 30 J over a point. In a first hypothesis, let’s imagine that 30 J are applied for one second, over an area of 1 cm². We will then have, irradiance equal to 30W/cm², and that probably it cause thermal damage to the biological tissue. Let’s imagine now that the 30 J are applied over the same area for 30 seconds. We will then have for this situation, irradiance equal to 1 W/cm², which will not cause thermal damage to the biological tissue.

Conclusion: The quantity of energy to be ministered is important; for the tissues will respond better to a proper dosage of energy, however, the way this energy is deposited is also very important.

Using as conventional systematic analogies adopted by Odontology or Medicine, when we prescribe an antibiotic, the medicine dosage is ministered as the following example: Amoxilina, 500 mg, 1 tablespoon every 8 hours, that is, the name of the active principle and its dosage (concentration of the active principle, milligrams, quantity and frequency of the mentioned drug use).

When we refer to laser therapy, it will be indicated the dosage expressed in Joules (energy, which is the quantity of laser light deposited in the tissue), the fluency is expressed in Joules per squared centimeter (cm²), which is the rate of deposition of this energy (the way how the energy will be deposited) and the estimate number of sessions, following the same adopted principle in the antibiotic prescription of the previously mentioned example.

The energy (quantity of laser light applied) and the fluency. Are essential concepts for the Biomedicine, but for Dentistry and Medicine, the term used to define the concept is dosage. Still using the analogy of the antibiotic prescription, in order to obtain a certain medicine effect, the ministered therapeutic dosage is vital, that is, a too low dosage prescription by kilogram/weight of the patient will bring the expected result. On the other hand, a too high dosage prescription, may lead the patient to intoxication, or even to an anaphylactic shock. The same holds true for the prescription of a therapy with low intensity laser, which means, too low dosages do not cause satisfactory effects on the tissues, whereas too high dosages in soft tissues, may lead to inhibition of the cicatrizing process (this is only true for soft tissue).

 

Wavelength

The wavelength is an extremely important characteristic, because it is what defines the penetration depth in the target tissue (Figure 14). Different wavelengths show different coefficient of absorption for the same tissue. Jacques, in 1995 (Figure 15), summarized the different coefficients of absorption for different chromophores depending on the wavelength (chromophores are molecular agglomerate capable of absorbing light).

As we can observe, the emitted radiations in the ultraviolet and in the middle infrared region.

Show high coefficient of absorption by the skin, causing the radiation to be absorbed in surface.

While in the region of the near infrared (820 nm and 840 nm) a low coefficient of absorption can be noticed, resulting in a maximum penetration in the tissue (Karu, 1985, 1987).

The tissues are heterogeneous from the optical point of view and thus, absorb and reflect energy in distinct ways. The importance of absorption occurring in diversified ways, according to the tissue in which the laser energy is deposited, is in the fact that, depending on the wavelength, this tissue either absorbs energy more superficially or allows the energy to go through it, acting on a target installed in the tissue’s intimacy (generally a cellular membrane). To this we give the name of laser’s selectivity.

Once the luminous energy is absorbed by the cell, it will be changed into another type of energy. When we use lasers operating in high intensity of energy, most of the times it will be changed into heat. When we use lasers operating in low intensity of energy, the low wavelengths are capable of electronically excite the molecules activating the cell respiratory chain, while for the higher wavelengths the excitation will take place through the cellular membrane.

Figure 14- Didactic drawing illustrated of the penetration of the laser in function of its Wavelength.

 

Figure 15- Absorption coefficients for different tissues in function of its Wavelength, proposed by Jacques in 1995.

As we can observe in the figure number 6, part of the light that falls upon a translucent surface is reflected back to the means where it came from, part is absorbed by the material which is falling upon and part goes through the material, and returns to the original means. The reflected light, as well as the transmitted one, does not have relevance from the clinical application point of view.

Only the absorption process will be considered, because when the light penetrates the tissues suffers a process called scattering or spreading, being then absorbed by the cells and converted in biological effects.

When a beam light falls upon a surface, a percentage of the light that will be reflected will depend on the incidence angle of this beam.

The smallest they formed angle is between the incidental beam and the irradiated surface, the greatest this beam reflection will be, and thus, we will have less energy absorption by the tissue (Figure 16). That is why it is so important to apply the laser with the light conductor always positioned in a perpendicular way to the tissue, avoiding this way the reflection and maximizing the laser absorption (Figure 17).

The reflection will still depend on the optical characteristics of the tissues, since they are very heterogeneous from this point of view, as each type of tissue absorbs and reflects light in distinct ways. Tissues with keratin, like the skin for example, reflect more the laser light than tissues without keratin, like the mucous!

What we search for in the treatment is the laser absorption by the tissue, for the laser light will only act if it is absorbed and thus converted in effects.

Figure 16 – The smallest they formed angle is between the incidental beam and the irradiated surface, the greatest the reflection of this beam will be, and thus we will have smaller energy absorption by the tissue.

 

Figure 17 – The hand held laser equipment must be always perpendicular to the target tissue so that to minimize the light reflection.

Biological Fundamentals

Photo activation Concept

The laser operating in low intensity of energy was considered by Mester (1969) as a Bio stimulator and, because of that we find in the literature the term bio stimulation laser used to designate this type of laser. In this time, its action mechanism was not well known yet and what was observed was that the therapists had excellent results in the treatment of wounds and open ulcers, stimulating its cicatrisation process. However, as time passed, this therapy began to be used not only to stimulate and accelerate processes, but also to stop them. Mester has chosen the terminology Bio stimulation because he basically used this therapeutic process to accelerate the cicatrisation process in varicose ulcers and of decumbence ones.

However this process started to be used many times in the search for antagonistic effects in the biological tissue, such as removal of pigment excess, but also to restore the lack of it (Sasaki e Ohshiro, 1989); to treat depressed scars, and also hypertrophic scars (Strong, 1997); for pain relief, but also to re establish the sensibility in areas with paresthesia or paralysis (Rochkind, et al., 1989); to control hypo tension, but also to treat hypertension (Asagai, et al., 1998). From these clinical and laboratorial studies, it was possible to conclude that this therapeutic process did not only accelerate certain processes, but also delayed others, or simply modulate many others. The authors then, started to understand that in this type of therapy the laser performed a normalizing role of the cellular functions and Oshiro and Calderhead (1991), proposed the name Function Balancer and normalizer, thus a Cellular function Bio modulator (Almeida-Lopes, 1997).

There is in the animal organism a photo regulating function, based on certain photoreceptors capable of absorbing photons of a given wavelength, which even end up causing a transformation in the functional and metabolic activity of the cell.

This mechanism is important in the applications of the therapeutic lasers; because it is from it that the bio modulator effect is observed.

Differences in the action mechanisms between the visible laser light and the infrared

The energy of the constituting photons of a laser radiation absorbed by a cell will be changed into biochemical energy and used in its respiratory chain. The interaction mechanism of the laser at molecular level was primarily described by Karu, in 1988, who verified a mechanism of different action for the lasers that emit radiation in the visible range and for those that emit it in the range of the near infrared (Figure 18).

As it has been discussed, the lasers used in laser therapy emit wavelengths either in the visible range (Helium-Neon, used in the past and the diode lasers), or in the near infrared (diode laser).

The visible laser light induces a photochemical reaction, that is, there is a direct activation of the enzymes synthesis (Bolognani, et al., 1993; Ostuni et al., 1994; Bolton, et al., 1995), and this light has as a primary target the lysosme and the mitochondria of the cells (Figure 19).The Organelles do not absorb infrared light; just the membranes demonstrate response to this kind of stimuli. The changes in the membrane’s potential caused by the photons energy in the range of the near infrared (Passarela et al., 1984) induce photo physical and photo electrical effects, thus causing excitation of the electrons, vibration and rotation of the molecules’ parts or rotation of the molecules as a whole, which are intra cellular transformed into an increment of the ATP synthesis (Colls, 1986).

The increment of the mitochondria ATP (Passarela, et al., 1984; Pourreau-chneider, et al., 1989; Friedmann, et al., 1991) that is produced after the irradiation with laser, promote a large number of reactions that interfere in the cellular metabolism. The laser interfere in the ionic process, accelerating the increment of the ATP (Karu, et al., 1991a; Loevschall e Arenholt-Bindslev, 1994; Lubart, et al., 1996, 1997), above all when the cell is in stress condition, that is, when the tissue or organ treated with laser is affected by any functional disorder or lesion.

Figure 18 – Model of KARU modified by SMITH. Photochemical action of the visible laser in the redox chain of the mitochondria. Photo physical action of the infrared laser in the cellular membrane. Both trigger cellular responses, which generate a cascade of biochemical reactions.

 

Figure 19 – Difference of action of different wavelengths of therapeutics laser at cellular level.

The skin is the main barrier for the irradiations. Most of the energy conducted by the ultraviolet irradiations is absorbed in the first structures of the epidermis. On the other hand, the emitted radiations in the visible range of the near infrared suffer a minor absorption, and that is why a larger transmission up to the deeper tissue layer takes place. Then, what wavelength should be used?

The visible lasers have got very little penetration in the tissue, whereas the infrared lasers penetrate several centimeters. On the other hand, the fiber blasts have a better response to wavelengths emitted in the visible. However, the therapeutic effectiveness do not correspond only to the level of penetration but to the interaction between the laser light and the different biological tissues invoived (for the photochemical and photo biological effects generated by the laser affect not only the area under application but also the surrounding area). Besides the wavelength, it is important to consider the level of irradiance (or potency density) applied. Higher potency densities (Irradiances) generate better results from the point of view of tissue reparation and tissue analgesia (Rochkind, 1992a e 1992b; Bradley, 1999, Bradley, et al., 2000; Almeida-Lopes, 1999; 2003). As a general rule, we can consider that for lesions located in the tissue intimacy, we will have to choose wavelengths emitted in infrared range.

 

Action of Therapy with Low Intensity Laser

According to what has been previously exposed, the lasers used in this kind of therapy are placed in the visible part of the near infrared and spectrum of the electromagnetic irradiations. The most frequently used wavelengths are between 600 and 1000 nm, and in a general way, they are relatively little absorbed, thus, they show a good transmission in soft tissues, either in skin or mucous.

In animal organisms, it is evident that a photo regulator function related to the existence of photore-ceptor structures. According to Baxter (1994), these organic molecules (photoreceptor structures) responsible for the luminous energy absorption are classified in two groups:


Group 1: Contain the amino acids and the DNA constituting nucleic acids, as well as the cellular proteins. The amino acids show a significant absorption in the intermediate and lower range of the ultraviolet, whereas the nucleic acids have got an absorption spectrum in the same range of the amino-acids, and also in the infrared range. Both do not show significant absorption in the ultraviolet range near to the visible.

Group 2: Formed by proteins, which show a chro-mophore as an added functional group. Chromophores in their turn are defined as molecular structures that absorb light in the visible range. They are classified as specialized or not specialized, and it may constitute enzymes, cellular membranes or even extra cellular substances:

Hemoglobin: Depending on the reduced or oxygenated condition describes a curve of characteristic absorption, since, in the oxygenated form it shows absorption peaks between 577 nm and 420nm, while in the reduced form, it shows an absorption peak of 600 nm.

Melanin: Shows a greater absorption in wave lengths higher than 300 nm, demonstrating a decrease in the absorption for wavelengths higher than 1200 nm.


Components of the respiratory chain, such as the cytochomes of the phosphorilation systems (cytochrome a-a3 and the cytochrome c oxidase), form the components of the terminal functions of the electrons transportation system, present in the mitochondria’s membrane.

Absorb in the near infrared range (between 700 and 900 nm) and in the visible range, when they are found in their intermediate redox status, which means, neither fully oxygenated nor reduced (excellent condition); derived components of porphyrins, low rotation iron and other molecules that absorb wavelengths in range between 950 and 1300 nm, however flavopro-teins and terminal oxidase, absorb in the visible range, more precisely between the violet and blue with a maximum absorption of wavelengths between 405 and 436nm. These are the responsible for the generation of molecular oxygen.

Then, we could also conclude that the photon absorption by the cell, takes place directly by the capitation of mitochondria’s chromophores or by an action in its cellular membrane, produces stimulation or inhibition of the enzymatic activities and photochemical reactions. These actions determine photodynamic changes in cascades of reactions and in physiological processes with therapeutic connotation (Loevschall e Arenholt-Bindslev, et al., 1994; Lubart, et al., 1997). It is important to emphasize that the cellular photo sensibility is pretty complex, for there is no threshold that simply determines if the laser sensitized or not the cell. The cells may respond to the luminous stimuli in several degrees and the magnitude of the photo response will depend on the their physiological condition, prior to the irradiation. This way, the cellular response will be either weak or absent when its redox potential is excellent, and the response will be present and strong when its potential is altered, by any reason.

These cellular photosensitization and photo response processes may clinically manifest in three ways. First, they will directly act on the cell, producing a primary or immediate effect, increasing the cellular metabolism (Karu et al., 1989; Rochkind, et al., 1989; Bolton et al. 1995) or, for example, increasing the endorphin synthesis and decreasing the liberation of nociceptive transmitters, such as bradikinin and serotonin (Ataka, et al., 1989).

They will also act in the stabilization of the cellular membrane (Palmgren, 1992; Lijima, et al., 1991). Clinically we will observe a stimulating and analgesic action of this therapy. Besides that, there will be either a secondary or indirect effect, increasing the blood flow (Kubota e Ohshiro, 1989; Maegawa, et al., 2000) and the lymphatic drainage (Lievens, 1986; 1988; 1990; 1991; Almeida-Lopes, et al., 2002b). This way, clinically we will observe a mediating action of the laser on the inflammation. Finally, there will be an instauration of the general and late therapeutic effects, being that, clinically we will observe for example, the activation of the immunological system (Trelles, 1986; Skobelkin et al.,1991; Velez-Gonzalez,et al., 1994; Tuaner e Hode, 2002). For these reasons, the laser is also currently used in the activation of the lymphatic drainage (Almeida-Lopes, 2002b). These Lasers therapeutic effects over different biological tissues are very wide inducing trophic-regenerating, anti inflammatory and analgesic effects, which have been frequently demonstrated in in vitro studies; emphasizing the works that corroborate an increase of the local micro circulation (Maier, et al., 1990; Maegawa, et al., 2000), activation of the lymphatic system (Lievens, 1986, 1988, 1990, 1991), proliferation of the epithelial cells (Steinlechner e Dyson, 1993) and Fiber blasts (Webb, et al., 1998; Almeida-Lopes, et al., 1998b) as well as increase of the collagen synthesis by the fiber blasts (Enwemeka, et al., 1990; Skinner, et al., 1996). This way, for didactic reasons we classify the laser effects in three types: primary effects, secondary effects and therapeutic effects wide or systemic, however, it is important to point out that the effects take place simultaneously.

In vitro studies about the fiber blasts, describe either a proliferative or activator effect of the proteinic synthesis, depending on the characteristics and parameters of the used laser, such as: wavelength, form of emission, potency density and density of the used energy, number and frequency of the application sessions of the laser. Several authors have worked in vitro with fiber blasts, main cell responsible for the tissue reparation (Halevy, et al., 1997; Al-Watban and Andres, 2001; Almeida-Lopes, et al., 2001, 2003), being that these studies correlate to other in vivo works and, show effects such as time reduction of the cicatrisation of wounds within the cutaneous extract and the mucous (Rochkind, et al., 1989; Al-Watban, Zhang, 1994; Lowe et al., 1998).

Another important factor to be observed is that the best results in terms of cellular proliferation have been obtained when, for a fixed dosage, the irradiances (potency density) were higher. That is, in a certain experiment a dosage work has been determined and the device potency has varied. When the potencies were higher, and consequently, the irradiation times were shorter, the results were better than those in the cases where it’s been worked with lower potencies, and, this way, longer times of irradiation (Almeida-Lopes, et al., 1999, 2001, 2003a, 2003b).

Also, when it comes to osseous reparation, the laser is found effective, that is in vitro works, in which an increase of the osteoblastic activity is observed (Freitas, et al., 2000; Yamamoto, et al., 2001; Cuzzardella, et al., 2002), either in in vivo works, in which an osseous gain is observed in animal works (Luger, et al., 1998; Oliveira, 1999; Kawasaky,et al., 2000; Silva Junior, 2000; Limeira Junior, 2001) or in human works (Hernandez, et al.,1997).

 

Clinical Applications

Due to the characteristics of pain relief, tissue reparation stimulation, reducing edema, hyperemia in anti inflammatory processes, preventing infections besides acting in paresthesia and paralysis, the low intensity laser has been frequently employed in multiple medical and odontological specialties.

In the Dentistry clinic there is a large number of applications, and the use of this therapy has already become a routine for the osseous bio stimulation, in cases of implant and minor oral surgery; to decrease the pain and edema in several post operation cases, recurring aphthous ulcers, herpes, neuralgias and tooth hyper sensibilities; besides activating the recuperation in paresthesia and paralysis cases.

It is also indicated in the treatment of systemic diseases with oral manifestation, such as Plain Liquen and the Mucous inflammation in general, as well as the self-immune like lupus erythematosus, wild fire (Pemphigus) Vulgar (Almeida-Lopes, 2002; Almeida-Lopes, Massini, 2002). The oral manifestation of these diseases is ulcerating lesions, with exposition of the conjunctive and thus extremely painful. These diseases don not have cure and cause great discomfort to the patients, when there is a lesion outbreak. They cyclically appear and, on these occasions, the patient feels a lot of pain and discomfort being necessary the use of powerful analgesic medication so that the patient may swallow and be fed. Besides that, these lesions have an esthetic compromising, then, the frequent indication of low intensity laser for the treatment during its cicatrisation. For the same reasons, this therapeutic process is recommended for treatment of immune depressed patients bearers of post radiotherapy and post chemotherapy mucous infections. It use is so widely spread that these lesions are preventively treated (Bensadoun, et al., 1999), immediately before the medullar infusion, to minimize the adverse reactions in mucous, after the pre-cognized chemotherapy.

In medicine, this therapeutic process is used to improve the cicatrisation in burned people treatment and in patients who received some kind of graft or morsel, where it works as an activator of the vascularization of theses regions. It is also used for the treatment of acute and chronic pains of several types and those caused by genital herpes, besides different post operation, in gynecology, dermatology, and plastic surgery. It is also frequently used in sports medicine and in physiotherapy, remarkably in patients who suffered trauma originated from sports activities, such as muscular distension and contracture, tendon rupture or yet repeated effort lesions (REL), arthritis, arthrosis, among others (Tuner, Hode, 2002).

We will see details about the applications in Dentistry on the following topics: protection devices as to avoid that any person be subjected to accidental exposure, when entering the mentioned room during the laser application (Figure 25).

The lasers are classified in categories according to their hazard degree. According to each category, safety rules that must be followed and that involve the dentistry surgeon, the assistant and the patient are required.

In our country does not exist a governmental organ that regulates the laser use, that is why, the rule that we have adopted is the ABNTIEC, which the European version of the 21 FCR American rule, chapter 1, Part 1040 and, according to it, the lasers equipment are classified in 06 categories: Class I, Class Ma and II, Class Ilia and 1Mb and Class IV and that basically depend on the optical potency density emitted by them and on the wavelength generated by them.

Class I – Harmless equipment that does not require the utilization of any safety procedure or equipment (Figure 20A e 20B).

Class II A – Harmless equipment that does not require the utilization of any safety procedure or equipment (Figure 21).

Class II B – Harmless equipment and does not require any safety procedure or equipment (Figure 22).

Class III A – Equipment that may harm the eyes, being necessary and vital the use of protection glasses compatible to the wavelength generated by the laser in question (Figure 23).

Class III B – Equipment that may harm the eyes, being vital the use of protection glasses compatible to the wavelength generated by the laser in question. The equipment present in this category, must count on internal interruption devices, so that to avoid accidents when handling the internal circuits of the equipment (Figure 24).

Class IV – This is a category where all the surgical lasers are classified. Thus, the equipment that may harm either the eyes as well as the soft tissues, being vital the use of protection glasses compatible to the wavelength generated by the laser in question. The equipment present in this category must count on internal, external and monitoring protection devices. The room where the equipment is installed must have protection devices so that to avoid that any person may be accidentally exposed, when entering the mentioned room during a laser application (Figure 25).

We will not detail the safety items required by the class IV laser equipment, because it is a work about the laser therapy. We will list here only the required devices for the equipment of laser therapy. (Figure 26), as well as the basic precautions that must be followed when installing, operating and giving maintenance to the equipment (Figure 27).

The protection glasses are specific for each one of the laser equipment and depend on the wavelength emitted and the maximum optical potency generated by the apparatus. It is important to mention that there are no universal glasses for surgical lasers, but for the therapeutic lasers there are already special lenses that may be used either for lasers that emit visible wavelengths or for those that emit infrared (figure 28)

Since the lasers are inherently dangerous for the eyes, we will list some measures aiming the safe operation of such devices (figure 29).

Figure 20A – Safety measures for lasers type I.

 

Figure 20B – Exposition limits Board.

 

Figure 21 – Safety measures for lasers type II A.

 

Figure 22 – Safety measures for lasers type II.

 

Figure 23 – Safety measures for lasers type III A.

 

Figure 24 – Safety measures for lasers type III B.

 

Figure 25 – Safety measures for lasers type IV.

 

Figure 26 – Devices obliged by norm.

 

Figure 27 – Cares that you must have with your equipment.

 

Figure 28 – Cares that we must have to choose the most suitable protection glasses.

 

Figure 29 – Safety measures that must be taken in relation to the equipment.

The adjustable parameters are the variables that we can modify in our equipment so that we obtain maxi-mum effectiveness. We list next, step-by-step which variables we should select before starting the clinic procedure in question.

A) Selection of the wavelength: Most of the devices already have the two types of laser emitter, and thus two wavelengths, and one of them is located between 630 e 685nm, and the other between 790 e 904nm. In most equipment there are handsets, where in each of them a different diode laser is assembled (Figure 30). In the latest generation equipment, although there is only one handset, the two different diode lasers are assembled, in a way that the selection of which one will be used is done directly in the control panel (Figure 31). There is still, a third type of device that includes accessory functions besides the laser therapy function, for example, the dental clearing function and the function photo polymerization of resins (Figure32).

Figure 30 – Photo of device with two parts of hand, and, therefore, with two different wave lengths, Photon Lase III of DMC Ltd. Equipment. In the panel of the device it is enough to select the type of injury on which the professional intends to apply the laser, and the equipment determines the protocol automatically.

 

Figure 31 – Photo of the Laser therapy device of last generation used in Odontology (Thera Lase of DMC Ltd. Equipment.). Of an only part of hand different wave lengths are produced.

B) Selection of laser emission mode: In a general way, it is possible to control the laser emission mode. Normally the option is between the continuous and the pulsating emission mode (switched), where the laser is emitted in pulses, with constant forms, duration and amplitude and adjustable frequency, according to the necessity of the clinic treatment (Figure 12).

C) Selection of the Potency: The potency is fixed, in most of the devices, but in the most sophisticated ones it is possible to vary it. The most important aspect, however, is to know the working optical potency of the equipment, that is, the measured potency in the handset output, since this is one the data that form the equation for the dosimetry calculation (Figure 36).

It is also important to remember that the potency itself, is a data that does not matter much the clinician, except for the fact that higher potencies will result, in the last instance, shorter clinic time of procedure. This, obviously, is not the most important, but the fact that higher potencies reflect in the tissue, higher densities of potency (or irradiance) and this indeed has a cellular significance of great importance, for, as we have previously discussed, the cell responds better to this condition.

Figure 32 – Photo of the equipment with multiple functions: laser therapy function, dental clearing function and photo polymerization of resins in just one device: Ultra Blue IV da DMC Equipamentos Ltda.

D) Spot Size: The area of transversal section of the laser bundle is expressed in squared centimeters (cm2) and varies according to the equipment that has been used. The value of this area is important, since it is also one of the data that form the equation for the fluency calculation (or dosimetry), when we use the Punctual Technique.

Historically the application techniques used are two: The Punctual Technique where we choose some strategic points over the affected area for the laser application; and the Scanning Technique where we cover all extension of the lesion through come-and-go movements.

The utilization of the latter has been abandoned, since its parameters of calculation are done subjectively, since the area that must be considered for the fluency calculation is the lesion area. The clinician must previously measure this area and the devices almost never foresee this kind of application. Another problem related to the Scanning Technique is that it cannot use the laser in contact with the tissue, and the laser equipment are made with the calculations based on contact technique, which is the internationally accepted and used technique. The value of the use of the Scanning Technique is merely historical. By the presented reasons, the Punctual Technique is the most divulged and used technique, either in the scientific – academic environment as in the clinic. This way, we will use it for this presentation of the clinic indications.

As it has been previously explained, in this technique we will consider, for calculations the area of transversal section of the laser bundle or the working area of the pointer or application probe, since we work in contact (Figure 34). It is important to point out that, in a general way, the devices are already adjusted for the Punctual Technique.

Figure 33 – Potency Selection, when the equipment allows that.

E) Fluency: The fluency (or density of energy or yet, dosime-try), as we have seen before, it is the way how the dosage is deposited per session of laser application, necesessary to obtain the desired effect, and it varies according to the type of tissue, the profile of the patient being treated and the lesion to be treated.

The fluency is the result of the product of the optical potency of laser expressed in watts, by the duration time of the session, expressed in seconds, divided by the area of the transversal section of the laser bundle, expressed in squared centimeters (cm²) (Figure 35).

Figure 34 – In the Punctual Technique, the area is equal to the area of the transversal section of the laser bundle or to Pie working area of the handset.

F) Application time: The time of exposition is the incognita we try to calculate from the rest of the data. It is important to point out that we should never have the exposition time as the basis when we discuss protocols, for it will always vary, depending on the equipment that is being used.

 

How do we obtain the exposition time?

We have as data, the fluency or density of energy (expressed in Joules by cm2) which is given through the user’s manual of the equipment; the working potency (expressed in Watts) that must also be given by the producer and the area of transversal section of the laser bundle (in case the Punctual Technique is used). In case the Scanning Technique is used, it is important to calculate the extension area of the lesion (also in cm²).

The time of exposition is the result of the product of the energy density, expressed in J/cm², multiplied by the area, expressed in cm2, divided by the potency expressed in Watts (Figure 36).

Figure 35- Fluency calculation, in most of the devices, is the only data to be determined by the operator of the equipment.

Next, we will discuss the used concepts in the fluency tables’ creation. The methodology in vigour considers the reaching area of the laser bundle as being equal to 1 cm2 (area identified as S2 in the Figure 37), for all and any type of tissue, (clear/dark, hard/soft, with keratin/without keratin). This methodology was created in the 60’s decade, in a time when there was only one wavelength for the laser therapy, which was 632,8 nm, emitted wavelength by the used laser then, the He-Ne laser and the area of the transversal section of the bundle laser was about the same in all the different available equipment. It also worthwhile to point out that the studies at that time were based on Caucasian patients, what caused the laser light penetration to be about the same, since the treated patients always had clear skin.

Nowadays, the methodology accepts, and in Brazil suggested by Almeida-Lopes, Massini (2002), considers the laser bundle area that effectively falls upon the tissue to be irradiated S1 (Figure 37).

Based on the current international literature, we consider being inappropriate to imagine that the laser light spread in an identical way in all tissues of distinct natures (hard and soft tissue for example; or clear and dark tissue), since the mentioned tissues are heterogeneous from the optical point of view. This way, we believe to be incorrect to use the standard area of 1cm’ as the reaching area of the laser bundle, and we suggest that the area to be used be the area of the transversal section of the laser bundle over the contact point with the tissue to be irradiated.

This way we will have much more control of the data when we develop a work protocol, for we believe to be impossible to precisely estimate which reaching area of the laser is when it penetrates the tissues, since they are different from each other. It is possible, however to precise how much laser is emitted in the extremity of the handset.

This method of calculation implies in the correction of the Fluency Table (multiplying it by a factor near 20, depending on the configuration of the laser bundle). But, it assures much more precise and stable protocols.

Once more, although these parameters serve as reference (Figure 38), it will be up to the clinician to define the dosage to be used for each patient, considering the type of lesion, its nature and depth, its duration time, the type of tissue involved, the patient’s age and the patient’s systemic condition, among other items analyzed by the time of the anamnesis.

In this work we will show the two tables currently used. In case the chosen option is method in vigour, the table of fluency to be used is the one listed under the title Conventional Methodology, otherwise, the table to be used is the one listed under the title Methodology Proposed by Almeida-Lopes Massini (2002).

Nowadays there are devices with different philosophy, where it is not necessary to adjust any of the physical parameters of the laser, being enough just to select the name of the lesion to be treated in the control panel of the equipment (Figure 30), and the parameters of the application of the mentioned lesion will be automatically set.

Figure 36 – How the laser application time is calculated.

We should warn that if any professional chooses to treat through the Scanning Technique, it is important not to use the same fluency defined for the Punctual Technique. For this technique, each lesion will have a different area, and for the fluency calculation, the professional will have to use the lesion area expressed cm2. We believe that this technique must only be used in case the equipment is able to precisely do these calculations.

Figure 37 – The methodology in vigour considers the reaching area of the laser bundle equal To 1 cm for all and any type of tissue and laser equipment.

 

Figure 38 – Fluency table with the calculations based on the methodology in vigour and the one proposed by Almeida-Lopes Massini em 2002.

General Considerations

Before we approach in details the clinic indications and start to develop our protocols, we will discuss some aspects that generally generate a lot of doubts for the users of laser therapy equipment.

A very important fact to be cleared out is that in the past, mainly in the 80’s decade, the used laser was exclusively the He-Ne visible laser. This laser has got intrinsically very little penetration in the biological tissues due to its wavelength. Besides that, the used lasers at that time and also in the middle of 90’s were lasers with extremely low potencies (of 10 a 20 mW).

Thus, in the first developed protocols we abused of the number of points. In a hyper sensibility for example, we managed to apply 6 point sin each tooth, because this way we could increase the laser effectiveness, and somehow, also the depth of penetration. We will see that thanks to the more powerful diodes, nowadays there are equipments with wavelength that penetrates a lot more (Infrared between 780 and 830 nm) and there are equipments with much higher potencies than those from the past decades (between 50 and 300 mW), consequently with higher densities (or irradiance). For this reason, in the current protocols, there is not the need to apply so many points in order to obtain a satisfactory result anymore.

We cannot, in any simplistic way, believe that the higher densities of potency only mean shorter times of procedure, but we should explore the fact that using higher densities of potencies we are able to sensitize deeper layers of biological tissues.

Another problem that we had when developing the protocols refers to the fluencies then considered ideal, they were extracted from in vitro study models, of cells in tillage plates, which were very delicate and weak, what caused us to work with low fluencies and these same fluencies were also used in humans. As the 80 e 90’s decades passes, several in vivo works were done proving that these fluencies considered ideal in cellular tillage were too low for clinic reality, where we did not only work with a single cell, or just a layer of them, but we worked with an entire complex system.

Involving blood, lymphatic and nervous system, and different tissues, such as muscular, adipose, among others. Also for the not knowing and the lack of scientific works, in the past decades we believe that the cells needed a long time of application of the light to reach the threshold of an answer. We were also afraid that therapeutic equipment with higher potencies could deposit energy quickly and this way preventing appropriate cellular absorption. Thanks to the boldness and scientific quality of authors like Simon Rochkind and his cooperators,

As well as Paul Bradley and his staff, we started to work with equipment with higher potencies (initially between 35 and 50 mw and currently between 100 and 300 mW), depositing higher energy densities (Rochkind, et al., 1992, Rochkind, 1992, Rochkind et al., 1996; Takeyoshi, et al., 1996; Hashimoto, et al. 1996; Kohelet et al., 1998, Bradley, 1999; Shaffer, et al., 2000; Bradley, et al. 2000; Wilden, 2000; Almeida-Lopes, 2002; Almeida-Lopes, et al, 2002; 2002).

This subject has been discussed in congresses and explained in mastering and doctoring thesis (Almeida-Lopes, 1999) (Almeida-Lopes, 2003), and today we can calmly affirm that the cell responds better to higher potencies, that is, for a fixed density of energy fixed, if we deposit this energy very quickly, we will have a higher potency density in certain cell, which will generate a greater cellular absorption and the responses will be more satisfactory. It is still left to know up to what level of potency density the tissues favorably respond, without having thermal heating that may interfere in the laser/tissue interaction. We believe that this will be the subject of the future scientific investigations.

According to what we have previously discussed, we verified that Tuner and Hode (2002) point out that when we use laser therapy equipment with higher potencies generated by the diode laser, we will have a shorter period of time to apply the same energy, and that we should consider this as a determinant factor in order to obtain a good therapeutic result in general. Now we can start to develop our treatment protocols based on the equipment that we have. (Figure 39).

Figure 39 – Main Lasers currently used in Dentistry in Brazil. Clockwise: 1- Biolux laser, from Bio-art; 2 – IR 100, Laser Beam; 3 – Photon Lase, from DMC; 4 – Thera-lase, from DMC; 5 -Ultra Blue IV, from DMC; 6 – Twin Laser, from MMOptics; 7 – Quasar, from Dentoflex.

In order to assemble a treatment protocol, we must take into account the condition of the tissue (whether it is an ulcerated, keratinized, pigmented tissue, its degree of vascularization); the age of the patient as well as their systemic condition and, mainly, to make the correct diagnosis of the lesion.

Regarding the parameters inherent to the laser equipment, we highlight the wavelength, mode of emission and power of the device. Regarding the application parameters, we will determine: session duration (application time), energy dose used, amount and frequency of applications. We will classify the clinical indications into categories according to the target tissue in which the laser will act.

To do so, we will present five blocks of protocols (Figure 40): Soft Tissue Repair, Bone Tissue Repair, Dental Tissue Repair, Nervous Repair, and a block on themes of various natures, which we will name Others (Figure 41). With regard to pain, it is important to remember that there are basically two forms of clinical treatment of pain using laser therapy; the immediate analgesia and the analgesia generated by the own solution of the pathological picture through the activation of the tissue regeneration. Of course, with regard to immediate analgesia and its maintenance, the application of laser therapy can be done daily, with excellent results. Already for the effect of tissue repair activation we must remember that the cell has a physiological cycle that must be respect. There is a minimum time for the cell to start a repair cycle, especially in chronic pathological processes. The repair cycle of any tissue is not a simple linear process but an integration of dynamic interactive mechanisms involving soluble mediators, blood elements, extracellular matrix production and parenchymal cells.

Figure 40 – Didactic division of lesion groups where the use of laser therapy is recommended.

Unleashed, these processes develop in a specific sequence and time. Therefore, it is no use, for example, to irradiate a wound daily so that it closes more quickly. There is a physiological period for the wound to close. What is sought with the laser is to remove this repair from a pathological condition and restore its physiological situation, but we can not expect results superior to the conditions of normality, it is not possible to shorten a physiological cell cycle, we can only measure it with the laser.

Another important observation is that, in chronic processes and in immunodepressed patients, we should start applications with more sessions and fluids lower than the recommended averages, and with the development of the treatment, we spaced the sessions and increased the fluences, reaching averages expressed in the tables already presented.

For teaching purposes, when presenting suggestions for treatment protocols, we will present tables informing the therapeutic action of the laser, the application points (and its respective schematic design), as well as literature directly or indirectly pertinent to the theme.

We suggest to beginners that, in order to obtain greater safety in the application of the laser at the right points, draw with pencil the points where the laser tip will be placed. We developed this technique in the 1990s (Almeida-Lopes, et al., 1994) with a didactic purpose for extra-oral applications, and it has been widely used in several teaching centers in Brazil and abroad, with excellent results. We usually call it Mask-Points, and the purpose is to “map” the points that will be irradiated so that the professional feels more secure. It is important to note that both the red and infrared laser are absorbed by any pigmented target, so we should never radiate directly on these points, but immediately next to them, otherwise a good part of the laser would be directly absorbed by the laser. contained pigment of the pencil used (Figure 41).

The treatment protocols suggested below were developed for an adult-young patient, without systemic impairment. Recommended protocols for immunosuppressed patients, elderly and children, should be changed in terms of number of sessions, fluency and consequently energy dose. For elderly and immunocompromised patients, the number of sessions tends to increase slightly, and for children, decreases. For all three groups, we will work with fluids at least 50% lower than the recommended averages.

In the cases of applications in large extensions the application of several points in horizontal is recommended, being that the distance between them should be of approximately 1 cm. In cases where the application should be spatially distributed, as in a tongue or in the jugal mucosa, we should maintain 1 cm of distance between the different application points.

Sometimes we use extra-oral points, for ease of manipulation of the patient and the lesion, but the application can be performed intraorally, without loss in the quality of the treatment. If the option is chosen for the extra-oral application, the patient’s skin should be clean, free of creams, makeup residue or fat inherent in sweat. Remember that the laser is light, and therefore, every border of medium that crosses, undergoes refraction, absorption and can undergo reflection on mirror surfaces. The cleaning of the surface to be treated must be done with water and neutral soap.

Figure 41 – We recommend using the “Mask-of-Points”, with didactic purpose, which consists of making points on the region to be irradiated with eye pencils.

In the soft tissue reparation, it is recommended that preferably wavelength emitted in the visible be used, since the fibroblast, main cell involved in this process, responds better to this kind of light. However, the infrared laser also may be used successfully in these cases.

The dosages for the stimulation of soft tissue reparation are low, varying between 0,9 e 1,6 J per application point, using fluencies between 25 and 45 J/cm². Too high dosage in only one point (that exceeds more than 5 times these values) may be inhibitory, delaying this way the reparatory process, instead of stimulating it.

It is important to point out that inhibitory dosages exist related to soft tissue cicatrisation. For hard tissue reparation (bone and tooth) and nervous reparation, there is not inhibitory dosage, at least in from the clinic aspect. The applications will have to be done each 2 or 3 days. The closing of the lesion, its clinic aspect and the absence of pain define the number of sessions.

Important observation: For immune depressed patients (like the bearers of mucous inflammation after treatment by chemotherapy or radiotherapy), children, old patients with degenerative diseases, the dosage must be drastically decreased. In these patients it recommended that low fluencies with dosage ranging between 0,1 and 0,4 J per application point be used, using fluencies between 25 and 45 J/cm².

Aphtha and traumatic ulcers

Figura 42 – Laser application is done directly over the lesion, in case of small lesions. In case of bigger lesions, apply over the lesion and around it

Action: analgesic; anti inflammatory; accelerates the reparation in patients with systemic alterations.
Application: 1 point directly over the lesion (in case of small lesions up to 1 cm2) and points along the edges of the wound (in case of bigger lesions).
Dosage: total of 2 applications in 48-hour intervals. If necessary, go on with the applications in 48-hour intervals until the complete remission of the signs and symptoms. The recommended dosage (energy) is 0,7 J using fluency of 25 J/cm².
Source: Wang HC, et al., (1989); Takashi (1987), Manne,(1985).

Gingivitis

Figure 43 – The laser application is done over the inserted gum, avoiding the taste buds, which have very little vascularization.

Action: Analgesic and anti-inflammatory.
Application: Over the inserted gum, along all the affected area.
Dosage: Total of 2 or 3 applications in 72-hour intervals.
Observation: It is important to orient the patient about the local hygiene, as well as to motivate him/her to do it. The recommended dosage (energy) is 0,7 J per application point, using fluency of 25 J/cm².
Source: Amorim et al. (2002); Kubota (1996); Kozlov et al. (1995); Yarita et al. (1993); Ryden et al. (1990).

Post-operations

Figure 44 – The laser is applied over the lesion edges, for the cicatrisation will occur through the proliferation of the mother cells (fibroblasts) present in these edges and that by, chemotaxis, will migrate up to the region to be repaired.

Action: Accelerates and improves the quality of the osseous reparations and of the soft tissue, reduces the post operation edema and the pain.
Application: Along the edges of the stitches in reparations as the first intentions and also over the wound bed, in the reparations as second intention.
Dosage: Applications in 72-hour intervals up to the suture removal. In cases where the edema and pain condition persists is recommended the application for two more sessions (respecting the same time interval). The recommended dosage (energy) is 0,8 J using fluency of: 30 J/cm².
Source: Ozawa et al. (1995); Fernando et al. (1993); Clokie et al. (1991).


Systemic diseases with oral manifestation

The laser is not capable of improving the condition of the patients who present oral manifestations of certain degenerative or self-immune diseases.In this patients, the laser may act as analgesic, activate the cicratrization and improve their esthetic, as well as increase the local immunity preventing this way the infection of certain oral lesions and the contamination by opportunist bacteria.

Vulgar Pemphigus

Figure 45 – The laser application is done over the lesions, which generally are ulcerated, with clinic aspect of aphthous stomatitis.

Action: Analgesic and anti-inflammatory, activates thepatient’s local immunity.
Application: Directly over the region of the lesion, overall its extension.
Dosage: Applications in 48-hour intervals, while theoutbreak lasts. The recommended dosage (energy) is 0,7 J per application point, using fluency of: 25 J/cm².

Lupus Erythematosus

Figure 46 – The laser application is done over all the lesion extension.

Action: Activates the local immunity of the patient, decreases the discomfort, improves the quality of the lesion cicatrisation.
Application: The laser application is done directly over the lesion. The applications are done in an average space of 1cm of distance between each application point.
Dosage: applications in 48-hour intervals, while the outbreak persists. The recommended dosage (energy) is 0,7 J per application point, using fluency of: 25 J/cm².

Hyperplasic Gingivitis (Diabetic)

Figure 47 – The laser application is done over the inserted gum, avoiding the extremities of the taste buds, where there is little vascularization.

Action: Accelerates and improves the tissue reparation, reduces the clinic post procedure.
Application: Over the gum taste buds, along the entire infected region.
Dosage: Application in 72-hour intervals, conjugated with prophylactic and systemic treatment for the diabetes, until the symptoms disappear. The recommended dosage (energy) is 0,7 J per application point, using fluency of: 25 J/cm².
Source: Amorim et al.; Kubota (1996); Kozlov et al. (1995); Yarita et al.(1993); Ryden et al. (1990).

Lichen Planus

Figure 48 – The laser is applied over the borders of the lesion, for the cicatrisation will occur through the proliferation of the mother cells (fibe blasts) present in these edges and that, by chemotaxis, they will migrate up to the region to be repaired.

Action: Activates the local immunity of the patient, decreases the discomfort.
Application: Directly over the lesion region, along all its extension.
Dosage: Applications in 72-hour intervals, while the outbreak persists. The recommended dosage (energy) is 0,85 J per application point, using fluency of: 25 J/cm².
Observation: The purpose of the applicattions is to activate the local immunity of the patient, without discarding the necessity of recommended sistemic treatment for those cases.

In the reparation of osseous tissues, it is recommended using wavelengths emitted in the infrared, since in these cases there is a necessity of deeper penetration of the laser. Besides that, this wavelength is more effective to activate the mechanisms involved in this kind of reparation, including the activation in the reproduction of growth factors, like the BMP (Bone Morphological Protein).

The used energy and the fluency for the osseous; tissue reparation is greater than that for soft tissue. It is suggested here that a larger number of sessions with dosage (energy) ranging from 3,2 to 4,3 J per application point, using fluencies between 90 and 120 J/cm².

Orthodontics

Figura 49 – The laser is applied in the region of osseous pressure and traction and over the tooth’s apex that suffer activation.

Action: Analgesic, after installation, replacement or adjustment of the arcs; activation of the osseous reparation, after palatine disjunction; modulates the lyses and bone formation process of the region where there is the activation of an orthodontic device.
Application: Over the region of activation of the strap or elastic; over the palatine raphe.
Dosage: In the conventional treatment the application will be done in the activation of strap and/or elastic. In cases of acute pain, repeat the application after 24 hours. About the palatine disjunction, the applications will have to be done in 72-hour intevals, or in the activation of each expander screw, lasting for up to 2 months after the disjunction has been accomplished.
The recommended dosage (energy) is 2,5 J per application point, using fluency of: 90 J/cm².
Source: Kawasaky y Shimizu (2000); Shimizu et al. (1995); Hong-Meng et al. (1995).

Periodontics

Figure 50 – The laser is applied perpendicularly to the scraped region, either over the remaining bone, or over the soft tissue of the region to be repaired.

Action: Eliminates the hyper sensibility post-periodontal treatment, mediate the inflammatory process accelerates the osseous neo formation, increases the periodontal fibers adherence.
Application: Over the scraped region and over the area of hyper sensibility.
Dosage: The applications to eliminate the dentinal hyper sensibility, we will have to be done according to the protocol of the dentinal hyper sensibility.
In case of the application for the periodontal treatment, the applications will have to be done in 72-hour intervals, during the first month of the osseous cicatrisation.
Observation: In cases that are more refractory to osseous formation, the treatment may be prolonged for 1 month. The treatment with laser should be initiated right after the periodontal treatment is complete.
The recommended dosage (energy) is 3,4 J per application point, using fluency of: 120 J/cm².
Source: Silveira et al (2002); Takema et al. (2000); Ozawa et al. (1997); Crespi et al. (1997); Kozlov et al. (1995).

Traumatology

Figure 51 – The laser is applied over the region where the tissue reparation is intended. A complement for the local treatment with the Almeida-Lopes* lymphatic drainage technique is recommended.

Action: Accelerates and improves the osseous reparation and the cicatrisation of the soft tissues; reduces the post operation pain and edema.
Application: In the reparations for first intentions, along the edges of the suture, in reparations for second intentions, besides this region, also over the wound bed.
Dosage: The applications will have to be done in 72-hour inter vals, during the first month of the osseous cicatrisation process. The recommended dosage (energy) is 2,5 J per application point, using fluency of: 90 J/cm².
Source: Limeira-Junior (2001); Oliveira (1999); Glinkowshi et al. (1995).

Implantology

Figure 52 – The laser is applied around the implants and over the suture after its closing. The use of the Almeida-Lopes* lymphatic drainage technique right after the placement of the implants, for the prevention of post-operation edema is recommended.

Action: Accelerates the osseous reparation, improves the histological quality.
Application: Directly over the place of the implant placement, along its entire axle, making a total of around of six points perimplant.
Dosage: The applications will have to be done in 72-hour intervals; during the first month of the osseous cicatrisation process. The recommended dosage (energy) is 2,5 J per application point, using fluency of: 90 J/cm².
Source: Limeira-Junior (2001); Silva-Junior (2000); Oliveira (1999); Lugeretal. (1998).

Exodontia

Figure 53 – The laser is applied over the remaining alveolus. There is no need to apply the laser inside the alveolus, since the wavelengths emitted in the infrared has great depth of penetration.

Action: It improves the tissue reparation; reduces the post operation edema and pain.
Application: Perpendicularly to the alveolus and over the region of the suture.
Dosage: In the traumatic exodontia cases, an application in the immediate post operation is done to prevent the post surgery edema. For that the utilization of the Almeida-Lopes* lymphatic drainage technique is recommended.
From the second application (which will have to be done 48 hours after the surgery) sessions of applications in 72-hour intervals will be established, until the complete reduction of the edema and the remission of the painful symptomatology.
The recommended dosage (energy) is 0,X J per application point, using fluency of 90 J/cm².
Source: Limeira-Junior (2001); Silva-Junior, (2000); Kawasaky e Shimizu, 2000; Oliveira, 1999; Freitas, 1998.

For the activation of the process of reparative dentine formation, both wavelengths are recommended. The energy and fluency used in these cases are higher than those used for sift tissue, and they are similar to those used for hard tissue, since the activation mechanisms of the reparative dentine formation are very similar to the osseous formation process (by the activation of cytokines or growth factors).

It is recommended at least three sessions, with dosage (energy) varying from 2,9 to 4,0 J per tooth, using fluencies between 80 and 110 J/cm². This energy will be divided in two points over the crown and one point on the dental apex. That is, if we define that 2,9 J will be used in one dental element, we will do the application of 2 points of 1,1 J in the crown and one point of 0,7 J in the apex, making the total of 2,9 J per tooth. Only one session, is not enough to activate this process, but to cause an effect of immediate analgesia, thus it may mask the healing process. This way, it always important to inform the patient that 3 and 4 application sessions will necessary, so that there is the activation of the process of reparative dentine formation in an effective way.

Hyper sensibility post-cavitations preparation/cementation

Figure 54 – The laser is applied over the exposed wall of the preparation. A complement is possible by applyin g one point over the dental apex to increment the circulation and to decrease the pulp inflammation.

Action: Immediate analgesia; formation of reparative dentine.
Application: Two points directly over the exposed wall; perpendicularly to the restoration, in the region of the pulp chamber or, in case the tooth already restored, in the cervical region, over the crown, and in one point over the dental apex.
Dosage: 4 applications in 72-hour intervals. It is recommended starting with one minimum dosage approved for a dental element, that is, dosage (energy) of 2,3 J using fluency of SO J/cm 2, increasing the dosage in the subsequent sessions, in case it is necessary.
Source: Lizarelli, et al (2001); Groth (1995); Gerschman, et al. (1994); Moustsen et al. (1991).

Post periodontal scraping

Figure 55 – The laser is applied over the exposed colon, in the tooth’s long axle, by vestibular. There is no need to apply it by lingual, since the laser has got a good penetration in the dental tissue. A complement is possible by applying one point over the dental apex to increment the circulation and to decrease the pulp inflammation.

Action: Immediate analgesia, formation of the reparative dentine.
Application: Two points directly over the scraped region, in the region of the dentinal colon, perpendicularly to the exposed region, and one point in the dental apex.
Dosage: 4 applications in 72-hour intervals. It is recommended starting with a minimum dosage approved for one dental element, that is, (energy) of 2,9 J using fluency of 80 J/cnV, increasing the dosage in the subsequent sessions, incase it is necessary.
This dosage (energy) will be divided in two points of 1,4 J, using fluency of 40 J/cm² in each one of them.Proceed with the periodontal treatment according to what was recommended in the item Periodontics.
Source Fonte: Lizarelli, et al (2001); Groth (1995); Gerschman, et al. (1994); Moustsen, et al. (1991).

Post dental clearing hyper sensibility

Figure 56 – The laser is applied directly over the sensibility region, which generally coincides with the cervical region.

Action: Immediate analgesia by re-polarization of the nervous membrane altered, prevention of the formation intra pulp edema.
Application: Two points directly over the region that presents the hyper sensibility and one point over the dental apex.
Dosage: Generally it is necessary only one application in the immediate post-clearing. In case the patient presents a persistent painful condition, 1 or 2 more applications are recommended in 24-hour intervals.
The recommended dosage (energy) is 0,X J per point of application, using fluency of: 40 J/cm².
Observation: The laser application in the immediate post-clearing may be used in all patients, as a preventive procedure.
Source: Lizarelli, et al (2001); Groth (1995); Gerschman, et al. (1994); Moustsen, et al. (1991).

Imperfect Amelogenese

Figure 57 – The laser is applied over the exposed dental wall.

Action: Immediate analgesia; induction of the reparative dentine formation.
Application: Directly over the region where the activation of the reparative dentine formation is intended.
Dosage: 4 applications in 72-hour intervals. It is recommended starting with a minimum dosage approved for a dental element, that is, dosage (energy) of 2,9 J using fluency 80 J/cm² increasing the dosage in the subsequent sessions, incase it is necessary. This dosage (energy) will be divided in two points of 1,4 J, using fluency of 40 J/cm² in each one of them.
Observation: It is necessary to refer the patient to a reparative dentistic clinic.

In the repair of nervous tissue, the use of wavelengths emitted in the infrared is recommended, since in these cases there is a need for a greater depth of penetration of the laser. In addition, the mechanisms of action of the infrared laser are more compatible with the physiology of the nerve cell.

The dose (energy) used for the regeneration of nervous tissue is quite high, and a large number of sessions are recommended (around ten). It is necessary to apply the laser throughout the path of the affected nervous branch, initially using dose (energy) between 1,1 and 1,4 J per point and fluence between 40 and 50 J/cm². After 3 or 4 sessions, the dose used should be between 2,8 and 4 J per point and the fluency between 100 and 140 J/cm². Few sessions are not enough to activate the nerve repair process. It is important to alert the patient that, in general, the clinical effects of the laser will only be noticed after the third application. This is important in order to maintain the motivation of the patient, since this will not feel concrete results of the treatment after the first sessions. It is also important to warn him that, especially in cases of paresthesia, it is not uncommon during the first applications to develop a clinical picture of hyperesthesia.

Neuralgias

Figure 58 – The application is performed in points directly on the nervous branch, with spacing of about 1 cm between these.

Action: Relief of neuralgic pain, relief of pain in the trigger region; relaxation of the musculature; repair of the injured nerve.
Application: Following the entire path of the affected branch, directly on the trigger points and on the regions of foramen.
Dosage: Treatment consists of about 10 applications at 72 hour intervals. Ideally, in the first two applications the dose (energy) should be lower, about 1.1 J per application point, using a fluency of 40 J / cm², gradually increasing until the fifth or sixth session reaches 2, 8 J per point, using fluence of 100 J / cm².
Note: It is recommended to prescribe B vitamins throughout the treatment period. It is important to alert the patient that it will only feel clinical improvement (on average) after the third application.
Source: Valiente-Zaldivar, et al. (nineteen ninety); Eckerdal, et al. (1996); Friedman (2000).

Paresthesias

Figure 59 – The laser is applied following the entire affected branch. The application is performed in points directly on the nervous branch, with spacing of about 1 cm between these.

Action: Relief of painful sensitivity (when available) and repair of damaged nerve branches.
Application: Following the entire path of the affected nerve. In the case of nerves with several branches, apply on all the branches belonging to the respective cranial pair.
Dosage: Treatment consists of about 10 applications at 72 hour intervals. Ideally, in the first two applications the dose (energy) should be lower, about 1,4 J per point, using a flow rate of 50 J/cm², increasing gradually until the fifth or sixth session reaches 3,5 J per point, using fluence of 120 J/cm².
Note: Prescription of B vitamins is recommended throughout the treatment period. It is important to alert the patient that he/she will only feel clinical improvement (on average) after the third application and sometimes that improvement will be accompanied by the unpleasant clinical sensation of pain, or tingling. The patient may report a strong hyperesthesia, alternated with moments of complete dysesthesia.
Source: Rochkind (1996); Khullar et al (1996, 1999); Midamba, et al.

Paralysis

Action: Relief of painful sensitivity (when available), repair of damaged nerve branches and relaxation of the muscles (when compromised).
Application: Following the entire path of the affected nerve. In the case of nerves with several branches, apply on all the branches belonging to the respective cranial pair.
Dosage: Treatment consists of about 10 applications at 72 hour intervals. Ideally, in the first two applications the dose (energy) should be lower, about 1,4 J per point, using fluence of 50 J/cm², increasing gradually until the fifth or sixth session reaches 3,5 J per using a flow rate of 120 J/cm².
Note: Prescription of B vitamins is recommended throughout the treatment period. It is important to alert the patient that he/she will only feel clinical improvement (on average) after the third application and sometimes that improvement will be accompanied by the unpleasant clinical sensation of pain, or tingling. The patient may report a strong hyperesthesia, alternated with moments of complete dysesthesia.
Source: Paolini (2000); Khullar, et al. (1996); Yamada, et al. (1995); Nissan et al. (1995); Anders, et al. (1993).

Here we present some types of clinic applications that have not been discussed yet.

Alveolar Inflammation (Alveolite)

Ação: Anti-inflamatória e analgésica.
Aplicação: Ao redor da região afetada e sobre a cadeia linfática responsável pela drenagem da região acometida (Técnica da Drenagem Linfática de Almeida-Lopes).
Posologia: O comprimento de onda recomendado é o infravermelho.
A primeira aplicação deverá ser realizada imediatamente após o procedimento terapêutico de rotina eleito para o tratamento dessa afecção. Mais duas aplicações deverão ser realizadas em intervalos de 48 horas. A dose (energia) recomendada é de 2.8 J por alvéolo, dividida em dois pontos de 1,4 J utilizando fluência de 50 J/cm².
Obs.: A aplicação é feita sobre o alvéolo. Não se recomenda a introdução da ponteira dentro dele, pois além de ser desnecessário, é um trauma mecânico que deve ser evitado.

Xerosis

Figure 62 – The laser is applied directly over the bigger affected glands.

Action: Stimulates the salvia secretion in patients who bear diseases or who use medication take leads to this condition; patients in chemotherapy or radiotherapy; in the auxiliary treatment of the Sjogren syndrome.
Application: Directly over the bigger affected glands.
Dosage: The infrared wavelength is recommended. The applications will have to be done in 96-hour intervals, while the xerosis condition lasts. The used dosage (energy) in the first 2 applications must be of 0,95 J, using fluency of 25 J/cm² per point making a total of 4 or 5 points over the bigger gland under treatment. From the third application, the used dosage will change to 2,2 J per point, using fluency of 60 J/cm2. It is recommended keeping the distance of 1 cm between these points.
Observation: The laser is indicated in these conditions not only to prevent the opportunist infections that attack these patients, but also to prevent and to treat the mucous inflammation, which invariably attack these patients.
Source: Ciais, et al. (1992); Nagasawa, 1991; Takeda, 1988; Kats, et al., 1985.

Pericoronarite (infectious)

Figure 63 – We have obtained better results when in the acute phase, we use the Almeida-Lopes Lymphatic Drainage Technique,. In case of associated tismus, we apply it over the region of origin and insertion of the Masseter muscle.

Action: Anti-inflammatory and analgesic.
Application: Around the affected region and over the lymphatic chain of the affected area (Almeida-Lopes* Lymphatic Drainage Technique).
Dosage: 2 applications in 24-hour intervals generally are enough to. 2,8 J is distributed in 4 points of 0,7 J, using fluency of 20 J/cm², around the affected region or directly using the lymphatic Drainage Technique. In the cases where there is associated trismus, it is recommended doing 4 or 5 points of extra oral application over the masseter, to relax this spasm, and starting the intra oral applications after 24 hours.
Observation: In cases of contaminated acute lesions, like this one, we should avoid the application directly over the lesion, because the contaminating microorganisms may be bio stimulated, exaggerating the process. We have obtained excellent results using technique of the indirect treatment of the lesion, that is, activating the lymphatic drainage of the involved lymph nodal chains in this process. The clinic procedures traditionally used in these cases may be kept.
Source: Roynesdal, et al. (1992); Honmura, et al. (1992); Lievens (1991); Lievens, et al.(1988)

Anesthesia

Figure 64 – The laser is applied directly over the apex (in case of infiltrating anesthetic) and in the region where the anesthetic was inserted (in case of trunk anesthetic).

Action: greater quickness in absorbing and metabolizingn anesthetic.
Application: over the point of the needle’s introduction and the injection of the anesthetic.
Dosage: 2 points of application over the region of the anesthetic injection (in cases of trunk anesthesia) it is only one point over the dental apex (incases of infiltrating anesthesia).
The use of the infrared in the trunk anesthesia and of both (infrared and visible) in the infiltrating anesthesia is recommended.
The used dosage (energy) is of 1,4 J per point, using the fluency of 40 J/cm² (in children use 1/3 of the dosage).
Observation: The laser increments the local circulation, causing the anesthetic to be quickly metabolized, and thus, making the dormancy sensation immediately disappear.
Source: Omura, et al. (1992); Velez-Gonzalez, et al. (1991); Tamachi (1991).

Benign Migratory Glossitis (Geographic Tongue)

Figure 65 – The laser application is done over all the tongue’s extension. Applications are done in points with distance of 1 cm between each other.

Action: Analgesic, relief from the discomfort sensation of the patient.
Application: In all the tongue’ extension.
Dosage: Applications in 48-hour intervals, while the symptoms persist.
The used dosage (energy) is of 1,3 J, using fluency of 35 J/cm², making a total of around 5 points distributed in all the tongue’s extension.
Observation: The Benign Migratory Glossitis, popularly known as geographic tongue, is not considered a disease, it is simply a anatomic variation, but that many times may cause ardency, pain or discomfort sensation.
Source: Mezawa, et al. (1988).

Herpes Simplex

Figure 66 – In the vesicle phase we do not directly irradiate the lesion, but around it associating with the Almeida-Lopes* lymphatic drainage Technique. If we are able to irradiate the patient in the sub clinic phase (itch), then, we will directly irradiate over the affected area.

Action:
Before the clinic manifestation (itch phase):
 Decreases the virulence and the lesion incidence.
During the manifestation (vesicles phase): Analgesic and anti-inflamatory (in this phase we recommend the Almeida-Lopes Lymphatic Drainage Technigue)*.
After the clinic manifestation (ulcerated vesicles): Accelerates the cicatrisation, decreases the pain of the remaining lesions, prevents opportunist infections, improves the post cicatrisation esthetic.
Application: Directly over the affected region, either in the itch phase or after the vesicles rupture over the lymphatic chain responsible for the drainage of the attacked region, in the vesicle phase.

Dosage:
Itch Phase: It is recommended using the infrared wavelength, 2 points over the itch region. The recommended dosage is 1,6 J using fluency of 45 J/cm², per point of application. The number of applications varies between 1 and 2 (the second, 24 hours after the first).
Vesicle Phase: It is recommended using the Almeida-Lopes Technique *, searching for the decrease of the local inflammation, as well as the increase of the local immunity. It is recommended using infrared wavelength, with applications at every 48 hours, over the lymph nodes responsible for the drainage in the region. The recommended dosage is of 2,5 J using fluency of 70 J/cm² per lymph node.
Ulcerated Vesicles Phase: 1 point of 1,1 J using fluency of 30 J/cm² over the lesion. In case of several lesions (Herpes multi focal) it should be applied 0,7 J using fluency of 20 J/cm² in each affected region.
Source: Almeida-Lopes (2002); Velez-Gonzalez, et al. (1995); Tardivo (1989).

Herpes Zoster

Figure 67 – The laser application in the Herpes Zoster follows the same protocol of the Herpes Simplex.

Action:
Before the clinic manifestation (itch phase): Decreases the virulence and the lesion incidence.
During the manifestation (vesicles phase): Analgesic and anti-inflammatory (in this phase we recommend the Almeida-Lopes Lymphatic Drainage Technique)*.
After the clinic manifestation (ulcerated vesicles): Accelerates the cicatrisation, decreases the pain of the remaining lesions, prevents opportunist infections, improves the post cicatrisation and principally, prevents the post-herpes neuralgia.
Application: Along the affected nerve (all the attacked branches).
Dosage: It is the same for each phase of the Herpes Simplex.
Source: McKibbin, et al. (1991); Hong, et al. (1990); Moore, et al. (1988).

TMJ Pain – Dysfunction Syndrome

Figure 68 – The laser is applied in one or two points directly over the temporal mandible articulation.

Action: Analgesic, anti-inflammatory, muscle relaxing, relief in the cases of trismus, reparation of the traumatized nerves.
Application: Points over the articulation region. In cases of trismus, treat the trigger points and involved muscles.
Dosage: 2 points of 1,8 J using fluency of 50 J/cm² in each ATM. It is recommended using the infrared, with applications every 72 hours, while the symptoms persist.
Observation: The use of laser does not mean that there is no need of oral rehabilitation in patients who need it.
Literature: Akai, et al., 1997; Bradley, et al., 1996; Tasaki, et al. 1992; Lopez, 1986.

Odontopediatry

Figure 69 – In Odontopediatry there are many indications. Basically they are the same for adult clinic, it is just to remember that here the dosage is a lot lower between 50% and 65% less.

– Over teeth with painful eruption.
– In teeth or lips trauma.
– In direct or indirect pulp coating
– After anesthesia.
– After Post cavity-preparation.

Observation: In all clinic procedures of Odontopediatry there is indication and application of Laser Therapy. It is important to point out, however, that these patients are young, with little weight and height and so, the dosage prescribed here will be around 1/3 smaller than those recommended in the adults protocols.
Older children (over 10 years) and with more weight, will have the
Source: Oasevich (1999); Rodrigues, et al. (1999); Manne (1985)

Edema

Figure 70 – The laser is applied over the main palpable Lymph nodes in the head and neck.

Action: Stimulation of the lymphatic system, increase of the local trophicity.
Application: Affected region and main lymph nodes of head and neck responsible for the drainage of the attacked region.
Dosage: The same described in the Almeida-Lopes Technique*.
Source: Piller et al. (1998); Roynesdal, et al. (1993); Honmura, et al. (1992); Lievens, 1991; Lievens, et al., 1988. Netter, et al. (1999).

Most of the lymphatic vases originate from the organs and tissues derived from the lymphatic capillary. They are formed by tubules limited by a very thin and totally closed endothelium, with a caliber a little bigger than the blood capillaries. The function of these lymphatic capillaries is to retrieve the liquid excess in the tissues. They unite and change into vases of caliber bigger and bigger provided with valves, and during its trajectory form a main block, the thoracic duct. Consequently, besides the closed circulatory system, through which the blood circulates, the organism also presents another circulatory system much more complicated, delicate and vast, which is the lymphatic system. Inside it the lymph flows, both intimately interrelating with the tissue liquids, because they meet in one side in contact with thinner roots of the initial part of the lymphatic system, and on the other side, in the final part, running into the venous system through a main collecting duct. The liquid of the tissues coming from blood capillaries goes back, just in part, to the blood in a direct way. Part of it is transported together through the lymphatic paths, which constitute, as an example, a lateral blind path of the venous system. Verlag (2001) considers the lymph nodes as secondary lymphoid organs. They are formed by mixed conglomerates and lymphocytes T and B, located in distinct regions and derived from the lymphocytes proliferation.

They are formed by the external cortical and internal medulla. The lymphatic chain is interrupted in the lymph node, when the lymph penetrates through the conducting vases in the marginal sinus located beneath the capsule that wraps the lymph node; from this point, the lymph spread throughout the surface of the mentioned lymphocyte formation. Each lymph node is provided with a wrapping capsule (cortex) and an internal part (medulla). Besides the cells, the lymph nodes have macrophages, more numerous in the medullar. The lymphocytes B (related to the humoral immunity) are found mainly in the cortical glands, whereas the lymphocyte T (related to the cellular immunity) house in the Para cortical and medullar areas (Michalany, 1995).

Basically, the lymph nodes functions would be to produce lymphocytes (lymphopoiesis) and operate as a mechanical filter of lymph.

There is no part of body without lymphatic vases. The distribution of the lymph nodes, however, is quite unequal through the entire body.There are regions like the axilla, the groin, the mesentery and the viscera cra-nium that concentrates greater quantities of lymph nodes. In the region of the head and neck, the pre auricular regions, parotid, sub-mentual and sub-mandibular, are the richest areas in lymph nodes agglomerated. Besides that, not even all lymph nodes are perceptible through the touch. Its tactile perception will depend on the thickness of the adipose panicle of the skin, on the individual age, the individuals heath condition, as well as the anatomical peculiarities of each patient. The presence of bigger or smaller formations of lymph nodes define and name the respective chains and are well defined structure surrounded by the capsule formed by conjunctive tissue and some elastic fibrils.

The size and the morphology of the lymph nodes are modified by the immunological responses. Since they are secondary lines of defense, they are continuously responding to stimuli, even if there is no clinic manifestation of the disease. No matter how minimum the aggressions and infections may be, almost imperceptible changes take place in a lymph node’s histology. Obviously, the bac-terial and viral infections of greater repercussion inevitably produce a significant increase of lymph node.

The normal lymph nodes have got the size of about a pea, they are painless to the touch, plain, mo-vable and of soft consistency.

Although there is a great variation of the distribution, form and number of the lymph nodes from individual to individual, the Anatomic Terminology of the Anatomy Brazilian Society (FCAT, 2000) gathers the regional lymph nodes net of the head and neck in 16. The main ones are: Occipital, Pre-Auricular, Right and Left Sub mandibular, Sub mentual, Lateral Cervical, Upper Deep Cervical, Deep Lower Cervical, Mastoid and Supra clavicular), as we observe in the Figure 71.

Since this is a work essentially clinic, we discuss the lymphatic drainage technique just in the lymph nodal nets that may be clinically touchable and that have some role in the drainage of regions that involve diseases or odontological iatrogenic.

Figure 71 – Main touchable lymph nodes in the head and neck.

Sub mentual Lymph nodes
It means infection or neoplasia alteration in the mouth flooring, tongue’s womb and mandibular incisive, besides sialoadenopathy of the glands of the region.

It always precedes acute inflammatory alterations of flooring, some very serious, as the Ludwig’s Angina. In the figure 72 A and B, we can observe in the irradiation process.

Figure 72 A – Submentual Lymph nodes.

Figure 72 B – Respective clinic application.

Sub mandibular Lymph nodes
Lts formed by two simetric chains: right and left. It denotes infection or neoplasm in the low part of the mouth, tongue’s womb and vestibular phase of the inferior lip. They are those that usually are affected in the tongue infections, low part of the mouth and maxillary molars and mandibular.

In Figures 73 A and B, we can observe the irradiation process.

Figure 73 A – Sub mandibular Lymph nodes.

Figure 73 B – Respective clinic application.

Cervical Lymph nodes
The cervical Lymph nodal chains are divided, for a methodological effect, In Superficial Cervical and Deep Cervical. Both can be Upper and Lower.

The Deep cervical lymph nodes cannot be easily touched and dispense the semiologic interest for the examiner, but the superficial, either front or the lateral, can be related to infection of the scalp and sometimes to the mouth or pharynx. In the Figures 74 A and B we can observe the irradiation process.

Figure 74A Superficial cervical Lymph nodes.

Figure 74B – Respective clinic application.

Pre Auricular Lymph nodes
The drainage area is limited to the cutaneous surface; it corresponds to ATM and the insertion of the masseter in the zygomatic are. It may occur from an infection or trauma in ATM, or represent the presence of impacted or included third mandibular molars.

In the Figures 75 A and B we can observe the irradiation process.

Figure 75 A – Pre auricular Lymph nodes.

Figure 75B – Respective clinic application.

The technique described here aims to activate the lymphatic drainage of a region where a inflammatory con-dition is established. This activation is done with the therapeutic laser, whose pointer is placed directly over the lymph nodes responsible for the drainage of the affected region, with the objective of directly stimulating them. The infrared laser is used (of 830 nm) and the pointer is placed over the lymph nodes responsible for the drainage of the affected region. The dosage (energy) of 2,5 J using fluency of 70 J/cm² in each lymph node is applied. The number of sessions varies from 2 to 6, with two-day interval between the sessions. The number of sessions varies according to the time that the inflammatory condition lasts.

In the Figures 73 B, 74 B, 75 B and 76 B, we show a series of pictures of patients subjected to the lymphatic drainage with the visible laser for didactic reasons, so that the readers may have a notion of the region where the laser is applied.

The advantage of the recommended and described technique is that it avoids the activation of microorga-nisms that infects the lesion, in case of highly contaminated lesions (like the herpes in the vesicle stage), acute apical lesions or purulent ones (also in pericoronarites or alveolar inflammation situations). This technique aims to activate the patient’s local immunity, through the drainage of the region, causing this way the patient to go through the inflammation with lower edema situation, and thus, less pain and discomfort.


HINTS!

  •  When applying intra orally, try to apply the laser in a relatively dry area. For hyper sensibility, use the relative insulation. The water and saliva serve as attenuating agents of the intensity of the laser.
  • When the application is extra oral, avoid applying it in skinrich in fat or makeup. If using a visible laser, avoid applying it over moles or spot, because this pigment may absorb the laser and this way decrease its absorption in the lesion area. * In case of the utilization of disposable pointers that can-not be sterilized in autoclaves, use the plastic pellicle kind of physical barrier for protection.

The use of laser therapy has been studied since the 60’s decade. It is therapeutic effects over different biological tissue are very vast, remarkably when indu-cing trophic-regenerative, anti-inflammatory and anal-gesic effects, emphasizing the works that show an increase of the local micro circulation, activation of the lymphatic system, proliferation of the epithelial cells and fiber blasts, as well as the increase of the collagen syn-thesis by the fiber blasts.

Due to its characteristics of relieving from pain, stimulating the tissue reparation, reducing the edema and the hyperemia in the inflammatory processes, pre-venting infections, besides acting in the paresthesia and paralysis, the low intensity laser has been frequently employed in the dentistry clinic. This therapy has turned into a routine for the osseous bio stimulation, in cases of implants or minor oral surgery to decrease the post operation pain and the edema in different cases, recur-ring aphthous ulcers, herpes, neuralgias and dentinal hyper sensibility.

It is indicated in the treatment of systemic diseases with oral manifestation, like the Liquen-Plain and the Mucosites in general, as well those self-immune ones like Lupus Erythematosus and the Pemphigus Vulgar. Also in the treatment of immune depressed patients with Mucous inflammation caused after radiotherapy or chemotherapy treatment. The Laser therapy is an effective method, very little invasive and accessible for the patient, without side effects and that can be routinely used in the dentistry clinic.

Like all therapy there is technique and the tactics. The technique would be the ingredients of the cake and the tactics would be the way the cake is made.

In this work we will show the technique of the laser therapy, Its physical and biological principles, the recommended safety rules for this therapy, and its main clinic indications. Based on 15 years of clinic experience and 13 years of teaching experience, our goal was to demonstrate the approaching tactics of this technique we have been using, adapted and developed in the passing of these years.

We hope that from these pieces of information and suggestions of work, each professional may be able to create an approaching tactic of his/her own, and this way beneficiate more and more, our patients and the laser therapy.

Oral mucositis (OM) is a very common side effect in patients undergoing chemotherapy (QT) and also when radiotherapy (RT) is used in the head and neck region for the treatment of cancer.

The cytotoxic effects of QT and RT affect cells with high turnover rate such as tumor cells, hair and mucosa. Initially, RT / QT causes damage to endothelial and epithelial cells, which lead to the generation of reactive oxygen species (EROS) (Sonis, 2004). These free radicals activate cell signaling pathways, determining the release of transcription factors such as nuclear kappa-B factor (NF-?B) and the activation of proinflammatory cytokines that lead to damage in the cell’s DNA. These events decrease the rate of cell turnover and result in tissue atrophy and ulceration. Simultaneously, some specific drugs alter the cellular production of the bone marrow leading to leucopenia and thrombocytopenia predisposing the patient to infections and spontaneous bleeding. The ulcerated oral epithelium allows the entry of microorganisms into the bloodstream exposing the patient to severe systemic infections.

MO has a significant negative impact on quality of life (Epstein et al., 2001), with high rates of morbidity and mortality and, according to Elting et al., 2007, there is an increase in costs associated with pain relief, nutritional support, secondary infections and hospitalization time. In addition, MO can lead to QT / RT interruptions and delays which compromise cancer treatment.

Photobiomodulation

The low intensity laser used in photobiomodulation (FBM) at the red and near infrared wavelengths is absorbed and activates a protein of the mitochondrial membrane, the cytochrome c oxidase, making faster the connection of electrons coming from the respiratory chain with the oxygen and as a product of this reaction, there is the formation of water and ATP (adenosine triphosphate) (KARU, 1999). FBM acts on metabolic pathways related to cell survival and reproduction such as increased production of ATP, respiratory chain homeostasis and decreased oxygen reactive species (ROS), which explains the possibility of acting in the various biological tissues (Karu et al., 2004).

The role of photobiomodulation in the patient undergoing oncological treatment

The FBM is a very important resource in the therapeutic arsenal to prevent and treat MO due to the therapies used in the treatment of cancer (Bjordal et al., 2011) because it acts in all phases of the evolution of OM by decreasing EROS release, reducing the inflammatory process, accelerate tissue repair and promote significant pain relief. Clinically the reduction in severity and repair time of MO is observed.

In cases where patients receiving RT in the head and neck region, depending on the dose and the location of the irradiated region, may compromise the salivary glands, resulting in xerostomia and consequent worsening of oral conditions. FBM increases the amount and salivary flow, which generates comfort to the patient (Lopes et al., 2006; Loncar et al., 2011).
Osteoradionecrosis is another highly debilitating side effect that compromises the patient’s aesthetic and functional restorative treatments. FBM improves the quality and increases the amount of newly formed bone after irradiated bone surgical procedure (Abramoff et al, 2014), and when associated with photodynamic therapy (PDT) improves tissue repair with exposed bone coverage (Ribeiro et al. al, 2018).
There are several complications arising from cancer treatment that can be treated or ameliorated with FBM such as: post-radiotherapy dermatitis, trismus, neuropathies and lymphoedema

This approach is well accepted by patients, including pediatric patients (Abramoff et al., 2008) because it is noninvasive and without risks of side effects.

Respect for the patient and the multidisciplinary team of cancer treatment

The patient undergoing cancer treatment has a multiprofessional service which includes medical staff, dentist, speech therapist, nutritionists, psychologists, physiotherapists and all kinds of support needed to achieve a cure with maximum quality of life.

To perform some dental procedure in these patients, there is a need for a deep understanding of the general state, to have knowledge about the chemotherapeutic agents and the effects that may or may not cause the mucosa and always act in harmony with the team of professionals involved.

Laser is undoubtedly a very important resource, but there is a context of oral health promotion measures that must be respected and the professional must be properly prepared to act in this area.

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