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FAQ

Dentistry

Answer: 25% Hydrogen peroxide:

  • Young patients
  • Tooth that are not too dark
  • Tooth with cracks in the enamel
  • Tooth with retraction and incisal and cervical wear
  • Patients with orthodontic braces and who did Slice in their tooth
  • Patients with sensitivity
  • Patients who use mouthwash. Ex.: Listerine, Plax, etc.
  • When the 2nd whitening session is required and the patient presented sensitivity in the 1st session, or when a 7-day period between the 2 sessions is not respected.

35% Hydrogen peroxide:

  • Patients who are unsatisfied with the original color of their tooth
  • Tooth darkened by age
  • Tetracycline-stained tooth
  • Cigarette, tea, coffee-stained tooth, etc.
  • Patients without sensitivity
  • Nonvital tooth

Yes. Although they both have the same function, they work differently: fluoride occludes dentinal tubules, preventing fluids from reaching the pulp, whereas potassium nitrate has an analgesic effect on the nervous fibers, preventing them from repolarizing, thus decreasing sensitivity.

Between the age of 15 and 17. It is important to take an x-ray for clinical evaluation and verify if the rhizogenesis of the tooth is already completed.

The length of tooth whitening will depend on many factors, such as: eating and oral habits, use of medicine, mouthwash or drugs, quality of oral hygiene, etc.

It is important to follow this patient and, whenever necessary, perform a maintenance whitening session every 1 or 2 years, preventing the color from coming back.

No. LEDs associated with laser diode in tooth whitening emit a kind of light radiation. When this light is absorbed by the hydrogen peroxide-based whitening agent of red color, it results in photo-chemical and photo-thermal effects, having as target the darkened molecules, potentializing the tooth whitening process. This mechanism generates a minimum increase in temperature without harming the pulp tissue, as it heats the gel, not the dental structure.

The gel must remain between light activations and gel rest, from 10 to 15 minutes, because the success of the treatment will depend on the potentiality of the whitening agent to penetrate as far as the darkened pigments and remain there long enough to oxidize said pigments, breaking molecular chains. It is not advisable to leave it any longer, as this could possibly cause tooth sensitivity.

Follow the step-by-step of tooth whitening correctly and also some recommendations:

  • Perform a good anamnesis, with medical and dental history.
  • Do a full clinical exam, checking for decay, retractions, wear, restorations with infiltration.
  • Use the appropriate whitening gel: red, with neutral pH 7.0, one that is more absorbing in the wavelength used in the equipment chosen.
  • The equipment used must have an appropriate light intensity.
  • Follow the protocol recommended by the manufacturer.
  •  Be familiar with the patient’s and the professional’s expectations.

If it is a I or II degree stain, the result will be satisfactory. A protocol will be established with more whitening sessions in the dental office.
If it is a III degree stain, we recommend the association of photoactivated whitening and at-home whitening.
If it is a IV degree stain, the prognostic is not favorable.

First do the photoactivated whitening. During tooth whitening, these fluorosis stains should be protected (covered) by the gingival barrier.

Unfortunately, whitening does not solve the problem. It will only soften the stains, whitening the tooth. After tooth whitening, we recommend the use of micro-abrasion whenever necessary.

Yes. Provided that it is a photoactivated whitening. At-home whitening is not indicated.

We recommend waiting at least 7 days, but the ideal is 14 days. This allows full liberation of oxygen and prevents resin restorations from falling out.

It is not always necessary to replace them. We should only polish them some days after the end of the treatment.

We recommend a maximum of 4 sessions, giving a minimum interval of 7 days (1 week) between these sessions. This wait is recommended because, throughout the whitening treatment, the whitening ability decreases, reaching an optimum whitening point, called saturation point. After this point, structural alterations in the enamel and dentine might happen, which include decrease in the enamel microhardness. The professional should be able to know when this point is reached and stop the whitening session.

 The responses of each patient are very different, and they depend on the penetration level of the whitening agent through the enamel and dentine. They can also be related to excessive loss of thickness or cracks in the enamel, cervical dentine exposition or abfraction, erosion and abrasion lesions or even the anatomy of the cemento-enamel junction that presents exposed dentine.

Things that also interfere in sensitivity:

  • Whitening agent pH
  • High energy doses without intervals between them
  • Hydraulic pressure of the whitening agent on exposed dentinal tubules
  • Patient’s age
  • Intake of drinks and foodstuffs with acid pH. Ex.: coca-cola, orange, lemon, apple, tomato, etc.
  • Orthodontical slice
  • Decays or restorations with infiltration
  • Use of mouthwash. Ex.: Listerine, Plax, etc.
  • Patients with spontaneous sensitivity
    In these cases, we recommend the use of 25% hydrogen peroxide or only 2 gel applications at 35% and whiten tooth in more than one session (application day).

After tooth whitening, apply therapeutic laser on the tooth with sensitivity.

Desensitizer can be applied with felt after laser therapy, taking care not to heat the tooth. Let it act on the dental surface for 2 minutes. If necessary, prescribe oral analgesic.

No. Composite resins are composed of monomers and glass charges, but these glass particles influence the photoactivation time due to the different mechanisms of interaction with the light emitted by the light curing unit.
Nanoparticled and microparticled resins need a longer activation time (40s) than hybrid and microhybrid resins (20s).

Yes. The greater opacity makes it difficult for the luminous energy to penetrate deeply. Therefore a greater photoactivation time or a high luminous intensity are essential for an appropriate light curing. Dentine colors or opaque colors usually need 40s for photoactivation, whereas enamel colors need 20s.

The light intensity can be understood as the amount of photons (luminous energy unit) measured at the optical tip of the light curing unit. The optical power generated by the equipment is provided in miliWatt. The more power – photons (mW) per area unit (cm²) emitted through the optical fiber tip, the greater its light or irradiance intensity (mW/cm²).

Light intensity is undoubtly important, but as important or more is the quality of luminous light emitted by the equipment. The quality of the blue light beam is essential for the resinous materials to reach their ideal properties at the end of the light curing process.

Light quality has to do with wavelengths (nanometers – nm) emitted by the light curing unit, which will determine the blue tone of the luminous beam. The hardening of a material only happens if the equipment light is absorbed by photoinitiator substances present in adhesives, resins and cements. After absorbing blue light, the photoinitiators generate the free radicals that will start the curing process. Therefore, the greater the purity of the blue light generated (quality), the more efficient the light curing.

It is important to mention that, although most resins and cements use a photoinitiator called camphorquinone, which has its absorption peak at 470 nm (nanometers), there are some other kinds of photoinitiators which have lower absorption peaks (between 415 and 425 nm). Only some few light curing units that use LED technology are capable of curing these resins and cements, but they are imported and expensive.