Laser bleaching (synonyms: laser bleaching; laser-assisted bleaching; laser-activated bleaching; laser-assisted tooth whitening) is a tooth whitening procedure in which a bleaching agent (bleaching agent) is applied to the teeth and activated by exposure to laser light. Today, a patient associates successful dental care not only with the desire to restore and maintain the health of his chewing function, but also hopes for aesthetic improvements that will help him achieve a beautiful smile and thus a more sympathetic and competent appearance. The most important contribution to radiant teeth is made by the patient himself through consistent, correct dental care at home, combined with largely avoiding staining stimulants such as coffee, certain types of tea, red wine and above all nicotine. However, medications such as chlorhexidine gluconate rinses can also lead to deposited discolorations. In addition, the first step in dental practice is thorough professional tooth cleaning (PZR): discoloration deposited on the tooth surface is removed, for example, by cleaning the teeth with a powder jet and subsequent polishing with pastes of different grit sizes. Although these deposited discolorations are also affected by the chemical reactions that take place during bleaching, they should still be removed beforehand, as they otherwise make it more difficult for the bleaching agent to penetrate the tooth surface. Mode of action of the bleaching agent:
The bleaching agent is usually 30% hydrogen peroxide (H2O2; hydrogen superoxide) in gel form. H2O2 is a strong radical former that has both reducing and oxidizing effects as it decays; larger colored molecules are thus broken down to smaller colorless reaction products, and colored metal oxides are reduced to colorless ones. This means that the coloring substances are not dissolved out of the melt structure, but remain in place as a decolorized reaction product.
Indications (areas of application)
Discoloration that has penetrated the uppermost layers of enamel cannot be removed by either home dental care or professional dental cleaning. This is where laser-assisted bleaching is used. Useful indications can be:
- Age-related tooth discoloration
- In the mineralization phase of the teeth occurred deposits, for example, tetracycline discoloration, but depending on the extent can be very stubborn and require multiple laser bleaching.
In this regard, not every laser used in dentistry is equally suitable. Rather, the absorption behavior and the penetration depth of the laser light must be precisely matched to the indication, so also to support the bleaching process. For this purpose, the use of a diode laser with a wavelength of 810 nm to 980 nm or also an Nd:YAG laser seems to make sense. The heat increase in the tooth structure is very low in laser-activated bleaching and contributes only minimally to the actual bleaching. This explains the comparatively low development of postoperative hypersensitivities (hypersensitivities), because unlike the use of thermocatalytic bleaching lamps, for example, there is no heat-induced expansion of the dentinal tubules with the laser and subsequent increased penetration of the bleaching agent, which can cause signs of inflammation in the pulp (tooth pulp).
Contraindications
For any purely cosmetic treatment, including laser bleaching, the contraindications should be particularly broad:
- Gravidity (pregnancy)
- Lactation phase (breastfeeding)
- Children and adolescents due to the still large expansion of the pulp (the dental pulp) and thus significantly increased risk of pulpitis (pulp inflammation), especially since no age-related discoloration can yet be present
- Pre-existing hypersensitivities (hypersensitive tooth necks).
- Insufficient restorations (leaking crown and filling margins).
- Carious defects
- General enamel formation disorders, e.g. amelogenesis imperfecta (genetic disease in which there is a disorder of enamel formation).
- Repeated bleaching before the expiry of three years.
- Excessive consumption of coloring stimulants such as coffee, tea, tobacco, red wine, for example, because in such cases the patient will very quickly complain about the perceived failure of bleaching
Before laser bleaching
Before laser bleaching, the following measures are required:
- Informing the patient about health risks and possible complications.
- Clarification of expectations regarding the extent and expected duration of the bleaching effect.
- Diagnostics to exclude leaking filling and crown margins and exposed tooth necks.
- Sensitivity check of the teeth to be whitened.
- If necessary, replacement of leaking fillings or temporary sealing of margins on restorations, which should be replaced and color-matched – about four weeks – after bleaching.
- Professional teeth cleaning
- Photos taken in daylight without flash with reference tooth of the color ring to document the success of treatment.
The procedure
Laser bleaching is the most expensive procedure in terms of equipment compared to other external bleaching methods. However, the time required is comparatively low, since the exposure time of the laser per tooth is only 30 sec. The following procedure is suitable:
- Installation of rubber dam to protect the gingiva from irritation by the bleaching agent.
- Alternatively, application of Gingival Protector (plastic-based material) from the application syringe to the gingiva (the gums) and to exposed tooth necks; followed by light curing
- Laser safety goggles for the treatment team and the patient.
- Application of the bleaching gel on the enamel with due distance to tooth necks and gingiva.
- Exposure time of the laser light 30 sec per tooth at 1 watt laser power.
- After one pass, the activated bleaching gel is completely removed and reapplied for another pass; there may be a maximum of three cycles per session
- Over-bleaching beyond the targeted shade, as the teeth darken again somewhat in the first four weeks
- Final careful removal of the bleaching gel by intensive spraying.
- Removal of the rubber dam or protective varnish from the gingiva.
- Post-treatment of the teeth with fluoride gel or potassium nitrate gel.
- Repeat sessions up to five times
Possible complications
- Pain reactions, which usually subside after removal of the bleaching gel
- Inflammatory reactions of the pulp (of the tooth pulp).
- Hypersensitivity (hypersensitivity)
- Inflammatory damage to the gingiva (gums) and periodontium (the gums and periodontium).
- Reduced flexural strength of the tooth enamel
- Reduced hardness of enamel and dentin (dentine)
- Poorer adhesion of adhesively cemented filling materials; for this reason (and others) place adhesive fillings after one week at the earliest.
- Reversible moisture removal from the tooth hard substances.
- Insufficient bleaching effect: not every tooth color can be lightened; the result is therefore unpredictable