cosmetic dentistry_ beauty & science

14 I I special topic _ TouchWhite There is no direct heating of dental tissue or pulp, as is the case with other laser-assisted whitening methods. The TouchWhite procedure, in fact, rep- resents the safest, least invasive laser-assisted tooth-whitening method available. ItisalsoworthnotingthatwithTouchWhite,the laser parameters are customised for bleaching treatments so that the laser fluence of each laser pulse is below 0.5 J/cm2 , which is well below the ablation threshold of dental tissues. Since the ablation threshold for enamel is approximately 3.5 J/cm2 , there is no risk of accidental damage.14 Figure 1 shows the lateral view thermal image of a tooth during Er:YAG and diode laser (810 nm) illumination of bleaching gel.15 As can be seen in the first image (Fig. 1a), the Er:YAG wavelength is fully absorbed by the gel, and there is no direct heating of the underlying tooth. In contrast, the diode wavelength is poorly ab- sorbed in the gel and the transmitted light directly heats the entire tooth. For this reason, the Er:YAG laser power is utilised more effectively and the gel can be heated to higher temperatures without compromising the safety of the tooth or the pulp. As a consequence, the tooth-whitening speeds can be safely increased by five to ten times with TouchWhite.15 _The TouchWhite procedure The Fotona TouchWhite bleaching kit contains gingival protection, bleaching gel and after- bleaching care material, packed in a syringe. The completebleachingkitshouldbestoredinarefrig- erator (3–8 °C). Before application, the kit is taken out of the refrigerator, the gel is mixed in the amount needed for the procedure, and the mixed gel is left to rest for four to eight minutes at room temperature. The gel is then applied to the teeth with a spatula in a predetermined sequence #11-21-13- 23-24-14-15-25-12-22 for the upper teeth and #33-43-34-44-35-45-32-42-31-41 for the lower teeth. Each tooth is irradiated for 20 seconds in the same sequence as the gel application. The param- eter settings for the Fotona Er:YAG laser are as follows: frequency 10 Hz, power 0.55 W, pulse duration VLP, handpiece R093. The handpiece is movedinasweepingmotionacrossthegelsurface. In the unlikely event that pain or sensitivity occurs in any tooth, the handpiece should be moved to the next tooth immediately. Paycarefulattentionnottoirradiatetwoneigh- bouring teeth at the same time. The whole proce- dure is repeated three times so that every tooth is irradiated three times for 20 seconds each. Once the three-cycle illumination of all teeth has been completed, the gel is removed with an aspirator and the tooth surface is thoroughly rinsed with a water spray. The colour is checked with a shade guide and shown to the patient. The procedure can be repeated up to three times in a single appointment if necessary. _Research supporting TouchWhite In vitro measurements and clinical studies have shown that with TouchWhite, whitening treatment times can be safely shortened to be- tween one to two minutes, down from ten to 15 minutes when no laser activation is applied. The method is effective and safe, as confirmed by temperature measurements in the pulpal cham- ber. TheTouchWhitemethodwasfirstproposedand studied by the Laser and Health Academy in part- nership with the European manufacturer Fotona. Later, the Aachen Dental Laser Center (AALZ) in Germanyperformedadetailedinvitro studyofthe temperature elevation in the pulp chamber under different Er:YAG laser-whitening scenarios, fol- cosmeticdentistry 1_2012 Figs. 2a & b_Before (a; A3 VITA shade guide) and immediately after (b; A1 VITA shade guide) images of the TouchWhite Er:YAG laser-assisted whitening procedure. Fig. 2bFig. 2a