Tooth bleaching by different concentrations of carbamide peroxide and hydrogen peroxide whitening strips: an in vitro study.

OBJECTIVE: To investigate the tooth whitening effects of various concentrations of carbamide peroxide (CP) gels and 6% hydrogen peroxide (HP) whitening strips used on an intrinsic, in vitro stain model in a simulated home-applied bleaching protocol. METHOD: Extracted third molars were sectioned and stained to Vita shade C4 using a standardized tea solution. Stained specimens were then bleached with 10, 15, 20, 22, and 30% CP gels applied in custom-made trays for 8-hour sessions for 14 days. A 6% HP whitening strip product was also tested in a regimen of twice-daily 30-minute treatments for 14 days. Shades were assessed at baseline and at 2, 5, 7, 10, and 14 days of treatment using a shade guide (SG) and a shade vision system (SVS), recorded as shade guide unit (SGU) changes from baseline, and CIE L*a*b* recordings using a chromometer. RESULTS: By day 14, all CP treatments resulted in at least 12 SGU improvements by SG and SVS methods: the HP treatment mean was just less than 12 SGU. With the chromometer, the CP improvements ranged from approximately 19 to 28 units and 16 units for the HP whitening strips. Observationally, by SG and SVS, CP treatments achieved the maximum improvement (12-13 SGU) at different time points: day 5 for 30% CP, day 10 for 22% CP, and day 14 for the other three treatments. SG and SVS data were virtually binary, switching from 0 to scores of 9 or above as bleaching progressed. The differences between the six treatments in the mean day to achieve a positive SG or SVS score (9 or more units) approached significance. For each of the SG, SVS, and L*a*b* scores, the dose-response correlation with CP concentration was significant at one or more assessment times. SG and SVS showed extremely strong agreement in detecting change and substantial agreement with L*a*b*. CONCLUSION: This in vitro study supports the limited data available from the very few available randomized controlled clinical trials indicating that CP and HP home-use bleaching systems can achieve considerable tooth whitening outcomes, albeit at different rates, which appear to be concentration dependent. CLINICAL SIGNIFICANCE: There is a clear significant relationship for both concentration and duration of exposure for CP bleaching agents. The final shade change is independent of the concentration of bleaching agent, with time as the dominant variable. Higher concentrations of CP that have not been investigated previously may be a treatment option for esthetic improvement of shade where time is at a premium, but caution must be exercised in view of the possible increased incidence of sensitivity.

Comparison of three in-office bleaching systems based on 35% hydrogen peroxide with different light activators.

PURPOSE: To compare in vitro the bleaching effects obtained with and without the use of the various lights on power bleaching systems. METHODS: 19 groups of five tooth specimens were prepared and allocated randomly to treatments. Only specimens with shade C4 were accepted for the study. Three commercial bleaching products all based on 35% hydrogen peroxide were used with and without four different light sources. Shade assessments were made using a Shade Guide (SG), Shade Vision System (SVS) and chromometer. RESULTS: For SG, all but the light only treatment resulted in measurable improvement in shade ranging from 4.6 to 14.6 shade guide units. Similar findings were apparent with SVS and chromometer. No change was seen in the light only treatments by SVS or SG with very small changes by chromometer. In mean terms with all three gels, least change was noted when there was no light used. For SG, SVS and chromometer data analysis over all treatment groups, excluding light only treatments, revealed highly significant differences. Within bleach product treatment differences were only significant with one gel both with and without light activation. Differences between gels with the same light and no light revealed some significant differences in SG and chromometer data but not SVS. In mean terms the order of efficacy of gels with each light and no light was the same for the majority of data sets.

An overview of the use of lasers in general dental practice: 2. Laser wavelengths, soft and hard tissue clinical applications.

UNLABELLED: The profession now benefits from many different laser wavelengths that enable their use in nearly every dental specialty. This article will cover these wavelengths and their uses for soft and hard tissue procedures. CLINICAL RELEVANCE: There are many laser wavelengths available but their use within dentistry is quite tissue specific. It is hoped the reader will be able to decide which wavelength is best for a particular procedure.

An overview of the use of lasers in general dental practice: 1. Laser physics and tissue interactions.

High tech dentistry now involves the routine use of lasers in general dental practice for various procedures once thought only possible with the conventional dental drill or scalpel. In 1990, the first dental laser, the dLase 300 (American Dental Lasers, Corpus Christi,TX 78405 USA), was introduced to the profession. There are now many different types of laser used in dentistry using a variety of wavelengths. Each laser wavelength is absorbed differently by soft and hard tissues and the efficiency of the laser has been determined by the ability of the tissue to absorb or reflect that wavelength. This and the following article hope to give a broad overview of dental lasers and their clinical uses. This article gives an overview of the relevant laser physics and highlights the laser-tissue interactions.