Tooth whitening: tooth color changes following treatment by peroxide and light.

OBJECTIVE: This study examined the use of color measurement to determine tooth color in a study of bleaching with peroxide and light used separately and in combination. Two measurement protocols were evaluated for their ability to reveal differences between treatments and confirm tooth shade evaluations. METHODOLOGY: Before and after treatment, 43 subjects were evaluated for tooth color using a shade guide and a chromameter. Two measurement procedures were used: one measured a single location on each tooth using a fabricated plastic stent, and the other measured nine locations across the buccal surface. Values from the two procedures were compared to each other, and to shade guide measurements. RESULTS: Tooth color, as measured by both procedures, significantly correlated with shade evaluation. Statistically significant differences between treatment groups were found more often with data from the multiple-site procedure than from the single-site procedure. Incisal-gingival color gradation on tooth surfaces was diminished as a result of whitening treatments. Chromameter measurement data showed that tooth whitening procedures reduced tooth yellowness (b) more reproducibly than they increased whiteness (L). CONCLUSION: When more sites per surface were measured, tooth color measurement by the chromameter more closely matched shade with less variability and greater statistical power. Chromameter-derived values can be used to estimate shade values to a reasonable level of accuracy. Decreasing yellowness, particularly at the gingival margin, was an important component of the tooth whitening effect. Following tooth whitening, teeth were more uniform in their color, and this may contribute substantially to the subjective patient recognition of whiter teeth.

Microbiological changes associated with dental prophylaxis.

BACKGROUND: Despite the common application of dental prophylaxis as part of patient therapy, there is little reported that describes the microbiological impact of this treatment. METHODS: The authors gave 20 healthy college-aged subjects three dental prophylaxes with a fluoride-containing prophylaxis paste during a two-week period and instructed them in oral hygiene. They evaluated the microbiological composition of dental plaque samples collected before and after treatment using DNA probe analysis. They analyzed 40 representative bacterial species in seven bacterial complexes by checkerboard DNA-DNA hybridization assay techniques. RESULTS: After three dental prophylaxes, the patients' mean Gingival Index score decreased from 0.82 to 0.77, the mean Plaque Index score decreased from 0.72 to zero, and the total number of bacteria per tooth decreased to approximately one-third of the original number. The authors computed two different measures of bacterial presence. The reduction in bacterial numbers was statistically significant and occurred in many species. Bacterial proportion (DNA percentage or percentage of the bacteria per tooth) did not change significantly. Greater reductions in bacterial count occurred in species that showed high numbers before treatment. The total bacterial count decreased by approximately 72 percent of its original level before prophylaxis was initiated. CONCLUSIONS: Professional dental prophylaxis did not target any particular bacteria or bacterial groups but removed bacteria nonspecifically and in proportion to their initial numbers. CLINICAL IMPLICATIONS: Repeated dental prophylaxes effect a reduction in bacterial amount that is commensurate with the initial amount, but they do does not alter composition. This suggests that mild gingivitis may be a bacterially nonspecific effect of plaque accumulation and emphasizes the need for regular plaque removal to maintain optimal gingival health.