Comparative Study Of Different Tooth Bleaching Protocols Based On Patient Satisfaction

Objective:(1)To investigate the general knowledge of dental aesthetics among young university students in Fuzhou city and the factors influencing their satisfaction with general dental appearance and the color of anterior teeth.(2)To evaluate the relationship between subjective satisfaction and objectively measured color change following nightguard vital bleaching and confirm the endpoint of tooth bleaching treatments.(3)To compare the treatment outcome of different tooth bleaching protocols and explore the suitable treatment protocols for young patients.Methods:(1)A cross-sectional questionnaire survey was done on 506 young university students of representative universities in Fuzhou city to identify their general knowledge of dental aesthetics. Logistic regression analysis was used to to evaluate the factors influencing the study populations' satisfaction with dental appearance and the color of anterior teeth.(2)A total of 50 university student volunteers(average age of 22.86±1.99 years old, Male/Female:23/27) were recruited and asked to sign informed consents before participating in the present clinical trial. The maxillary anterior teeth of subjects were treated with 10% carbamide peroxide gel(nightguard vital bleaching) over a 28-day period. The color parameters(CIE L*, a*, b*) and shade score of bleached teeth were measured before and after 7, 14, 21, and 28 days treatment using Vita Easyshade Advance 4.0 spectrophotometer and Shofu Vintage shade guide. The color differences(?E values) due to bleaching treatment were also calculated. Subjects rated whitening satisfaction using a 4-point scale from “0”(not at all satisfied) to “3”(extremely satisfied). Logistic regression analysis with a significance level of 0.05 was used to analyze the relationship between subjective responses and objective color change. Regression analysis equation was then employed to confirm the tooth bleaching target of subjects.(3)Eighty buccal enamel specimens and eighty lingual enamel specimens, which obtained from eighty freshly extracted human premolars, were randomly distributed into eight groups accepted different bleaching protocols. All specimens were stored in artificial saliva between bleaching interval. Tooth bleaching target obtained from the second experiment was regarded as the treatment endpoint, then t-test and oneway ANOVA with a significance level of 0.05 was used to compare the differences among groups on average treatment time, total cost of bleaching agents, change of enamel surface microhardness, and color regression after 7 days post-bleaching treatment.Results:(1)The 506 respondents consisted of 220 males(43.5%) and 286 females(56.5%), of mean age 22.65 years(SD 1.95). 53.6% of these participants were not satisfied with their dental appearance, 57.2% of those were not satisfied with the color of their anterior teeth. Majority of the participants(66%) chose tooth bleaching as the most desired treatment to improve their dental appearance. Multivariate logistic regression analysis showed that respondents' dissatisfaction with dental appearance was significantly associated with gender(OR = 1.94, 95% CI: 1.03-3.68), the opinion that their teeth were irregular(OR2.70, 95% CI: 1.61-4.54) and unhappiness with anterior teeth color(OR = 4.27; 95% CI: 2.47-7.33). Results also indicated that respondents' dissatisfaction with the color of anterior teeth was significantly associated with the professional learning experience of stomatology(OR = 0.26, 95% CI: 1.61-4.54) and gender(OR = 1.76, 95% CI: 1.05-2.96).(2)Color change was evident and subjective satisfaction was generally high after tooth bleaching treatment. After treatment, there were increases in L* values, ?E values, and shade scores, with decreases in a* and b* values. When comparison in color parameters of the bleached teeth, the result was that ?b* was the most obvious. The mean values of ?L*, ?a*, ?b*, ?E, and shade score were 4.72,-2.21,-8.21, 10.38, and 5.74 after 28 days treatment. Among the 3 color parameters(?L*, ?a*, and ?b*), only ?b* values was found to have the significant influence on subjective responses regarding tooth bleaching treatment(p=0.009). At-7.7 ?b*, the regression equation predicted that all subjects would report whitening satisfaction at a level of 2 or 3.(3)As the concentration of bleaching agents was increased, all groups produced similar behavior that average treatment time was decreased and color regression was more obvious. The descent rate of most protocols on enamel surface microhardness was less than 10%. All groups showed color regression to some degree after 7 days post-bleaching treatment(?E=0.89~2.04).Conclusions:(1)Most of the respondents in this study were not satisfied with their dental appearance and the color of anterior teeth. Tooth bleaching was the treatment most desired by the participants. Tooth color was one of the most important factors that decided whether respondents were satisfied with their dental appearance. Females paid greater attention to dental aesthetics than males. Over one year professional learning experience of stomatology was the protective factor of respondents' satisfaction with the color of their anterior teeth.(2)Objectively measured yellowness, ?b*, was the most significant and highly predictive variable related to subjective whitening satisfaction responses. At-7.7 ?b*, the regression equation predicted that all subjects would report whitening satisfaction at a level of “satisfied” or “extremely satisfied”.(3)Bleaching procedures caused a slight enamel surface microhardness alteration, which was partly eliminated due to the remineralization of artificial saliva. There was not significance correlation between change of enamel surface microhardness and concentration of bleaching agents. Color regression after 7 days post-bleaching treatment is bleaching regimes dependent. When compared the differences among groups on average treatment time and adverse effects in vitro, it can be concluded that the suitable protocols for young patients was at-home tooth bleaching treatment(using 10% carbamide peroxide or 15% carbamide peroxide, once daily for 6 hours) or combined tooth bleaching treatment(firstly using 40% hydrogen peroxide, once weekly for 60 minutes with changing gel per 20 minutes, two courses later then using 15% carbamide peroxide, once daily for 6 hours).