| Objective: ①To determine the prevalence of tooth discolouration in china andto evaluate demographic, behavioural parameters that impact tooth colour and its perception. ② To evaluate the tooth-whitening efficacy and safety of a new professional chair-side whitening system containing 35% hydroxide peroxide (Beyond Whitening Accelerator technology).Methods: ①A cross-sectional survey was carried out using a broad sample.Tooth colour(L*a*b*)was measured on the maxillary central incisors using a chronometer, and matched to the closest of a set of photo cards demonstrating different levels of tooth discolouration by researchers. First-person satisfaction with tooth colour and other five psychological tooth whitening questions were assessed using a five-point qualitative scale, information on socio-demographic characteristics of the population were gathered at the same time. Demographic, behavioural, and oral care parameters were modelled using multiple regressions. (2) 34 subjects with stained anterior teeth (including general discolouration teeth, dental fluorosis and tetracycline stained teeth) participated in the study and received three 10-minute cyclic treatments. Beyond Whitening Accelerator's high-intensity blue light activated its whitening formula containing 35% hydroxide peroxide, which is covered on the subjects' tooth surface. Theresearchers evaluated tooth shade, colour and subject response at baseline and posttreatment and at three and six months posttreament.Results: ? 405 Chinese adults and teenagers participated in the experiment, with a comparable representation of males and females in 6 different age strata, ranging from 13 to 64 years, the average L* was 70.67±1.91, a* was 4.29±2.05, b* was 17.51±4.13. Age and sex were the most prominent factors that impacted tooth colour, hi the current study, 48% suffered tooth discoloration, 52.6% were dissatisfied with their tooth colour. Satisfaction with tooth colour decreased with increased discolouration. L*, b*, education and smoking had statistically significant effects on the satisfaction with tooth colour (P<0.05). (2) 31 subjects were taken into analysis. The statistical analysis of Vita Shade Scores indicated that the product significantly lighted the colour of the teeth (PO.05). Analysis of the L*a*b* showed that no differences could be detected in the a* parameter. Changes were observed in the L*(brightness) and b*(yellow) parameters. These findings were corroborated by subject evaluation. Signs of mild irritation were seen after treatment (11.6%), the Gingival Index decreased significantly after therapy with no change in Plaque Index; 88.2% reported sensitivity during the following 24 hours after treatment, and 20.5% reported sensitivity at the one-week checkpoint, the treatment for one subject with dental fluorosis was suspended because of sever toothache. Two subjects with tetracycline stained teeth extended the range of Vita shade and couldn't be measured at baseline. These 3 subjects were excluded from analysis.Conclusion: ? About half population suffered tooth discoloration and were dissatisfied with their tooth colour, which predicted the increasing of need fortooth whitening therapy in the future. (2) The application of Beyond whitening accelerator in tooth bleaching was effective and safe. The whitening outcome was able to persist for a minimum of six months. General tooth discolouration, the first type of tetracycline stain and the second type of tetracycline stain which was yellow and grey showed satisfactory results after treatment. |
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