Andrea Corby

The aim of this study was to determine heritability estimates of treatment responses to a 10% hydrogen peroxide strip-based whitening system in twins. Eighty-five twin pairs were randomly assigned to 10% hydrogen peroxide whitening strips or placebo strips without peroxide. Both twins (monozygotic or dizygotic) received the same treatment. Maxillary teeth were treated for 30 minutes twice daily for 7 days. Efficacy was measured objectively as L* (light-dark), a* (red-green), and b* (yellow-blue) color change from digital images at baseline (∆) and day 8. Heritability estimates for tooth whitening treatment responses for changes from day 8 to baseline were obtained using variance-component methodologies. Whitening treatment responses were highly heritable (h(2) = 71.0) for ∆b* and ∆a*(p < .0001), but not for ∆L* (h(2) = 27.0), which was essentially modulated by environmental factors. This study has demonstrated that both genetic and environmental factors significantly contributed to seven-day whitening treatment responses achieved with 10% hydrogen peroxide strips.

The purpose of this study was to assess treatment responses to dental flossing in twins. The study was a two-treatment, examiner-blind, randomized parallel group, controlled study. Fifty-one twin pairs between 12 and 21 years of age were randomized to a 2-week supervised and unsupervised treatment regimen consisting of 1) tongue brushing and toothbrushing (TB) and 2) TB + flossing (TB + Fl). Clinical endpoints were gingival bleeding (papillary bleeding score [PBS]) and oral malodor (levels of volatile sulfur compounds [VSC]). Analysis of variance and covariance methodologies were employed to analyze the data. Baseline average PBS values were 1.352 and 1.345 for the TB + Fl and TB groups, respectively (P=0.937). After 2 weeks of treatment, the TB + Fl group had a statistically significant decrease in PBS values of 0.558 (41.5% versus baseline), whereas the TB group showed no improvement from baseline. The change from baseline for the TB + Fl group was superior to that for the TB group (P<0.001). Similar findings were observed for the number of baseline papillary bleeding sites. Baseline average intraoral halimeter values were 45.91 and 41.75 for the TB+Fl and TB groups, respectively (P=0.504). Both treatment regimens demonstrated highly statistically significant reductions in intraoral halimeter values versus baseline (all P<0.001) and the difference between treatment groups was not statistically significant (P=0.339). Similar findings were found for expired air. In a well-matched twin cohort, tongue and toothbrushing plus flossing significantly decreased gingival bleeding after 2 weeks.