Method: The pooled analysis was inclusive of all subjects in six clinical trials who were assigned a whitening dentifrice and had stain levels measured after 2-weeks usage. In each study, institutional review and informed consent were obtained, after which, adults with natural tooth stain were assigned one of 6 different marketed whitening dentifrices for at-home unsupervised use. At baseline, and again after 2 weeks treatment, extrinsic tooth stain area and intensity were measured by a treatment-blinded examiner using the Lobene index (LSI). The inclusive evidence (all subjects and whitening dentifrices) was analyzed using a General Linear Mixed Model with baseline characteristics as fixed effects and study as a random effect.
Result: The meta-analysis consisted of 144 subjects with natural extrinsic tooth stain. Mean (SD) age was 44.3 (12.3) years, males comprised 51% of subjects, 24% used tobacco products, while 51% and 78% consumed tea or coffee,. At baseline, subjects exhibited appreciable stain accumulation, as evidenced by an LSI mean (SD) of 1.6 (0.55). Subjects exhibited significant (p<0.0001) stain reduction after 2-weeks use of an assigned whitening dentifrice. In the pooled data, baseline stain was a significant effect in the model (p<0.0001). Behavioral factors, such as coffee or tea consumption or smoking, and demographic factors such as age or gender, were not significant effects.
Conclusion: Meta-analysis of data from clinical trials that evaluated effectiveness of whitening dentifrice for natural stain removal demonstrated that starting stain level, but not demographics or behavioral factors, affected response.