Home teeth whitening utilizing thermal diffusion in vivo

Objectives: The efficacies of teeth-whitening processes are markedly dependent on the diffusion of active bleaching agents [ABAs] to teeth stain sources, i.e. chromophores present within enamel and dentine. This diffusion process is correlated to the ABA-surface temperature gradient. Here, the ability of a novel thermal diffusion system [1] to promote the tooth-whitening actions of a bleaching gel containing 10% (w/v) hydrogen peroxide (H2O2) [2] towards discoloured upper canine teeth (the most difficult to bleach in view of their denser enamel layer) was examined. Methods: 50 upper canine teeth in 25 volunteers aged 18-62 yrs. were investigated. Vitapan shade scores (VSSs) were recorded at three separate tooth area sites (cervical, body and incisal) with a Crystaleye spectrophotometer (both prior and subsequent to completion of the 14-day trial). The tooth-whitening process involved essential mouth retraction followed by the application of product [2] to tooth surface enamel (isolated from all exposed dentine and soft tissues). Product [1] was then mounted over the retractor in order to elevate the gel temperature on enamel surfaces to 40°C. After instructing participants how to perform this treatment, they then applied it ‘at-home' (twice-daily episodes of 20 min. each) for a 10-day period (total bleaching time 400 min.). Results: Post-treatment mean decreases in the VSS values were 7.52, 8.78 and 8.32 for the cervical, body and incisal areas respectively (p < 10-37, 10-36 and 10-29 respectively, Student's t-test). The overall mean VSS values of teeth prior and subsequent to tooth-whitening were 11.91 (A3.5) and 3.70 (B2) respectively. Conclusions: The tooth-whitening system tested exerted extremely powerful bleaching actions in all tooth areas investigated. The order of tooth-whitening effectiveness may reflect product [1]'s ability to promote the penetration of H2O2 to intrinsic stain sites. [1] and [2]: get2smile Thermal Diffuser and get2 smile Bleaching Gel respectively, Smile Studio (UK).