2016 Volume 59 Issue 2 Pages 197-205
Purpose: Teeth whitening (bleaching) has been become an indispensable procedure. However, after home bleaching, the consumption of colored foods or acidic drinks was strictly prohibited. Recently, a home bleaching agent containing polyphosphate (polyP) has been introduced into clinical practice to reduce the influence of stain accumulation or acidic effects. In this study, we used extracted human incisors to evaluate the effects of polyP on tooth bleaching, inhibition of stain accumulation and prevention of decalcification (SEM observation and Ca release).
Methods: 35 extracted human incisors were divided into five treatment groups (n=7) : 10% sodium polyphosphate and 10% carbamide peroxide (PPa+CP), 10% sodium polyphosphate (PPa), 10% carbamide peroxide (CP), Nite White Excel (NWE) and Salivate (SA). These agents were applied to specimens for 2 h a day, for 14 times. Colorimetric measurement was performed after 14 times of bleaching. The color difference ΔE*ab was calculated by baseline L*a*b* values, and L*a*b* values after 14 times of bleaching. The preparation of specimens and treatment agents for the stain accumulation test was the same as for the bleaching effect. Another 35 extracted human incisors were divided into five groups. Stain accumulation was considered as the color difference ΔE*ab between baseline L*a*b* values and after immersion in coffee solution for 15 min. Prevention of decalcification by polyP used five extracted human maxillary central incisors. Two incisors were used for SEM observation and three incisors for capillary gel electrophoresis. The surface was treated with PPa and SA or ultra-pure water for 2 h and etched with 40 w/v% phosphoric acid (K-etchant) for 30 sec. These specimens (n=2) were observed by SEM, and diluted solution from another specimen surface (n=3) was analyzed by capillary gel electrophoresis using a cation analysis kit (Beckman Coulter).
Results: Regarding ΔE*ab after 14 times of bleaching, NWE, PPa+CP and CP showed larger values, but no significant difference was noted between PPa+CP and NWE. Regarding stain accumulation, PPa+CP and PPa showed significantly lower ΔE*ab values than CP and SA. Regarding SEM observation, both images of the enamel surface commonly exhibited honeycomb structures attributed to hyper and lower calcified structures of the enamel prism. However, the image of the enamel surface treated by PPa showed mild decalcification. Ca2+ release from the enamel surface treated with polyP was 66.3% compared with that from the non-treated surface.
Conclusion: It is suggested that the experimental teeth bleaching agent containing polyP had the same bleaching effect as conventional bleaching agent, and also prevented stain accumulation and decalcification.
