Efficacy of Teeth Whitening with a Mouthwash: In Vitro and In Vivo Approaches

Abstract

Objectives: Two different studies were conducted to evaluate the whitening efficacy of a mouthwash versus a placebo using in vitro and in vivomodels. The tested mouthwash was formulated with no oxidizing or abrasive agents containing chlorhexidine (CHX) and polyvinylpyrrolidone (PVP).

Methods: The purpose of the in vitro study was to determine whether the mouthwash formulation OC15AB could reduce the accumulation of staining in an accepted stain model. Bovine central incisors were cut to obtain enamel specimens of ~8 × 8 mm2. The specimens were then immersed in human saliva (room temperature, slight stirring) for one hour to allow a pellicle film to form. They were then placed in contact with a staining solution containing coffee and tea. The amount of stain (tooth color) was quantified photometrically (Minolta C221 colorimeter) using the L* value of the L*a*b* scale. The purpose of the in vivo study was to evaluate the whitening power and tolerability of OC15AB versus a placebo mouthwash in a double-blind, randomized clinical study. In total, 40 subjects were divided randomly into two homogeneous groups. Each group used a different mouthwash (OC15AB or placebo) for 56 consecutive days. During this period, clinical and instrumental parameters, namely variations in tooth color and mucosal and gum alterations, were evaluated. The in vivo study analyses used a two-sided Student's t-test. Evaluations within groups used t-tests for paired data.

Results: From the in vitro test, OC15AB had a significant effect in reducing stain accumulation over the entire treatment period. The in vivo test showed that OC15AB was well tolerated and had whitening power in the subjects. OC15AB demonstrated a statistically significant reduction in extrinsic tooth staining from baseline and versus the placebo.

Conclusions: The in vitro and in vivo methods used to investigate the whitening efficacy of the mouthwash formulation produced similar and consistent results. The experimental model used is an important tool in the search for new technologies for teeth whitening. Our preliminary experimental data confirm the possibility of achieving a whitening effect using a mouthwash formulation with no oxidizing or abrasive agents containing CHX and PVP. The formulation tested demonstrated a significant reduction, in vitro and in vivo, in extrinsic tooth staining from baseline and versus the placebo.

Keywords: CHX; extrinsic stain; in vitro study; in vivo study; stain accumulation.