Am J Dent. 2021 Dec;34(6):307-312.
ABSTRACT
PURPOSE: To investigate the tooth-whitening effects of mouthrinses containing different sizes of hydroxyapatite (HAP) particles after prolonged application time and compare them with a commercial whitening mouthrinse.
METHODS: 50 bovine incisors were stained and randomly distributed into five groups: the HAP groups with 3 µm, 200 nm and 50 nm particle size, the commercial whitening mouthrinse group and the distilled water group. The teeth underwent prolonged mouthrinse applications that were equivalent to simulated 3- and 6-month mouthrinsing. Tooth color was measured and calculated before and after mouthrinsing. The group and application time effects were analyzed with a nonparametric analysis of longitudinal data using the nparLD package in R and ANOVA-type statistic was reported. Pairwise Wilcoxon rank-sum tests with BH correction were performed to compare the tooth color changes of individual groups. The mouthrinse-treated enamel was observed by SEM.
RESULTS: The whitening effect of HAP mouthrinses after the prolonged application time was confirmed. The HAP mouthrinses exhibited similar whitening effects to the commercial mouthrinses. The particle size and application time could significantly affect the whitening performance of HAP mouthrinses. The 50 nm HAP group exhibited significantly higher ΔE values than the 3 µm group after the 6-month-equivalent application (P= 0.024). A longer period of application increased significantly the ΔE and ΔL values (P< 0.05). The HAP-treated enamel surfaces were entirely covered with HAP after the 6-month-equivalent application.
CLINICAL SIGNIFICANCE: The HAP nanoparticles showed better tooth-whitening performance after a longer period of mouthrinsing than the microsized HAP particles. This should be taken into consideration by dental manufacturers for optimizing the particle size for their HAP-containing products. To achieve a better outcome in tooth-whitening, the patients should apply the mouthrinse regularly for an extended period of time.
PMID:35051317
