Treatment of Dentin Hypersensitivity Using Nano-Hydroxyapatite Pastes: A Randomized Three-Month Clinical Trial.

OBJECTIVES: This randomized clinical trial tested the three-month desensitizing effect of two protocols using nano-hydroxyapatite formulations compared with Pro-Argin and fluoride varnish. METHODS: Twenty-eight subjects with 137 teeth presenting dentin exposure with a minimal hypersensitivity of four on the visual analog scale (VAS) took part of this study. The subjects were randomly assigned to four groups: Desensibilize Nano-P paste (20% hydroxyapatite [HAP], potassium nitrate, and sodium fluoride [NaF]; 9000 ppm fluoride [F]); Desensibilize Nano-P associated with experimental home-care pastes (10% HA, potassium nitrate, and NaF; 900 ppm F); Pro-Relief professional paste (8% arginine with Pro-Argin technology) associated with home-care toothpaste (8% arginine, sodium monofluorophosphate, 1450 ppm F); and Duraphat professional varnish (NaF varnish, 22,600 ppm F). The professional treatments were performed in weekly appointments over three weeks. The home-care products were used continuously for three months. A VAS was used to assess the tooth sensitivity response after standardized evaporative stimulus at baseline and after one month and three months. The baseline score was deducted from the final score, and the means were analyzed using nested analysis of variance, while the comparison between times was performed by a general linear model (p<0.05). RESULTS: At the first month all treatments were effective, but there were no significant differences among them (p=0.94). At the third month, despite the fact that NaF varnish had the lowest effect in reducing hypersensitivity, no significant difference was found among the treatments (p=0.09). Only Pro-Relief increased its effect over time (p=0.049). CONCLUSIONS: Nano-hydroxyapatite formulations (with or without home->care product association) were as effective as the other treatments in reducing dentin hypersensitivity over three months.

Impact of protease inhibitors on dentin matrix degradation by collagenase.

This proof-of-concept study assessed whether the reduction of the degradation of the demineralized organic matrix (DOM) by pre-treatment with protease inhibitors (PI) is effective against dentin matrix loss. Bovine dentin slices were demineralized with 0.87 M citric acid, pH 2.3, for 36 hrs. In sequence, specimens were treated or not (UT, untreated) for 1 min with gels containing epigallocatechin 3-gallate (EGCG, 400 µM), chlorhexidine (CHX, 0.012%), FeSO(4) (1 mM), NaF (1.23%), or no active compound (P, placebo). Specimens were then stored in artificial saliva (5 days, 37°C) with the addition of collagenase (Clostridium histolyticum, 100 U/mL). We analyzed collagen degradation by assaying hydroxyproline (HYP) in the incubation solutions (n = 5) and evaluated the dentin matrix loss by profilometry (n = 12). Data were analyzed by ANOVA and Tukey's test (p < 0.05). Treatment with gels containing EGCG, CHX, or FeSO(4) led to significantly lower HYP concentrations in solution and dentin matrix loss when compared with the other treatments. These results strongly suggest that the preventive effects of the PI tested against dentin erosion are due to their ability to reduce the degradation of the DOM.