Effect of potential remineralizing agents on acid softened enamel

PURPOSE

To assess whether pastes containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and calcium sodium phosphosilicate (CSP) protect acid softened enamel against further erosive episodes.

METHODS

Enamel slabs of bovine teeth with preformed erosion-like lesions were randomly assigned to five treatment groups (n = 15): A) CPP-ACP (MI Paste, GC America); B) CPP-ACP+Fluoride (CPP-ACP+F, MI Plus Paste, GC America); C) CSP (Tooth Revitalizing Paste, Oravive); D) fluoridated dentifrice (FD, Sensodyne Cool Gel, GSK); E) control (CO, unexposed to any product). Paste treatments (1:3 slurry in deionized water or undiluted product in the case of the CPP-ACP formulae) were performed between five cycles of alternating erosive challenge (0.3% citric acid, pH = 3.2) and remineralization in artificial saliva. Specimens were analyzed by Knoop surface microhardness (SMH).

RESULTS

ANOVA indicated a significant (P< 0.0001) difference among the SMH values attained by acid softened enamel following the exposure to the pastes interspersed with erosion-remineralization cycles. Tukey's test ascertained that SMH values observed for the CPP-ACP+F and CSP groups did not differ from that of FD group, which were significantly higher than that found for the CO group. Specimens treated with CPP-ACP did not differ from any of the other groups.

Sodium bicarbonate solution as an anti-erosive agent against simulated endogenous erosion

This study investigated whether sodium bicarbonate solution, applied on enamel previously exposed to a simulated intrinsic acid, can control dental erosion. Volunteers wore palatal devices containing enamel slabs, which were exposed twice daily extra-orally to hydrochloric acid (0.01 M, pH 2) for 2 min. Immediately afterwards, the palatal devices were re-inserted in the mouth and volunteers rinsed their oral cavity with a sodium bicarbonate solution or deionized water for 60 s. After the washout period, the palatal devices were refilled with a new set of specimens and participants were crossed over to receive the alternate rinse solution. The surface loss and surface microhardness (SMH) of specimens were assessed. The surface loss of eroded enamel rinsed with a sodium bicarbonate solution was significantly lower than the surface loss of eroded enamel rinsed with deionized water. There were no differences between treatments with sodium bicarbonate and deionized water for SMH measurements. Regardless of the solution used as an oral rinse, eroded enamel showed lower SMH than uneroded specimens. Rinsing with a sodium bicarbonate solution after simulated endogenous erosive challenge controlled enamel surface loss but did not alter the microhardness.

Brushing abrasion of dentin: effect of diluent and dilution rate of toothpaste

PURPOSE

To determine whether toothpaste diluent type and dilution rate influence abrasion of dentin.

METHODS

Slabs of human root dentin (4 x 3 x 2 mm) were embedded in epoxy resin, ground and polished. Adhesive tape was placed on the specimen's surface leaving an exposed central area of 1 x 4 mm. Specimens (n = 15) were then brushed for 1,000 strokes in a reciprocal action brushing simulator using toothpaste that had been diluted in a carboxymethylcellulose-based artificial saliva (CMC) or deionized water (DW) from 1:1 to 1:4 (toothpaste:diluents, in weight). Control groups were brushed with undiluted toothpaste, CMC-based saliva or DW only. Brushing simulation was run at 300 g load at 37 degrees C. After brushing, adhesive tape was removed and wear analyzed by optical profilometry.

RESULTS

One-way ANOVA (P < 0.0001) and Tukey's test revealed that, in general, wear depth (microm) declined with increasing dilution, regardless of the diluent. Brushing with CMC- or DW-only caused the least abrasion.