Susceptibility of partially desalivated rats to erosive tooth wear by calcium-supplemented beverages.

OBJECTIVES: To investigate the susceptibility of partially desalivated rats to erosive tooth wear (ETW); the anti-erosive effect of a calcium-supplemented beverage; and the quantification of ETW by microcomputed tomography (micro-CT). METHODS: The study population consisted of thirty-eight rats, divided into partially desalivated (n = 19) and normal salivary flow (n = 19). They were randomly allocated into three subgroups (n = 6-7): A-diet soda, B-diet soda + calcium, C-water (control). Solutions were provided ad libitum for 28 days, and the rats were euthanized afterwards. Each left hemi-mandible was scanned using micro-CT for enamel volume (three molars) calculation. Visual analysis of photographs of the lingual surface of first molars was performed independently by three blinded examiners. Data were statistically analysed (α = .05). RESULTS: Micro-CT revealed no significant differences between partially desalivated or normal groups. Rats consuming A had more enamel loss than those consuming B or C, which did not differ from each other. For visual analysis, desalivation did not affect ETW. Rats consuming C showed the lowest ETW, followed by B and then A, for both partially desalivated and normal rats. Spearman correlation between the two ETW quantification methods was -.65. CONCLUSIONS: Partial desalivation did not increase ETW. Ca-containing beverage prevented ETW. Micro-CT quantified ETW, although it was not as sensitive as visual analysis.

Toothbrushing abrasion susceptibility of enamel and dentin bleached with calcium-supplemented hydrogen peroxide gel.

UNLABELLED: The objective of this study was to evaluate enamel and dentin susceptibility to toothbrushing abrasion, after bleaching with 7.5% hydrogen peroxide (HP) gel supplemented or not with 0.5% calcium gluconate (Ca). Toothbrushing was performed immediately and 1h after bleaching, with two suspensions (high and low abrasivity). Bovine enamel and dentin specimens were divided into 12 groups (n=10) according to the bleaching gel (with and without Ca), slurry abrasivity (high or low) and elapsed time after bleaching (immediately and after 1h). As control, a group was not bleached, but abraded. The treatment cycle (7 d) consisted of bleaching (1h) and toothbrushing (135 strokes/day) immediatelly or after 1h of artificial saliva exposure. Surface roughness and surface loss (µm) were measured by profilometry and analysed by three-way ANOVA (5%). Surface roughness means were significantly influenced by slurry abrasivity (p<0.0001). For enamel loss, significant triple interaction was observed (p<0.0001). HP-bleached groups and immediately brushed with high-abrasive slurry exhibited increased loss (1.41±0.14) compared to other groups (µm). Control and HP+Ca-bleached groups brushed after 1h with low abrasive slurry presented the lowest loss (0.21±0.03/0.27±0.02). For dentin loss, significant interaction was observed for bleaching and interval factors (p<0.001). 7.5%HP-bleached groups and immediately brushed showed significantly higher loss (8.71±2.45) than the other groups. It was concluded that surface roughness increased when high abrasive was used, independently of bleaching. 7.5%HP increased enamel and dentin loss, mainly with high abrasive slurries. Calcium supplementation of bleaching gel reduced surface loss. Additionally, in order to minimize tooth wear susceptibility, it is recommended to delay brushing after bleaching. CLINICAL RELEVANCE: After bleaching gel application, postponing toothbrushing is recommended, as well as brushing with low abrasive dentifrices. Additionally, supplementation of hydrogen peroxide gel with calcium-based remineralizing agent potentially reduces tooth loss after abrasion.

Biomimetic approach for root caries prevention using a proanthocyanidin-rich agent.

The aim of this study was to evaluate the effects of a proanthocyanidin-rich grape seed extract (GSE) on the in vitro demineralization of root dentine. Root fragments were obtained from sound human teeth. The fragments were randomly assigned to different treatments solutions: GSE, fluoride (F), GSE+F and distilled water (control). Samples were treated daily for 30 min and subjected to a pH cycling artificial caries protocol using demineralization cycles (2.2 mM CaCl(2)×H(2)O, 2.2 mM KH(2)PO(4), 50 mM acetic acid, pH 4.3) for 6 h and remineralization cycles (20 mM HEPES, 2.25 mM CaCl(2)×H(2)O, 1.35 mM KH(2)PO(4), 130 mM KCl, pH 7.0) for 17.5 h. Mineral loss (ΔZ) and lesion depth (LD) were determined after 18 days of treatment/pH cycling, by transverse microradiography. GSE was able to minimize ΔZ and LD compared with the control group (p < 0.0001). The GSE+F and F groups showed the lowest values of ΔZ and LD (p < 0.05), with no statistically significant differences between them (p = 0.554 and p = 0.726, respectively). A biomimetic approach to strengthen root dentine using GSE results in decreased rates of root demineralization and may be used in conjunction with F to prevent root caries.

Evaluation of a desensitizing test dentifrice using an in situ erosion remineralization model.

OBJECTIVE: To evaluate, in an in situ remineralization model, the ability of a low abrasion fluoride dentifrice containing potassium nitrate to enhance the remineralization of enamel that was previously subjected to an in vitro dietary erosion challenge. METHODOLOGY: Thirteen subjects completed a single-blind (to specimen analyst) crossover design study with four randomly assigned dentifrice treatments: placebo dentifrice (0 ppm F; PD); dose response control dentifrice (250 ppm F; DD); clinically tested fluoride dentifrice (1100 ppm F; FD); and test dentifrice (1150 ppm F + 5% KNO3; TD). Each subject wore a palatal appliance holding eight bovine enamel blocks that were previously exposed for 25 minutes to an in vitro erosive challenge with grapefruit juice. Surface microhardness (SMH) was determined prior to the erosive challenge (baseline), after the in vitro erosive challenge, after in situ remineralization, and after a second in vitro erosive challenge. Statistical analyses included ANOVA and pair-wise comparisons between treatments, testing at a 5% significance level. RESULTS: The mean percent SMH recovery (SD) was 20.4 (7.7)a for PD; 27.4 (5.9)b for DD; 29.5 (8.9)bc for FD; 33.4 (6.7)c for TD. The mean percent net erosion resistance (SD) was -57.7 (10.8)a for PD; -41.3 (11.6)b for DD; -28.7 (9.7)c for FD; -23.6 (7.3)c for TD. Different superscript letters following the means imply statistically significant differences between groups for each response. CONCLUSION: The test dentifrice was shown to significantly enhance the remineralization of enamel previously subjected to an erosion challenge.