Abstract Vaccinium macrocarpon (cranberry) is a fruit that has an inhibitory effect on matrix metalloproteinases (MMPs) present in dentin and saliva. The inhibition of MMPs has been shown to prevent dentin erosion. The aim of this study was to analyze the effect of cranberry juice on the reduction of dentin erosion in vitro. Specimens of bovine dentin (4×4×2 mm) were randomized and divided into 4 groups (n = 17/group): distilled water (C-control, pH 7.2); green tea extract solution containing 400 µm epigallo-catechin-gallate (EGCg, positive control, pH 4.5); 10% cranberry extract (CrE, pH 3.9), and cranberry juice (CrJ, Cranberry JuxxTM, pH 2.8). Specimens were submitted to erosive pH cycles for 5 days. Each day, four demineralizations were carried out with 0.1% citric acid (90 s). After the acid challenges, specimens were rinsed and kept in treatment solutions for 1 min; afterwards, they were rinsed and stored in artificial saliva for 1 h at 37°C (or overnight at the end of each day). After the experimental period of 5 days, dentin loss was evaluated by contact profilometry. Data were analyzed by ANOVA and Tukey’s test (p < 0.05). Dentin loss (µm ± SD) was significantly lower for all treatments (EGCg = 9.93 ± 2.90; CrE = 12.10 ± 5.44; CrJ = 11.04 ± 5.70) compared to control (21.23 ± 11.96), but it did not significantly differ from each other. These results indicate that the commercial cranberry juice, despite its low pH, is able to reduce dentin erosion, which might be due to the ability of cranberry components to inhibit MMPs.

Abstract Objective: To evaluate the efficacy of xylitol varnishes in the inhibition of enamel demineralization in vitro. Material and Methods: Bovine enamel blocks (n=120) were randomly allocated to four groups (n = 30), and the surface hardness (SH) was measured at baseline. The blocks were treated with the following varnishes: 20% xylitol, 20% xylitol plus F (5% NaF), Duraphat™ (5% NaF, positive control), and placebo (no-F/xylitol, negative control). The varnishes were applied and removed after 6 h of immersion in artificial saliva. The blocks were subjected to pH cycles (demineralization and remineralization for 2 and 22h/day, respectively, for 8 days). Surface and cross-sectional hardnesses were measured to calculate the percentage of SH loss (%SHL) and the integrated loss of the subsurface hardness (ΔKHN). Data were statistically analyzed using Kruskal-Wallis and Tukey’s tests (p<0.05). Results: %SHL was significantly decreased by 20% xylitol plus F, Duraphat™, and 20% xylitol varnishes compared to placebo. The use of 20% xylitol plus F varnish led to a significantly lower percentage of SH loss compared to the use of 20% xylitol varnish without F. However, the experimental and commercial varnishes led to significantly lower subsurface demineralization compared to placebo and did not differ from each other. Conclusion: Xylitol varnishes, especially when combined with F, effectively prevent enamel demineralization.

Abstract The standardization of in situ protocols for dental erosion is important to enable comparison between studies. Objective: Thus, the objectives of this study were to evaluate the influence of the location of in situ intraoral appliance (mandibular X palatal) on the extent of enamel loss induced by erosive challenges and to evaluate the comfort of the appliances. Material and Methods: One hundred and sixty bovine enamel blocks were selected according to their initial surface hardness and randomly divided into two groups: GI - palatal appliance and GII - mandibular appliance. Twenty volunteers wore simultaneously one palatal appliance (containing 4 enamel blocks) and two mandibular appliances (each one containing 2 enamel blocks). Four times per day during 5 days, the volunteers immersed their appliances in 0.01 M hydrochloric acid for 2 minutes, washed and reinserted them into the oral cavity for 2 hours until the next erosive challenge. After the end of the in situ phase, the volunteers answered a questionnaire regarding the comfort of the appliances. The loss of tissue in the enamel blocks was determined profilometrically. Data were statistically analyzed by paired t-test, Chi-square and Fisher's Exact Test (p<0.05). Results: The enamel blocks allocated in palatal appliances (GI) presented significantly higher erosive wear when compared to the blocks fixed in mandibular appliances (GII). The volunteers reported more comfort when using the palatal appliance. Conclusions: Therefore, the palatal appliance is more comfortable and resulted in higher enamel loss compared to the mandibular one.

Abstract Objective The prevalence of dental erosion has been recently increasing, requiring new preventive and therapeutic approaches. Vegetable oils have been studied in preventive dentistry because they come from a natural, edible, low-cost, and worldwide accessible source. This study aimed to evaluate the protective effect of different vegetable oils, applied in two concentrations, on initial enamel erosion. Material and Methods Initially, the acquired pellicle was formed in situ for 2 hours. Subsequently, the enamel blocks were treated in vitro according to the study group (n=12/per group): GP5 and GP100 – 5% and pure palm oil, respectively; GC5 and GC100 – 5% and pure coconut oil; GSa5 and GSa100 – 5% and pure safflower oil; GSu5 and GSu100 – 5% and pure sunflower oil; GO5 and GO100 – 5% and pure olive oil; CON− – Deionized Water (negative control) and CON+ – Commercial Mouthwash (Elmex® Erosion Protection Dental Rinse, GABA/positive control). Then, the enamel blocks were immersed in artificial saliva for 2 minutes and subjected to short-term acid exposure in 0.5% citric acid, pH 2.4, for 30 seconds, to promote enamel surface softening. The response variable was the percentage of surface hardness loss [((SHi - SHf) / SHf )×100]. Data were analyzed by one-way ANOVA and Tukey’s test (p<0.05). Results Enamel blocks of GP100 presented similar hardness loss to GSu100 (p>0.05) and less than the other groups (p<0.05). There was no difference between GP5, GC5, GC100, GSa5, GSu100, GSa100, GSu5, GO5, GO100, CON− and CON+. Conclusion Palm oil seems to be a promising alternative for preventing enamel erosion. However, further studies are necessary to evaluate a long-term erosive cycling.

ABSTRACT Objective This in situ/ex vivo study investigated the effect of CO2 laser irradiation and acidulated phosphate fluoride gel (APF) application, separately and in combination, on enamel resistance to erosion. Material and Methods During 2 experimental 5-day crossover phases, 8 volunteers wore intraoral appliances containing bovine enamel blocks which were submitted to four groups: 1st phase - control, untreated and CO2 laser irradiation, 2nd phase - fluoride application and fluoride application before CO2 laser irradiation. Laser irradiation was performed at 10.6 µm wavelength, 5 µs pulse duration and 50 Hz frequency, with average power input and output of 2.3 W and 2.0 W, respectively (28.6 J/cm2). APF gel (1.23%F, pH 3.5) was applied on enamel surface with a microbrush and left on for 4 minutes. Then, the enamel blocks were fixed at the intraoral appliance level. The erosion was performed extraorally 4 times daily for 5 min in 150 mL of cola drink. Enamel loss was measured profilometrically after treatment and after the in situ phase. The data were tested using one-way Repeated Measures Anova and Tukey's test (p<0.05). Results CO2 laser alone (2.00±0.39 µm) did not show any significantly preventive effect against enamel erosion when compared with the control group (2.41±1.20 µm). Fluoride treated enamel, associated (1.50±0.30 µm) or not (1.47±0.63 µm) with laser irradiation, significantly differed from the control. Conclusion The APF application decreased enamel wear; however, CO2 laser irradiation did not enhance fluoride ability to reduce enamel wear.

Abstract This in situ study assessed the effect of different times of salivary exposure on the rehardening of acid-softened enamel. Bovine enamel blocks were subjected in vitro to a short-term acidic exposure by immersion in 0.05 M (pH 2.5) citric acid for 30 s, resulting in surface softening. Then, 40 selected eroded enamel blocks were randomly assigned to 10 volunteers. Intraoral palatal appliances containing 4 enamel blocks were constructed for each volunteer, who wore the appliance for 12 nonconsecutive hours: initial 30 min, followed by an additional 30, and then by an additional 1 hour. For the last additional 10 hours the appliances were used at night, during the volunteers’ sleep. Surface hardness was analyzed in the same blocks at baseline, after erosion and after each period of salivary exposure, enabling percentage of surface hardness recovery calculation (%SHR). The data were tested using repeated measures ANOVA and Tukey’s test (α = 0.05). Increasing periods of salivary action promoted a progressive increase in the surface hardness (p < 0.001). However a similar degree of enamel rehardening (p = 0.641) was observed between 2 hours (49.9%) and 12 hours (53.3%) of salivary exposure. Two hours of salivary exposure seems to be appropriate for partial rehardening of the softened enamel surface. The use of the intraoral appliance during sleep did not improve the enamel rehardening after erosion.