The aim of this study was to investigate the effects of some acidic drinks on dentin erosion, using methods of surface profile (SP) analysis and energy-dispersive X-ray fluorescence spectrometry (EDXRF). One hundred standardized dentin slabs obtained from bovine incisor roots were used. Dentin slabs measuring 5x5 mm were ground flat, polished and half of each specimen surface was protected with nail polish. For 60 min, the dentin surfaces were immersed in 50 mL of 5 different drinks (Gatorade®, Del Valle Mais orange juice®, Coca-Cola®, Red Bull® and white wine), 20 blocks in each drink. The pH of each beverage was measured. After the erosive challenge, the nail polish was removed and SP was analyzed. The mineral concentration of dentin surfaces was determined by means of EDXRF. Data were analyzed statistically by ANOVA and Tukey's test (α=0.05). SP analysis showed that Red-Bull had the highest erosive potential (p<0.05). EDXRF results exhibited a decrease in phosphate in the groups immersed in Red-Bull, orange juice and white wine (p<0.05), and no significant difference in calcium content between the reference surface and eroded surface. In conclusion, this study demonstrated that all studied beverages promoted erosion on root dentin and Red Bull had the highest erosive potential. There was no correlation between pH of beverages and their erosive potential and only the P content changed after erosive challenge.

Aim: This in vitro study evaluated the effect of calcium hydroxide on pH changes of the external medium after intracoronal bleaching. Materials and methods:A total of 50 extracted human premolars were prepared and filled with gutta-percha and endodontic sealer. The teeth were randomly divided into five groups according to the bleaching agents employed: (a) Sterile cotton pellet with distilled water (control group); (b) sodium perborate and distilled water; (c) sodium perborate and 10% carbamide peroxide; (d) sodium perborate and 35% hydrogen peroxide; (e) 35% hydrogen peroxide. The teeth were stored in vials containing distilled water and the pH values of the medium surrounding the teeth were analyzed. After 7-day storage, the bleaching agent was removed and replaced by calcium hydroxide, and the distilled water was changed, in which the teeth were kept stored for further 14 days. Measurement of pH of the external medium (distilled water) was performed 7 days after insertion of the bleaching agents, immediately, 7 and 14 days after insertion of the calcium hydroxide. Data were submitted to statistical analysis by the two-way ANOVA and Tukey , s test.Results: There were pH changes of the external medium at 7-day period after bleaching procedures. These results confirmed the diffusion of bleaching agents to the external medium. Conclusion:Calcium hydroxide increased the external medium pH and was effective for pH alkalinization after intracoronal bleaching.Clinical significance: Intracoronal bleaching of endodontically treated teeth may cause cervical root resorption. A possible explanation for this process is the passage of bleaching agents to the periodontal tissues yielding an inflammatory process. In an attempt to keep the neutrality of the periodontal pH, the calcium hydroxide has been recommended.Results of this study showed that this material should be always used after intracoronal bleaching.

Different techniques are employed to control de caries progression, However, the interference of these techniques on further adhesive procedures on the treated tissue is still controversial. The aim of this study was to evaluate the bond strength (BS) of the bovine enamel and Methods: The tooth fragments were randomly divided into 4

Objective The aim of this study was to evaluate the effects of dental bleaching with 35 and 38% hydrogen peroxide and soft drink immersion on the chemistry and color of the bovine enamel fragments before and after treatment using reflectance and Fourier transform-Raman spectroscopy (FT-Raman spectroscopy). Materials and methods Sixty bovine enamel fragments were prepared and randomly divided into six experimental groups according to the hydrogen peroxide gel concentration or immersion in soft drink (n = 10): G1-Whiteness HP Maxx; G2-Whiteness HP Maxx + light lemon coke immersion; G3-Opalescence Xtra Boost; G4-Opalescence Xtra Boost + light lemon coke immersion; G5-Whiteform Perox Red Form gel; G6-Whiteform Perox Red Form gel + light lemon coke immersion. The bleaching treatment was performed in two sessions with a 7 days interval and the analysis before treatments were used as control (baseline). Samples were submitted to reflectance and FT-Raman spectroscopy analysis to evaluate surface mineral content and the reflectance before and after treatments. Results There was no significant statistical difference among the bleaching agents in the reflectance analysis (p = 0.63). The FT-Raman spectroscopy data showed significant loss in enamel mineral content after immersion in the light lemon coke and statistical significant differences for the interactions between ‘bleaching agent’ and ‘immersion in soft drink’ (p = 0.03) and between ‘bleaching agent’ and ‘time’ (p = 0.04). With regards to the whitened specimens, the Opalescence Xtra Boost agent demonstrated the greatest loss in enamel mineral content. Conclusion All bleaching agents exhibited great bleaching potential in reflectance analysis. This highly concentrated hydrogen peroxide gel (38%) changed significantly the enamel mineral content with or without immersion in soft drink. The specimens immersed in soft drink showed significant loss in enamel mineral content. Clinical relevance Some investigations have shown that hydrogen peroxide and beverages can modify enamel dental components, but more studies are necessary to explain its effects.