Dental implants have increased the use of titanium and titanium alloys in prosthetic applications. Whitening toothpastes with peroxides are available for patients with high aesthetic requirements, but the effect of whitening toothpastes on titanium surfaces is not yet known, although titanium is prone to fluoride ion attack. Thus, the aim of the present study was to compare Ti-5Ta alloy to cp Ti after toothbrushing with whitening and conventional toothpastes. Ti-5Ta (%wt) alloy was melted in an arc melting furnace and compared with cp Ti. Disks and toothbrush heads were embedded in PVC rings to be mounted onto a toothbrushing test apparatus. A total of 260,000 cycles were carried out at 250 cycles/minute under a load of 5 N on samples immersed in toothpaste slurries. Surface roughness and Vickers microhardness were evaluated before and after toothbrushing. One sample of each material/ toothpaste was analyzed by Scanning Electron Microscopy (SEM) and compared with a sample that had not been submitted to toothbrushing. Surface roughness increased significantly after toothbrushing, but no differences were noted after toothbrushing with different toothpastes. Toothbrushing did not significantly affect sample microhardness. The results suggest that toothpastes that contain and those that do not contain peroxides in their composition have different effects on cp Ti and Ti-5Ta surfaces. Although no significant difference was noted in the microhardness and roughness of the surfaces brushed with different toothpastes, both toothpastes increased roughness after toothbrushing.

Objectives: Chitosan has been widely investigated and used. However, the literature does not refer to the shelf life of this solution. This study evaluated, through the colorimetric titration technique and an analysis of dentin micro-hardness, the shelf life of 0.2% chitosan solution. Materials and Methods: Thirty human canines were sectioned, and specimens were obtained from the second and third slices, from cemento-enamel junction to the apex. A 0.2% chitosan solution was prepared and distributed in 3 identical glass bottles (v1, v2, and v3) and 3 plastic bottles (p1, p2, and p3). At 0,7,15,30, 45, 60, 90, 120, 150, and 180 days, the specimens were immersed in each solution for 5 minutes (n = 3 each). The chelating effect of the solution was assessed by micro-hardness and colorimetric analysis of the dentin specimens. 17% EDTA and distilled water were used as controls. Data were analyzed statistically by two-way and Tukey-Kramer multiple comparison (α = 0.05). Results: There was no statistically significant difference among the solutions with respect to the study time (p = 0.113) and micro-hardness/time interaction (p = 0.329). Chitosan solutions and EDTA reduced the micro-hardness in a similar manner and differed significantly from the control group (p < 0.001). Chitosan solutions chelated calcium ions throughout the entire experiment. Conclusions: Regardless of the storage form, chitosan demonstrates a chelating property for a minimum period of 6 months. (Restor Dent Endod 2017;42(2):87-94)

Aos meus pais, Regina e Darwin, pelos conselhos, amor e apoio incondicional aos meus objetivos e sonhos. Sempre guiando meus passos e me amparando nos momentos difíceis dessa jornada. Devo a vocês tudo que conquistei. À minha namorada Vannessa, pelo carinho, apoio e incentivo em todos os momentos. Sempre compartilhando as dificuldades dessa caminhada e me erguendo os momentos de dificuldade. Agradecimentos A Deus por estar sempre presente em minha vida, guiando meus passos. Ao meu orientador Prof. Dr. Antonio Miranda da Cruz Filho, pelos ensinamentos transmitidos, disponibilidade e pela imensa paciência e compreensão em todos os momentos. Obrigado por me orientar e ajudar a conquistar mais esse objetivo. Ao Prof. Dr. Jesus Djalma Pécora e ao Prof. Dr. Manoel Damião de Sousa Neto pelo constante incentivo à pesquisa e conhecimentos científicos transmitidos. Aos Professores do Departamento de Odontologia Restauradora da Faculdade de Odontologia de Ribeirão Preto, que por meio das disciplinas ministradas, contribuíram para meu crescimento profissional. Ao Prof. Dr. Silvio Rocha Corrêa da Silva pela disponibilidade, paciência e ajuda na realização da análise estatística deste estudo. À Profª. Drª Débora Fernandes Costas Guedes pela imensa ajuda e participação.