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The aim of this research was to verify, in vitro, the effect of various porcelain surface treatments on the shear strength of orthodontic brackets bonded to porcelain and the mode of fracture after debonding. Eighty-eight samples of metallic supported feldspathic porcelain were randomly divided into four groups according to their surface preparation as follows: the porcelain was maintained intact (GI), roughened with a diamond bur (GII), etched with 10% hydrofluoric acid (GIII), or sandblasted with aluminum oxide (GIV). The specimens were treated with silane (Scothprime) and brackets were bonded with Concise. Each sample was subjected to a shear load at a crosshead speed of 1 mm/min and a recording was made at the point of failure. Bond strengths, adequate to withstand the application of orthodontic forces, were achieved in all groups. The Kruskal-Wallis statistical test showed no significant differences in bond strength between the groups (p>0.05). However, many more porcelain fractures occurred on deglazed porcelain. This study indicates that with the appropriate material selection, the silane/composite procedure alone may be adequate for bonding.

This work evaluated the remineralization of demineralized enamel of pits and fissures of human third molars sealed with a glass ionomer cement (Fuji IX, GC Corporation -Japan) or with a Bis-GMA sealant (DeltonDentsply). Ten volunteers participated in this in situ study that consisted of two thirty-day periods using intra-oral devices, with a week's interval in between. Four experimental treatment procedures and one control were randomly assigned to the volunteers' specimens: Group I, no treatment, control; Group II, artificial caries process; Group III, same treatment as Group II, but sealed with Delton (Dentsply); Group IV, same treatment as Group II, but sealed with Fuji IX (GC Corporation -Japan); Group V, same treatment as Group II and no sealing. Groups I and II were not submitted to the oral environment and served as controls. After a period of 30 days in the oral environment, the specimens were removed from the devices, embedded in acrylic resin, ground flat and polished. Then, Knoop hardness tests were performed, with a 25 g static load applied for 15 seconds. The measurements were made from the base of the fissure up to an opening of 600 µm, pre-established between the inclines of the cusps. Three indentations were then made, located at 25, 75, and 125 µm in depth from the outer enamel margin and 100 µm apart from each other (Micromet 2003). The Brieger F and Bonferroni's tests were applied to the measurements. It was concluded that sealing with the glass ionomer cement Fuji IX was capable of making the enamel of pits and fissures more resistant by increasing the value of Knoop hardness. DESCRIPTORS: Glass ionomer cements; Dental enamel; Hardness. RESUMO:Esta pesquisa avaliou a remineralização do esmalte de fóssulas e fissuras de terceiros molares humanos previamente desmineralizados e selados com um cimento de ionômero de vidro (Fuji IX, GC Corporation -Japão) ou com um selante de Bis-GMA (Delton-Dentsply). Dez voluntários participaram deste estudo in situ que consistiu de dois períodos de 30 dias com intervalo de 1 semana entre eles, usando dispositivos intra-orais. Quatro procedimentos de tratamento experimental e um controle foram aleatoriamente distribuídos entre os espécimes que foram usados pelos voluntários: Grupo I, sem qualquer tratamento, controle; Grupo II, processo de cárie artificial; Grupo III, igual ao Grupo II, porém selados com Delton (Dentsply); Grupo IV, igual ao Grupo II, porém selados com Fuji IX (GC Corporation -Japão); Grupo V, igual ao Grupo II, mas sem selamento. Os Grupos I e II não foram submetidos ao meio bucal e serviram de controle. Após um período de trinta dias no meio bucal, os espécimes foram removidos dos dispositivos, montados em resina acrílica, planificados e polidos. Realizaram-se então testes de Dureza Knoop com carga estática de 25 g por 15 segundos. As medidas foram realizadas desde a base da fissura até uma abertura de 600 µm, preestabelecida entre os planos inclinados das cúspides. A cada 100 µm, três penetrações foram realizadas: a primeira a 25 µm...

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