Avaliação da resistência ao microcisalhamento na interface de união entre a porcelana feldspática e esmalte

• Ano de defesa: 2013
• Autor(a) principal: Rodrigo Cavalcanti Nascimento
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de Minas Gerais; UFMG
• Palavras-chave em Português: Cimentação; Resistência ao Cisalhamento; Porcelana dentária; Cerâmicas; Facetas dentárias; Envelhecimento; Resistência ao cisalhamento; Microscopia eletrônica de varredura; Cimentos dentários; Restauração (Odontologia); Adesivos dentários
• Link de acesso: http://hdl.handle.net/1843/ZMRO-9BPJ9J

This study aimed to assess the influence of the type of activation of the resin cement agent, the thickness of restorative material and the aging of restoration on bond strength to feldspathic porcelain enamel by means of microshear testing. Sixty feldspathic porcelain ceramic blocks (VITA VM7) were obtained in the color A1, with dimensions of 5x5x10mm. The surface was treated with 10% hydrofluoric acid, silane and adhesive system. Parallel to the treatment of the porcelain, sixty freshly extracted human molars were flattened in their vestibular surface and treated with 37% phosphoric acid and adhesive system. Afterwards, the ceramic blocks were divided according to the thickness of porcelain: 1 mm (G1) or 2 mm (G2) and were cemented with resin cements with different activation types: A - photopolymerizable, B - dual and C - chemical. After cementation, they were again divided into two subgroups: (I) were submitted to microshear testing after cementation; (T) were stored in distilled water at 37°C for 30 days and then underwent aging process by thermal cycling (3500x, 4°C/60°C). All Bodies of Evidence (BE) were taken to the machine cuts (Isomet) to obtain specimens with 1 ± 0.1 mm². The specimens were mounted on the testing machine (Bisco) associated with a device adapted to microshear testing. The maximum load to failure (N) was recorded and the calculation of the area of the specimen was carried out to obtain the bond strength in MPa: A1I - 12.35 (1.77), B1I - 11.42 (0.23), A2I - 11.68 (2.63), B2I - 10.98 (1.07), CI - 10.14 (1.57), A1T - 9.93 (0.92), B1T - 10.02 (1,56), A2T - 9.65 (1.17), B2T - 10.88 (2.26), CT - 9,97 (2,35). The ANOVA with 95 % confidence revealed that resistance to microshear union was not influenced by the thickness of porcelain and resin cement. The average resistance to microshear was significantly greater in the groups immediatelly fractured, when compared to the delayed group. The failure modes were identified in stereoscopic microscope (Stemi DV4) and a unit of each failure mode was analyzed in a Scanning Electron Microscope (Quanta 200). Adhesive fracture predominated in all groups, regardless of the variables displayed.