Resistencia e morfologia da união de cimentos resinosos dual, autopolimerizavel e auto-adesivo a dentina / Bond strength and interface morphology of dual-cure, auto-cure and self-adhesive resin cement to dentin

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The aim of this study was to evaluate bond strength and the interface morphology between human dentin and resin cements. Oclusal surfaces of 20 third molars were removed and middle dentin was finished with #600 grit SiC. Circular, 2mm thick, indirect composite resin restorations (Sinfony) were made and sandblasted with aluminum oxide and then silanized. Teeth were divided in five groups according to luting technique: Group I - Rely X Unicem/ light-cure; Group II - Rely X ARC/ Single Bond 2/ light-cure; Group III - C&B Cement/ All Bond 2; Group IV - Rely X ARC/ Single Bond 2/ self-cure and Group V - Rely X Unicem/ self-cure. After cementation the teeth/restoration samples were stored in distilled water for 24 hours at 37oC and cut into beam specimens with 0.8±1.0mm2 cross-sections and microtensile tested after 24 and 30 days using a universal testing machine. Fracture patterns were observed and classified by SEM. Results were submitted to ANOVA and Tukey s Test to compare groups and pared t-test to compare the storage times of 24hours and 30 days (p<0,05). To analyze interface morphology, 2mm thick flat dentin discs were obtained. After cementation according to the experimental groups the dentin discs were cut vertically and embedded in epoxy resin for the procedures of finishing and gold-sputter. Results revealed that groups III, IV and V presented statistically significant bond strength increase after a storage period of 30 days. Light-cure groups revealed greater bond strength values at the storage times of 24hours and 30 days. SEM fracture pattern evaluation revealed a predominance of cohesive fractures in cement for groups I and V at 24 hours and 30 days. Group II revealed a higher frequency of mixed fractures which were cohesive in cement, hybrid layer and adhesive at 24 hours and cohesive in cement at 30 days. Group III presented more cohesive fractures at the hybrid layer at 24 hours and 30 days while group IV showed a predominance of mixed fractures which were cohesive in cement, hybrid layer and adhesive at 24hours and 30 days. While the morphologic analysis of bonded areas for the self-adhesive cement Rely X Unicem did not reveal the formation of a hybrid layer, the dual-cure cement Rely X ARC/Single Bond 2 and the self-cure cement C&B Cement/All Bond 2 presented hybrid layers with similar morphology.

ASSUNTO(S)

resistencia a tração cementation materiais dentarios dental materials cimentação tensile strength

ACESSO AO ARTIGO

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