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|Type:||Artigo de periódico|
|Title:||Long-term bond strength of restorations subjected to thermo-mechanical stresses over time|
|Abstract:||Purpose: To evaluate the long-term effect of thermal and mechanical cycling on dentin bond strength to cervical margins of Class II restorations. Methods: Sixty Class II slot cavities were prepared in bovine incisors. The cavities were restored with Single Bond and Z-250 composite according to manufacturer's instructions. The teeth were then divided into two groups (n=30): specimens that would receive thermo-mechanical load cycling (2,000 cycles 550degreesC/ 100,000 cycles of 50 N loading) (TM) and the control (C). Fifteen specimens from each group were tested at baseline and the remaining 30 specimens were stored in distilled and deionized water at 37degreesC and tested after 1 year. For microtensile evaluation, the restorations were sectioned perpendicular to the cervical bonded interface into 0.7 +/- 0.2 mm thick slabs. The slabs were further trimmed at the interface to 1.4 +/- 0.2 mm with a fine diamond bur to produce a cross-sectional surface area of ca. 1 mm(2). Specimens were then subjected to microtensile bond testing. The bond strength data were analyzed using two-way ANOVA and Fisher's PLSD test (P< 0.05). Fracture mode analysis was performed using SEM. Results: At baseline, bond strength of the TM group was significantly lower when compared to the C group (P= 0.012). However, after 1 year storage, a significant decrease in bond strength was observed for the C group compared to baseline. No significant differences were noted between the C and TM groups at 1 year. No interaction was observed between groups (C and TM) and storage time (P= 0.098). For the fracture mode evaluation, at baseline, mixed failure was predominant for the C group, and increased after TM. Decreased mixed failure was observed after 1-year storage, with a concomitant increase in interphase failure.|
|Editor:||Mosher & Linder, Inc|
|Appears in Collections:||Unicamp - Artigos e Outros Documentos|
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