Micro-mechanical bond strength tests for the assessment of the adhesion of GIC to dentine

Background. The aim of this study is to critically evaluate the bond strength (BS) of Glass-Ionomer Cements (GIC) to dentine with microtensile (mu TBS) and microshear (mu SBS) BS tests by assessing their rankings and failure patterns. Methods. Samples were made on flat dentine surfaces and submitted to mTBS and mSBS. The materials used were: high viscosity GIC (Ketac (TM) Molar Aplicap-KM), resin-modified GIC (Fuji II-FII), nano-filled resin-modified GIC (Ketac (TM) N100-N100) and an etch-and-rinse adhesive system with a composite resin (Adper (TM) Single Bond 2 and Z100 (TM)-Z100). All tests were performed with a Universal Testing Machine (24 h water storage, crosshead speed of 1 mm/min). Debonded surfaces were examined with a stereomicroscope (x40) to identify the failure mode. The data was analyzed with two-way ANOVA (p < 0.05) and LSD test. Results. Means were statistically different regarding the tests and materials, indicating that values for BS obtained for each material depend on the test performed. Failure analysis revealed that failures produced by mTBS were mainly cohesive for KM and FII. mu SBS failures were mainly adhesive or mixed for all materials. For the mTBS, the rank was Z100 > FII > KM = N100, whereas for the mSBS it was Z100 = FII = KM > N100. Conclusion: It may be concluded that distinct micro-mechanical tests present different failure patterns and rankings depending on the material to be considered.

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