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

Abstract

Background. The aim of this study is to critically evaluate the bond strength (BS) of Glass-Ionomer Cements (GIC) to dentine with microtensile (μTBS) and microshear (μSBS) BS tests by assessing their rankings and failure patterns. Methods. Samples were made on flat dentine surfaces and submitted to μTBS and μSBS. The materials used were: high viscosity GIC (Ketac^™ Molar Aplicap-KM), resin-modified GIC (Fuji II-FII), nano-filled resin-modified GIC (Ketac^™ N100-N100) and an etch-and-rinse adhesive system with a composite resin (Adper^™ Single Bond 2 and Z100^™-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 (×40) 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 μTBS were mainly cohesive for KM and FII. μSBS failures were mainly adhesive or mixed for all materials. For the μTBS, the rank was Z100 > FII > KM = N100, whereas for the μSBS 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.

Key Words::

• adhesion
• bond strength
• glass-ionomer cements
• microshear
• microtensile

Acknowledgments

The authors wish to thank Mrs Gianne dos Santos and Dr Mariana Braga for their statistics assistance. The authors would like to express their gratitude to 3M ESPE and GC Europe for kindly donating the materials used in this study. Furthermore, the authors want to thank Marcio Vivan Cardoso for his valuable comments and Thiago Saads de Carvalho for English revision and CAPES for financial support.

Declaration of interest: The authors report no conflicts of interest. The authors alone are responsible for the content and writing of the paper.