Bonding of contemporary glass ionomer cements to dentin

Abstract

Objective: The objective of this study was to investigate the microtensile bond strength (μTBS) of contemporary glass ionomer cements (GIC) to sound coronal dentin. Methods: Three specimen teeth were prepared for each material tested: Fuji IX GP (GC), ChemFlex (Dentsply) and Ketac-Molar Aplicap (ESPE). GIC buildups were made according to the manufacturers' instructions. After being stored at 37°C, 100% humidity for 24 h, the teeth were vertically sectioned into 1 × 1 mm beams for μTBS evaluation. Representative fractured beams were prepared for scanning (SEM) and transmission electron microscopic (TEM) examination. Results: Results of the μTBS test were: Fuji IX GP (12.4 ± 8.6 MPa), ChemFlex (15.0 ± 9.3 MPa) and Ketac-Molar Aplicap (11.4 ± 7.7 MPa). One-way ANOVA and a multiple comparison test showed that ChemFlex had a statistically higher μTBS (p < 0.05). SEM fractographic analysis showed that the predominant failure modes were interfacial and mixed failures. The GIC side of the fractured beams revealed dehydration cracks, a high level of porosity, and voids with an eggshell-like crust. TEM analysis of the demineralized dentin sides of the fractured beams revealed the presence of an intermediate layer along the GIC-dentin interface. This zone was present on the fractured dentin surface in the case of interfacial failure, and beneath GIC remnants in specimens that exhibited a mixed failure mode. Significance: The findings suggest that the bonding of GIC to dentin is not weak and that the μTBS values probably represent the weak yield strengths of GICs under tension. © 2001 Academy of Dental Materials. Published by Elsevier Science Ltd. All rights reserved.