Microshear Bond Strength of High-viscosity Glass-ionomer to Normal and Caries-affected Dentin Under Simulated Intrapulpal Pressure.

OBJECTIVES

: The use of high-viscosity glass-ionomer cements (HVGICs) for atraumatic restorative treatment (ART) restorations is widely practiced with the advent of various HVGICs. However, the bonding of the latter to caries-affected dentin (CAD) should be validated, especially because it is the common substrate left after conservative caries removal following the ART approach. Hence, this study was carried out to evaluate the microshear bond strength (μSBS) of three HVGICs to normal dentin (ND) and CAD under intrapulpal pressure (IPP) simulation.

METHODS AND MATERIALS

: The occlusal enamel of 90 molars with mid-coronal caries was cut to expose flat dentin surfaces containing both ND and CAD. Dentin substrates (ND and CAD) were differentiated using visual, tactile, caries-detecting dye, and dye-permeability methods. Prepared crown segments were equally divided (n=30) according to the tested HVGICs into GC Fuji IX GP Fast, Fuji IX GP containing chlorhexidine, and zinc-reinforced ChemFil Rock HVGIC. Microcylinders of tested HVGICs were built up on both dentin substrates (n=30 for each tested HVGIC per each substrate) using starch tubes while the specimens were subjected to simulated IPP of 15 mm Hg. The μSBS test was conducted using a universal testing machine, and failure modes were determined using a scanning electron microscope. Data were statistically analyzed using two-way analysis of variance (ANOVA) with repeated measures, one-way ANOVA, and Bonferroni post hoc tests (α=0.05).

RESULTS

: For both dentin substrates (ND and CAD), the μSBS values of ChemFil Rock were significantly higher than those recorded for the other HVGICs. The μSBS values of each tested HVGIC to ND and CAD were not statistically different. Failure modes were mainly mixed.

CONCLUSIONS

: Zinc-reinforced HVGIC ChemFil Rock showed superior bonding to ND and CAD compared to the GC Fuji IX GP Fast and Fuji IX with chlorhexidine. However, each of the tested HVGICs showed comparable bonding to both dentin substrates (ND and CAD).