In vitro dentin bond strength and microleakage of nano-ionomer restorative in comparison with compomer

The aim of this study was to evaluate the microleakage and microtensile bond strength (mu TBS) of a nano-ionomer restorative in comparison with a compomer in primary teeth. Standardised class V cavities were prepared at the cementoenamel junction on the buccal and lingual surfaces of 10 teeth to test microleakage of materials. Cavities were randomly distributed into one of two groups for restoration with either a nano-ionomer RMGIC (Ketac N100; 3M ESPE, St Paul, MN, USA) or a compomer (Dyract Extra; Dentsply, Konstanz, Germany). After thermocycling, specimens were immersed in a 0.5% aqueous solution of basic fuchsine for 24 h at 37 degrees C. After sectioning buccolingually, dye penetration scores were determined under a stereomicroscope. Occlusal surfaces of 20 teeth were cut to expose a flat dentin surface and abraded with wet 600 grit silicon carbide paper to evaluate mu TBS of materials. Specimens were randomly distributed into two groups and the restoratives were applied to all dentin surfaces according to manufacturer's instructions. Specimens were stored in distilled water at 37 degrees C for 24 h and tested for mu TBS (1 mm min(-1)). Failure modes were determined under a stereomicroscope. Differences in microleakage between groups were not statistically significant (p>0.05). Bond strength of Ketac N100 (13.8 MPa) was found significantly lower than Dyract Extra (44.6 MPa) (p<0.05). While adhesive failure (65%) was the most common failure type in Ketac N100 group, cohesive resin (40%) and adhesive failures (40%) were generally observed in Dyract Extra. There was no significant relationship between bond strength and failure type (p>0.05). Although nano-ionomer restorative presented lower bond strength compared to compomer, no difference was observed between microleakage of the two materials.