39^th Asia-Pacific Dental and Oral Care Congress

This study evaluated the shear bond strength (SBS) of experimental one-step self-etch adhesives containing three different concentrations of acidic monomer (GDMA-P) to sound dentin (SD) and caries-aff ected dentin (CAD). Microcosm biofilms were formed over dentin discs and cultivated under anaerobic conditions for 14 days. A biofi lm model was used with intermittent availability of 1% sucrose in a culture medium for 4 hours daily. Six groups were defi ned by diff erent GDMA-P concentrations (5%, 20% and 35%) and dentin type. Bovine dentin discs for each group (n=10) were included in acrylic resin and the adhesives were applied. An elastomer mold with cylindrical orifi ces (1.5 mm diameter) was used to obtain two cylinders of composite resin on the surface. Aft er 24 hours, the cylinders were subjected to SBS test in a mechanical testing machine. Data were analyzed by ANOVA and Student-Neuman-Keuls test (5%). Failure modes were observed under magnifi cation. SBS results were statistically diff erent between substrates. Mean±standard deviations to sound dentin (MPa) were: 5.62±1.90AB (5%), 4.82±2.3B (20%), 6.41±1.91A (35%) and to caries-aff ected dentin were: 3.81±1.46B (5%), 5.91±1.55A (20%) and 3.52±1.3B (35%). The group of 20% GDMA-P showed higher bond strength to caries-aff ected dentin than sound dentin. In all the groups adhesive failures were predominant.