| Bis-GMA-containing resin-composites undergo biodegradation in human saliva, yielding Bis-hydroxy-propoxy-phenyl-propane (Bis-HPPP). This may compromise the integrity of the resin-tooth interfacial interface, contributing to bacterial microleakage. The objective of this work was to determine whether the biodegradation of resin-dentin restorative margins and bacterial microleakage are correlated with eachother. Resin-composites (Scotchbond, Z250, 3M) bonded to human dentin were incubated in either buffer, or dual-esterase media (pseudocholinesterase/cholesterol-esterase) with activity levels matching that of human saliva, for up to 90 days. Incubation solutions were analyzed for resin degradation by-products using high-performance liquid-chromatography. Post-incubation, specimens were suspended in a chemostat-based biofilm fermentor cultivating Streptococcus mutans NG8 for 7 days. Bacterial microleakage was assessed through confocal laser scanning microscopy. Bis-HPPP production, as well as depth and volume of bacterial cell penetration within the interface were higher at 30 and 90 days PCE-CE incubation vs. buffer incubation (p<0.05). A high correlation (R 2=0.97) was found between Bis-HPPP and cumulative interfacial bacterial count. An overall decline in interfacial integrity was observed following exposure to human saliva-like esterases over time. |
