Bis-GMA-containing resin-composites undergo biodegradation by human saliva derived esterases, yielding Bis-hydroxy-propoxy-phenyl-propane (Bis-HPPP). The hypothesis of this study is that the exposure of dental restorations to saliva-like esterase activities accelerates marginal bacterial microleakage. Resin-composites (Scotchbond, Z250, 3M) bonded to human dentin were incubated in either buffer, or dual-esterase media (pseudocholinesterase/cholesterol-esterase; PCE-CE) with activity levels simulating 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 by confocal laser scanning microscopy. Bis-HPPP production, as well as depth and spatial volume of bacterial cell penetration within the interface increased with incubation time. Biodegradation and bacterial microleakage were significantly higher for 30 and 90 day PCE-CE vs. buffer incubated groups (p<0.05). Conclusion: An overall decline in interfacial integrity was observed following exposure to human saliva-like esterases over time.
| Identifer | oai:union.ndltd.org:TORONTO/oai:tspace.library.utoronto.ca:1807/18775 |
| Date | 12 February 2010 |
| Creators | Kermanshahi, Sanaz |
| Contributors | Finer, Yoav |
| Source Sets | University of Toronto |
| Language | en_ca |
| Detected Language | English |
| Type | Thesis |
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