Biodegradation of commercial dental composites by cholesterol esterase

The research literature suggests that current dental polymeric composites a re not chemically inert at the material/biological interface. Several studi es have investigated the process of "biodegradation" on dental composites i n the presence of enzymes, by monitoring changes in weight loss and surface hardness properties. However, it is hypothesized that these methods can pr ovide an erroneous measure of biochemically induced degradation, since they are less sensitive to molecular events and lack the ability to provide che mical information. Knowledge of the latter is important because it relates to the biological significance of biodegradation, i.e., the identification and quantification of released compounds that may be capable of influencing cell, bacteria, or enzyme function. It was the objective of this study to compare three methods (weight loss, surface microhardness, and liquid chrom atography combined with mass spectrometry) for their ability to measure the effect of enzyme-induced biodegradation on three commercial composite resi n materials. The enzyme was cholesterol esterase, and the composites were S ilux Plus XL, Z100 A2 (3M),and TPH XL (L.D. Caulk). Biodegradation was read ily detected by liquid chromatography, and its sensitivity was shown to be substantially greater than that of weight loss or surface hardness measurem ents, although surface hardness measurements did show some agreement with l iquid chromatography data. The data also indicated that the levels and dist ribution of released degradation products can vary substantially from one p roduct to the next, and that this merits further investigation if the poten tial impact of different commercial restorative materials on cell and bacte ria function is to be assessed.