title: Mutual influence of cholesterol esterase and pseudocholinesterase on the biodegradation of dental composites.
abstract: It has been demonstrated that human saliva contains cholesterol esterase (CE)- and pseudocholinesterase (PCE)-like hydrolase activities. While PCE has been shown to preferentially degrade triethylene glycol dimethacrylate (TEGDMA) and its derivatives, CE has a greater catalytic effect on the breakdown of bis-phenol-A-diglycidyl dimethacrylate (bisGMA) components in composite dental resins. The current study seeks to determine if there is a mutual influence between the different esterases with respect to the biodegradation of resin composite. Photopolymerized model composite resin samples (containing 60% by weight fraction of silanated barium glass filler) based on bisGMA/TEGDMA (bis) or urethane-modified bisGMA/TEGDMA/bisEMA (ubis) monomers were incubated in buffer, CE and/or PCE solutions (pH=7.0, 37 degrees C) for 8 and 16 days. The incubation solutions were analyzed for degradation products using high-performance liquid chromatography, UV spectroscopy and mass spectrometry. In the bis system, higher amounts (p<0.05) of a bisGMA derived product, bishydroxy-propoxyphenyl-propane (bisHPPP), were detected in the combined enzyme group as compared to the sum of the two individual enzyme groups. In the ubis system, similar comparisons showed that higher levels (p<0.05) of bisHPPP were detected in the combined group at 8 days while higher amounts (p<0.05) of a bisEMA derived product, ethoxylated bis-phenol A, were detected in the combined group at 16 days. The study concluded that CE and PCE act synergistically to increase the biodegradation of both composite resin materials.
authors.affiliation: Prosthodontics Discipline, Faculty of Dentistry, University of Toronto, Ont., M5G 1G6, Toronto, Canada.
authors.forename: Y
authors.initials: Y
authors.lastname: Finer
authors.forename: F
authors.initials: F
authors.lastname: Jaffer
authors.forename: J P
authors.initials: JP
authors.lastname: Santerre
mesh_terms: D000180:Acrylic Resins / Q000737:chemistry; D001673:Biodegradation, Environmental; D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002091:Butyrylcholinesterase / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry; D004357:Drug Synergism; D004789:Enzyme Activation; D004795:Enzyme Stability; D006801:Humans; D006868:Hydrolysis; D011092:Polyethylene Glycols / Q000737:chemistry; D011109:Polymethacrylic Acids / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D012463:Saliva / Q000737:chemistry; D002787:Sterol Esterase / Q000737:chemistry*
chemical_list: D000180:Acrylic Resins; C029012:Composite Dental Resin; D003188:Composite Resins; D003764:Dental Materials; D011109:Polymethacrylic Acids; D011140:Polyurethanes; C020946:triethylene glycol dimethacrylate; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; D002787:Sterol Esterase; D002091:Butyrylcholinesterase