Extent of Leaching of BADGE from Photopolymerized Oxirane-based Dental Composites

Studies have shown that photopolymerized oxirane-based dental composites to potentiallyhave desirable physical properties such as reduced polymerization shrinkage.  One prototype composite contained the oxirane/polyol resin of Cyracureä UVR-6105 (48 wt%) with poly(tetrahydrofuran (wt4%) in combination with bisphenol A diglycidyl ether (BADGE) (48%), which was formulated into composite containing 72.9-74.9 % quartz filler. Objective: To determine the amount of unreacted BADGE that may potentially leach out of the oxirane composite after polymerization.  Method: High performance liquid chromatography (HPLC) was used to analyze two extracts of the prototype oxirane composite.  The extraction solvents were acetone and an ethanol/saline (1:20) solution.  The cured composite disk specimens (15-mm diameter x 1-mm thick) were tested intact or after grinding with a mortar and pestle.  Composite specimens were exposed to the extraction solvent in glass vials at 37^oC for 30 sec. and 72 hours. Results: BADGE was not extracted by the ethanol/saline (1:20). BADGE was present in the acetone extracts, along with additional unidentified materials. Extracts of crushed composite disks in acetone yielded a ten-fold increase in the amount of BADGE (44 ppm) compared to the amount extracted from whole disks. Conclusion:  HPLC results indicatedthat BADGE could potentially leach from photocured composites into lipophilic microenvironments. This study was supported by NIH/NIDCR grant DE09696. mahlin.scott@lycos.com