Variables affecting silicone-polymethyl methacrylate interfacial bond strengths.

PURPOSE This study investigated the effects of various polymerization methods and of various types of silane coupling agents on the interfacial bond strengths of Molloplast-B and of two types of heat-processed polymethyl methacrylate (PMMA). MATERIALS AND METHODS Standardized blocks of PMMA were processed and stored in 100% humidity for 14 days. Silicone of equal dimensions was flasked and processed with premixed and fresh-mixed silane coupling agents interposed. Processing utilized both a typical heated-water system and a dry-heat oven. Following recovery, the specimens were peel-tested at an angle of 180 degrees in an Instron machine. RESULTS There was no significant difference between the test variables of Lucitone (Dentsply/York Division, York, PA) versus Lucitone 199 (Dentsply/York Division), nor with wet versus dry heat polymerization methods. However, the mean bond strengths for premixed silane improved slightly in a wet polymerization environment. Conversely, fresh-mixed silane's mean bond strength increased slightly with dry-heat polymerization. CONCLUSIONS The bond strength between a methyl methacrylate denture base and a silicone soft liner varies only slightly when either Lucitone, Lucitone 199, or polymerization in a wet or dry environment is used. Under the conditions of this study, a fresh-mixed silane coupling agent produced a distinctly superior bond strength.