INTERFACIAL GAPS OF RESIN CEMENTED CERAMIC INLAYS

A method was developed for measuring presence, location and extent of interfacial contraction gaps of resin-cemented ceramic inlays in denti n cavities. Cylindrical ceramic inlays were cemented using one of 12 c ommercially available resin composite cements to make a film thickness of 200-mu m. Cross-sections revealed absence of marginal gaps but con traction gaps occurred at all dentin-cement interfaces at the cavity f loors and ranged from 1.6 to 7.1 mu m. This was equivalent to 0.8-3.5% of the cement film thickness and was 3-10 times greater than the wall -to-wall contraction in percent observed when resin composites are use d as filing materials in 3-5 mm butt-joint dentin cavities. The result s support the theory that contraction gaps developing adjacent to thin films of resin cements reach a size equivalent to the cement film thi ckness multiplied by the volumetric polymerization shrinkage of the ce ment.