A clinical evaluation of porcelain inlays

Sparse data are available concerning the survival rate of porcelain inlays or onlays to inform the dentist and address the expectations of patients. A total of 25 posterior porcelain inlays were inserted by two dentists at a private Danish clinic; the time elapsed since cementation was 20 to 57 months (average 40.4 months). Tooth preparations for MOD porcelain inlays were completed for 13 premolars and 12 molars but most did not include cuspal coverage. All inlays were constructed at the same commercial dental laboratory and according to the manufacturer's recommendations; they were etched and treated with silane before they were cemented. The cementation included etching of cavosurface enamel and treatment of the dentin with a dentinal bonding system. A thin layer of composite resin luting agent was applied to the tooth preparation before the porcelain inlays were cemented. The first 10 porcelain inlays were cemented with a light-curing composite resin cement and the remaining 11 with a dual-curing composite resin cement. Twelve of the 25 porcelain inlays failed and were replaced during the observation period. Ten failures were due to a fracture of the inlay, one was caused by secondary caries, and the final failure was attributed to a marginal gap between the inlay and proximal tooth surface. Porcelain inlays cemented with light-curing composite resin exhibited more failures (p = 0.05) than those cemented with dual-curing composite resin. In addition, more failures (p = 0.07) were recorded among inlays inserted in molars than among those in premolars.