Comparison of strains produced in a bone simulant between conventional cast and resin-luted implant frameworks

Complete-arch implant prostheses continue to exhibit horizontal and vertical misfit between frameworks and abutments. It has been suggested that these gaps may be eliminated and that restoration-induced stresses may be reduced by luting frameworks to screw-retained abutments intraorally. This study measured and compared the strains generated by clinically acceptable, conventional frameworks were made from a single master cast representing a bone simulant model of an edentulous mandible with five Nobel Biocare implants and 4-mm abutments. Two strain gauges were also embedded in the bone simulant model to measure strains at two locations. Resin-luted frameworks were made by securing abutments to the clinical model with five gold slot screws tightened to 10 Ncm. Strain-indicator readings were recorded at a standardized time following the initial fastening of each prosthesis (n = 3). Mean principal strains were determined and compared using a one-way repeated measures analysis of variance. A statistically significant difference was found in the principal strains between the conventional cast and the resin-luted frameworks. Overall, there was a decrease in the magnitude of strain for the resin-luted frameworks. Intraoral luting of frameworks may decrease the strains produced in the bone around implants.