Comparison of Fracture Resistance in Two Marginal Designs in IPS e.max Restorations

Introduction: One of the problems of all ceramic restorations is their probable fracture against the occlusal force. The aim of the present study was to compare the effect of two marginal designs (shoulder & chamfer) on the fracture resistance of all ceramic restorations, IPS e.max. Materials & Methods: On an extracted first maxillary premolar, a chamfer 50' margin (0.8 mm) was prepared. Twenty impressions were taken using polyvinyl siloxane. Then the chamfer was converted into shoulder 90' (1 mm). After impressing, epoxy resin dies were fabricated. Impressions of each epoxy resin die were taken and poured with die stone. Next, twenty Press crowns and twenty Zircad crowns were made on stone dies and cemented on resin dies. After that, samples underwent a fracture test with a universal testing machine. Data were analyzed by one-way ANOVA test. Results: The mean value of fracture resistance was 1426N, for the chamfer Zircad samples 1361.3N, for the shoulder Zircad samples 1059.9N, for the chamfer Press samples and 1295.8N, for the shoulder Press samples. The One-way ANOVA test revealed no difference among the groups (P=0.095). Conclusion: After porcelain application, marginal design does not affect fracture resistance of single IPS e.max posterior crowns.