FRACTURE RESISTANCE OF CEMENTED AND INTEGRATED CERAMIC CROWNS SUPPORTED ON ZIRCONIA IMPLANT ABUTMENTS (IN VITRO STUDY)

Abstract

Introduction: Even-though the demand for esthetics amplified the popularity of all-ceramic restorations, failures are reported at the interface between zirconia core and ceramic-veneer. Objectives: Comparing fracture resistance and mode of failure of cemented and integrated ceramic crowns supported on zirconia implant abutments. Materials and Methods: Cast having missing upper first premolar; was chosen. Silicone mold was made to duplicate fifteen polyurethane models. Clear surgical guide was fabricated for precise insertion of implant analogue. Models were divided into three groups (n=5). Group I (cemented crowns) Group II(integrated crowns with composite plug) Group III(integrated crowns with ceramic plug). Group I: Optical impression of zironia abutment was made then crowns were designed, milled, crystallized, and glazed. Then crowns were cemented using resin cement. Group II and III crowns were constructed using same technique as Group I but with 2 mm occlusal hole. CAD-on was used to join crowns onto abutments. Group II screw-holes were closed using composite resin, while Group III screw holes were scanned, designed, milled using Emax-CAD, then cemented using resin cement. Specimens were subjected to cyclic loading machine for 120,000 cycles, then attached to universal testing machine by cross-head speed (0.5mm/min). Specimens were examined using stereomicroscope and scanning electron microscope. Results: Highest mean fracture load value was GroupI (901.4±54.90)N followed by Group II (790.7±187.4)N then Group III (621.5±97.42)N. Only Group I and III showed significant difference.(P2*=0.011) Conclusions: Cemented crowns showed significant superior fracture resistance than integrated crowns with ceramic plug, and no significant difference with integrated crowns with composite plug.