Effect of abutment angulations on fit accuracy of screw-retained zirconia fixed partial denture

Abstract

Abstract Background: Passivity of an implant-supported restoration is fundamental for its long-term survival. The aim of this study was to assess the accuracy of interface fit of screw-retained implant-supported zirconia fixed partial denture with different abutment angulations. Methods: 50 epoxy resin casts were randomly assigned into 5 groups (n=10) according to the implant placement angulations: group I; the casts received two non-tilted implants with two straight abutments, group II; the casts received a non-tilted implant with straight abutment and 17.5° tilted implant with 17.5° angled abutment, group III; the casts received a non-tilted implant with straight and 35°tilted implant with 35° angled abutment, group IV the casts received two 17.5-degree tilted implants with 17.5° angled abutments, and group V; the casts received two 35-degree tilted implants with 35° abutments. For each cast, a 3-unit zirconia fixed partial denture was fabricated. Titanium caps were bonded to corresponding zirconia fixed partial denture. For each specimen, the accuracy of fit was assessed by measuring the gap at the interface when one prosthetic screw was tightened, and when both prosthetic screws were tightened. The data were analyzed using Kruskal Wallis test followed by post-hoc dunn’s test (P<.05). Results: When the canine prosthetic screw was tightened, the median of the gab at central interface showed statistical significant difference (P=.037) between studied groups. Also, a significant difference was revealed between Group I and Group III (P=.002), Group III and Group IV (P=.026), and Group IV and V (P=.035). When central prosthetic screw was tightened, the median of the gab at canine interface showed statistical significant difference (P=.02) between studied groups. Also, there was a significant difference between Group I and Group II (P=.001), Group I and Group III (P=.02), and Group I and V (P=.04). However, there were no significant differences between studied groups when both prosthetic screws were tightened. Conclusions: The screw-retained zirconia fixed partial denture has interface fit within the clinical acceptable value regarding the precision of fit. The use of angled abutment endanger the accuracy of interface fit of screw-retained implant-supported zirconia fixed partial denture.