Evaluation of the influence of crown material and abutment material on the retrievability of cement-retained implant-supported crowns with lingual retrieval slots

Abstract

Background and goal: The ability to the retrieve implant-supported crowns is important to solve mechanical, biological and aesthetic problems. The aim of this study was to evaluation of the influence of crown material and abutment material on the retrievability of cement-retained implant-supported crowns with lingual retrieval slots. Materials and methods: In this in-vitro study, 24 samples were examined in three groups. Group 1: base metal crowns cemented to titanium abutments (n=8), Group 2: zirconia crowns cemented to titanium abutments (n=8), Group 3: zirconia crowns cemented to zirconia abutments (n=8). All abutments were have rectangular ledges (2mm*1mm) for the retrieval slots and all crowns were have lingual retrieval slots (2mm*1mm), coronally to abutment ledge. All abutments, zirconia crowns and resin copings (for casting base metal crowns) were be fabricated using a CAD/CAM system. The abutments and crowns were be cemented together with RMGI cement, followed by 24 hours in demineralized water at room temperature. Using a custom-made device we were record the maximum torque (N.cm) required to remove the crowns. Data were analyzed by SPSS 20 software using t-test. (P value≤0.05) Results: The removal torque in group two (zirconia crowns cemented to titanium abutments) was significantly lower than group one (base metal crowns cemented to titanium abutments). Mean removal torque for each group was 38.75±3.53 (BM-Ti) , 31.75±2.86 (Zr-Ti) and 37.33±11.9 (Zr-Zr). Discussion The influence of crown material and abutment material on the retrievability of cement-retained implant-supported crowns with lingual retrieval slots is significant.