Influence of sterilization on the retention forces of lithium disilicate and polymer-infiltrated ceramic-network crowns bonded to titanium base abutments: An in-vitro study

Objectives: The aim of this study was to evaluate the effect of sterilization on the retention forces of lithium disilicate (LD) and polymer-infiltrated ceramic network (PICN) crowns bonded to titanium base (Ti -base) abutments.Materials and methods: Forty LD and 40 PICN crowns were milled and then bonded to 80 Ti -bases with two resin composite cements: Multilink Hybrid Abutment (mh) and Panavia V5 (pv) for a total of 8 groups (n = 10). Half of the specimens (test) underwent an autoclaving protocol (pressure 1.1 bar, 121 degrees C, 20.5 min) and the other half not (control). Restorations were screw-retained to implants, and retention forces (N) were measured with a pull -off testing machine. The surfaces of the Ti -bases and the crowns were inspected for the analysis of the integrity of the marginal bonding interface and failure mode. Student's t -test, chi-square test, and univariate linear regression model were performed to analyze the data (alpha= 0.05).Results: The mean pull -off retention forces ranged from 487.7 +/- 73.4 N to 742.2 +/- 150.3 N. Sterilized groups showed statistically significant overall higher maximum retention forces (p < .05), except for one combination (LD +mh). Sterilization led to an increased presence of marginal gaps and deformities compared to no-sterilization (p < .001), while no statistically significant relationship was found between failure mode and sterilization (p > .05).Conclusions: Sterilization may have a beneficial effect on the retention forces of LD and PICN crowns bonded to titanium base abutments, although it may negatively influence the integrity of the marginal bonding interface.