Evaluation of the marginal adaptation and debonding strength of two types of CAD-CAM implant-supported cement-retained crowns

Abstract

Background. Resin-based materials are becoming increasingly popular in implant dentistry even though there is not enough clinical data on the long-term success of such restorations on implant abutments. However, in-vitro data in relation to a clinically well-known lithium disilicate ceramic reference, may help to assess information about the expected performance. The purpose of this in vitro study was to evaluate the marginal adaptation and bond strength of nano-ceramic hybrid composite crowns cemented to stock cement retained abutments in comparison to those of lithium disilicate. Methods. Twenty abutment analogs were embedded into auto-polymerizing acrylic resin blocks. The blocks were divided into 2 groups according to the restorative crown material. Abutment analogs in both groups were scanned using a laboratory scanner, and the restorations designed, manufactured, and cemented over the corresponding group. All samples were tested for marginal adaptation and bond strength after storage for 24 hours at 37°C in 100% humidity. Results. Marginal gap and debonding force values were significantly different according to the type of material used (P<.05). Resin nano-ceramic crowns (Grandio blocs: VOCO GmbH) presented lower marginal gap values before (20.80±8.87μm) and after (52.11±22.92μm) cementation than lithium disilicate crowns (IPS e.max CAD: ivoclar vivadent). The debonding force value for resin nano-ceramic crowns (284.30±26.44N) was significantly higher than that for lithium disilicate crowns (253.30±33.26N). Adhesive failure mode was detected in all the specimens in both groups. Conclusions. The type of material used for implant-supported cement-retained crowns had a statistically significant effect on the marginal adaptation and bond strength. Resin nano-ceramic implant-supported cement-retained crowns had better marginal adaptation and higher bond strength than those manufactured using lithium disilicate. CLINICAL IMPLICATIONS Nano-ceramic hybrid composite can be an alternative to lithium disilicate when restoring single unit implant restorations.