The International Tinnitus Journal

In Vitro Evaluation of the Fracture Strength of Four Contemporary CAD/CAM Resin Based Composite Materials Used in the Fabrication of Implant Supported Dental Crowns

Introduction: To compare the fracture strengths of crowns cemented to implant abutments using four monolithic resins based composite materials. Methods: For the monolithic crowns, 40 titanium implant abutments were attached on implant analogs, split into four groups of ten each. The groups were divided as follows: BRILLIANT Crios Resin-Based Composite Block (RBC) (COLTENE, Switzerland), VITA ENAMIC Polymer-Infiltrated Ceramic Networks (PICNs) (VITA Zahnfabric, Germany), GRANDIO Blocs Resin-Based Composite Block (RBC) (VOCO GmbH, Germany), Tetric CAD Resin-Based Composite Block (RBC) Tetric CAD (Ivoclar Vivadent, Liechtenstein). The abutments of all groups were scanned then crowns design was done with InLab software, then milled using InLab MC XL milling unit. Airborne-particle abrasion (Al2O3, 50 μm) was used on the external surfaces of the implant abutments. Then, saline containing adhesive was applied. The inner surfaces of each crown were surface treated as directed by the manufacturer, and then were cemented with a dual cured adhesive resin (RelyXTM Ultimate, 3M ESPE, Germany). Then stored in distilled water in laboratory incubator at 37°C for 1 week. After that thermo cycling was done at 5 to 55°C, 1minute cycle time for total 500 cycles. The crowns then were subjected to compressive axial loading until rupture at a 1 mm/min crosshead speed. In a universal testing machine (LARYEE, China), one-way ANOVA and LSD tests was then used to examine the data. Results: The highest mean value of fracture strength was obtained by GRANDIO Blocs (4.32 kN), followed by Tetric CAD (3.89 kN), BRILLIANT Crios (3.78 kN), VITA ENAMIC (3.01 kN) respectively, indicating statistically significant differences (p<0.01) among the different groups. Regarding the fracture mode, the majority of samples of all groups showed crown fracture and total deboning. Conclusion: Differences related to chemical composition and microstructure of the studied hybrid ceramics and resin composite CAD/CAM materials resulted in statistically significance difference in the fracture strength of the implant supported crowns.