Evaluation of Vertical Misfit of CAD/CAM Implant-Supported Titanium and Zirconia Frameworks

Purpose: This study compared the vertical misfit of fixed implant-supported titanium (Ti6Al4V) and yttria-stabilized tetragonal zirconia frameworks milled using the computer-aided design/computer-aided manufacturing (CAD/CAM) Zirkonzahn system. Materials and Methods: An aluminum mandibular master cast was used, and four analogs of the Regular CrossFit implant for straight multibase titanium alloy abutments (Institut Straumann) were fixed with self-curing acrylic resin in mandibular canine and second premolar tooth locations with the aid of a parallelometer. Scan abutments were placed over the four straight multibase Regular CrossFit abutments to determine their correct three-dimensional (3D) positioning in the virtual model. Implant frameworks were designed virtually, and five frameworks of each material (titanium alloy or yttria-stabilized tetragonal zirconia) were milled using the CAD/CAM system. Scanning electron microscope (SEM) images, with magnifications of 50×, 250×, and 1,000×, were obtained from three points on the buccal surface, three points on the lingual surface, and three points on the mesial surface of each abutment. The measurements were performed in the center of each of the thirds, thus defining points one, two, and three. The degree of vertical misfit at the framework-abutment interface was determined using ImageJ software and analyzed using the Student t test (P = .05). Results: The mean misalignment value was 6.011 ± 0.750 μm for the titanium group and 9.055 ± 3.692 μm for the zirconia group. Conclusion: Within the limitations of this study, there was no significant difference in vertical misfit between the titanium and zirconia implant frameworks produced using the CAD/CAM system. Regardless of the material used, the CAD/CAM frameworks achieved an adequate vertical fit. Keywords: computer-aided design, dental implants, dental materials, prostheses and implants, restorative dentistry