An In Vitro Model to Evaluate the Accuracy of Guided Surgery Systems

Purpose: An in vitro model was developed and tested to evaluate the precision of guided implant systems. The accuracy of dental implants placed with a flapless technique was analyzed using a stereolithographic template in vitro. Differences between the virtual and actual positions of the implants were measured. Materials and Methods: Six polyurethane mandibles with artificial silicone gums were fabricated, and each was fitted with an individual computed tomography (CT) guide. Stereolithographic guides were created using computer-aided design/computer-assisted manufacturing technology and virtual planning software. All stereolithographic guides had four holes for stabilization pins and three holes for cylindric implants. After implant placement, the mandibles were subjected to another CT scan to compare the actual implant positions with the planned positions. The pre- and postimplantation CT images were superimposed using digital processing image software to evaluate the linear and angular deviations between the virtual planning data and the surgical results. Results: The mean angular discrepancy between the virtual and actual positions of the 18 placed implants was 2.16 ± 0.92 degrees. Among the placed implants, 66.7% were situated a mean of 0.38 ± 0.03 mm apical to the planned vertical position, and 33.3% were situated 0.39 ± 0.03 mm coronal to the planned position. Conclusions: Within the limitations of the present study, this tool showed promising accuracy in virtual implant placement. Keywords: accuracy of computer-generated templates, computed tomography, dental implants, flapless surgery