A clinically relevant validation method for implant placement after virtual planning

Abstract

To design a relevant method to compare the virtual planned implant position to the ultimately achieved implant position and to evaluate, in case of discrepancy, the cause for this. Five consecutive edentulous patients with retention problems of the upper denture received four implants in the maxilla. Preoperatively, first a cone-beam CT (CBCT) scan was acquired, followed by virtual implant planning. Then, a surgical template was designed and endosseous implants were flapless installed using the template as a guide. To inventory any differences in position, the postoperative CBCT scan was matched to the preoperative scan. The accuracy of implant placement was validated three-dimensionally (3D) and the Implant Position Orthogonal Projection (IPOP) validation method was applied to project the results to a bucco-lingual and mesio-distal plane. Subsequently, errors introduced by virtual planning, surgical instruments, and validation process were evaluated. The bucco-lingual deviations were less obvious than mesio-distal deviations. A maximum linear tip deviation of 2.84 mm, shoulder deviation of 2.42 mm, and angular deviation of 3.41° were calculated in mesio-distal direction. Deviations included errors in planning software (maximum 0.15 mm), for surgical procedure (maximum 2.94°), and validation process (maximum 0.10 mm). This study provides the IPOP validation method as an accurate method to evaluate implant positions and to elucidate inaccuracies in virtual implant planning systems.