Accuracy of the evaluation of implant position using a completely digital registration method compared with a radiographic method

Statement of problem. Conventional radiographic methods are widely used to evaluate the clinical accuracy of implant position. However, such methods require a second computerized tomography (CT) scan and manual registration between presurgical and postsurgical CT data. The alignment errors cannot be calculated. Purpose. The purpose of this clinical study was to introduce a completely digital registration method to evaluate the clinical accuracy of implant position. The digital registration method was then compared with the radiographic method in evaluating accuracy. Some of the alignment errors produced in the digital registration procedures were recorded. Material and methods. A total of 32 implants from 19 patients with sufficient bone volume were enrolled in the study, and all implant surgeries were conducted by one experienced practitioner. Before the surgery, a cone beam computerized tomography (CBCT) scan was made for each patient along with a diagnostic impression to design the ideal implant position using the Simplant software. After the surgery, the postsurgical implant position was determined using an optical scan of the dentition cast and a series of custom registration models (the digital registration method). A simulated cylinder was designed using the Geomagic Studio software to represent the implant, and the deviation of the ideal and postsurgical implant position was calculated. The accuracy evaluated by the 2 methods was also compared. The parameters of the entrance point, apical point, and axis were recorded for each implant. A part of the alignment errors in the digital registration was calculated automatically and recorded. One sample t test and paired t test were conducted by using a statistical software program. Results. The mean deviation between the ideal and postsurgical implant positions evaluated using the digital registration method was 0.84 +/- 0.57 mm for the entrance point, 1.03 +/- 0.78 mm for the apical point, and 4.52 +/- 2.37 degrees for the angulation. No significant difference was found between the accuracy evaluated by the digital registration method and the radiographic method (P>.05). In the digital registration procedure, the alignment error was 0.03 mm for the registration model and 0.29 mm for the dentition. Significant differences were found in the alignment procedure of the impression cylinder (P<.001) and dentition (P<.001). The average positive and negative errors were +0.09 and -0.19 mm for the simulated cylinder of the ideal implant and +0.08 and -0.15 mm for the simulated cylinder of the postsurgical implant. Conclusions. The precision of the digital registration method could be accepted in clinical applications. No significant difference was found between the digital registration method and the radiographic method in evaluating the clinical accuracy of the implant position. The digital registration method was able to control and minimize the alignment errors produced during data processing.