The Accuracy of Implant Placement by Experienced Surgeons: Guided vs Freehand Approach in a Simulated Plastic Model

Purpose: To investigate the difference in accuracy between freehand and guided single-implant placement in situations with one or more missing teeth as performed by experienced surgeons. Materials and Methods: A total of 80 implants were placed by 10 experienced clinicians in the anterior site of maxillary models, made of polyamide by selective laser sintering and mounted in a dummy head. Each clinician performed the same four single-implant cases via freehand surgery and then with a three-dimensional fabricated SIMPLANT Guide. Two of the four cases had a single anterior tooth missing and the other two models represented a partially edentulous situation with several missing anterior teeth. For all 80 implants the average vertical, lateral, and angular deviations between the virtually planned and the achieved implant positions were measured based on a cone beam computed tomography (CBCT) scan. Results: Regarding the whole sample, angular deviation was 7.63 degrees for the freehand method and 2.19 degrees for guided surgery. The mean difference in angular deviation differed significantly between groups and was more than three times larger for the freehand method. Lateral deviation at the coronal level of the implants was 0.42 mm and 1.27 mm for the guided and freehand methods, respectively, and at the apical level was 0.52 mm and 1.28 mm for the guided and freehand methods, respectively; the deviation at the coronal and apical levels was significantly smaller for guided surgery than for the freehand method (P = .001). Differences in the depth deviation at the apical and coronal levels were smaller (guided vs freehand surgery at the coronal level: 0.54 mm vs 0.78 mm; apical level: 0.54 mm vs 0.73 mm) but also of statistical significance (P = .05). Differences in angular, global, and lateral deviations between the clinical situations (single vs multiple missing teeth) were also significantly smaller for guided surgery, whereas the deviations in depth did not reveal any statistically significant difference between both methods for the single-spaced units. Conclusion: In cases of one or more missing teeth in the anterior maxilla, guided surgery gives even experienced surgeons significantly higher predictability and accuracy than freehand surgery in transferring the virtual implant position to a model situation. Keywords: 3D-implant planning, freehand surgery, guided surgery, implant deviation