The accuracy of static Computer-Assisted Implant Surgery using a drill-key guiding system in a partially edentulous models

Introduction Discrepancies between planned and actual implant positions are the result of cumulative errors occurring at different stages of the sCAIS workflows. Deviations from the planned implant positions can compromise treatment or lead to complications related to implant positioning. Different locations of implantation sites of partial edentulism are characterized by distinct distribution and morphology of surrounding teeth. Aim This study aimed to evaluate the accuracy of static guided implant surgery in different implantation sites of partially edentulous anatomical models. Methods Two prototype anatomical models of partially edentulous maxillae were digitally designed. Dental models simulated implantation sites in six different edentulous areas: anterior extended (AntExt), anterior single-tooth gap (AntSTG), proximal posterior single-tooth gap (ProPosSTG), distal posterior single-tooth gap (DisPosSTG), proximal and distal sites in distal extension (ProDE and DisDE, respectively). Ten polyamide-12 dental models were fabricated using a SLS technology. For each model full-arch tooth-supported surgical guides were designed and 3D printed. A total of 70 replica implants were placed in 7 designated implantation sites. Standard Tesselation Language (STL) datasets of planned and post-op implant positions were uploaded to the 3D inspection software. Each dataset with actual implant positions was superimposed with reference model. To evaluate the deviations between planned and actual implant positions 3D crestal, 3D apical, and angular distances were measured. Statistical analysis was conducted via one-way analysis of variance and Kruskall-Wallis H test. Pairwise comparisons were performed using Tukey HSD and Dunn's procedures respectively, with statistical significance accepted at the p < 0.003 level after a Bonferonni correction. Results The overall 3D crestal, 3D apical, and angular deviations did not exceed the recommended safety margins. Statistical analysis revealed significant differences between the tested groups of implantation sites. The mean 3D crestal (0.41 mm ± 0.17) and 3D apical (0.59 mm ± 0.26) deviations at the AntExt site were significantly lower (p < 0.001) compared to all other implantation sites. The median angular deviations (1.52° [1.12 – 2.11]) in the AntExt group were also significantly lower (p < 0.001) compared to the ProPosSTG (3.52° [2.59 – 4.96]), DisPosSTG (6.06° [5.03 – 6.49]), and DisDE (4.23° [3.09 – 4.75]) groups. The highest mean 3D crestal (1.03 mm ± 0.16), 3D apical (1.57 mm ± 0.28), and angular deviations were observed in the DisPosSTG group. These values were significantly higher compared to the 3D crestal deviations at the ProPosSTG (0.70 mm ± 0.13) and DisDE (0.75 mm ± 0.15) sites, the 3D apical deviations at the AntSTG (1.07 mm ± 0.27) and ProDE (1.05 mm ± 0.26) sites, and the angular deviations at the AntSTG (2.63° [2.13 – 3.41]) and ProDE (1.79° [1.37 – 2.60]) sites. Conclusions Higher accuracy was observed in anterior extended area and lower at the posterior sites of implantation. The results on accuracy of sCAIS in particular site of implantation should not be generalized across all types of partial edentulism. The findings indicate that site of implantation could influence the accuracy of sCAIS.