[Comparing intraoral scanning and cone beam CT for the assessment of implant position accuracy]

Objective: To compare cone-beam CT (CBCT) and intraoral scanning (IOS) in evaluating dental implant placement accuracy. Methods: This prospective study included patients scheduled for single implant placement at the Department of Oral Implantology, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, from December 2024 to June 2025. Preoperative CBCT and IOS data were acquired, and implant positions were virtually planned following a prosthetically driven approach. Implants were placed freehand according to the planned positions. Postoperatively, CBCT and IOS datasets containing the actual implant positions were obtained. Three-dimensional deviations between the planned and actual implant positions were measured using both CBCT-and IOS-based methods, including apex deviation, platform deviation, angular deviation, as well as mesiodistal, buccolingual, and depth deviations at both apex and platform levels. The Wilcoxon test was used to compare differences between the two measurement methods. A linear mixed-effects model was employed to explore factors influencing the discrepancies between the two methods, including the presence of intraoral restorations, simultaneous bone grafting, CBCT image quality, and tooth region (anterior vs. posterior). Consistency was assessed using the intraclass correlation coefficient (ICC) and Bland-Altman analysis. Results: A total of 36 patients (17 males) with a age of (38.2±10.6) years were included. The median apex deviation, platform deviation, and angular deviation measured by CBCT were 1.4 (1.0) mm, 1.2 (0.8) mm, and 5.2° (4.1°), respectively; those measured by IOS were 1.3 (0.7) mm, 1.0 (0.6) mm, and 4.6° (4.3°), respectively. No statistically significant differences were observed between the two methods for any of the three-dimensional deviation parameters (all P>0.05). The ICCs between the two methods were greater than 0.90, indicating good overall consistency. Bland-Altman analysis revealed that the 95% limits of agreement (LoA) for the difference in apex linear deviation (IOS minus CBCT) between two methods ranged from -0.67 mm to 0.67 mm, and for the difference in angular deviation ranged from -2.34° to 2.64°. The mixed-effects model identified the presence of intraoral restorations as a significant factor affecting discrepancies between the two methods in platform depth, apex depth, and apex mesiodistal deviation. Conclusions: IOS and CBCT methods demonstrated comparable accuracy and relatively high consistency in measuring three-dimensional implant placement deviations. However, the 95% limits of agreement for the measurement discrepancies were relatively wide.