Accuracy of smartphone-based photogrammetry for full-arch implant position transfer: a controlled in vitro comparison with scan body-based intraoral scanning

Objective: To evaluate and compare the accuracy, defined as trueness and precision, and the acquisition time of digital impressions for edentulous full-arch implant position transfer obtained using conventional scan bodies and a novel smartphone-based photogrammetry system. Methods: A maxillary edentulous model with four multi-unit abutment replicas was scanned using two acquisition methods: (1) an intraoral scanner with conventional scan bodies and (2) a smartphone-based photogrammetry system (PIC APP, iPhone 16 Pro). Each workflow was repeated 20 times. A high-accuracy industrial scanner served as the reference dataset. Accuracy was assessed using centroid root mean square deviation (CRMS), body root mean square deviation (BRMS), and angular deviation. Acquisition time was also recorded. Statistical comparisons were performed using the Mann-Whitney U test (α = 0.05). Results: Smartphone-based photogrammetry demonstrated significantly lower CRMS trueness (54.8 ± 6.57 µm) compared with conventional scan body-based intraoral scanning (244.13 ± 162.66 µm, p < 0.001). BRMS values were also significantly lower for the photogrammetry workflow (31.70 ± 14.15 µm vs. 67.62 ± 40.52 µm, p < 0.001). Angular deviation was slightly greater with photogrammetry (0.54° ± 0.03 vs. 0.39° ± 0.13, p = 0.001), although both remained within clinically acceptable limits. Acquisition time was longer for the smartphone-based workflow (97 vs. 50 seconds, p < 0.001). Conclusion: Within the limitations of this in vitro study and with reference to the intraoral scanning workflow evaluated, the smartphone-based photogrammetry system demonstrated trueness and precision values compatible with the requirements for full-arch implant position transfer accuracy. Compared with conventional scan body-based intraoral scanning, the system showed reduced linear deviations and greater consistency in implant position transfer under controlled experimental conditions. Clinical significance: Smartphone-based photogrammetry may represent a promising digital approach for implant position acquisition in full-arch rehabilitations. Its use of widely available mobile hardware and reduced system complexity suggests potential advantages in accessibility compared with conventional photogrammetry systems. However, the clinical performance, economic impact, and workflow efficiency of this technology must be confirmed with prospective clinical trials and dedicated cost-benefit analyses before definitive clinical recommendations can be made.