Abstract
AIM: The aim of this study was to evaluate the effect of the number of intraoral scan bodies (ISBs) on the accuracy of digital impressions and the resulting master casts in full-arch maxillary implant rehabilitations in "all-on-4" and "all-on-6" situations. SETTINGS AND DESIGN: This was an in vitro comparative study. MATERIALS AND METHODS: Forty-two digital impressions were obtained for all-on-4 (Group A) and all-on-6 (Group B) implant situations. Group A had three scan situations-1, 2, and 3-using 1, 2, and 4 scan bodies, respectively. Group B had four scan situations-1, 2, 3, and 4-employing 1, 2, 4, and 6 scan bodies, respectively, with six scans per situation. Linear and angular measurements were digitally evaluated by superimposing STL files onto reference models using Geomagic Control X. One master cast was fabricated for each scan situation, and verification jigs were assessed for passivity and fit. STATISTICAL ANALYSIS USED: Data were analyzed using the Shapiro-Wilk test to confirm normal distribution, followed by one-sample t-test for comparison of linear and angular deviations between scan and reference models (p < 0.05). RESULTS: In Group A, regardless of the scan situation, the differences in the measurements between the scan and reference model were statistically significant. In Group B, the study showed that scan situation 4 yielded the most accurate measurements when compared with reference model (P = 0.136). In both Groups A and B, master models fabricated using four and six scan bodies, respectively, exhibited the best passive fit of the verification jig. CONCLUSION: Within the limitations of this study, scan body quantity significantly influenced digital impression accuracy in full-arch implant prosthodontics. All-on-4 achieved reliable results with two ISBs but benefited from four for angular accuracy, while all-on-6 required six ISBs for optimal trueness and passive fit, underscoring their importance in complex rehabilitations.