Accuracy and clinical passive fit of reverse and standard scan body protocols for complete-arch implant-supported digital impressions: An in vitro study.

PURPOSE: The purpose of this in vitro study was to compare the reverse scan body (RSB) and standard scan body (SCB) protocols for complete-arch implant-supported digital impressions with respect to root mean square (RMS), linear deviation, and angular deviation values, as well as clinical passive fit. MATERIALS AND METHODS: Configurations with four and six implants were created on edentulous maxillary and mandibular casts. Digital impressions were obtained with an intraoral scanner using the standard and RSB protocols (10 scans per subgroup; 80 datasets total) and superimposed onto reference datasets acquired with a laboratory scanner. RMS, linear, and angular deviation values were calculated. Clinical passive fit of cobalt-chromium verification jigs fabricated from digital data was evaluated by visual inspection, screw-resistance test, and radiographic assessment. RESULTS: Total RMS values did not differ significantly between the standard and RSB protocols (0.0384 ± 0.0017 vs. 0.0395 ± 0.0012 mm; p = 0.530), although the scan protocol × jaw interaction was significant (p = 0.001). In four-implant casts, the RSB protocol demonstrated significantly lower linear deviation than the SCB protocol (0.0618 vs. 0.0951 mm; p < 0.001); in six-implant casts, no main effect of protocol was found, although several interactions were significant. Angular deviation findings were configuration-dependent. Clinical passive fit was acceptable in 95% of verification jigs fabricated with the RSB protocol and 90% of verification jigs fabricated with the SCB protocol. CONCLUSIONS: Within the limitations of this in vitro study, the RSB protocol demonstrated accuracy comparable to the SCB protocol, with more stable implant position transfer in four-implant configurations and a high clinical passive fit rate, supporting its use as a reliable alternative in complete-arch digital implant workflows.