Influence of Scan Path and Operator Experience on the Trueness of Extraoral Complete Denture Digitization with an Intraoral Scanner: An Exploratory In Vitro Study

Background/Objectives: Previous studies on the digitization of complete dentures with intraoral scanners (IOSs) have reported inconsistent effects of scan path, and whether these effects depend on operator experience remains unclear. This exploratory in vitro study investigated the effects of scan path and operator IOS experience on the trueness of extraoral scanning of complete dentures. Methods: One maxillary and one mandibular complete denture were scanned with a TRIOS 5 IOS using four scan paths: TRIOS denture, TRIOS dentate, rolling, and BOPLM (buccal–occlusal–palatal/lingual–mucosal) methods. Two experienced and two novice dentists repeated each scan path 10 times per arch. Root mean square (RMS) values relative to reference data obtained with a noncontact three-dimensional scanner (FLARE Pro 16M) were analyzed using linear mixed models with operator as a random effect. Results: In the maxilla, the experience group × scan path interaction was significant (p = 0.034): among novice operators, the rolling method yielded smaller RMS values than the BOPLM method (mean difference = −0.0170 mm, p = 0.001), whereas scan paths did not differ among experienced operators (p = 0.114). No significant effects were found in the mandible. Scanning time did not differ among scan paths. Conclusions: Among novice operators, the rolling method showed higher trueness than the BOPLM method for maxillary dentures. The effect of scan path may depend on operator experience; however, this exploratory finding requires confirmation with a larger number of operators.