Effect of different scanning protocols on the regional accuracy of digitized washed complete denture prototypes: An in vitro study

PURPOSE: This in vitro study aimed to evaluate the regional trueness and precision of three scanning protocols for digitizing complete denture prototypes that have undergone border molding and wash impression procedures. MATERIALS AND METHODS: Maxillary and mandibular edentulous typodonts were scanned and used to fabricate complete denture prototypes. The complete denture prototypes were additively manufactured using try-in resin. Both prototypes were utilized to obtain final impressions using polyvinylsiloxane material. Scans of the washed prototypes were made using a desktop E4 scanner (3Shape A/S) to serve as the reference control. Test scans were acquired using an intraoral scanner TRIOS4 (3Shape A/S). Three scanning protocols were employed to digitize the washed prototypes: Intaglio-First (IF), Occlusal-First (OF), and Peripheral Frame (PF), with 10 scans per group (n = 10). Reference meshes were segmented into three regions of clinical interest: overall prosthesis, denture-bearing area (DBA), and dentition. Test scans were superimposed onto reference scans using best-fit alignment in reverse engineering software. Trueness was quantified as the root mean square (RMS) deviation, and precision was assessed as the standard deviation of RMS values among repeated scans. A one-way analysis of variance (ANOVA) with post hoc comparison was used to analyze the data (α = 0.05). RESULTS: For the maxillary arch, the IF protocol demonstrated significantly superior trueness compared to the PF protocol for the dentition (p = 0.0147) and overall prosthesis (p = 0.0053) regions. The IF and OF protocols also showed significantly higher precision than the PF protocol for maxillary dentition and overall prosthesis regions. No significant differences among protocols were found for the maxillary DBA. For the mandibular arch, no significant differences in trueness or precision were observed among protocols for any region. Trueness values across all protocols and regions ranged from 0.048 to 0.088 mm. CONCLUSIONS: Scanning protocol significantly influenced the trueness and precision of maxillary digitized prototypes, with the IF protocol demonstrating superior accuracy. However, this did not hold true for mandibular prototypes. All scanning protocols produced accuracy values that were clinically acceptable for complete denture fabrication, supporting the clinical viability of intraoral scanning for digitizing border-molded denture prototypes regardless of scanning protocol selection.