Accuracy, scanning time, and number of photograms of various scanning patterns for the extraoral digitalization of complete dentures by using an intraoral scanner

Abstract

Statement of problem

The use of intraoral scanners (IOSs) has been described as a method of digitizing complete dentures (CDs) extraorally; however, accuracy, scanning time, and number of photograms remain unclear.

Purpose

The purpose of this in vitro study was to assess the accuracy, scanning time, and number of photograms of different scanning patterns for digitizing CDs extraorally with an IOS.

Material and methods

The virtual design of a maxillary and mandibular CD was used to manufacture milled CDs. The maxillary (Mx group) and mandibular (Mb group) CDs were digitized extraorally by using an IOS (Medit i500). Three subgroups were created depending on the scanning pattern: using the protocol of the IOS selected (Medit Link) (ML subgroup), using the technique recommended by the implant manufacturer (DIOnavi) (DIO subgroup), and using a custom method (C subgroup). The design of the CDs (reference files) was used to compare the discrepancy between each virtual design and the corresponding scans by using the root mean square (RMS) error. The scanning time and number of photograms were recorded. Two-way ANOVA and Tukey tests were used to analyze the trueness data. The Bartlett test was used to analyze the precision values (α=.05).

Results

The group (P<.001) was a significant predictor of trueness. The Mx group (RMS mean of 0.452 mm) obtained higher trueness than the Mb group (RMS mean of 0.536 mm). The Mx-C and Mb-DIO subgroups obtained the highest trueness, and the Mx-ML and Mb-ML subgroups showed the lowest trueness. Significant differences were found in precision among groups (P<.01) and across subgroups (P<.01). The Mb group obtained the highest precision mean (0.586 mm) and was significantly different from the Mx group that obtained the lowest precision mean (0.611 mm). The C subgroup obtained the highest precision mean (0.339 mm) and was significantly different from the DIO subgroup that obtained the lowest precision mean (0.425 mm). The group (P<.01) and scanning pattern (P<.01) were significant predictors of the scanning time and number of photograms obtained. The Mb group showed lower scanning time and number of photograms than the Mx group.

Conclusions

The scanning patterns tested significantly influenced the trueness and precision values, scanning time, and number of photograms of the extraoral digitalization of maxillary and mandibular CDs by using the IOS tested.