Date of Award

2018

Document Type

Thesis

Degree Name

Master of Science (MS)

Department

Orthodontics

College

College of Dental Medicine

First Advisor

Walle Renne

Second Advisor

Timothy J. Tremont

Third Advisor

Jing Zhou

Abstract

Objective: Digital impression systems, both direct and indirect, are becoming more common in orthodontics. Intraoral scanners (IOS) are devices that are used to directly capture dental impressions. With upgrades and new systems being released at a rapid pace, continued evaluation of device accuracy is essential. This study aims to determine the effects of scan strategy on 4 intraoral digital impression systems. Materials and Methods: Four digital intraoral impression systems were used to scan a custom made typodont that had a refractive index within the range of enamel and dentin. Four distinct scan patterns, each based off of manufacture suggested patterns, were tested and compared to the reference model. The comparison of test and reference models were completed using an industrial grade metrology software program that allowed both 3D files to be compared for discrepancies. Trueness and precision were then compared for patterns and scanners to determine whether scan pattern affects each. Scan time was also recorded and evaluated for effects on trueness and precision. Results: Six comparisons were made during this study. Overall scanner comparisons were made, overall patterns were compared, patterns for each scanner were compared, scanners for each pattern were evaluated, maximum deviations were analyzed, and a visual analysis was completed on the superimposed models. Overall, the trueness ranking was as follows: Element>Trios>Emerald>Omnicam. The Omnicam showed some statistically significant differences in trueness and precision with changes in scan patterns. The Element scan showed statistically significant differences in precision among two of the scan patterns. No statistically significant differences were noted when scan time was evaluated against changes in precision and trueness. Conclusions: Two of the scanners showed changes in either trueness or precision when scan patterns were altered. Scan times were not found to affect trueness or precision of the scanners. As new scanners are released, further research is warranted to verify manufacturer claims of accuracy. Although statistically significant differences in trueness and precision were noted between scanners, most showed clinically acceptable accuracy values.

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