Abstract

Digital intraoral imaging has become more utilized in contemporary dental practice. This is performed using an intraoral scanner and it can be used as an alternative to making conventional impressions when indicated. This technology has many advantages, such as decreasing the number of appointments by eliminating traditional techniques, along with a reduction of laboratory time and improved patient comfort. The accuracy of intraoral scanners is currently being assessed in various aspects. To our knowledge, no study has yet addressed the accuracy of intraoral scanners in regards to total occlusal convergence (TOC) of complete coverage of anterior and posterior preparations in the presence of adjacent teeth. Data was collected by scanning a standard dental typodont affixed on a manikin. The aim of this study was to compare the accuracy (precision and trueness) between two intraoral scanners of an affixed typodont on a manikin, comparing different angles of total occlusal convergence of one anterior and one posterior complete coverage all-ceramic tooth preparations. A second objective was to evaluate the influence of location of tooth preparation relative to the arch position (anterior v. posterior). This study was performed on a printed poly(ethyl methacrylate)(PEMA) model of an affixed typodont on a manikin with two different anterior and posterior complete coverage all-ceramic crown preparations (Teeth #9 & #15). Each preparation incorporated -8, 0, 8, 16 and 22 degrees of TOC as a retrievable printed PEMA die preparation. A reference desktop scan was taken of each of the die preparation models using the D900L (3Shape) desktop scanner, which was then used as the control. Each die model was then placed in the typodont and the typodont was subsequently affixed to a manikin. 10 sample scans were taken of each preparation with each intraoral scanner, the Trios 3Shape Intraoral scanner and True Definition Intraoral scanner. The reference and intraoral scans were then saved as stereolithography (STL) files. The intraoral scans were compared to the specific reference desktop model. Surface to surface registration was then conducted in order to overlay the samples with the control using Geomagic Control X version 2018.1.1 (3D Systems) was performed in order to obtain the best fit alignment of the evaluated tooth preparation to its corresponding control tooth preparation. Trueness was determined through the significance in the mean distance discrepancy of the desktop scan and intraoral scan. Precision was determined through the standard deviation of each scanner for each die preparation. Both trueness and precision were used to determine the accuracy of each scanner.

There will be no significant difference in the accuracy of the Trios 3Shape intraoral scanner to the True Definition intraoral scanner when comparing total occlusal convergence angles of -8, 0, 8, 16 and 22 degrees for complete coverage tooth preparations. In addition, there will be no significant difference in the accuracy of both scanners in terms of the arch location of each preparation. Implementation of an affixed typodont on a manikin when using the intraoral scanners and comparison of total occlusal convergence angles of complete coverage preparation in the presence of adjacent teeth of a typodont have not been evaluated. This study concluded that the Tru Def Scanner revealed more accuracy compared to the Trios scanner for all variables under the conditions in this study. Anterior preparations were less accurately read by the scanners than for the posterior preparations. Parallel preparations were the least accurate for the anterior tooth and undercut preparations were the least accurate in the posteriors. Overall, the decrease in taper decreased the accuracy of intraoral scanners, however, this was not clinically significant. Further clinical studies need to be carried out to confirm the findings of this study.

LLU Discipline

Periodontics

Department

Periodontics

School

School of Dentistry

First Advisor

Erik Sahl

Second Advisor

Mathew T. Kattadiyil

Third Advisor

Rami Ammoun

Degree Name

Master of Science (MS)

Degree Level

M.S.

Year Degree Awarded

2019

Date (Title Page)

5-2019

Language

English

Library of Congress/MESH Subject Headings

Computer-Aided Design; Dental Impression Technique; Imaging, Three-Dimensional

Type

Thesis

Page Count

xi, 35 p.

Digital Format

PDF

Digital Publisher

Loma Linda University Libraries

Usage Rights

This title appears here courtesy of the author, who has granted Loma Linda University a limited, non-exclusive right to make this publication available to the public. The author retains all other copyrights.

Collection

Loma Linda University Electronic Theses and Dissertations

Collection Website

http://scholarsrepository.llu.edu/etd/

Repository

Loma Linda University. Del E. Webb Memorial Library. University Archives

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