Student Theses, Dissertations and Capstones

Document Type

Thesis - NSU Access Only

Degree Name

Master of Science (M.S.) in Dentistry

Copyright Statement

All rights reserved. This publication is intended for use solely by faculty, students, and staff of Nova Southeastern University. No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, now known or later developed, including but not limited to photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author or the publisher.

Department

College of Dental Medicine

First Advisor

Niranjan Joshi

Date of original Performance / Presentation

January 2024

Publication Date / Copyright Date

1-1-2024

Abstract

Introduction Intraoral scanners (IOS) and extraoral desktop scanners (EOS) are devices that capture direct optical impressions as documented in literature.1,2 Extraoral desktop scanners digitize patient physical models or patient impressions indirectly. Cone beam computed tomography (CBCT) helps capture three-dimensional radiographic data. There are alternative ways of acquiring surface data of a patient’s dentition other than using an intraoral or extraoral scanner. CBCT scans of an impression taken in Polyvinyl siloxane (PVS) is one such alternative. Hence, this study aims to examine the trueness and precision of models generated by CBCT when compared to extraoral scanner generated models. Materials and Methods Standardized partially dentate typodont models will be ordered from Nissin Kilgore that will be used for the purpose of the study. Extraoral desktop scans (Inlab InEos X5) of the maxillary and mandibular models will be taken for the purpose of generating a reference digital model for each model. Polyvinyl siloxane (Aquasil heavy and light body) impressions of each reference typodont model will be made. PVS impressions will be digitized using two methods. Forty scans of the PVS impression will be taken with the CBCT machine (Carestream 8100) and 40 scans will be taken with an extraoral desktop scanner (Inlab InEos X5) in order to get a total of 80 STL scans of the impression. Each working model is then imported into a reverse engineering metrology software (Geomagic Control X) to compare the trueness and precision between scans. The 3D analysis software from Geomagic will generate values for comparison of trueness and precision based on multiple reference points chosen between digital STL models. Results A total of 40 CBCT scan generated digital models were prepared with 20 belonging to the maxillary group and 20 digital models belonging to the mandibular group. (Test group) A total of 40 laboratory scan generated digital models were also prepared with 20 digital models each for both maxillary and mandibular groups. (Control group) The study compared the reference model to all the CBCT scan generated digital models. This comparison yielded an RMS and InTol percentage value for each of the CBCT scan generated digital models. The difference was equivalent to approximately RMS values of 115 microns for the maxillary test group and 111 microns for the mandibular test group respectively when compared to the corresponding reference mean values. An intra group comparison was instituted between every digital model in the CBCT scan group and all other digital models in the same group. These comparisons yielded a sample size of 190 values that were subjected to statistical assessment to calculate the precision of the technique. Conclusion The study showed that the comparative analysis between the test and control group yielded a value that was statistically significant. Although this means that our null hypothesis is rejected, these values were still regarded as clinically acceptable for the purpose of this study.

Disciplines

Dentistry

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