Marginal Fit of PMMA CAD/CAM Crowns Fabricated by using Photogrammetry Scanning method. (an invitro study)

Document Type : Original Article

Authors

1 Lecturer, Fixed Prosthodontics, Conservative Dentistry Department, Faculty of Oral and Dental Medicine, Misr International University.

2 PhD candidate; Faculty of Oral and Dental Medicine, Cairo University. Assistant Lecturer, Fixed Prosthodontics, Conservative Dentistry Department, Faculty of Oral and Dental Medicine, Misr International University

3 Associate, Professor Fixed Prosthodontics, Conservative Dentistry Department, Faculty of Oral and Dental Medicine, Misr International University.

Abstract

Purpose.
The aim of this study was to assess the marginal accuracy of provisional CAD/CAM PMMA crowns fabricated by two-dimensional image-based rendering (IBR) photogrammetry scanning method.
Materials and Methods.
10 epoxy resin dies, duplicated from an anatomically reduced maxillary central incisor. Epoxy dies were distributed into two groups according to the method of die scanning (n=5). Gp I the dies were scanned with extraoral desktop scanner. For Gp II photogrammetry scanning for the dies was done using standardized photos using a professional digital single reflex (DSLR) camera for photo acquisition. Photography technique was standardized using a custom-made device to ensure adequate overlap between acquired photos, further rendering of photos was done using specialized photogrammetry software. Produced standardized tessellation Language (STL) files from both scanning methods were used for fabrication of CAD/CAM Polymethylmethacrylate crowns. Mean vertical marginal gap of crowns fabricated by both scanning methods was measured using stereomicroscope at 20 equidistant points (5 points in each surface), and results were statistically analysed using paired t-test.
Results.
Mean marginal gap for Gp I (extraoral scanner) was (106.3 + 12.3 microns), while for Gp II (photogrammetry scanning) mean marginal gap was (99.6 + 28.3 microns). There was no statistically significant difference between marginal gap distances measurement by extraoral scanner and photogrammetry scanning method (p>0.05). produced marginal accuracy results were within the clinically acceptable range below 120 µ.
Conclusion.
Photogrammetry scanning image-based rendering can be an affordable and reliable method to fabricate CAD/CAM crowns with proper marginal accuracy.

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Egyptian Dental Journal
Volume 68, Issue 4 - Serial Number 4
October (Fixed Prosthodontics, Removable Prosthodontics and Dental Materials)
October 2022
Pages 3537-3544

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