Computerized optical scanning of ears: An in vitro evaluation with an intraoral scanner

Mariko Hattori; Sebastian B M Patzelt; Sandra Stadler; Ralf J Kohal; Kirstin Vach; Mahmoud E Elbashti; Yuka I Sumita

doi:10.1016/j.prosdent.2022.11.010

Computerized optical scanning of ears: An in vitro evaluation with an intraoral scanner

J Prosthet Dent. 2022 Dec 29:S0022-3913(22)00707-7. doi: 10.1016/j.prosdent.2022.11.010. Online ahead of print.

Authors

Mariko Hattori¹, Sebastian B M Patzelt², Sandra Stadler³, Ralf J Kohal⁴, Kirstin Vach⁵, Mahmoud E Elbashti⁶, Yuka I Sumita⁷

Affiliations

¹ Assistant Professor, Department of Maxillofacial Prosthetics, Tokyo Medical and Dental University, Tokyo, Japan.
² Adjunct Professor for Computerized Dentistry, Medical Center - University of Freiburg, Center for Dental Medicine, Department of Prosthetic Dentistry, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany; Director, Private Dental Clinic, Zimmern o.R., Germany.
³ Oral Surgeon, Private Dental Clinic, Burglengenfeld, Germany.
⁴ Professor, Medical Center - University of Freiburg, Center for Dental Medicine, Department of Prosthetic Dentistry, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany.
⁵ Scientist, Medical Center - University of Freiburg, Institute for Medical Biometry and Statistics, Faculty of Medicine, University of Freiburg, Freiburg im Breisgau, Germany.
⁶ Lecturer, Department of Maxillofacial Prosthetics, Tokyo Medical and Dental University, Tokyo, Japan.
⁷ Associate Professor, Department of Maxillofacial Prosthetics, Tokyo Medical and Dental University, Tokyo, Japan. Electronic address: yuka.mfp@tmd.ac.jp.

PMID: 36586814
DOI: 10.1016/j.prosdent.2022.11.010

Abstract

Statement of problem: Making conventional facial impressions can be uncomfortable for the patient and complicated for the prosthodontist. Using facial scanners to digitize faces is an alternative approach. However, the initial costs of the equipment have prevented their widespread use in dental practice, and the accuracy of ear scanning is unclear.

Purpose: The purpose of this in vitro study was to investigate the accuracy of a widely used intraoral scanner for digitizing an ear model.

Material and methods: For reference, a silicone model of an ear was scanned with an industrial scanner. Then, the model was scanned 5 times with an intraoral scanner. Five conventional impressions of the model were made with a hydrocolloid impression material and poured with dental stone. The stone casts were then digitized with a desktop scanner. The data sets acquired with the 3 approaches were analyzed by using a 3-dimensional (3D) evaluation software program. Trueness and precision values were calculated for each approach. Linear mixed models with random intercepts were fitted to each sample to evaluate the effects of the impression method on mean deviations (α=.05).

Results: Mean ±standard deviation trueness and precision values were 0.097 ±0.012 mm and 0.033 ±0.015 mm, respectively, for the digital scan, and 0.092 ±0.022 mm and 0.081 ±0.024 mm for the conventional impression, showing a significantly lower deviation in precision for the digital approach (P<.001).

Conclusions: The feasibility of digitizing an ear efficiently by using the investigated intraoral scanner was demonstrated, and similar trueness and significantly better precision values were achieved than when using conventional impressions. These promising results suggest the need for clinical investigations.