In vivo evaluation of inter-operator reproducibility of digital dental and conventional impression techniques.

Emi Kamimura,Masayuki Takaba,Kazuyoshi Baba,Keita Tachi,Shinpei Tanaka,Yudong Zhang

doi:10.1371/journal.pone.0179188

Abstract

PurposeThe aim of this study was to evaluate and compare the inter-operator reproducibility of three-dimensional (3D) images of teeth captured by a digital impression technique to a conventional impression technique in vivo.Materials and methodsTwelve participants with complete natural dentition were included in this study. A digital impression of the mandibular molars of these participants was made by two operators with different levels of clinical experience, 3 or 16 years, using an intra-oral scanner (Lava COS, 3M ESPE). A silicone impression also was made by the same operators using the double mix impression technique (Imprint3, 3M ESPE). Stereolithography (STL) data were directly exported from the Lava COS system, while STL data of a plaster model made from silicone impression were captured by a three-dimensional (3D) laboratory scanner (D810, 3shape). The STL datasets recorded by two different operators were compared using 3D evaluation software and superimposed using the best-fit-algorithm method (least-squares method, PolyWorks, InnovMetric Software) for each impression technique. Inter-operator reproducibility as evaluated by average discrepancies of corresponding 3D data was compared between the two techniques (Wilcoxon signed-rank test).ResultsThe visual inspection of superimposed datasets revealed that discrepancies between repeated digital impression were smaller than observed with silicone impression. Confirmation was forthcoming from statistical analysis revealing significantly smaller average inter-operator reproducibility using a digital impression technique (0.014± 0.02 mm) than when using a conventional impression technique (0.023 ± 0.01 mm).ConclusionThe results of this in vivo study suggest that inter-operator reproducibility with a digital impression technique may be better than that of a conventional impression technique and is independent of the clinical experience of the operator.

Highlights

A significant change taking place this century is the introduction of digital technology into dental practice; “Digital Dentistry” is becoming more prevalent each year
The visual inspection of superimposed datasets revealed that discrepancies between repeated digital impression were smaller than observed with silicone impression
Confirmation was forthcoming from statistical analysis revealing significantly smaller average interoperator reproducibility using a digital impression technique (0.014± 0.02 mm) than when using a conventional impression technique (0.023 ± 0.01 mm)

Summary

Introduction

A significant change taking place this century is the introduction of digital technology into dental practice; “Digital Dentistry” is becoming more prevalent each year. Digital impression techniques with three-dimensional (3D) intra-oral scanners have been attracting attention gaining in popularity around the world [1]. In contrast to conventional impression techniques, their application clearly simplifies workflow and makes the impression procedure easier and visible for dentists, dental technicians and patients [4,5,11,12]. This method avoids inaccuracies linked to the conventional impression technique, since silicone impression materials are prone to dimensional changes because of on-going chemical reactions and dental stone expands because of secondary reactions. There is only a limited number of in vivo studies in the literature [19,20] and no study has systematically investigated inter-operator reproducibility of a digital impression technique

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