Accuracy of intraoral scanning in completely and partially edentulous maxillary and mandibular jaws: an in vitro analysis

Abstract

Objectives New generation intraoral scanners are promoted to be suitable for digital scans of long-span edentulous spaces and completely edentulous arches; however, the evidence is lacking. The current study evaluated the accuracy of intraoral scanning (IOS) in partially and completely edentulous arch models and analyzed the influence of operator experience on accuracy. Materials and methods Four different resin models (completely and partially edentulous maxilla and mandible) were scanned, using a new generation IOS device (n = 20 each). Ten scans of each model were performed by an IOS-experienced and an inexperienced operator. An industrial high-precision scanner was employed to obtain reference scans. IOS files of each modeloperator combination, their respective reference scan files (n = 10 each; total = 80), as well as the IOS files from each model generated by the same operator, were superimposed (n = 45; total = 360) to calculate trueness and precision. An ANOVA for mixed models and post hoc t tests for mixed models were used to assess group-wise differences (α = 0.05). Results The median overall trueness and precision were 24.2 μm (IQR 20.7-27.4 μm) and 18.3 μm (IQR 14.4-22.1 μm), respectively. The scans of the inexperienced operator had significantly higher trueness in the edentulous mandibular model (p = 0.0001) and higher precision in the edentulous maxillary model (p = 0.0004). Conclusion The accuracy of IOS for partially and completely edentulous arches in in vitro settings was high. Experience with IOS had small influence on the accuracy of the scans. Clinical relevance IOS with the tested new generation intraoral scanner may be suitable for the fabrication of removable dentures regardless of clinician's experience in IOS.

Accuracy of Intraoral Scanners for Recording the Denture Bearing Areas: A Systematic Review

“…In general, the accuracy results were superior for the partially edentulous models than completely edentulous models. Moreover, statistical analysis revealed a direct correlation between scanning duration and trueness, where the longer scanning duration was associated with superior trueness 20 …”

“…Trueness is defined as the closeness of the test object to the actual reference object, and precision represents the similarity between the different test objects. From the 18 studies, 17 of them used the superimposition method to measure the congruence between the reference and the test group 3D data (trueness) and/or the congruence of the 3D data within each test group (precision) 18–34 . To do so, 11 studies obtained the reference 3D data through a laboratory scanner, 18,19,21,25–32 3 used an industrial scanner, 20,22,34 and 1 used the same IOS employed to capture the direct digital impression 23 .…”

“…c) Qualitative evaluation: Out of the 17 studies that used the superimposition method, 14 described the pattern of the positive and negative differences between the IOS‐generated virtual model and the reference 3D data by visualizing through a color map 18,20–25,27–30,32–34 …”

“…A total of 2 laboratory studies evaluated the accuracy of digital scans in partially and fully edentulous arches in comparison to reference models (Table 5). 19,20 Tasaka et al investigated the trueness of TR2 scans in certain areas of an edentulous maxilla and a partially edentulous mandibular model during the evaluation of the inter‐operator validity. Their results revealed a significant inter‐operator difference in the maxilla only.…”

“…When scanning an edentulous mucosa is considered, studies showed that the accuracy was influenced by the presence of an artificial marker, 26 distribution and length of the edentulous area, 19,24 operator's experience, 20,31 IOS system characteristics including the head size, 16,20–22,26,28,29,33 soft tissue characteristics (flexibility, mobility, dimension), 23,25,27,29–32 and the scanning strategy 18,34 . Accuracy reports varied among studies according to their different methodologies, evaluated area of interest, and scanning condition.…”