Precision of maxillo-mandibular registration with intraoral scanners in vitro

Abstract

Purpose: To compare the precision of maxillo-mandibular registration and resulting full arch occlusion produced by three intraoral scanners in vitro. Methods: Six dental models (groups A-F) were scanned five times with intraoral scanners (CEREC, TRIOS, PLANMECA), producing both full arch and two buccal maxillomandibular scans. Total surface area of contact points (defined as regions within 0.1 mm and all mesh penetrations) was measured, and the distances between four pairs of key points were compared, each two in the posterior and anterior. Results: Total surface area of contact points varied significantly among scanners across all groups. CEREC produced the smallest contact surface areas (5.7-25.3 mm 2), while PLANMECA tended to produce the largest areas in each group (22.2-60.2 mm 2). Precision of scanners, as measured by the 95% CI range, varied from 0.1-0.9 mm for posterior key points. For anterior key points the 95% CI range was smaller, particularly when multiple posterior teeth were still present (0.04-0.42 mm). With progressive loss of posterior units (groups D-F), differences in the anterior occlusion among scanners became significant in five out of six groups (D-F left canines and D, F right canines, p<0.05). Conclusions: Maxillo-mandibular registrations from three intraoral scanners created significantly different surface areas of occlusal contact. Posterior occlusions revealed lower precision for all scanners than anterior. CEREC tended towards incorrect posterior open bites, whilst TRIOS was most consistent in reproducing occluding units.

Influence of Edentulous Conditions on Intraoral Scanning Accuracy of Virtual Interocclusal Record in Quadrant Scan

“…In addition, Edher et al reported that the tilting effect could occur in the area away from the section recorded by VIR in the full-arch scan [11]. In other studies, a similar effect was observed mainly in the posterior area [12,18,19]. Schmidt et al explained that the cumulative errors in superimposition and stitching processes contributed to the angular deviation in the posterior region [18].…”

“…The results of this study showed that the registration of the occlusal relationship using IOSs in the edentulous area with more than two missing teeth might be clinically more inaccurate than that obtained with a laboratory scanner [12,13]. In this situation, it is recommended to apply a digital workflow including a laboratory scanner.…”

“…The results of our study suggested that the accuracy of arch scan data obtained by the IOS could affect the accuracy of VIR [7,12]. In this study, we calculated the trueness and precision of the maxillary quadrant arch scan data to assess the effect of the distortion of the scan data on the VIR.…”

“…Previous studies about the accuracy of the VIR had a limitation in that there was no evaluation for the distortion of the arch scan data itself, even though the full arch model was used to assess the VIR [9,12,13,15]. Gintaute et al evaluated the accuracy of VIR using the total occlusal surface area [12]. However, the author considered the precision of the scan data by comparing only the distance of the key points and not the scan data itself.…”

“…Alteration of occlusal contact points could occur more in the complete arch scan than in the quadrant arch scan [11]. In addition, the deviations of occlusal contact points are higher in the posterior teeth than in the other regions of the arch [12]. The span and location of the edentulous area in the full arch model could also affect the dimensional accuracy of a VIR [13].…”