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

Abstract

Reproduction of the exact interocclusal relationship using digital workflow is crucial for precise fabrication of accurate prostheses. Intraoral scanner is known to be valid for the measurement of quadrants, however, the role of missing area in the quadrant scan on the virtual interocclusal record (VIR) is uncertain. This study aimed to evaluate the accuracy of VIR in quadrant scans using an intraoral scanner (IOS) under four different edentulous conditions. Eight scans per group were obtained using a laboratory scanner and three IOSs (Trios3, CS3600, i500). Based on trueness and precision, Trios3 had the best results, followed by CS3600 and i500. The trueness and precision were affected by edentulous conditions. The three IOSs showed deviation in the posterior region during assessment of VIR for the missing area with posterior support. CS3600 and i500 showed deviation in the short-span edentulous area without support. In extended edentulous condition without support, Trios3 showed overclosure, while i500 showed an angular deviation. In some groups scanned with Trios3 and i500, the tilting effect was observed. Based on the edentulous condition and type of IOS used, local or general deviations in occlusion were seen. The accuracy of VIR was dependent on accurate scan data. Thus, registration of the occlusal relationship in an edentulous area with more than two missing teeth using IOSs may be clinically more inaccurate than that with a laboratory scanner.

Virtual occlusal records acquired by using intraoral scanners: A review of factors that influence maxillo‐mandibular relationship accuracy

“…On comparison of TRIOS, CS 3600, and i500, with a laboratory scanner, TRIOS had the best trueness (43.4 μm) followed by CS3600 (45.4 μm) and i500 (65 μm) 25 . A study carried out in dentate models has shown a significant difference between intraoral scanners.…”

“…According to the study conducted by Lee, 25 a tilting effect was observed in the quadrant arch scan with the absence of posterior support or with more than two missing teeth. A possible explanation for this finding is the lack of landmarks in the edentulous area and the limitation of the scanner tip size, both of which could have contributed to the compromised estimation 25 . Depending on the scanner there can be overestimation or underestimation of the interocclusal distance hence, it might be necessary to compensate for the distortion of the occlusal relationship during the CAD or milling process 44 .…”

“…16 On comparison of TRIOS, CS 3600, and i500, with a laboratory scanner, TRIOS had the best trueness (43.4 μm) followed by CS3600 (45.4 μm) and i500 (65 μm). 25 A study carried out in dentate models has shown a significant difference between intraoral scanners. CERAC Omnicam (165.5 μm) has shown the least deviation followed by true definition (250.5 μm), iTero (327.5 μm), Trios (347.5 μm), and CS3500 (369 μm).…”

A guide for selecting the intraoral scan extension when fabricating tooth‐ and implant‐supported fixed dental prostheses

“…When a greater number or locations of teeth are being restored or when a patient has more than one missing tooth, complete-arch intraoral scans are recommended (Figures 2 and 3). [15][16][17][18][19]31,[63][64][65] It is important to remember that the accuracy of complete-arch intraoral scans for fabricating more than 4 restorations or FDPs involving more than 4 units, or complete-arch tooth-and implant-supported restorations by using IOSs is uncertain. [42][43][44][45][46][47]…”

“…Due to the lack of anatomical landmarks and the presence of mobile tissue, edentulous spaces reduce the accuracy of the virtual definitive casts obtained by using IOSs 19,60–62 . Additionally, the accuracy of the maxillomandibular relationship at MIP captured by using IOSs can be also decreased when edentulous areas are present in a dental arch 19,63–65 . Studies have shown that the accuracy of recorded maxillomandibular relationship at MIP was significantly reduced in patients with edentulous spaces of two or more missing teeth 63,65 .…”