Discrepancies of centric occlusion located by using a conventional method and four intraoral scanners combined with a computer-aided design program: A pilot investigation.

Statement Of Problem: Intraoral scanners (IOSs) can be used to record the maxillomandibular relationship at centric relation (CR). The articulated digital scans can be imported into a dental computer-aided design (CAD) program and used to locate centric occlusion (CO); however, the accuracy of the CO recorded by using IOSs and a dental CAD program remains unknown.

Purpose: The purpose of this clinical study was to compare the position of the CO located by using a conventional method and 4 IOSs combined with a dental CAD program.

Material And Methods: A patient volunteered to participate in this study. Conventional diagnostic stone casts were obtained. A facebow record (Kois Dentofacial Analyzer) was used to transfer the maxillary cast into a semi-adjustable articulator (Panadent PCH Articulator). A Kois deprogrammer (KD) was used to record the maxillomandibular relationship at CR and to transfer the mandibular cast into the articulator. Afterwards, CO was located in the articulated casts by removing the incisal pin and using an 8-µm articulating foil. CO was marked in the casts by using a blue articulating paper (control). Three groups were created based on the IOS used: TRIOS 4, iTero Element 5D Plus, i700, and Primescan. In each IOS group, a maxillary and mandibular scan were obtained. The scans were duplicated 10 times. Afterwards, a bilateral occlusal record captured with the KD was used to articulate each pair of duplicated scans. Each articulated specimen was imported into a CAD program (DentalCAD) and CO was virtually located. The teeth contacting at the CO of each specimen were compared with the control group. Categorical data were analyzed by using the chi-squared test (α=.05).

Results: The chi-squared test revealed a significant association between the IOS system and the location of the CO (P=.004). The highest association was found between the TRIOS 4 and CO position, in which 100% of the specimens obtained the same CO position as in the conventional group. The lowest association was found between the i700 and CO position. In the i700 group, 20% of the specimens showed the same CO position as in the control group. A similar outcome was obtained in the iTero and Primescan groups. In both groups, 60% of the specimens demonstrated the same CO position as the control group.

Conclusions: The IOS system used to acquire articulated scans at CR impacted the CO position located by using the evaluated digital methods. The TRIOS 4 system was the only IOS that consistently reproduced the same CO position as the conventional method.