Discrepancies of maximal intercuspal position recorded by using four intraoral scanners at different dental chair positions: A clinical study.

STATEMENT OF PROBLEM: Discrepancies in the maximal intercuspal position (MIP) recorded using intraoral scanners (IOSs) have been reported. Additionally, changes in the mandible position have been reported when altering patient head posture, influencing the occlusal contacts between the maxillary and mandibular dentition. However, clinical studies analyzing MIP discrepancies recorded using different IOSs at different dental chair positions are scarce.

PURPOSE: The purpose of this clinical study was to assess the trueness and precision discrepancies of the MIP captured using 4 IOSs at 3 different dental chair positions (0, 45, and 90 degrees).

MATERIAL AND METHODS: A completely dentate patient participated in the study. Three groups were created based on the dental chair position at which the virtual occlusal records were obtained: 0, 45, and 90 degrees. Four IOSs were tested: i700, TRIOS 5, Primescan, and iTero Element 5D Plus. The i700 and TRIOS 5 had the capability of leaving or correcting the occlusal collisions (OC or Non-OC, respectively). Therefore, 6 subgroups were developed depending on the IOS tested and occlusal collision correction: i700-NonOC, i700-OC, TRIOS 5-NonOC, TRIOS 5-OC, Primescan, and iTero subgroups (n=15). Maxillary and mandibular scans were captured by using the corresponding IOS and duplicated 45 times for each IOS tested. In the 0-i700, 0-TRIOS 5, 0-Primescan, and 0-iTero subgroups, the patient was positioned completely horizontal in a dental chair. Then, a bilateral occlusal record at MIP was captured with the corresponding IOS. Each occlusal record contained 4 maxillary and 4 mandibular teeth. In the i700-NonOC and TRIOS 5-NonOC, the occlusal collisions were eliminated by using the corresponding IOS tools. In the i700-OC and TRIOS 5-OC, the occlusal collisions were maintained. Each IOS automatically postprocessed the articulated scans. The linear model was used to analyze trueness, and the Levene test was used to examine precision (α=.05).

RESULTS: The linear model revealed an overall significant effect in the trueness among the group (P<.001), IOS (P<.001) and subgroup (P<.001). The post hoc multiple pairwise comparison revealed that the Group 0 and Group 45 (P<.001) and Group 0 and Group 90 (P<.001) were significantly different. Furthermore, the i700 and TRIOS 5 (P<.001) and Primescan and iTero (P<.001) IOSs were significantly different. Lastly, the articulated scans with collisions and without collisions from the i700 and TRIOS 5 IOSs (P<.001) were significantly different. The Levene test revealed significant precision discrepancies among the groups (P<.001) and IOSs (P<.001). The Group 0 and Group 45 (P<.001) and Group 0 and Group 90 (P<.001) were significantly different. The i700 and TRIOS 5 (P=.038) and TRIOS 5 and iTero (P=.039) were significantly different. Lastly, the Levene test revealed significant precision discrepancies among the articulated scans with and without collisions from the i700 and TRIOS 5 IOSs (P=.003).

CONCLUSIONS: The dental chair positions and IOSs tested created trueness and precision discrepancies in the maxillomandibular relationship recorded at MIP.