ABSTRACT
PURPOSE: The effect of scan range and the number of scanned images on the precision of in vivo intermaxillary relationship reproduction was evaluated using digital scans acquired with an intraoral scanner. METHODS: The study involved 15 participants with normal occlusion. Two different interocclusal recording settings were employed using the intraoral scanner (TRIOS 4): 'MIN,' focusing on the minimal scan range of the first molar region, and 'MAX,' including the scan range from the right first premolar to the right second molar. These settings were combined with three different image counts, resulting in six experimental conditions. Interocclusal recordings were performed four times for each condition. Dimensional discrepancies between datasets were analyzed using three-dimensional morphometric software and compared using two-way analysis of variance. RESULTS: Median dimensional discrepancies (interquartile range; IQR) of 39.2 (30.7-49.4), 42.2 (32.6-49.3), 30.3 (26.8-44.1), 20.1 (16.0-34.8), 21.8 (19.0-25.1), and 26.6 (19.9-34.5) µm were found for MIN/200, MIN/400, MIN/600, MAX/200, MAX/400, and MAX/600, respectively. Significant differences in dimensional discrepancies according to scan range were found. Wilcoxon signed-rank test showed significant differences between MAX and MIN (P < 0.01). CONCLUSION: Scan range may affect the precision of intermaxillary relationship reproduction. Thus, scanning of the most extensive region practically achievable is recommended.
Subject(s)
Imaging, Three-Dimensional , Models, Dental , Humans , Computer-Aided Design , Dental Impression TechniqueABSTRACT
STATEMENT OF PROBLEM: Although studies have evaluated the accuracy of data obtained by intraoral scanners (IOSs), studies on the precision of interocclusal registrations made with IOSs are lacking. PURPOSE: The purpose of this clinical study was to compare the precision of IOS interocclusal registration with that of conventional methods with a silicone impression material and a gypsum cast. MATERIAL AND METHODS: Eight participants with complete natural dentitions were enrolled. Images of their maxillary and mandibular quadrant arches and their interocclusal relationship were scanned with 2 IOSs: the 3M True Definition Scanner and the TRIOS Scanner 3. In the conventional method, impressions of complete-arch dentition and quadrant-arch dentition were made with a silicone impression material, and gypsum casts were fabricated, mounted on a dental articulator related with a silicone interocclusal record, and scanned with a 3D laboratory scanner. These procedures were repeated 4 times, and 4 sets of interocclusal registration data in standard tessellation language (STL) format were generated for each condition. Interocclusal registration precision was evaluated by determining the discrepancy of the STL data between repeated measurements by using the best-fit-algorithm method. RESULTS: The average discrepancies for all participants were 25 ±12 µm for the True Definition, 31 ±7 µm for the TRIOS 3, 154 ±59 µm for the complete arch, and 128 ±33 µm for the quadrant arch. The Kruskal-Wallis test revealed that the effect of the impression methods on the discrepancy was statistically significant (P<.001). The Steel-Dwass test showed that both digital scan methods exhibited significantly smaller discrepancies than the 2 conventional methods (P=.005). CONCLUSIONS: These results suggest that the intermaxillary relationship captured by the digital scan method by using IOSs had better precision than that obtained by the conventional method.
