Three-Dimensional Accuracy of Digital Static Interocclusal Registration by Three Intraoral Scanner Systems

Abstract

Purpose: Prior studies have defined the accuracy of intraoral scanner (IOS) systems but the accuracy of the digital static interocclusal registration function of these systems has not been reported. This study compared the three-dimensional (3D) accuracy of the digital static interocclusal registration of 3 IOS systems using the buccal bite scan function.

Materials and methods: Three IOS systems compared were 3M^TM True Definition Scanner (TDS), TRIOS Color (TRC), and CEREC AC with CEREC Omnicam (CER). Using each scanner, 7 scans (n = 7) of the mounted and articulated SLA master models were obtained. The measurement targets (SiN reference spheres and implant abutment analogs) were in the opposing models at the right (R), central (C), and left (L) regions; abutments #26 and #36, respectively. A coordinate measuring machine with metrology software compared the physical and virtual targets to derive the global 3D linear distortion between the centroids of the respective target reference spheres and abutment analogs (dR_R , dR_C , dR_L , and dR_M ) and 2D distances between the pierce points of the abutment analogs (dX_M , dY_M , dZ_M ), with 3 measurement repetitions for each scan.

Results: Mean 3D distortion ranged from -471.9 to 31.7 μm for dR_R , -579.0 to -87.0 μm for dR_C , -381.5 to 69.4 μm for dR_L , and -184.9 to -23.1 μm for dR_M . Mean 2D distortion ranged from -225.9 to 0.8 μm for dX_M , -130.6 to -126.1 μm for dY_M , and -34.3 to 26.3 μm for dZ_M . Significant differences were found for interarch distortions across the three systems. For dR_R and dR_L , all three test groups were significantly different, whereas for dR_C , the TDS was significantly different from the TRC and CER. For 2D distortion, significant differences were found for dX_M only.

Conclusions: Interarch and global interocclusal distortions for the three IOS systems were significantly different. TRC performed overall the best and TDS was the worst. The interarch (dR_R , dR_C , dR_L ) and interocclusal (dX_M ) distortions observed will affect the magnitude of occlusal contacts of restorations clinically. The final restoration may be either hyperoccluded or infraoccluded, requiring compensations during the CAD design stage or clinical adjustments at issue.

Keywords: 3D; CMM; Static interocclusal registration; accuracy; intraoral; scanner.