Registration of digitized index tray of an extraoral scan body with virtual casts: Influence of interocclusal registration material, edentulous area, and tooth anatomy.

OBJECTIVES

To assess the impact of interocclusal registration material, edentulous span, and tooth anatomy on the accuracy of the registration between digitized interocclusal records and dental casts.

METHODS

A tray of an extraoral scan body and 8 3D printed maxillary casts, representing fully edentulous, partially dentate, and fully dentate patients with both sound and worn dentition, were obtained. Four fiducial spheres were affixed to the tray and each cast to serve as reference markers. Three bite registration materials were used to attach each cast to the tray: OBS(O-Bite Scan; DMG), BM (Blu-Moose-Parkell), and VCB (VirtualCAD Bite Registration; Ivoclar). Scanning was performed using a laboratory scanner (T710; Medit) to capture the tray alone, the tray with each cast attached, and each cast independently. Virtual attachment of each cast to the tray was completed using dental CAD software program (DentalCAD; Exocad). A metrology software program (Geomagic Control X; 3D Systems) was used to calculate linear deviaitons between corresponding fiducial spheres and angular deviations between defined reference planes. The scan of the tray with the attached dental cast served as the reference for evaluating registration discrepancies.

RESULTS

The type of interocclusal registration material was significantly associated with registration accuracy (p < 0.05). Regarding tooth anatomy, statistically significant differences were observed only when the BM material was used (P < 0.05). In fully dentate models, significantly greater discrepancies were observed compared to fully edentulous models when OBS and BM materials were used (p < 0.05).

CONCLUSIONS

The accuracy of virtual registration between digitized interocclusal records and casts was associated with the type of registration material, tooth anatomy, and the extent and location of edentulous areas. Scannable bite registration materials optimized for CAD/CAM workflows demonstrated improved registration accuracy, particularly in cases with worn dentition or missing anterior teeth.