2017 年 30 巻 4 号 p. 294-300
Purpose : The aim of this study was to introduce a new digital workflow using an intraoral digital scanner and a computer-aided design/computer-aided manufacturing (CAD/CAM) technology to transfer the shape of the provisional restoration to the final restoration supported by a bone-anchored dental implant.
Explanation of the workflow and its trial : In this study, an actual oral plaster cast of a patient with bounded edentulism in the right mandibular premolar region was set as a virtual oral cavity. In this region, a bone-anchored dental implant was placed and a replica of the implant was installed in the plaster cast, where the adjusted provisional restoration was screwed. In the new digital workflow, three types of digital scanning, e.g., the plaster cast, the die with a titanium abutment cylinder being connected to the implant replica, and the die with the implant replica including the provisional restoration, were conducted using an intraoral scanner (Trios2®, 3Shape, Copenhagen, Denmark). The scanned images of the gingiva and the provisional restoration were superimposed on the working cast image utilizing the surface shape of the die with a titanium abutment cylinder and remaining teeth. The final restoration was designed using this three-dimensional digital data by CAD software (Dental Designer™, 3Shape) and was milled from a zirconia disk. The final restoration was adhered to the titanium abutment cylinder on the cast. The provisional restoration and the final restoration were scanned by a 3D scanner (D-810, 3Shape). The morphological discrepancies among the two restorations were calculated as the total volume discrepancy by adding concave and convex volumes using Boolean operations. In addition, the volume ratios of the discrepancies were calculated. When the new digital technique was utilized, the total volume discrepancy was 12.7mm3 (concave:4.6mm3;convex:8.0mm3). The volume ratio of the discrepancy was 3.7%.
Conclusions : A new digital workflow to transfer the shape of the provisional restoration to the final restoration using an intraoral digital scanner, CAD/CAM technology and a plaster cast used for production of provisional restorations was successfully developed and introduced.