Complete Digital Workflow for Prosthesis Prototype Fabrication with the Double Digital Scanning (DDS) Technique: A Prospective Study on 16 Edentulous Maxillae

Abstract

Purpose To assess the accuracy of fit of milled prosthesis prototypes for completely edentulous patients using a digital workflow. Materials and methods Sixteen patients received intraoral full‐arch digital scans with the double digital scanning (DDS) technique and the generated standard tessellation language (STL) files were superimposed and imported into computer‐aided design software (Exocad DentalCAD, exocad GmbH, Darmstadt, Germany) for design. After the design, each master STL file was used for computer‐aided manufacturing of the prosthesis prototypes through a complete digital workflow. The primary outcome was the accuracy of fit assessment of the digitally fabricated prototypes on verified patient master stone casts. Two blinded clinicians tested the accuracy of fit of the milled prosthesis prototypes on the verified master stone casts utilizing the screw‐resistance test and direct observation. Results Out of the 16 digitally fabricated prototypes from intraoral full‐arch digital scans, all 16 presented with an accurate fit on verified master stone casts. Conclusions Digitally fabricated full‐arch prosthesis prototypes can be generated with a complete digital workflow leading to clinically acceptable fit.

Reverse scan body: A complete digital workflow for prosthesis prototype fabrication

“…This reduces the number of required appointments and most importantly allows for implant data acquisition in the edentulous mandible which has been reported to be problematic. [3][4][5][6][7][8][9][10] The fact that 44 out of 50 3D-printed prosthesis prototypes presented with acceptable fit highlights the limitations with 3D printing full-arch prototypes that may include the resin being used, the nesting orientation of the STL file, and the post-processing procedures. The same STL files were used for both milling and 3D printing, yet 88% fit was achieved with 3D printing compared to 100% fit with milling.…”

“…Two experienced clinicians (PP, AB) tested the accuracy of fit of each prototype prosthesis on the master cast using the screw‐resistance test, visual inspection, and periapical radiographs 12‐15 . For each prototype to be tested, the prosthesis prototype was placed on the master cast, anthe prosthetic screws were placed and hand‐tightened in a sequence from one terminal abutment to the other starting from the maxillary right side to the maxillary left side (maxillary right molar, maxillary right canine, maxillary left canine, and last maxillary left molar) 7,10,13‐15 . During the tightening of each prosthetic screw, if complete seating required more than half a turn of the screwdriver after initial resistance was felt, it was deemed a misfit (Figure 6).…”

“…During the tightening of each prosthetic screw, if complete seating required more than half a turn of the screwdriver after initial resistance was felt, it was deemed a misfit (Figure 6). 7,10,13‐15 Cohen's κ ‐score was used for assessment of inter‐examiner reliability.…”

“…The double digital scanning technique with the use of fiducial markers has been introduced for complete digital workflow for prosthesis prototype fabrication 2 . Fiducial markers are used to aid in data acquisition during edentulous jaw intraoral scanning and to assist in the merging of multiple digital scans 7‐12 . However, even with the use of fiducial markers, intraoral scanning especially in the edentulous mandible remains challenging.…”

“…2 Fiducial markers are used to aid in data acquisition during edentulous jaw intrao-ral scanning and to assist in the merging of multiple digital scans. [7][8][9][10][11][12] However, even with the use of fiducial markers, intraoral scanning especially in the edentulous mandible remains challenging. The presence of saliva, sensor fogging, and lack of keratinized mucosa coupled with advanced mandibular resorption may affect negatively data acquisition with intraoral scanning.…”