Verification of the Definitive Cast During Fabrication of Implant-Supported Restorations

Scan bodies used during intraoral scanning are made of different materials, which may affect digital scan accuracy.1Arcuri L. Pozzi A. Lio F. Rompen E. Zechner W. Nardi A. Influence of implant scanbody material, position and operator on the accuracy of digital impression for complete-arch: a randomized in vitro trial.J Prosthodont Res. 2020; 64: 128-136Abstract Full Text Full Text PDF PubMed Scopus (28) Google Scholar Some of them do not have a metal connection, so it is not possible to verify fit with a radiograph. As various three-dimensional printers have been reported to exhibit different accuracy levels,2Buda M. Bratos M. Sorensen J.A. Accuracy of 3-dimensional computer-aided manufactured single-tooth implant definitive casts.J Prosthet Dent. 2018; 120: 913-918Abstract Full Text Full Text PDF PubMed Scopus (23) Google Scholar the position of the analog on the definitive cast during the metal framework clinical evaluation should be evaluated before applying the veneering ceramic. The following tip shows a straightforward method of verifying the accuracy of the definitive cast. 1.Screw the metal framework onto the implant or abutment (Certain Implant System; Zimmer Biomet 3i Corp) ensuring the same position as that on the definitive cast.2.Make a radiograph to ensure correct fit.3.Apply a 4-fold thick layer of extra-hard wax (Dental Wax; Moyco Union Broach), polyvinyl siloxane (regular or heavy) (Virtual; Ivoclar Vivadent AG) or gypsum (Snow White Plaster #2; Kerr Corp) on the occlusal surface of the metal framework and the 2 adjacent teeth. Make sure the space between the metal framework and the adjacent teeth is filled with the record material (Figs. 1, 2).Figure 2Detail of occlusal record with extra-hard wax.View Large Image Figure ViewerDownload Hi-res image Download (PPT)4.Remove the metal framework and place it on the definitive cast.5.Evaluate the correct fit of the extra-hard wax, polyvinyl siloxane, or gypsum record on the definitive cast. If it does not precisely adapt, there are discrepancies between the clinical situation and the cast, and a new scan is required. If it fits correctly, complete the restoration.