An indirect method of verifying passive fit of complete arch implant-supported frameworks fabricated from photogrammetry scans

Abstract

The passive fit of frameworks on multi-unit abutments has been considered crucial for the long-term success of complete arch, implant-supported, fixed prostheses. 1 Jokstad A. Shokati B. New 3D technologies applied to assess the long-term clinical effects of misfit of the full jaw fixed prosthesis on dental implants. Clin Oral Implants Res. 2015; 26: 1129-1134 Crossref PubMed Google Scholar Photogrammetry has demonstrated better accuracy than intraoral scanning and conventional impression techniques to record the position of implants. 2 Sallorenzo A. Gómez-Polo M. Comparative study of the accuracy of an implant intraoral scanner and that of a conventional intraoral scanner for complete-arch fixed dental prostheses. J Prosthet Dent. 2022; 128: 1009-1016 Abstract Full Text Full Text PDF PubMed Scopus (13) Google Scholar However, errors introduced during fabrication may still compromise the passive fit of the definitive prosthesis, even with accurate scanning using the photogrammetry technique. 3 Al-Meraikhi H. Yilmaz B. McGlumphy E. Brantley W. Johnston W.M. In vitro fit of CAD-CAM complete arch screw-retained titanium and zirconia implant prostheses fabricated on 4 implants. J Prosthet Dent. 2018; 119: 409-416 Abstract Full Text Full Text PDF PubMed Scopus (22) Google Scholar The current intraoral methods of verifying passive fit, including visual inspection, tactile sensation, radiography, disclosing materials, screw resistance test, and the Sheffield test, are subjective and not capable of detecting lingual or subgingival misfit. 4 Abduo J. Bennani V. Waddell N. Lyons K. Swain M. Assessing the fit of implant fixed prostheses: a critical review. Int J Oral Maxillofac Implants. 2010; 25: 506-515 PubMed Google Scholar In the conventional protocol, the definitive cast made from a custom tray elastomeric impression can be verified with a dental gypsum device. 5 Manzella C. Burello V. Bignardi C. Carossa S. Schierano G. A method to improve passive fit of frameworks on implant-supported prostheses: an in vivo study. Int J Prosthodont. 2013; 26: 577-579 Crossref PubMed Google Scholar However, since the frameworks made from photogrammetry are manufactured without a definitive cast, verifying the passive fit of the frameworks is challenging. 6 Rutkunas V. Larsson C. Vult von Steyern P. Mangano F. Gedrimiene A. Clinical and laboratory passive fit assessment of implant-supported zirconia restorations fabricated using conventional and digital workflow. Clin Implant Dent Relat Res. 2020; 22: 237-245 Crossref PubMed Scopus (11) Google Scholar In the treatment of the first patient, misfits were found between the frameworks and the 3-dimensional printed cast; therefore, the accuracy of the frameworks needed to be verified to determine whether the distortion was introduced during printing of the cast (Fig. 1A-C). An inexpensive and user-friendly method of verifying the passive fit of frameworks is described. Figure 1A, Intraoral view after removal of interim prosthesis. B, Impression scanning using photogrammetry technology. C, Misfits between framework and printed cast. D, Placement of abutment replicas. E, Fixture of replicas with dental gypsum. F, Evaluating fit of framework. View Large Image Figure Viewer Download Hi-res image