Effect of Angulation Between Multi-Unit Abutments on Accuracy of Photogrammetry Scanning

Abstract

A study to comparing the accuracy between analog elastomeric impressions and photogrammetry scanning utilized for full-arch implant supported prosthesis was conducted to investigate the clinical implications of misfit values in terms of 3-dimentional deviation and angular deviation. Furthermore, the effect of increased inter-abutment angulation between multiunit abutments was evaluated; the angulations evaluated were zero-degree, 10-degree, and 20-degree inter-abutment angulations. Using a reverse engineering software, and utilization of reference best-fit algorithms, conventional impression technique, PIC Dental Photogrammetry technique and ICam4D photogrammetry technique were compared. The accuracy determined via the 3-dimentional deviation and angular deviation were analyzed for each technique and for each of the three inter-abutment angulations. Conventional impressions scans exhibited lower deviation values compared to both photogrammetry techniques. Additionally, the increased inter-abutment angulation did not negatively affect the accuracy of the conventional impression samples. However, increased inter-abutment angulation had a variable effect on the accuracy of the photogrammetry scanning. The study emphasized that traditional impressions are more accurate for recording implant positions in full-arch implant-supported prostheses, while the photogrammetry techniques showed comparable accuracy influenced by the inter-abutment angulation. Differences observed between groups and other literature cited, can best be explained by the superior control of settings of the conventional impression technique, including setting time, polymerization shrinkage and thermal contraction of the dental materials used.