Assessment Of Intraoral Scanning For Three-Unit Implant-Supported Bridges

To evaluate the dimensional accuracy of intraoral scanning (IOS) for three-unit implant-supported fixed prostheses in posterior regions and compare it with conventional impression methods to determine its clinical applicability. A reference resin model was fabricated with two implants (positions 25 and 27 in the maxillary arch) and digitized. Nine intraoral scans were acquired with a intraoral scanner. Comparative conventional impressions were obtained through three established techniques (n=9 per group): open-tray splinted (OTS), open-tray non-splinted (OTNS), and closed-tray (CT) methods. Three-dimensional deviations were analyzed through metrological comparisons between test models and the master model using specialized CAD software. RMS values of each implant were calculated after superimposing the nature teeth of digital models. Coronal, apical and angular deviations of implant 27 were calculated after superimposing implant 25 to compare the relative position between implants in each model. One-way ANOVA and post-hoc test were adopted to compare the differences among different impression techniques. There was a statistical difference in RMS of two implants between four groups (P < 0.01). The RMS of group CT was significantly higher than the others (P < 0.01). There were significant differences in Coronal, apical and angular deviations of implant 27 (P < 0.01). The study substantiates that digital intraoral scanning demonstrates comparable accuracy to conventional impression techniques for posterior three-unit implant-supported fixed prostheses. Clinical implementation should prioritize scan body selection and scanning sequence optimization.