Comparison of Non-Calibrated Splinting Bodies and T-Marker for Complete-Arch Implant Scanning

Overview

This randomized crossover clinical trial aims to compare the accuracy and scanning efficiency of two digital techniques for recording implant positions in completely edentulous patients receiving implant-supported full-arch prostheses. Each participant will undergo digital impressions using both a non-calibrated splinting scan body system (IoConnect) with an intraoral scanner and a mobile phone-based photogrammetry system (T-Marker). The order of the two scanning methods will be randomized. The primary outcome is the accuracy (trueness) of implant position recording, assessed by comparing each digital impression with a verified reference model. Secondary outcomes include the time required to complete each digital impression. The findings of this study may help determine whether these digital workflows provide accurate and efficient alternatives for complete-arch implant impressions, thereby supporting clinical decision-making in implant prosthodontics.

Detailed Description Accurate recording of implant positions is essential for the fabrication of passively fitting implant-supported full-arch prostheses. Although intraoral scanners have demonstrated acceptable accuracy for single implants and short-span restorations, complete-arch implant scanning remains challenging because of the absence of stable anatomical landmarks, long interimplant distances, and cumulative image stitching errors. To overcome these limitations, several digital impression techniques have been developed, including splinted implant scan body systems and photogrammetry-based workflows. Recently, non-calibrated splinting scan body systems have been introduced to improve the stability of implant scan bodies during intraoral scanning without requiring scanner-specific calibration. In parallel, mobile phone-based photogrammetry systems have emerged as simplified and more accessible alternatives for capturing implant positions. However, clinical evidence directly comparing these technologies is limited. This prospective randomized crossover clinical trial will compare the accuracy and scanning efficiency of a non-calibrated splinting scan body workflow (IoConnect) with a mobile phone-based photogrammetry system (T-Marker) for complete-arch implant impressions. Twenty-four completely edentulous patients rehabilitated with four implant-supported multiunit abutments will undergo digital impressions using both techniques. The order of the scanning procedures will be randomized using a computer-generated randomization sequence, allowing each participant to serve as their own control. A verified conventional splinted impression and master cast will be fabricated for each participant and digitized with a high-accuracy laboratory scanner to generate the reference dataset. Digital impressions obtained with both workflows will be compared with the reference model using three-dimensional metrology software. Trueness will be evaluated by measuring linear and angular deviations of implant positions after standardized replacement of the scan bodies with their corresponding CAD library files and construction of an identical virtual implant-supported bar for all datasets. The primary objective is to compare the trueness of implant position acquisition between the two digital workflows. The secondary objective is to compare the effective chairside scanning time required for implant position acquisition. The results of this study are expected to provide clinical evidence regarding the accuracy and efficiency of these emerging digital workflows and to support evidence-based selection of digital impression techniques for complete-arch implant rehabilitation.