Accuracy of Full Arch Intraoral Scanning

Effect of Different Intraoral Scanning Approaches on the Passive Fit of Mandibular All-on-Four Screw-Retained Frameworks

Although an intraoral scanner IOS can offer the clinician a completely digital workflow, achieving trustworthy digital scans in edentulous jaws is challenging because of the lack of fixed anatomical landmarks. From this perspective, several methods have been proposed to improve the accuracy of digital scanning, however, related results remain inconclusive, and previously proposed devices have had limitations, such as bulkiness, excessive manufacturing requirements, and poor commercial applicability.

Thus, this study aims to clinically compare the effect of conventional versus photogrammetry intraoral scanning methods on the passive fit of mandibular all-on four screw-retained frameworks.

The current study will be designed to be a crossover, double-blinded randomized clinical trial. Eighteen edentulous patients will be selected to share in the study to be rehabilitated by screw-retained prostheses following the all-on-4 protocol. After guided implant surgery, patients will be immediately restored by screw-retained acrylic provisionals following the traditional denture conversion technique. The definitive prosthesis will be fabricated after osseointegration starting with the intraoral scanning procedure; each patient will be subjected to three different scanning methods that can enhance the existing IOS workflow; for group I, the Medit i600 will be used to obtain direct intraoral scans while the scan bodies are combined with extra photogrammetry system scanning assistance, for group II, Medit i600 direct intraoral scans will be obtained while applying basic simple splinting along with incorporating a unique tip in the scanning protocol and scanner software, for group III, Medit i600 direct intraoral classical scans will be obtained while applying only a basic simple splinting. The STL file obtained from the different scans will be sent directly to the dental laboratory and three CAD/Milled frameworks will be realized based on the acquired scans. The jigs' passivity will be tested in the patient's mouth by the single screw test followed by the screw resistance test and the screw resistance test parameter will be calculated. The results will be collected for statistical analysis.

Inclusion Criteria:

• Patients having a completely edentulous lower arch that could be restored by fixed screw-retained implant prosthesis.
• Patients having a substantial bone height and width at prospective implant sites to install four standard-size implants following the all-on-4 protocol.
• Patients having Sufficient crown height space.

Exclusion Criteria:

• Patients with bad oral hygiene.
• Patients with limited mouth opening.
• Vulnerable groups.
• Uncooperative patients.
• Patients receiving or undergoing radiotherapy or chemotherapy. Patients with systemic diseases affecting bone metabolism. Smokers.