Accuracy of the Calibrated Framework for Intra Oral Full Arch Scan (A Cross-over Study)

The passive fit of full-arch implant-supported prostheses is a critical factor influencing the long-term success of implant rehabilitation. Because dental implants lack a periodontal ligament, inaccuracies in transferring implant positions may result in framework misfit, leading to biological and mechanical complications such as screw loosening, component fracture, or implant failure. Conventional splinted open-tray impressions are considered the reference standard for full-arch implant impressions; however, they are technique-sensitive, time-consuming, and susceptible to material distortion and operator-related errors.

Advances in digital dentistry have enabled the use of intraoral scanners for implant impressions. Nevertheless, complete-arch digital scanning remains challenging because cumulative stitching errors may reduce scanning accuracy. The use of a calibrated framework has recently been proposed to improve the accuracy of complete-arch intraoral scanning by providing stable geometric reference points during image acquisition. Although promising, clinical evidence comparing this technique with the conventional splinted open-tray impression technique remains limited.

The purpose of this crossover clinical trial is to compare the accuracy of conventional splinted open-tray impressions and intraoral digital scanning using a calibrated framework in completely edentulous patients receiving full-arch implant rehabilitation.

Twenty healthy completely edentulous patients will be recruited. Following implant placement, each participant will undergo both impression techniques. The conventional workflow will consist of a verified splinted open-tray implant impression, while the digital workflow will involve intraoral scanning using a calibrated stock framework attached to implant scan bodies. STL datasets obtained from both techniques will be analyzed using Geomagic Control X software. The digital models will be superimposed to assess linear deviations along the x-, y-, and z-axes, angular deviations, and global three-dimensional deviations. The results will be statistically analyzed to determine whether the calibrated framework-assisted digital workflow provides transfer accuracy comparable to or greater than the conventional impression technique.

• Conventional Splinted Open-Tray Implant Impression (Other), also known as Conventional Implant Impression Open-Tray Impression Splinted Open-Tray Technique: A conventional verified splinted open-tray implant impression will be performed after implant placement. Multi-unit impression copings will be splinted using dental floss and autopolymerizing resin, followed by a polyvinyl siloxane (PVS) impression. The master cast will be fabricated, verified, and scanned with a laboratory scanner to generate an STL file for accuracy analysis.
• Intraoral Digital Scanning Using a Calibrated Framework (Other), also known as Calibrated Framework Technique Intraoral Digital Impression Full-Arch Intraoral Scanning: An intraoral digital impression will be obtained after implant placement using an intraoral scanner and a calibrated stock framework attached to implant scan bodies. The resulting STL dataset will be compared with the conventional impression using Geomagic Control X software to evaluate linear, angular, and global deviations in implant position transfer accuracy.

Primary outcomes

• Implant Position Transfer Accuracy (Linear deviations) [Immediately after impression procedures following implant placement (same study visit).]: by superimposing STL files obtained from the conventional splinted open-tray impression and intraoral digital scanning using a calibrated framework with Geomagic Control X software. Linear deviations (x-, y-, and z-axes)

Secondary outcomes

• Implant Position Transfer Accuracy (Angular deviations) [Immediately after impression procedures following implant placement (same study visit).]: Accuracy of implant position transfer will be assessed by superimposing STL files obtained from the conventional splinted open-tray impression and intraoral digital scanning using a calibrated framework with Geomagic Control X software

Sex: All, ages: 35 Years to 60 Years

Inclusion Criteria:

* Adults aged 18 years or older.
* Completely edentulous maxilla and mandible for at least 6 months following the last tooth extraction.
* Angle's Class I maxillomandibular relationship with adequate interarch space.
* Sufficient residual alveolar bone quantity and quality to receive dental implants.
* Good oral hygiene.
* Free from uncontrolled systemic diseases or conditions that may interfere with implant osseointegration.
* Able and willing to provide written informed consent.

Exclusion Criteria:

* Temporomandibular joint disorders or parafunctional habits.
* Heavy smokers.
* Uncontrolled systemic diseases.
* History of chemotherapy or radiotherapy to the head and neck region.
* Poor neuromuscular coordination.
* Localized bone defects that could compromise implant placement.

• osama asker, PHD, Study chair, Mansoura University