The goal of this clinical trial is to evaluate and compare three digital workflows for the fabrication of definitive implant-supported full-arch prostheses in adult patients requiring fixed implant rehabilitation.
The main questions it aims to answer are:
* Does an automated AI-assisted digital workflow improve the passive fit of definitive full-arch implant-supported prostheses compared with manual and splint-guided alignment workflows? * Are there differences in marginal, geometric, mechanical, and radiographic passivity among the three digital workflows? Researchers will compare manual CBCT-STL alignment, splint-guided alignment, and automated AI-assisted CBCT-STL alignment to see if the degree of digital workflow automation affects the passive fit of definitive full-arch implant-supported prostheses.
Participants will:
* Be adults (18 years and older) indicated for fixed implant-supported full-arch rehabilitation. * Receive a definitive, screw-retained, full-arch implant-supported prosthesis fabricated using one of the three assigned digital workflows. * Undergo standardized clinical and radiographic assessments at the time of definitive prosthesis placement to evaluate prosthesis passive fit.
Adults aged 18 years or older.
Patients indicated for fixed implant-supported full-arch rehabilitation in the maxilla or mandible.
Presence of clinically stable, osteointegrated titanium implants suitable for prosthetic rehabilitation.
Absence of clinical or radiographic signs of peri-implant disease.
Presence of peri-implant mucositis or peri-implantitis at the time of evaluation.
Implant mobility or implant positioning that prevents proper prosthetic rehabilitation.
Uncontrolled systemic medical conditions that could interfere with study participation or prosthetic treatment.
Cognitive, psychological, or medical conditions that limit the ability to comply with study procedures.
Parallel
CBCT-STL Alignment Workflow
Procedure/SurgeryThis procedure consists of a fully digital workflow for fabricating a screw-retained, implant-supported full-arch prosthesis using manual alignment between CBCT and intraoral scan (STL) data. Scannable healing abutments (Tissue Shapers-IF; MedicalFit, Úbeda, Spain) are attached to multi-unit abutments torqued to 10 Ncm. A CBCT scan and an intraoral scan are acquired and manually aligned in CAD software using operator-defined reference points. Passive fit is adjusted manually during the CAD design stage. The definitive framework is milled from monolithic zirconia (IPS e.max ZirCAD Prime; Ivoclar, Schaan, Liechtenstein). This workflow is operator-dependent and serves as the control procedure.
Splint-Guided Alignment Workflow
Procedure/SurgeryThis procedure employs a rigid reference splint with metallic abutment cylinders to guide dataset alignment for full-arch prosthesis fabrication. Scannable healing abutments (Tissue Shapers-IF; MedicalFit, Úbeda, Spain) are connected to multi-unit abutments torqued to 10 Ncm. The splint is attached intraorally and scanned extraorally to capture implant positions. The splint and intraoral scans (STL) are imported into CAD software, where manual alignment is performed using the splint as a reference. The final monolithic zirconia framework (IPS e.max ZirCAD Prime; Ivoclar, Schaan, Liechtenstein) is designed and milled via CAD/CAM. This workflow is operator-dependent and used as an active comparator.
Automated AI-Assisted CBCT-STL Alignment Workflow
Procedure/SurgeryThis procedure uses AI-assisted software (Pdental, MedicalFit, Úbeda, Spain) to automate the alignment of CBCT and intraoral scan (STL) datasets for full-arch prosthesis fabrication. After placement of scannable healing abutments (Tissue Shapers-IF; MedicalFit), intraoral and CBCT scans are obtained. The software automatically detects healing abutments, performs CBCT-STL registration, and corrects deviations greater than 120 µm to achieve passive fit within clinically acceptable limits. The corrected digital model is exported in STL format for CAD design and CAM milling of a monolithic zirconia screw-retained prosthesis (IPS e.max ZirCAD Prime; Ivoclar, Schaan, Liechtenstein). This workflow minimizes operator dependency based on an AI-assisted automation. .
Multi-assessment global passive fit score of definitive full-arch implant-supported prostheses
Passive fit of the definitive full-arch implant-supported prosthesis will be evaluated using a standardized multi-assessment clinical approach. Marginal, geometric (modified Sheffield test), mechanical (passive screw test sensitivity), and radiographic passive fit will be assessed independently at each implant-prosthesis connection. Each assessment will be scored using an ordinal scale (0-2) based on predefined clinical criteria: 0 = no detectable discrepancy, indicating adequate passive fit; 1 = minor discrepancy, indicating a cl To obtain the prosthesis-level outcome, a conservative aggregation rule will be applied: for each assessment dimension, the prosthesis score will be defined as the worst score observed among all implant-prosthesis connections. The global multi-assessment passive fit score (0-2) will then be defined as the worst score observed across all assessment dimensions.
Clinical marginal passive fit (probe assessment)
Marginal passive fit will be evaluated clinically by direct inspection using a calibrated probe to assess the presence of marginal discrepancies between the prosthesis and the transepithelial abutment. Outcomes will be recorded using an ordinal scale (0-2) based on visual and tactile criteria defined as follows: 0 = no visible gap and no probe penetration; 1. = visible marginal discrepancy without probe penetration; 2. = clinically detectable gap with probe penetration or visually, indicating lack of passive fit.
Radiographic marginal gap at the prosthesis-abutment interface
Marginal gaps between the definitive prosthesis and the transepithelial abutment will be evaluated on standardized periapical radiographs. Measured gaps will be classified using an ordinal scale (0-2) as follows: 0 = gap \< 100 µm; 1. = gap between 100 and 130 µm; 2. = gap \> 130 µm, indicating a clinically relevant misfit.
Geometric passive fit assessed by the modified Sheffield test
Geometric passive fit will be evaluated using the modified Sheffield test by tightening a single distal prosthetic screw and assessing the presence of lifting or separation at the non-tightened implant-prosthesis connections. Outcomes will be classified as follows: 0 = no visible or tactile separation; 1. = slight visible separation without probe penetration; 2. = clear separation with probe penetration, indicating absence of passive fit.
Mechanical passive fit assessed by passive screw test sensitivity
Mechanical passive fit will be evaluated qualitatively based on tactile resistance perceived during tightening of the prosthetic screws. Outcomes will be classified using an ordinal scale (0-2) defined as follows: 0 = smooth screw tightening without perceptible resistance; 1. = mild or transient resistance without need for force; 2. = clear resistance or framework flexure during tightening, indicating internal stress and lack of passive fit.
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