PRINTOW: Occlusal Wear of Denture Teeth in Digitally Fabricated Complete Dentures

A Randomized, Double-Blind, Three-Arm Superiority Trial Comparing Occlusal Wear of 3D-Printed, CAD/CAM-Milled, and Prefabricated Denture Teeth in Digitally Fabricated Complete Dentures in Edentulous Patients

This randomized controlled trial evaluates the occlusal wear of denture teeth fabricated using three digital workflows: 3D-printed denture teeth, CAD/CAM-milled double cross-linked denture teeth, and prefabricated denture teeth. Occlusal wear will be assessed over 24 months using digital superimposition techniques. The study aims to determine whether 3D-printed denture teeth demonstrate superior wear resistance compared to CAD/CAM-milled denture teeth.

This is a single-center, prospective, randomized, controlled, double-blind clinical investigation comparing three digitally fabricated complete removable dental prosthesis workflows in edentulous patients. The study will be conducted at the University Clinics of Dental Medicine, University of Geneva.

The study includes adult patients who are completely edentulous in the maxillary and mandibular arches and require new complete removable dental prostheses. Participants may be rehabilitated with either a conventional mandibular complete denture or a mandibular implant overdenture supported by clinically stable implants. This inclusion strategy is intended to improve recruitment feasibility and reflect real-world clinical practice. Mandibular prosthetic status at baseline will be used as a stratification factor during randomization and will be accounted for in the statistical analysis.

A total of 48 participants** will be randomized in a 1:1:1 allocation ratio to one of three treatment groups: fully 3D-printed complete dentures with printed denture base and printed denture teeth; CAD/CAM-milled complete dentures with milled double cross-linked denture teeth; or CAD/CAM-milled complete dentures with prefabricated denture teeth, serving as a clinical benchmark group.

The primary objective is to compare occlusal wear performance of denture teeth between the fabrication workflows. The primary confirmatory comparison will be conducted between the fully 3D-printed workflow and the CAD/CAM-milled double cross-linked workflow. Occlusal wear will be assessed by three-dimensional digital superimposition of intraoral scans acquired at baseline and follow-up visits. The primary endpoint is the average negative deviation of occlusal surfaces at 24 months, representing material loss over time.

> Secondary outcomes include root mean square surface deviation, patient-reported outcomes assessed with the Oral Health Impact Profile for Edentulous Patients and the Denture Satisfaction Index, chewing efficiency, bite force, prosthetic retention, color stability, prosthesis-related costs, maintenance interventions, and prosthetic complications. These outcomes will be assessed according to the study schedule at baseline and during follow-up visits at 12, 24, and 60 months.

Participants and outcome assessors will be blinded to denture fabrication workflow and denture tooth material allocation. Prostheses will be labeled using anonymized codes, and digital files used for wear analysis will be anonymized using participant study ID and time point. Treating clinicians and laboratory personnel will not be blinded due to the nature of the intervention, but they will not be involved in blinded outcome assessment.

All prostheses will be fabricated according to standardized clinical and laboratory procedures using CE-marked medical devices and materials according to the manufacturers' instructions for use. The prosthetic treatment phase will include clinical evaluation, impressions, intermaxillary records, prototype try-in, and delivery of the final prostheses. Follow-up assessments will be performed after prosthesis delivery to evaluate clinical, functional, patient-reported, material-related, and maintenance outcomes.

Inclusion Criteria:

• Written informed consent provided by the participant
• Age ≥ 18 years
• Fully edentulous maxilla and mandible requiring rehabilitation with new complete removable dental prostheses
• Patients with or without mandibular implants (implant overdenture or conventional denture)
• Clinical indication for fabrication of new maxillary and mandibular complete removable dental prostheses
• Currently wearing complete dentures, or a maxillary denture combined with a mandibular denture or overdenture
• Ability and willingness to attend all scheduled follow-up visits for the duration of the study

Exclusion Criteria:

• Contraindications to the medical devices used, e.g. known hypersensitivity or allergy;
• Known or suspected non-compliance, drug or alcohol abuse; Inability to follow the procedures of the investigation;
• Enrolment of the investigator, his/her family members, employees and other dependent persons;
• Reported severe bruxism or clenching habits, identified through patient interview and clinical examination, including self-reported grinding or clenching, partner reports, morning jaw discomfort, and other signs of parafunctional activity;
• Width of the edentulous maxilla >80 mm;
• Width of the edentulous mandible >80 mm; Vertical prosthetic space <38 mm (maxilla or mandible);
• Depression: Geriatric Depression Scale >9;
• Xerostomia: UFR ≤ 0.2ml/2min;
• Dementia: Clock-Drawing Test ≤5;
• Active peri-implant disease or instability of the two mandibular implants at baseline when implants are present;
• Presence of an implant-retained prosthesis in the maxilla;
• Planned implant-related surgical intervention during the study period.