A crossover clinical trial investigates two novel CAD/CAM techniques for complete removable dental prostheses for edentulous patients, milling and rapid prototyping (3D-printing) in a clinical setting of an undergraduate student clinic. Outcome parameters concern the dentures' trueness, retention, stability, esthetics and occlusion. Secondary outcome parameters include willingness to pay and prosthetic maintenance need.

The process of fabricating complete removable dental prostheses (CRDPs) by novel CAD/CAM manufacturing technique has in the recent years gained immense popularity with clinicians as well as dental technicians worldwide. CRDPs can be manufactured by a subtractive process (milling technique) or by an additive process (rapid prototyping or 3D printing). The milling technique is the frequently employed technique for fabricating CRDPs; it is well documented in terms of precision, material properties, and a few clinical trials have even demonstrated good patient and clinician satisfaction. The rapid prototyping (3D printing) method however, is still in the developing stages for this particular application. Although both methods seem to yield clinically acceptable results, there are no studies in current literature which compare the CRDPs manufactured by the two CAD/CAM methods.

The proposed single-center, double-blind, randomized crossover clinical trial specifically aims to test the following hypothesis that:

• there is no difference between the two types of CRDPs (milled, and rapidly prototyped) in terms of trueness, denture quality, patient satisfaction, prosthodontic maintenance and adjustments requirements and incurred costs.

Fifteen pre-doctoral final year dental students and their respective completely edentulous patients will be recruited in this RCT. A traditional clinical complete denture protocol will be followed to record the clinical steps. Two sets of CRDPs will be manufactured (CAD/CAM milling and 3D printing). The CRDPs will be randomized before denture insertion and then delivered to the patient. Each CRDPs will be worn by the patient for a period of 6 weeks, before crossing over. Clinical examinations and data collection will be performed at baseline (T0), at denture insertion stage (T1), and at the end of 6 weeks (T2) for each of the investigated CRDPs. Assessments will comprise of comparison of trueness of denture intaglio surfaces against the corresponding master cast, denture quality assessments, patient satisfaction scores, prosthodontic maintenance needs and willingness-to-pay analysis and cost minimization analysis.

This RCT will contribute significantly in the development of CAD/CAM treatment concepts for fabricating complete removable dental prostheses (CRDPs). The study would highlight the differences, if any, between the two manufacturing methods for CRDPs, in terms of trueness, quality of the prostheses, clinician and patient satisfaction and also incurred costs. Clinically, the planned RCT hopes to demonstrate the feasibility of these novel treatment concepts in frail elderly edentates. A significant reduction in the treatment times, maintenance visits, and costs along with high patient satisfaction with these newer CRDPs would be added advantages when treating the elderly edentates.

Inclusion Criteria:

• patient of undergraduate student at the University clinics of dental medicine Geneva
• completely edentulous
• requesting novel complete dentures

Exclusion Criteria:

• not willing to sign informed consent

neither the patients, nor the operator knew which type of denture was inserted