3D Printing for the Fabrication of Mandibular Implant Overdentures

CAD/CAM (computer-aided design and computer-aided manufacturing) can be a game-changer for better access to care by edentulous patients. Digital overdentures offer potential for more satisfied patients due to better fit and can be provided faster/with lower costs. Providing digital overdentures has potential to enhance access to oral healthcare by the elderly, given the expected benefits (better quality, simpler, faster and more affordable than those obtained traditionally). However, evidence from randomized trials is crucial to verify the relevance of those benefits, especially from the patient perspective, and to confirm those benefits. This trial also serves as an opportunity to improve CAD software and materials, since it will identify technical challenges specific to the provision of digital overdentures.

This randomized cross-over trial aims to reveal whether implant-retained mandibular overdentures (IMO) produced by CAD and 3D printing are more satisfactory to edentulous seniors than those fabricated using traditional methods.

The investigators will recruit 26 edentulous participants (any sex/gender) amongst previous patients at McGill University, based on the following eligibility criteria: complete edentulism, elderly (age ≥60 years, according to the WHO), need for new maxillary and mandibular complete dentures, ability to complete questionnaires, and previous treatment with two implants in the anterior mandible. Each participant will receive two pairs of dentures, as per the McGill Consensus on Implant Overdentures (i.e., a mandibular overdenture opposed by a maxillary complete denture: (i) one by digital rendering of the mouth, virtual prosthetic design and 3D printing; (ii) a control pair, by traditional clinical and laboratory methods. Each pair will be worn for 3 months according to a random sequence (total follow-up: 6 months after the delivery of the first pair of dentures). Both overdentures will be retained by 2 Novaloc abutments and medium retention matrices.

Outcomes will include patient satisfaction ratings and oral health-related quality of life. The investigators will evaluate other patient-reported outcomes, as well as clinician-assessed quality and cost. Outcome assessment will occur at baseline, then at three months after participants have worn each pair of dentures. Following the cross-over, participants will keep their preferred denture pair and return after 12 months to evaluate maintenance requirements, including stained and broken dentures.


Eligibility Criteria:
Inclusion criteria:

* elderly according to the age cut-off purported by the World Health Organization (age \>=60 years) and living independently;
* completely edentulous;
* no tooth extraction within the past 12 mo;
* two Straumann tissue level RN implants symmetrically distributed in the anterior mandible for 3 or + mo before the trial interventions;
* desire to receive both upper denture and lower IMO with new stud attachments;
* good understanding of spoken and written English or French;
* Ability to provide written informed consent.

Exclusion criteria:

* severe systemic disease or needing frequent hospitalization (i.e. American Society of Anesthesiologists Physical Status class \>II);
* evidence of cognitive or motor impairment;
* acute or chronic symptoms of parafunctional or temporomandibular disorders;
* intraoral pathologies, either acute, progressive, potentially malignant or capable to hamper denture fit;
* signs of endosseous lesions or residual dental structures in panoramic radiographs;
* signs of implant failure, including clinical mobility, peri-implant radiolucency, unacceptable bone loss (0.2mm/year after 1st year, or \<2mm any time) and persistent signs/symptoms (pain, neuropathy, infection or exudate).