The objectives of the present study are to compare the survival rates and possible biological and technical complications of metal-ceramic, veneered and monolithic zirconia posterior three-unit fixed partial dentures. The null hypothesis is that no differences would be found between the parameters studied for each type of restoration.

Ninety patients requiring at least one 3-unit Fixed partial denture (FPD) in the posterior region of the maxilla or mandible were included in this study. All subjects were recruited from the Master in Buccofacial Prostheses and Occlusion (Faculty of Odontology, University Complutense of Madrid, Spain). Before treatment, patients were informed of the study objectives, clinical procedures, materials used, advantages and possible risks of the ceramic material, and other therapeutic alternatives. Prior to the study, participants were asked to provide written informed consent. Ninety posterior FPDs were produced and allocated in parallel and randomly to either monolithic zirconia, veneered zirconia or MC restorations. The clinical procedures were performed by two experienced clinicians. All participants received oral hygiene instructions and a professional tooth cleaning prior to prosthetic treatment. The abutment teeth were prepared with a 0.8- to 1-mm-wide circumferential chamfer, an axial reduction of 1 mm and an occlusal reduction of 1.5- to 2.0-mm. A 10- to 15- degree angle of convergence was achieved for the axial walls. Tooth preparations were scanned with an intraoral scanner and the FPDs were designed using specific software. The restorations were then cemented using a resin self-adhesive cement. After cementation, occlusal contacts were evaluated, and the adjusted surfaces were polished using a porcelain polishing kit. The 90 FPDs were examined at 1week (baseline),1, 2 and 2 years by 2 researchers who were not involved in the restorative treatment.

Inclusion Criteria:

• One posterior tooth (molar or premolar) to be replaced
• Vital abutments or abutments with an adequate endodontic treatment
• Abutment not crowned previously
• Periodontally healthy abutments with no signs of bone resorption or periapical disease
• Adequate occlusogingival height for an appropiate connector area of at least 9 mm2
• Stable occlusion and the presence of natural dentition in the antagonist arch.

Exclusion Criteria:

• Patients who require a Fixed Dental Prosthesis of more than three units
• Patients who present reduced crown length (less than 3 mm occlusogingival heigth)
• Poor oral hygiene, high caries activity, or active periodontal disease