Comparing the long-term clinical outcome of two designs of high strength ceramic (zirconia) crowns on dental implants

INTERVENTION: Implants will be surgically inserted as per routine surgical procedure. After the integration of the implant (3 months after surgery), the implant will be restored with a crown. Any implant restoration needs 3 clinical appointments. The first appointment will be used to take an impression of the implant (about 1 hour). The impression is needed to fabricate a cast that will be used to fabricate the implant crown. In the second appointment (about 1 hour), the implant crown will be fitted on the implant. A third appointment (about 30 minutes) is needed to review the implant, and normally scheduled within 2‐4 weeks after fitting of the implant restoration. Traditionally, implant crowns are fabricated from porcelain‐fused to metal. Recently, full contour (monolithic) zirconia is proposed for implant restoration and believed to be durable and aesthetic. The crown can be designed and fabricated to fit directly on the implant, or it can be designed and fabricated to fit on an intermediate component (abutment). The abutment has been suggested to reduce soft tissue manipulation. Therefore, implant full contour (monolithic) zirconia crowns for 2 different designs will be evaluated: 1. Nobel FCZ‐ protocol: Full contoured zirconia crown on implant 2. Nobel on‐1‐abutment protocol: Full contoured zirconia crown on intermediate abutment All restorative steps will b e completed under supervision of prosthodontics dental specialists who are familiar with all the applied restorations of the study. To standardise the treatment, the involved clinicians will be calibrated and will follow a data collection form to ensure consistent data gathering for each step of treatment. CONDITION: Restoration of single‐tooth dental implants PRIMARY OUTCOME: Implant restoration survival in the form of incidence of complications (biological and mechanical) in percentages, as assessed by researcher clinician. The complications can be peri‐implant soft tissue inflammation, discoloration of peri‐implant soft tissue, loosening of restoration screw, chipping of ceramic restoration and restoration fracture. These complications are composite primary outcome and can be detected by visual inspection of the soft tissue and the restoration, routine radiographic evaluation and palpation of the restoration. SECONDARY OUTCOME: Clinical accuracy of each system in the form of occlusal and proximal contacts at the time of restoration fitting on the implant. The clinical accuracy is composite measurement of occlusal and proximal contacts: ; ‐ Occlusal contacts will be evaluated evaluated qualitatively and rated as: ideal, minor adjustment (chairside). major adjustment (return to manufacturer) or misfitting (remake) ; ‐ Proximal contacts against adjacent teeth will be evaluated qualitatively and rated as: ideal, tight (minor adjustment, open (major adjustment) or misfitting (remake) Clinician satisfaction of the treatment will be rated via visual analogue scale. Patient satisfaction of the treatment will be rated via visual analogue scale. Restoration aesthetics will be rated as acceptable on not acceptable by clinician. Restoration aesthetics will be rated as acceptable on not acceptable by patient. Soft tissue response will be evaluated by composite measurements of the probing pocket depth (mm), bleeding on probing (present or absent) and metallic discoloration (present or absent). ; The probing depth and bleeding on probing will be assessed by periodontal probe. The metallic discoloration will be assessed by visual inspection of the peri‐implant soft tissue. INCLUSION CRITERIA: Single implant Minimum of 20 functional teeth