Randomized Controlled Clinical Trial of CAD/CAM and Conventionally Fabricated Singl Implant Abutments.

CAD/CAM technology has been introduced to the field of implant dentistry in the beginning of 1990's (Priest 2005). Since their introduction, the use of CAD/CAM technology in the production of dental implant restorations has been rapidly expanding. However, little evidence is currently present supporting its clinical viability (Henriksson 2003, Canullo 2007).

Therefore, the suggested prospective randomized study includes bone level placed Straumann implants restored with transmucosal elements and crowns fabricated using either CAD/CAM "Etkon" technology (Zirconia abutment and ceramic crown) or a conventional technique (Crossfit titanium abutment and a ceramometal crown).

The aim of this randomized controlled clinical trial is to examine single-tooth implant restorations in the esthetic zone. An esthetic area is defined as any area that is visible in the patient's full smile. [3rd ITI consensus conference 2004] The rehabilitations will be fabricated using two different techniques. Zirconia CAD/CAM (ZCC) implant restorations (tests) will be compared to Titanium conventionally-fabricated (TCF) implant restorations (controls) using, reproducible esthetic (objective/subjective) and biologic parameters.

This in vivo study is a randomized study with two groups of 15 patients with one implant each for a total of 30 patients and 30 implants. The implants will be examined for successful tissue integration according to the criteria of success (Buser et al. 1990) at every recall visit.

In addition, the following parameters will be evaluated for each restoration:

• Esthetic: A. Objective: PES/WES Score (Belser et al. 2009) from 1:1 digital photograph, study casts, and spectrophotometric measurements, and B. Subjective: VAS questionnaire for patients and VAS questionnaire from experts.
• Biologic (mPI, mB, simplified GI, microbial sample, periapical radiograph for DIB, and width of keratinized facial mucosa)

Finally, an evaluation of the mechanical, biologic and technical complications will be performed at every recall visit. Mechanical complications would be defined as those complications that involve the prosthesis such as abutment screw loosening, fracture of the veneer material, fracture of the crown framework, abutment screw fractures, and implant fractures. The category of biologic complications will include those complications that involve the soft tissues (e.g., fistula, suppuration, bleeding, gingival inflammation, and soft tissue dehiscence). Technical complications are defined as those related to restorative components and crowns (e.g. crown emergence profile, abutment and crown fit, screw loosening, ceramic fracture).