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6 CASE STUDY ALLEGEDLY THE SAME, BUT DO NOT WORK THE SAME: INDIVIDUAL TWO-PART ABUTMENTS PART 1: PRECISION DURING FABRICATION AND BONDING Dr. Peter Gehrke, Carsten Fischer The authors are among the pioneers of individual implant abutments. For over ten years they have been involved with CAD/CAM-fabricated implant abutments and will discuss two-piece abutments (hybrid abutments) in this series of articles. The rst part discusses fabrication precision and a tested protocol for bonding. Customized abutments signi cantly in- crease the lasting success of implant- prosthetic work. The shape of the abut- ment should follow natural anatomy. Particularly in the case of deeply placed implants, the peri-implant tissue is to be adapted to the natural pattern of the sul- cus, which is generally associated with a “curved” implant shoulder (corresponding to the enamel-cement border). State-of- the-art scanning and design options al- low perfect reproduction of the complex peri-implant geometry with customized abutments. Standardized abutments are not suitable in this case. However, the quality and merit of pre-fabricated abut- ments is exemplary due to industrial pro- duction. Pre-fabricated abutments could therefore be regarded as the products of choice. On the other hand, there is the pressing demand for individuality. A ge- ometry congruent with the natural course is an expectation experienced daily in den- tal practice and the laboratory. The treat- ing team is therefore faced with a balanc- ing act which allows only a single choice: customized abutments which correspond to the benchmark of industrially pre-fab- ricated abutments in terms of quality and merit. A plea for clear speci cations Numerous aspects relating to the custom- ized abutment affect the long-term stable outcome. To be on the safe side, we need reproducible rules, for example for the titanium bases, for fabrication and bond- ing, for the surface and the hygiene pro- tocol. Guidelines need to be established, an important issue, to which we have been committed for years. There are clear speci cations for the enossal region of implants based on scienti c research and clinical studies. Such solid and validated parameters also need to be created for im- plant abutments. The objective must be to achieve predictable good results with con- crete rules. There are three points which can give a rough classi cation. This article is therefore split into 3 parts. 1. The fabrication of hybrid abutments (in- house vs. outsourcing) 2. The precision and topography of the sur- face in the sub-mucosal region (rough- ness) 3. Finishing of the abutment (hygiene pro- tocol) Why hybrid abutments? “Hybrid” means a combination of two things of different origin. The objective is to combine the best of both worlds and to open up new application areas as an example. To identify the advantages of two-piece abutments (hybrid abutments), it rst pays to examine one-piece zirconium oxide