Constant and healthy vertical dimensions of the peri-implant soft tissues are very important with regard to pink esthetics and peri-implant papilla formation. Around teeth and implants, these vertical soft tissue dimensions are represented by sulcus depth, junctional epithelium and connective tissue contact, which as a unit make up the biologic width. Experimental studies reported similar qualitative and quantitative soft tissue integration and biologic width dimensions for monotype and 2-piece tissue level zirconia implants compared to 2-piece tissue level titanium implants. However, faster maturation processes of epithelial and connective tissues around zirconia implants were assumed. For both implant materials, biologic width dimensions and peri-implant papilla height were independent from loading and surgical protocol but dependent on implant design and position of the micro-gap between implant and prosthetic supra structure. Over time, clinical studies reported a significant increase in peri-implant papilla height formation for zirconia implants, whereas the distance between the alveolar crest at the neighboring tooth and the lowest point of the contact area of the crown were considered to be an important factor affecting papilla formation. In conclusion, material characteristics – ceramics compared to titanium – did not have any major/significant effects on peri-implant soft tissue integration. Thus, similar physiological processes might be supposed for both materials with regard to morphogenesis of peri-implant soft tissues.
In the first decades of implant dentistry, the achievement of biological stabilization of the implant in the surrounding bone tissue known as osseointegration was the major goal for clinicians, scientists and patients. The development of micro-roughened surfaces made titanium and titanium-alloy implants a standard and extremely reliable treatment procedure in dentistry since their osseous integration as well as their clinical performance were significantly improved (Roehling et al. 2015). Nowadays, patients’ demands with regard to implant dentistry have changed. Besides successful osseous integration, esthetic outcomes – especially in the anterior region – have become even more important. With regard to pink esthetics like soft tissue margin and interdental peri-implant papilla formation, healthy and constant vertical peri-implant soft tissue dimensions – represented by the biologic width – are very important. Moreover, from a periodontal point of view, gingival tissues around implants have a similar barrier function to dento-gingival tissues around teeth to help prevent bacterial peri-implant diseases (Berglundh et al. 1991). Thus, peri-implant soft tissue integration – represented by epithelial and connective tissue – is as important as osseous integration (Cochran et al. 1997).
In recent years, based on increasing demand from patients for metal-free reconstructions, ceramic implants made from zirconium dioxide (zirconia, ZrO2) have become a viable and evidence-based treatment option. The latest market analyses have even concluded that ceramic implants could become a “game changer” in implant dentistry. However, the first generation of zirconia implants had a rather smooth implant surface and, consequently, showed decreased survival rates compared to established titanium implants (Roehling et al. 2016). Later on, manufacturing processes were improved to fabricate fracture-resistant, micro-roughened zirconia implants. Experimental and clinical studies reported that the latest generation zirconia implants with a micro-rough surface show a similar osseointegrative capacity and comparable clinical outcomes to micro-rough titanium implants (Gahlert et al. 2016, Grassi et al. 2015, Janner et al. 2017). Empirical and clinical experience confirms stable and healthy peri-implant soft tissue conditions around zirconia implants (Figs 1 and 2) and might even assume advantages with regard to pink esthetics compared to titanium implants. However, little evidence-based data dealing with soft tissue integration around zirconia dental implants is available.