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Zirconia has been used in biomedical applications for a long time. Its biocompatibility is not in question. However for structural applications such as in dental implants, zirconia must show improved mechanical performance in addition to its biocompatibility and bone integration aspects. This paper addresses mainly the mechanical issues surrounding zirconia materials in four sections looking at zirconia as a structural biomaterial in terms of processing aspects, flaws and surface characteristics, and design as well as low temperature degradation.
Schlagwörter: Zirconia, implant, aging
Background: Due to its advantageous physical, biological, and esthetic properties as well as its resistance to corrosion, zirconia as a biomaterial to replace missing tooth roots has been the focus of great interest and may become a reliable alternative to titanium implants.
Aim: To present and discuss the preclinical data available on osseointegration of zirconia implants placed in the jawbone.
Results: A great number of preclinical studies on zirconia implants with histologic and histomorphometric data are available. Zirconia implants were tested with different implant dimensions and designs, different surface treatments (e.g. machined, sandblasted, acid-etched, alkaline-etched, fusion-sputtered, selective infiltration-etched, powder injection molding, laser-treated, plasma-treated, microgrooved), in different species (i.e., rabbit, monkey, sheep, miniature pig, rat, dog) and different anatomical locations (i.e. tibia, femur, pelvis, maxilla, mandible), under different loading conditions, and with different observation periods (i.e. 1-56 weeks). Taken together, the boneto- implant (BIC) values reported in the literature for zirconia implants placed in the jawbone range from 18% to 89% with many values in the order of 50%-75%. All in all, most preclinical studies and reviews concluded that the BIC values did not reveal statistically significant differences between zirconia and titanium implants. Furthermore, most studies and most reviews come to the conclusion that modified zirconia surfaces have higher BIC values than machined ones.
Conclusions: Most preclinical studies and reviews conclude that zirconia and titanium implants have similar BIC values. Nevertheless, the survival and success rates of zirconia implants documented in clinical studies are dependent on the implant type/system and somewhat inferior to those of titanium implants. More solid, long-term clinical data on zirconia implants are needed and differences between implant systems and surgical procedures need to be evaluated.
Schlagwörter: Zirconia, dental implant, osseointegration, bone-to-implant contact
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 periimplant 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.
Schlagwörter: Zirconia implants, titanium implants, soft tissue integration, biologic width
Zirconia ceramic implants have become one of the hottest topics in implant dentistry. Different systems with a wide variety of implant composition, surface modifications, designs and prosthetic connections are available on the market. Yet is there sufficient scientific evidence to validate their use in routine clinical practice? This is an overview of the existing clinical evidence on zirconia implants, highlighting their strengths and limitations as an alternative to titanium implants.
Schlagwörter: Zirconia, oral implants, clinical outcomes
The clinician is confronted with the availability of a huge number of dental implants and components today. As a consequence, the choice for the ideal implant and abutment type in each individual situation is quite complex. The goal of implant treatment is to achieve long-term stable implants and restorations which are functionally and esthetically appealing, exhibit healthy peri-implant conditions and create high patient satisfaction. For the survival of implants and prostheses, both the biomechanical stability of the implant components and the biologic response of the surrounding tissues are of relevance. Knowledge of biomechanical and biological principles leads to an understanding of the existing implant types and their range of indications, which facilitates the decision-making process for the clinician. Furthermore, the consequences of implant placement at, below or above the bone crest on the bone reaction are reflected for each implant type. Three levels of significance in implant dentistry are highlighted using basic and recent scientific evidence - the bony part, the interface area between implant and abutment, and the transmucosal part. Key issues such as the formation of a biologic width, the platform switching concept, the influence of microgaps, microleakage and micromovements, and the pros and cons of internal and external implant-abutment connections are discussed. In addition, a short overview on abutments and few condensed clinical recommendations are given.
Schlagwörter: Implant-abutment interface, internal connection, external connection, microgap, bone level