Hindawi Publishing Corporation International Journal of Dentistry Volume 2013, Article ID 463073, 7 pages http://dx.doi.org/10.1155/2013/463073 Clinical Study Evaluation of the Success Criteria for Zirconia Dental Implants: A Four-Year Clinical and Radiological Study Andrea Enrico Borgonovo, 1 Rachele Censi, 2 Virna Vavassori, 1 Marcello Dolci, 1 Josè Luis Calvo-Guirado, 3 Rafael Arcesio Delgado Ruiz, 3 and Carlo Maiorana 1 1 Department of Implantology, Dental Clinic, Fondazione IRCCS Ca’ Granda Ospedale Maggiore Policlinico, School of Oral Surgery, University of Milan, Milan, Italy 2 Department of Implantology and Periodontology III, Istituto Stomatologico Italiano, Milan, Italy 3 Faculty of Medicine and Dentistry, Murcia University, Spain Correspondence should be addressed to Virna Vavassori; virna.vavassori@hotmail.it Received 11 May 2013; Accepted 15 July 2013 Academic Editor: Carlo Monaco Copyright © 2013 Andrea Enrico Borgonovo et al. Tis is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. Objectives. Te aim was to evaluate survival and success rates, sof tissue health, and radiographic marginal bone loss (MBL) of zirconia implants placed in the esthetic and posterior areas of the jaws and in association with multiple or single implant restorations afer at least 6 months of defnitive restoration. Material and Methods. 35 one-piece zirconium implants were utilized for single or partially edentulous ridges rehabilitation. All implants received immediate temporary restorations and six months afer surgery were defnitively restored. Every 6 months afer implant placement, a clinical-radiographic evaluation was performed. For each radiograph, the measurements of MBL were calculated. Results. Te results showed that the mean MBL at 48-month followup was 1.631 mm. Te mean MBL during the frst year of loading was not more signifcant for implants placed in the frst molar regions than for those positioned in other areas. Moreover, no diferences in marginal bone level changes were revealed for multiple and single implants, whereas MBL in the frst year was observed to be slightly greater for implants placed in the maxilla than for those placed in the mandible. Conclusion. Zirconia showed a good marginal bone preservation that could be correlated with one-piece morphology and characteristics of zirconia implants. 1. Introduction Te use of endosseous implants achieves predictable results in terms of survival and success rates of oral rehabilitation [1]. More recently, greater interest is directed towards esthetics of the prosthetic rehabilitations. Successful esthetic results of dental implant placement require knowledge of essential biological concepts and skill in diferent surgical techniques [2]. Anyway, the surgical techniques or prosthetic [3] solu- tions by now proposed are not always sufcient to achieve long-term esthetic results; in fact, it was demonstrated that periimplant sof tissues tend to recede afer positioning a defnitive prosthetic restoration [4]. In order to avoid gray- ish transparency of titanium implants through sof tissues, ceramic materials were tested. All-ceramic dental implants were introduced in dental implantology as an alternative to titanium implants. Another reason to fnd an alternative material to titanium was sensibilization, possible release of metallic ions, and allergy to this material, as reported in some studies [5, 6]. Alumina was one of the frst ceramic materials used but because of its hardness combined to a low fectural and fracture strength poor long-term results were achieved and this material was abandoned [7]. More recently, research was oriented towards new gen- eration ceramic materials such as zirconia, which has more favorable mechanical properties (high fexural strength 900– 1200 Mpa, hardness 1200 Wickers, and Weibull modulus 10– 12). In addition, zirconia has a high biocompatibility and low plaque adhesion [8, 9] and several animal studies showed