ZIRCONIA IMPLANTS: AN ODE TO THE BEGINNING OF A NEW ERA

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1 ZIRCONIA IMPLANTS: AN ODE TO THE BEGINNING OF A NEW ERA P. Laxman Rao 1, Shilpi Bhattacharyya 1, G. Ajay Kumar 2 1 Head Of The Department, Department Of Prosthodontics And Crown And Bridge And Implantology, Army College Of Dental Sciences,Secunderabad-087,Telangana,India 1 Post Graduate Trainee, Department Of Prosthodontics and Crown And Bridge And Implantology, Army College Of Dental Sciences, Secunderabad-087, Telangana, India 2 Professor, Department Of Prosthodontics And Crown And Bridge And Implantology, Army College Of Dental Sciences, Secunderabad-087, Telangana, India ABSTRACT: Titanium and its alloys have been dominating the field of implantology for a long time. It is considered the gold standard in the field. Yet with the increasing demand of esthetics and the fear of potential immunological reactions, it is time to look towards new materials. Zirconia in this aspect is proving to be a promising product. It is being touted as an alternative to dental implants. With its high esthetic results, biocompatibility, low plaque affinity and good mechanical properties it is becoming a popular choice. The goal of the current article is to provide a comprehensive literature on the topic of zirconia implants. Major subtopics include its comparison with titanium implants and various properties. For zirconia implants further clinical trials and in vivo studies need to be conducted before it becomes the material of choice. KEYWORDS: Zirconia, implant, gold standard, immunological reactions, titanium, clinical trials Introduction With the overwhelming increase in popularity of implantology in the dental field, it is an everyday challenge to provide a better treatment choice. The increase in information is becoming a challenging endeavour for the dentist to keep up and apply in practice. In order to achieve both safe and higher standards of excellence in this field it is necessary to keep exploring newer avenues.in implantology titanium has been the gold standard for years, yet it misses the mark when it comes to higher end aesthetics and also reports of allergic reactions have spawned an interest in other directions. Ceramics Copyright to IJIRDS 304

2 were introduced in the year 1992 and since then its increasing application in the field of dentistry is enviable. Zirconia is a highly renowned biomaterial with various widespread positive effects. Its usage in the field of implantology is increasing day by day. WHAT ARE CERAMIC IMPLANTS? As an alternative to titanium, metal free implants came into being; starting with aluminium oxide.since aluminium oxide did not show good compatibility with long term loading, the next material to be chosen was zirconia. Zirconia possesses enviable properties of high mechanical properties as in high flexural strength ( Mpa), hardness (1200 Vickers), and Weibull modulus (10-12) than aluminium oxide.this biomaterial also has a high biocompatibility and low plaque adhesion. Zirconia exists in three phases: Monoclinic (M), Cubic (C) and Tetragonal (T).A stress induced transformation toughening makes the zirconia exist in the Tetragonal state which is used in its applications EVOLUTION OF CERAMIC IMPLANTS It began in 1960 s with the consideration of aluminium oxide implants, yet the first oral implant in ceramic was introduced by Sandhaus. In 1970 s Tubingen implant came into being, after which Sandhaus introduced the Cerasand oral implant. The Bioceram implant made of single crystal alumina came after this. In 1990 Muller, Piesold and Glien produced the Bionit implant system. Akagawa, Dubruille became the first to use zirconia implants on an experimental basis. Finally in 2004 Kohal and Klaus performed the first case of zirconia implant. PROPERTIES OF ZIRCONIA IMPLANTS The high strength and toughness seen in zirconia implants is due to transformation toughening seen in its constituent Y-ZTP. It possesses bio inertness, nonresorbability and excellent resistance to corrosion and wear. High flexural strength ( MPa), Vickers hardness (1.200) and Weibull modulus (10 12), high fracture resistance, high radiopacity, low thermal conductivity. It has no effect Copyright to IJIRDS 305

3 on magnetic fields, no cytotoxic effects, the mechanical strength and toughness seen is similar to stainless steel alloys. It is as biocompatible as titanium and it is gives more esthetic results due to whitish coloration. Zirconia has seen to be less tissue reaction provoking in comparison to titanium. Degidi et al 1 confirmed this and he reported that the level of the bacterial products measured with nitric oxide synthase, inflammatory infiltrate, micro vessel density, and vascular endothelial growth factor expression were found higher around the titanium caps than around the ZrO2 ones. Zirconia can up- or down-regulate gen expressions, so zirconia can be a self-regulatory material that can modify turnover of the extracellular matrix. 2 Implant success is contributed to by contact between bone and implant material. Animal studies have demonstrated that zirconia implants showed direct bone apposition, and it has been concluded that osteoblastic cells have good proliferation and surface attachment to zirconia. 3, 4, 5,6,7,8 Also zirconia shows low porosity, high density and high compressive strength. ADVANTAGES OF ZIRCONIA IMPLANTS It serves as alternative to titanium in case of titanium induced allergic reaction. The higher esthetic results in comparison to titanium make it a more desirable material. It does not interfere with magnetic fields. It produces less tissue reaction. Hoffmann et al 9 histologically assessed the degree of early bone apposition around zirconia dental implants (Z-system, Konstanz, Germany) at 2 and 4 weeks following insertion. The zirconia implants demonstrated a slightly higher degree of bone apposition (54% 55%) compared with the titanium implants (42% 52%) at the 2-week time point. Langhoff et al 10 compared the BIC (Bone to Implant contact) of chemically modified (plasmaanodized or coated with calcium phosphate) titanium implants, pharmacologically coated (bisphosphonate or collagen type I with chondroitin sulphate) titanium implants, SLA titanium implants, and SLA zirconia implants. The zirconia implants presented 20% more bone contact than the titanium implants at 2 weeks, improved toward 4 weeks, then were reduced at 8 weeks. Although statistically not significant, a clear tendency was noted for the chemically and pharmacologically modified implants to show better BIC values at 8 weeks compared with the anodic plasma treatedsurface of zirconia implants. All titanium implants had similar BIC at 2 weeks (57% 61%); only zirconia was found to be better (77%). Copyright to IJIRDS 306

4 ZIRCONIA VERSUS TITANIUM DENTAL IMPLANTS Even though clinical studies and research is less in zirconia as an implant material, excellent esthetics and biocompatibility has been established. 11, 12 Most studies 13, 14 reported no significant differences in bone-to-implant contact and removal torque value between zirconia and titanium implants. Bone-to-implant contact values ranged from 26% to 71% for zirconia implants compared with 24 84% for titanium implants. In terms of soft tissue integration, comparison of the mucosal seal around zirconia and titanium implants with machined necks in five adult pigs found that collagen fibres in the connective tissue had a similar orientation (parallel and parallel-oblique) on both implant surfaces. 15 Soft-tissue healing around abutments made of titanium or zirconia 16 was studied in another experiment in dogs, in which,it was seen that the dimensions of the peri-implant mucosa were similar around titanium and zirconia abutments, and that they remained stable over a period of 5 months. More mature soft tissue integration could be seen around zirconia implants Colonization and early adhesion of bacteria on zirconia surfaces were seen to be much less in comparison to titanium thus favouring higher implant success. 17 It was also seen that zirconia abutments had a low surface free energy and surface wettability resulting in reduced adhesion of bacteria. 18 In an in vivo study comparing 24-h plaque accumulation on zirconia and titanium disks with similar surface roughness, placed in a removable device 19, a significant difference was found in the area covered by bacteria between zirconium (12.1 ± 1.96%) and titanium (19.3 ± 2.9%) disks. Titanium surfaces also displayed higher proportions of rods and filamentous bacteria and fewer cocci compared with zirconia surfaces. After its introduction in dentistry, zirconia has shown excellent biocompatibility. In study 20, gingival biopsies were harvested around titanium and zirconia healing caps placed on titanium implants in five patients. The inflammatory infiltrate around the titanium specimens was more prominent and there were signs of ulceration of the mucosa in a case. Also, the micro-vessel density, the expression of vascular endothelial growth factor and the expression of nitric oxide synthase were all higher in the mucosa around titanium healing caps compared with the mucosa around zirconia healing caps. Copyright to IJIRDS 307

5 Peri-implantitis also seems to be of less concern in case of zirconia implants. Cases with periimplantitis have till now only been described in one single series of 34 patients with 45 zirconia implants. 21 In all more clinical studies are required for more information on zirconia implants, a final verdict would be misplaced without further information. Yet the trend seen is towards the positive in case of zirconia implants. Figure 3: Titanium Implant Figure 1: Zirconia implant placement Figure 4: Titanium implant placement Figure 2: Post Placement ZIRCONIA IMPLANT SYSTEMS Commercial zirconia implant systems currently available are: 22 Ceraroot (Oral Iceberg, Barcelona, Spain) Sigma (Incermed, Lausanne, Switzerland) White Sky (Bredent Medical, Senden, Germany) Z-Systems (Z-Systems, Konstanz, Germany) Copyright to IJIRDS 308

6 Zit-Z (Ziterion, Uffenheim, Germany) Ziunite (Nobel Biocare) CONCLUSION Titanium has been dominating the field of implantology since its arrival, yet there is room for further technical progress. Zirconia has been showing promising results and may become a viable alternative to titanium. At present more clinical trials and research need to be carried out to make zirconia a mainstay in the field of implant ology. With increasing patient awareness it is the responsibility of the dentist to be aware and to be able to provide for higher demands. REFERENCES [1] Degidi M, Artese L, Scarano A, et al. Inflammatory infiltrate, microvessel density, nitric oxide synthase expression, vascular endothelial growth factor expression, and proliferative activity in peri-implant soft tissues around titanium and zirconium oxide healing caps. J Periodontol. 2006;77:73 80 [2] Carinci F, Pezzetti F, Volinia S, et al. Zirconium oxide: analysis of MG63 osteoblast-like cell response by means of a microarray technology. Biomaterials. 2004; 25: [3] Depprich R, Zipprich H, Ommerborn M, et al. Osseointegration of zirconia implants compared with titanium: an in vivo study. Head Face Med. 2008; 4,1 8. [4] Hoffmann O, Angelov N, Gallez F, Jung RE, Weber FE. The zirconia implant-bone interface: a preliminary histologic evaluation in rabbits. Int J Oral Maxillofac Implants. 2008; 23: [5] Kohal RJ, Wolkewitz M, Hinze M, Han JS, Bachle M, Butz F. Biomechanical and histological behavior of zirconia implants: an experiment in the rat. Clin Oral Implants Res. 2009;20: Copyright to IJIRDS 309

7 [6] Gahlert M, Gudehus T, Eichhorn S, Steinhauser E, Kniha H, Erhardt W. Biomechanical and histomorphometric comparison between zirconia implants with varying surface textures and a titanium implant in the maxilla of miniature pigs. Clin Oral Implants Res. 2007;18: [7] Depprich R, Zipprich H, Ommerborn M, et al. Osseointegration of zirconia implants: an SEM observation of the boneimplant interface. Head Face Med. 2008;4:1 7. [8] Gahlert M, Rohling S, Wieland M, et al. Osseointegration of zirconia and titanium dental implants: a histological and histomorphometrical study in the maxilla of pigs. Clin Oral Implants Res. 2009;20: [9] Hoffmann O, Angelov N, Gallez F, Jung RE, Weber FE. The zirconia implant-bone interface: a preliminary histologic evaluation in rabbits. Int J Oral Maxillofac Implants. 2008;23: [10] Langhoff, J. D., Voelter, K. Scharnweber, D. et al. Comparison of chemically and pharmaceutically modified titanium and zirconia implant surfaces in dentistry: a study in sheep. Int J Oral Maxillofac Surg : [11] Ichikawa Y, Akagawa Y, Nikai H, Tsuru H. Tissue compatibility and stability of a new zirconia ceramic in vivo. J Prosthet Dent 1992: 68: [12] Moller B, Terheyden H, Açil Y, Purcz N, Hertrampf K, Tabakov A, Behrens E, Wiltfang J. A comparison of biocompatibility and osseointegration of ceramic and titanium implants: an in vivo and in vitro study. Int J Oral Maxillofac Surg 2012: 41: [13] Kohal RJ, Weng D, Bachle M, Strub JR. Loaded custom-made zirconia and titanium implants show similar osseointegration: an animal experiment. J Periodontol 2004: 75: [14] Sennerby L, Dasmah A, Larsson B, Iverhed M. Bone tissue responses to surface-modified zirconia implants: a histomorphometric and removal torque study in the rabbit. Clin Implant Dent Relat Res 2005: 7: s13 s20. [15] Tete S, Mastrangelo F, Bianchi A, Zizzari V, Scarano A. Collagen fiber orientation around machined titanium and zirconia dental implant necks: an animal study. Int J Oral Maxillofac Implants 2009: 24: [16] Welander M, Abrahamsson I, Berglundh T. The mucosal barrier at implant abutments of different materials. Clin Oral Implants Res 2008: 19: [17] J Biomed Mater Res Part B 2009; [18] Al-Radha ASD, Dymock D, Younes C, O'Sullivan D. Surface properties of titanium and zirconia dental implant materials and their effect on bacterial adhesion. J Dent 2012: 40: Copyright to IJIRDS 310

8 [19] Scarano A, Piattelli M, Caputi S, Favero GA, Piattelli A. Bacterial adhesion on commercially pure titanium and zirconium oxide disks: an in vivo human study. J Periodontol 2004: 75: [20] Degidi M, Artese L, Scarano A, Perrotti V, Gehrke P, Piattelli A. Inflammatory infiltrate, microvessel density, nitric oxide synthase expression, vascular endothelial growth factor expression, and proliferative activity in peri-implant soft tissues around titanium and zirconium oxide healing caps. J Periodontol 2006: 77: [21] Schwarz F, John G, Hegewald A, Becker J. Non-surgical treatment of peri-implant mucositis and peri-implantitis at zirconia implants: a prospective case series. J Clin Periodontol 2015: 42: [22] Kohal RJ, Wolkewitz M, Hinze M, Han JS, Bächle M, Butz F. Biomechanical and histological behavior of zirconia implants: An experiment in the rat. Clin Oral Implants Res 2009; 20: BIOGRAPHY Dr P Laxman Rao Head Of The Department, Department of Prosthodontics And Crown And Bridge And Implantology, Army College Of Dental Sciences,Secunderabad-087,Telangana,India Dr Shilpi Bhattacharyya Post Graduate Trainee, Department Of Prosthodontics and Crown and Bridge and Implantology, Army College Of Dental Sciences, Secunderabad-087, Telangana, India Copyright to IJIRDS 311