- Email: [email protected]
A single-tooth, two-piece zirconia implant located in the anterior maxilla: A clinical report
A single-tooth, two-piece zirconia implant located in the anterior maxilla: A clinical report Cemal Aydın, DDS, PhD,a Handan Yılmaz, DDS, PhD,b and Merve Bankoºlu, DDSc Faculty of Dentistry, Gazi University, Ankara, Turkey It can be difficult to achieve a natural appearance in the anterior region with implant-supported restorations because metal components may show through the soft tissue. Zirconia implants, therefore, should be considered as an alternative treatment for improved esthetics. The goal of this clinical report was to evaluate a new 2-piece zirconia implant system for the maxillary anterior region. A 2-piece zirconia dental implant was placed in the maxillary left lateral incisor position and left in place for 6 months to osseointegrate. Panoramic and periapical radiographs were examined for bone-implant osseointegration. The plaque control record (PCR), bleeding on probing (BOP), and probing depth (PD) were measured after the cementation of the definitive restoration and a 6-month follow-up period. The PCR, BOP, and PD values were compared and the marginal bone level was also evaluated by making standardized periapical radiographs. The results showed that over the 6-month follow-up period, the marginal area was healthy and presented no bleeding on probing, no plaque accumulation, and no change in periimplant marginal bone level. (J Prosthet Dent 2013;109:70-74) Replacing teeth with implantsupported restorations in the anterior maxilla is one of the most complex treatments used to provide an esthetic result.1-4 Titanium implants are successful and their clinical survival rates are good, but the grayish color of the implants and/or soft tissue shrinkage and recession can result in an unnatural appearance.5-8 To overcome this problem, zirconia, with its good long-term results as a medical implant and with its more natural color, has recently been suggested for dental implants.9-14 The main reasons for the clinical use of zirconia implants are their biocompatiblity, good chemical and dimensional stability, high flexural strength (900 to 1200 MPa), adequate hardness (1200 Vickers) and Weibull modulus (10 to 12), tooth-like color, low thermal conductivity, machinability, comparable osseointegration to titanium implants, reduced plaque affinity, and low corrosion potential.11,12,15-18 The long-term success of an implant requires a sufficient degree of
osseointegration of the material.13 Animal studies have demonstrated encouraging results regarding the osseointegration of zirconia implants.1,9,11-13,15,19,20 Kohal et al20 compared loaded titanium implants with loaded zirconia implants in the same monkey model. No implant was lost over an observation period of 14 months, and no mechanical problem was reported. Histological examination showed no difference in the bone tissue response between the titanium and zirconia implants. The osseointegration and removal torque of zirconia and titanium implants investigated by Sennerby et al11 in an animal study showed similar osseointegration, but the removal torque of pure zirconia implants was lower. Zirconia implants present acceptable osseointegration, but only minimal information about the biomechanical behavior of zirconia oral implants is available.21-28 In a biomechanical study, Caglar et al27 compared the different kinds of stresses
occurring on implants, abutments, and surrounding bone by using 3-dimensional finite element analysis in the anterior maxilla. A single titanium implant with a titanium abutment, a single titanium implant with a zirconium abutment, and a 1-piece zirconia implant were evaluated in this study. The results showed that the zirconia implant generated the lowest stresses in cortical bone and the von Mises and compressive stresses were lower than the titanium abutment when compared with the zirconia abutment. In an in vitro investigation, Kohal et al28 evaluated the effects of cyclic loading and preparation on zirconia implants. It was concluded that loading can decrease the fracture strength of the zirconia implants. Zirconia implants can be manufactured in 1-piece3,7,28-30 or 2-piece10,20,24,31 designs. Clinical experience with zirconia implants is limited, but some patient treatment reports3,10,29-32 and some retrospective long-term clinical studies7,17,33 have been published. The
Presented at the 35th Annual Congress of European Prosthodontic Association, Bern, Switzerland, September 2011. a
Professor, Department of Prosthodontics. Professor, Department of Prosthodontics. c Research Assistant, Department of Prosthodontics. b
The Journal of Prosthetic Dentistry
Aydın et al
71
February 2013 purpose of this clinical report was to evaluate a single tooth, 2-piece zirconia implant located in the anterior maxillary region.
CLINICAL REPORT A 23-year-old man with endodontic failure of his maxillary left lateral incisor was referred to the Department of Prosthetic Dentistry at Gazi University, Faculty of Dentistry. After clinical examination, panoramic and periapical radiographs were obtained (Figs. 1, 2). A zirconia implant was used because of the esthetic expectation of the patient. The treatment protocol, comprising risks, benefits, and alternative treatments were explained to the patient, who signed an informed consent form based on the revised Helsinki Declaration. A cylindrical screw type, subgingival, platform switched, 2-piece zirconia implant (Zit-Vario; Ziterion GmbH, Uffenheim, Germany), 4.0 mm in diameter and 11.5 mm in length, was placed in the maxillary left lateral incisor position (Fig. 3). The buccal defect area was filled with a xenogeneous bone graft (Bio-Oss; Geistlich Biomaterials, Wolhuser, Switzerland). The implant surgical procedure was performed under local anesthesia (Ultracain DS Forte; Sanofi-Aventis, Istanbul, Turkey). The implant was left in place for 6 months, the recommended healing period for dental implants in the maxilla, to osseointegrate.10,20,31 During this period, the patient wore an interim removable prosthesis, replacing the missing dentition. After the 6-month healing period, panoramic and periapical radiographs were made and examined for osseointegration (Fig. 4), and the definitive restoration was begun. The implant was uncovered, the abutment healing cap removed, and an abutment analog placed in order to choose a suitable abutment. The abutment analog was made of a biocompatible synthetic material with the same geometry as the zirconia abutment.
Aydın et al
1 Intraoral view.
2 Preoperative panoramic radiograph.
3 Placement of 2-piece zirconia implant. The selected definitive abutment was cemented into the implant with an autopolymerizing universal composite resin cement (RelyX Unicem; 3M ESPE, Seefeld, Germany) (Fig. 5). Excess cement was removed from the implant-abutment interface. During the soft tissue healing period, the patient wore an interim fixed prosthesis, replacing the missing tooth. After a
2-week healing period, an elastomeric impression material (Zeta Plus; Zhermack, Badia Polesine, Italy) was used to make the maxillary impression of the soft tissue. The impression was made directly of the abutment cemented into the implant. After the milled zirconia framework was evaluated clinically, a definitive crown was made of zirconia. The restoration was
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4 Periapical radiograph after 6-month healing period.
5 Periapical radiograph of cemented abutment.
6 Cemented restoration. left out of occlusion, and contacts in lateral excursions were avoided. It was then cemented onto the implant by using an autopolymerizing universal composite resin cement (RelyX Unicem; 3M ESPE) (Fig. 6). Excess cement was removed and the patient was instructed in oral hygiene procedures. The esthetic appearance was improved, and the patient was satisfied with the final result. The plaque control record (PCR), bleeding on probing (BOP), and probing depth (PD) were measured after the cementation of the definitive restoration and also after a 6-month follow-up period. The PCR, BOP, and PD values were compared and
the marginal bone levels evaluated by making standardized periapical radiographs. The radiographs were made by using a long cone paralleling technique. The results showed that the marginal area was healthy and presented no bleeding on probing, no plaque accumulation, and no change in periimplant marginal bone level (Figs. 7, 8) 6 months after cementation of the restoration.
DISCUSSION The esthetics of implant-supported restorations can be improved because of developments in ceramic materials, implant components, and
The Journal of Prosthetic Dentistry
surgical techniques.3 Zirconia ceramics have been used successfully in implant-supported restorations for abutments and crowns, but zirconia implants are a new application.32,34 Most of the available zirconia implant systems are a 1-piece design. However, there are situations where 2-piece implant systems are indicated.24 One-piece zirconia implants are inserted with minimal surgical invasion and maximum soft tissue preservation and are immediately restored with an interim crown, reducing the treatment time.22,35 However, 1-piece implants have to be inserted into an accurate anatomic position and are more difficult to position perfectly
Aydın et al
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February 2013
7 Intraoral view after 6-month follow-up period.
8 Periapical radiograph after 6-month follow-up period. especially in the esthetic regions.36 If the zirconia implant fractures, it is not possible to repair it, and it must be removed.22 Gahlert et al17 reported a fracture rate of 1-piece zirconia implants of nearly 10% after an average follow-up period of 38 months from prosthetic loading. In another study, Andreiotelli and Kohal22 reported that the in vitro preparation of zirconia implants significantly and negatively influenced the fracture strength of the implants. In a long-term clinical study by Oliva et al,33 the 5-year success rate of 831 1-piece zirconia implants with 3 different roughened surfaces was reported to be 95%. Primary stability and the elimination of micromovements are the main factors required for successful osseointegration. Two-piece implants can minimize the forces transmitted to the bone implant interface and can be used when accurate primary stability is not achieved.35,37 The information on 2-piece zirconia implants is limited to 1 biomechanical,24 1 animal,20 and 2 clinical10,31 studies. In a biomechanical study, Kohal et al24 compared the fracture resistance of restored prototype 2-piece zirconia with restored ti-
Aydın et al
tanium implants after artificial aging. The biomechanical performance of all tested implant groups was marginal for clinical use. A high number of failures with the titanium implants occurred at the abutment screw level, and the zirconia implant groups showed implant head fractures at relatively low fracture loads. In 2004, Kohal et al10 reported on the first 2-piece zirconia implant patient treatment. A custom-made zirconia implant was placed in the patient, and after a healing period of 6 months, the single ceramic crown was cemented onto the implant, demonstrating that zirconia implants could be used for the esthetic restoration of missing teeth. Nevins et al31 reported the histological and clinical evaluations of 2-piece zirconia implants and compared them with titanium implants. Four titanium and 2 zirconia implants were placed in a healthy woman. One 2-piece zirconia implant was removed for biopsy after 6 months. Clinical and radiographic examinations showed that both the zirconia and titanium implants achieved osseointegration. Gingival tissues were healthy, and excellent vertical bone height was demonstrated in the radiographs. The
bone-to-implant contact with a zirconia implant surface was adequate to provide clinical and histologic evidence of osseointegration, demonstrating that zirconia implants provided suitable conditions for soft and hard tissue healing. In the clinical report presented here, a 2-piece zirconia implant was placed in the anterior region. After 6 months, radiographic and esthetic outcomes were successful. The color of the zirconia was also attractive because of its similarity to the color of the natural tooth. However, the present clinical report evaluated only the short term performance of a new 2-piece zirconia implant; studies focusing on the long term clinical performance of zirconia implants are necessary.
SUMMARY This clinical report presents the results of placing a 2-piece zirconia implant in the anterior maxillary region. In a short-term, 6-month evaluation, the radiographic and clinical outcomes were successful, and the patient was satisfied with the final result. In esthetically demanding situa-
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Volume 109 Issue 2 tions, zirconia implants may provide an alternative to titanium implants. To properly evaluate their clinical performance and recommend them for routine clinical use, well planned, controlled animal investigations and clinical trials with longer-term followup are necessary.
REFERENCES 1. Gahlert M, Röhling S, Wieland M, Sprecher CM, Kniha H, Milz S. Osseointegration of zirconia and titanium dental implants: a histological and histomorthometrical study in the maxilla of pigs. Clin Oral Implants Res 2009;20:1247-53. 2. den Hartog L, Slater JJ, Vissink A, Meijer HJ, Raghoebar GM. Treatment outcome of immediate, early and conventional single-tooth implantsin the aesthetic zone: a systematic review to survival bone level, soft-tissue, aesthetics and patient satisfaction. J Clin Periodontol 2008;35:1073-86. 3. Sierraalta M, Razzoog ME. A maxillary anterior partially edentulous space restored with a one-piece zirconia implant fixed partial denture: a clinical report. J Prosthet Dent 2009;101:354-8. 4. Felser UC, Mericske-Stern R, Bernard JP, Taylor TD. Prosthetic management of the partially dentate patient with fixed implant restorations. Clin Oral Implants Res 2000;11:126-45. 5. Stadlinger B, Henning M, Eckelt U, Kuhlisch E, Mai R. Comparison of zirconia and titanium implants after a short healing period. A pilot sudy in minipigs. Int J Oral Maxillofac Surg 2010; 39:585-92. 6. Att W, Kurun S, Gerds T, Strub JR. Fracture resistance of single-tooth implant supported all-ceramic restorations: an in vitro study. J Prosthet Dent 2006;95:111-6. 7. Oliva J, Oliva X, Oliva JD. One-year followup of first consecutive 100 zirconia dental implants in humans: a comparison of 2 different rough surfaces. Int J Oral Maxillofac Implants 2007;22:430-5. 8. Heydecke G, Kohal R, Glaser R. Optimal esthetics in single-tooth replacement with the Re-Implant system. Int J Prosthodont 1999;12:184-9. 9. Akagawa Y, Hosokawa R, Sato Y, Kamayama K. Comparison between freestanding and tooth-connected partially stabilized zirconia implants after two years’ function in monkeys: a clinical and histologic study. J Prosthet Dent 1998;80:551-8. 10.Kohal RJ, Klaus G. A zirconia implantcrown system: a case report. Int J Periodontics Restorative Dent 2004;24:147-53. 11.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;7:13-20.
12.Gahlert M, Gudeus 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;18:662-8. 13.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;23:691-5. 14.Scarano A, Di Carlo F, Quaranta M, Piatelli A. Bone response to zirconia ceramic implants: an experimental study in rabbits. J Oral Implantol 2003;29:8-12. 15.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;20:333-9. 16.Piconi C, Maccauro G. Zirconia as a ceramic biomaterial. Biomaterials 1999;20:1-25. 17.Gahlert M, Burtscher D, Grunert I, Kniha H, Steinhauser E. Failure analysis of fractured dental zirconia implants. Clin Oral Implants 2012;23:287-93. 18.Andreiotelli M, Wenz HJ, Kohal RJ. Are ceramic implants a viable alternative to titanium implants? A systematic literature review. Clin Oral Implants Res 2009;20:32-47. 19.Depprich R, Zipprich H, Ommerborn M, Mahn E, Lammers L, Handschel J et al. Osseointegration of zirconia implants: an SEM observation of the bone-implant interface. Head Face Med 2008;4:25. 20.Kohal RJ, Weng D, Bächle M, Strub JR. Loaded custom-made zirconia and titanium implants show similar osseointegration: an animal experiment. J Periodontol 2004;75:1262-8. 21.Kohal RJ, Klaus G, Strub JR. Zirconia-implant-supported all-ceramic crowns withstand long-term load: a pilot investigation. Clin Oral Implants Res 2006;17:565-71. 22.Andreiotelli M, Kohal RJ. Fracture strength of zirconia implants after artificial aging. Clin Impl Dent Relat Res 2009;11:158-66. 23.Silva NR, Coelho PG, Fernandes CA, Navarro JM, Dias RA, Thompson VP. Reliability of one-piece ceramic implant. J Biomed Mater Res B Appl Biomater 2009;88:419-26. 24.Kohal RJ, Finke HS, Klaus G. Stability of prototype two-piece zirconia and titanium implants after artificial aging: an in vitro pilot study. Clin Implant Dent Relat Res 2009;11:323-9. 25.Kohal RJ, Papavasiliou G, Kamposiora P, Tripodakis A, Strub JR. Three-dimensional computerized stress analysis of commercially pure titanium and yttrium-partially stabilized zirconia implants. Int J Prosthodont 2002;15:189-94. 26.Caglar A, Bal BT, Aydin C, Yilmaz H, Ozkan S. Evaluation of stresses occuring on three different zirconia dental implants: threedimensional finite element analysis. Int J Oral Maxillofac Implants 2010;25:95-103.
The Journal of Prosthetic Dentistry
27.Caglar A, Bal BT, Karakoca S, Aydin C, Yilmaz H, Sarisoy S. Three-dimensional finite element analysis of titanium and yttrium-stabilized zirconium dioxide abutments and implants. Int J Oral Maxillofac Implants 2011;26:961-9. 28.Kohal RF, Wolkewitz M, Tsakona A. The effects of cyclic loading and preparation on the fracture strength of zirconium-dioxide implants: an in vitro investigation. Clin Oral Implants Res 2011;22:808-14. 29.Oliva J, Oliva X, Oliva JD. Zirconia implants and all-ceramic restorations for the esthetic replacement of the maxillary central incisors. Eur J Esthet Dent 2008;3:174-85. 30.Oliva X, Oliva J, Oliva JD. Full-mouth oral rehabilitation in a titanium allergy patient using zirconium oxide dental implants and zirconium oxide restorations. A case report from an ongoing clinical study. Eur J Esthet Dent 2010;5:190-203. 31.Nevins M, Camelo M, Nevins ML, Schupbach P, Kim DM. Pilot clinical and histologic evaluations of a two-piece zirconia implant. Int J Periodontics Restorative Dent 2011;31:157-63. 32.Aydin C, Yilmaz H, Ata SO. Single-tooth zirconia implant located in anterior maxilla. A clinical report. N Y State Dent J 2010;76:30-3. 33.Oliva X, Oliva J, Oliva JD. Five-year success rate of 831 consecutively placed zirconia dental implants in humans: a comparison of three different rough surfaces. Int J Oral Maxillofac Implants 2010;25:336-44. 34.Andersson B, Glauser R, Maglione M, Taylor A. Ceramic implant abutments for short-span FPDs: a prospective 5-year multicenter study. Int J Prosthodont 2003;16:640-6. 35.Esposito M, Grusovin MG, Chew YS, Coulthard P, Worthington HV. Interventions for replacing missing teeth: 1-versus 2-stage implant placement. Cochrane Database Syst Rev 2009;3:CD006698. 36.Parel SM, Schow SR. Early clinical experience with a new one-piece implant system in single tooth sites. J Oral Maxillofac Surg 2005;63:2-10. 37.Albrektsson T, Branemark PI, Hansson HA, Lindström J. Osseointegrated titanium implants. Requirements for ensuring a long lasting, direct bone-to implant anchorage in man. Acta Orthop Scand 1981;52:155-70. Corresponding author: Dr Cemal Aydın Gazi University Faculty of Dentistry Department of Prosthodontics 06510, Emek, Ankara TURKEY Fax: +90-312-2239226 E-mail: [email protected] Copyright © 2013 by the Editorial Council for The Journal of Prosthetic Dentistry.
Aydın et al
osseointegration of the material.13 Animal studies have demonstrated encouraging results regarding the osseointegration of zirconia implants.1,9,11-13,15,19,20 Kohal et al20 compared loaded titanium implants with loaded zirconia implants in the same monkey model. No implant was lost over an observation period of 14 months, and no mechanical problem was reported. Histological examination showed no difference in the bone tissue response between the titanium and zirconia implants. The osseointegration and removal torque of zirconia and titanium implants investigated by Sennerby et al11 in an animal study showed similar osseointegration, but the removal torque of pure zirconia implants was lower. Zirconia implants present acceptable osseointegration, but only minimal information about the biomechanical behavior of zirconia oral implants is available.21-28 In a biomechanical study, Caglar et al27 compared the different kinds of stresses
occurring on implants, abutments, and surrounding bone by using 3-dimensional finite element analysis in the anterior maxilla. A single titanium implant with a titanium abutment, a single titanium implant with a zirconium abutment, and a 1-piece zirconia implant were evaluated in this study. The results showed that the zirconia implant generated the lowest stresses in cortical bone and the von Mises and compressive stresses were lower than the titanium abutment when compared with the zirconia abutment. In an in vitro investigation, Kohal et al28 evaluated the effects of cyclic loading and preparation on zirconia implants. It was concluded that loading can decrease the fracture strength of the zirconia implants. Zirconia implants can be manufactured in 1-piece3,7,28-30 or 2-piece10,20,24,31 designs. Clinical experience with zirconia implants is limited, but some patient treatment reports3,10,29-32 and some retrospective long-term clinical studies7,17,33 have been published. The
Presented at the 35th Annual Congress of European Prosthodontic Association, Bern, Switzerland, September 2011. a
Professor, Department of Prosthodontics. Professor, Department of Prosthodontics. c Research Assistant, Department of Prosthodontics. b
The Journal of Prosthetic Dentistry
Aydın et al
71
February 2013 purpose of this clinical report was to evaluate a single tooth, 2-piece zirconia implant located in the anterior maxillary region.
CLINICAL REPORT A 23-year-old man with endodontic failure of his maxillary left lateral incisor was referred to the Department of Prosthetic Dentistry at Gazi University, Faculty of Dentistry. After clinical examination, panoramic and periapical radiographs were obtained (Figs. 1, 2). A zirconia implant was used because of the esthetic expectation of the patient. The treatment protocol, comprising risks, benefits, and alternative treatments were explained to the patient, who signed an informed consent form based on the revised Helsinki Declaration. A cylindrical screw type, subgingival, platform switched, 2-piece zirconia implant (Zit-Vario; Ziterion GmbH, Uffenheim, Germany), 4.0 mm in diameter and 11.5 mm in length, was placed in the maxillary left lateral incisor position (Fig. 3). The buccal defect area was filled with a xenogeneous bone graft (Bio-Oss; Geistlich Biomaterials, Wolhuser, Switzerland). The implant surgical procedure was performed under local anesthesia (Ultracain DS Forte; Sanofi-Aventis, Istanbul, Turkey). The implant was left in place for 6 months, the recommended healing period for dental implants in the maxilla, to osseointegrate.10,20,31 During this period, the patient wore an interim removable prosthesis, replacing the missing dentition. After the 6-month healing period, panoramic and periapical radiographs were made and examined for osseointegration (Fig. 4), and the definitive restoration was begun. The implant was uncovered, the abutment healing cap removed, and an abutment analog placed in order to choose a suitable abutment. The abutment analog was made of a biocompatible synthetic material with the same geometry as the zirconia abutment.
Aydın et al
1 Intraoral view.
2 Preoperative panoramic radiograph.
3 Placement of 2-piece zirconia implant. The selected definitive abutment was cemented into the implant with an autopolymerizing universal composite resin cement (RelyX Unicem; 3M ESPE, Seefeld, Germany) (Fig. 5). Excess cement was removed from the implant-abutment interface. During the soft tissue healing period, the patient wore an interim fixed prosthesis, replacing the missing tooth. After a
2-week healing period, an elastomeric impression material (Zeta Plus; Zhermack, Badia Polesine, Italy) was used to make the maxillary impression of the soft tissue. The impression was made directly of the abutment cemented into the implant. After the milled zirconia framework was evaluated clinically, a definitive crown was made of zirconia. The restoration was
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4 Periapical radiograph after 6-month healing period.
5 Periapical radiograph of cemented abutment.
6 Cemented restoration. left out of occlusion, and contacts in lateral excursions were avoided. It was then cemented onto the implant by using an autopolymerizing universal composite resin cement (RelyX Unicem; 3M ESPE) (Fig. 6). Excess cement was removed and the patient was instructed in oral hygiene procedures. The esthetic appearance was improved, and the patient was satisfied with the final result. The plaque control record (PCR), bleeding on probing (BOP), and probing depth (PD) were measured after the cementation of the definitive restoration and also after a 6-month follow-up period. The PCR, BOP, and PD values were compared and
the marginal bone levels evaluated by making standardized periapical radiographs. The radiographs were made by using a long cone paralleling technique. The results showed that the marginal area was healthy and presented no bleeding on probing, no plaque accumulation, and no change in periimplant marginal bone level (Figs. 7, 8) 6 months after cementation of the restoration.
DISCUSSION The esthetics of implant-supported restorations can be improved because of developments in ceramic materials, implant components, and
The Journal of Prosthetic Dentistry
surgical techniques.3 Zirconia ceramics have been used successfully in implant-supported restorations for abutments and crowns, but zirconia implants are a new application.32,34 Most of the available zirconia implant systems are a 1-piece design. However, there are situations where 2-piece implant systems are indicated.24 One-piece zirconia implants are inserted with minimal surgical invasion and maximum soft tissue preservation and are immediately restored with an interim crown, reducing the treatment time.22,35 However, 1-piece implants have to be inserted into an accurate anatomic position and are more difficult to position perfectly
Aydın et al
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February 2013
7 Intraoral view after 6-month follow-up period.
8 Periapical radiograph after 6-month follow-up period. especially in the esthetic regions.36 If the zirconia implant fractures, it is not possible to repair it, and it must be removed.22 Gahlert et al17 reported a fracture rate of 1-piece zirconia implants of nearly 10% after an average follow-up period of 38 months from prosthetic loading. In another study, Andreiotelli and Kohal22 reported that the in vitro preparation of zirconia implants significantly and negatively influenced the fracture strength of the implants. In a long-term clinical study by Oliva et al,33 the 5-year success rate of 831 1-piece zirconia implants with 3 different roughened surfaces was reported to be 95%. Primary stability and the elimination of micromovements are the main factors required for successful osseointegration. Two-piece implants can minimize the forces transmitted to the bone implant interface and can be used when accurate primary stability is not achieved.35,37 The information on 2-piece zirconia implants is limited to 1 biomechanical,24 1 animal,20 and 2 clinical10,31 studies. In a biomechanical study, Kohal et al24 compared the fracture resistance of restored prototype 2-piece zirconia with restored ti-
Aydın et al
tanium implants after artificial aging. The biomechanical performance of all tested implant groups was marginal for clinical use. A high number of failures with the titanium implants occurred at the abutment screw level, and the zirconia implant groups showed implant head fractures at relatively low fracture loads. In 2004, Kohal et al10 reported on the first 2-piece zirconia implant patient treatment. A custom-made zirconia implant was placed in the patient, and after a healing period of 6 months, the single ceramic crown was cemented onto the implant, demonstrating that zirconia implants could be used for the esthetic restoration of missing teeth. Nevins et al31 reported the histological and clinical evaluations of 2-piece zirconia implants and compared them with titanium implants. Four titanium and 2 zirconia implants were placed in a healthy woman. One 2-piece zirconia implant was removed for biopsy after 6 months. Clinical and radiographic examinations showed that both the zirconia and titanium implants achieved osseointegration. Gingival tissues were healthy, and excellent vertical bone height was demonstrated in the radiographs. The
bone-to-implant contact with a zirconia implant surface was adequate to provide clinical and histologic evidence of osseointegration, demonstrating that zirconia implants provided suitable conditions for soft and hard tissue healing. In the clinical report presented here, a 2-piece zirconia implant was placed in the anterior region. After 6 months, radiographic and esthetic outcomes were successful. The color of the zirconia was also attractive because of its similarity to the color of the natural tooth. However, the present clinical report evaluated only the short term performance of a new 2-piece zirconia implant; studies focusing on the long term clinical performance of zirconia implants are necessary.
SUMMARY This clinical report presents the results of placing a 2-piece zirconia implant in the anterior maxillary region. In a short-term, 6-month evaluation, the radiographic and clinical outcomes were successful, and the patient was satisfied with the final result. In esthetically demanding situa-
74
Volume 109 Issue 2 tions, zirconia implants may provide an alternative to titanium implants. To properly evaluate their clinical performance and recommend them for routine clinical use, well planned, controlled animal investigations and clinical trials with longer-term followup are necessary.
REFERENCES 1. Gahlert M, Röhling S, Wieland M, Sprecher CM, Kniha H, Milz S. Osseointegration of zirconia and titanium dental implants: a histological and histomorthometrical study in the maxilla of pigs. Clin Oral Implants Res 2009;20:1247-53. 2. den Hartog L, Slater JJ, Vissink A, Meijer HJ, Raghoebar GM. Treatment outcome of immediate, early and conventional single-tooth implantsin the aesthetic zone: a systematic review to survival bone level, soft-tissue, aesthetics and patient satisfaction. J Clin Periodontol 2008;35:1073-86. 3. Sierraalta M, Razzoog ME. A maxillary anterior partially edentulous space restored with a one-piece zirconia implant fixed partial denture: a clinical report. J Prosthet Dent 2009;101:354-8. 4. Felser UC, Mericske-Stern R, Bernard JP, Taylor TD. Prosthetic management of the partially dentate patient with fixed implant restorations. Clin Oral Implants Res 2000;11:126-45. 5. Stadlinger B, Henning M, Eckelt U, Kuhlisch E, Mai R. Comparison of zirconia and titanium implants after a short healing period. A pilot sudy in minipigs. Int J Oral Maxillofac Surg 2010; 39:585-92. 6. Att W, Kurun S, Gerds T, Strub JR. Fracture resistance of single-tooth implant supported all-ceramic restorations: an in vitro study. J Prosthet Dent 2006;95:111-6. 7. Oliva J, Oliva X, Oliva JD. One-year followup of first consecutive 100 zirconia dental implants in humans: a comparison of 2 different rough surfaces. Int J Oral Maxillofac Implants 2007;22:430-5. 8. Heydecke G, Kohal R, Glaser R. Optimal esthetics in single-tooth replacement with the Re-Implant system. Int J Prosthodont 1999;12:184-9. 9. Akagawa Y, Hosokawa R, Sato Y, Kamayama K. Comparison between freestanding and tooth-connected partially stabilized zirconia implants after two years’ function in monkeys: a clinical and histologic study. J Prosthet Dent 1998;80:551-8. 10.Kohal RJ, Klaus G. A zirconia implantcrown system: a case report. Int J Periodontics Restorative Dent 2004;24:147-53. 11.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;7:13-20.
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