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CLINICAL

Zirconia Removable Telescopic Dentures Retained on Teeth or Implants for Maxilla Rehabilitation. Three-Year Observation of Three CasesGregory-George Zafiropoulos, DDS, Dr Dent, Dr Habil1* Jochen Rebbe, DT2 Ulrich Thielen, MDT2 Giorgio Deli, DDS, MD3 Christian Beaumont, DDS, Dr Med Dent2 Oliver Hoffmann, DDS, MSc, Dr Med Dent4 This report addresses maxillary restoration with removable telescopic crown-retained palatal free dentures. One patient with 7 natural teeth (PERIO), a second patient with 6 dental implants (IMPL), and a third patient with 2 natural teeth and 4 dental implants (IMPL-PERIO) were treated. Zirconia copings for natural teeth and individual zirconia implant abutments were fabricated in CAD/CAM and used as primary crowns. Electroformed gold copings were used as secondary telescopes. All maxilla supraconstructions were fabricated with zirconia and CAD/CAM. Patients were monitored during a 3-year period; all teeth and implants survived, and no biological or mechanical complications occurred. The peri-implant and periodontal conditions were healthy. While recognizing the limitations of this report, results showed that fabricating removable zirconia structures by means of CAD/CAM can yield highly functional and esthetic results. Galvanoforming technology is the preferable means of fabricating secondary crowns. The combination of these techniques and materials results in a prosthetic reconstruction of high quality, good fit, and biocompatibility. Long-term studies of large populations are necessary to investigate the clinical properties of the material utilized in this type of construction. Key Words: dental implants, zirconia, telescopic crowns, removable dentures, implant abutments, electroformed crowns

Department of Operative Dentistry and Periodontology, University of Mainz, Germany, and Blaues Haus Dental Center, Duesseldorf, Germany. 2 Herrmann Dental Studio, Duesseldorf, Germany. 3 Division of Periodontology, Catholic University of Sacro Cuore, Rome, Italy. 4 Department of Periodontics, School of Dentistry, Loma Linda University, Calif. * Corresponding author, e-mail: zafiropoulos@blaueshaus-duesseldorf.de DOI: 10.1563/AAID-JOI-D-09-00065

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INTRODUCTION

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number of recent studies recommend the use of removable prostheses with telescopic attachments fastened to natural teeth and/or implants for prosthetic restoration.14 This restoration techJournal of Oral Implantology 455

Zirconia Telescopic Dentures for Maxilla Rehabilitation

nique is preferred in Central Europe for partially edentulous and periodontologically injured dentition. It has existed as a broadly accepted and scientifically recognized approach within dentistry and predates the establishment of oral implantology.5 In a current publication, our team also discusses the advantages of telescope-borne structures.6 Briefly, these advantages are: (1) the distribution of force on the abutment; (2) the provision of a foundation for effective oral hygiene, and maintenance of periodontal health; (3) the arrangement of teeth in the desired position; (4) circumvention of several augmentative measures in the soft and hard tissues for esthetic reasons; (5) achievement of favorable esthetics, even with there is substantial recession of the periodontal tissue or severe atrophy of the jaw; (6) creation of a gum-free structure in the maxilla; (7) longevity of the structure (eg, veneers can be reapplied at any time, and the structure remains in place even if one of the abutment teeth or implants is lost); and (8) avoidance of augmentative measures if gingival and/or peri-implant recessions arise before the construction is fabricated or while it is being worn since recessions can be covered by the lip shield. The disadvantages of this type of construction are: (1) high costs and technical requirements; (2) the need for the dental technician to master the individual steps for creating such constructions; and (3) any psychological burden experienced by the patient provided with a removable construction. Today, patients with periodontally reduced dentition and partially or fully edentulous patients who are to be provided with implants have become sensitized to esthetic appearance in addition to the maintenance of oral health. The introduction of zirconium oxide (zirconia) as a biocompatible material in restorative dentistry, the light weight of the structures made with this material, the456 Vol. XXXVI/No. Six/2010

development of new ceramics and composites for veneers, and the ongoing development of CAD/CAM technology were the factors that led us to manufacture telescope-borne zirconia constructions.

MATERIALS AND METHODS Patients Three nonsmoking patients (1 female and 2 male) were selected for this retrospective study. In 2005, all 3 patients presented for treatment of advanced chronic periodontitis7 in the office of one of the authors (G.G.Z., Duesseldorf, Germany). After multiple extractions over the previous 2 years, the first patient (PERIO, female, 58 years old) had 7 natural maxillary teeth that were retained by periodontal treatment. This patient rejected the placement of an implant. The maxillary teeth of the second patient (IMPL, male, 65 years old) had been extracted 4 years earlier, with the exception of teeth number 2 and 15. These 2 teeth possessed class II mobility but no defect in the region of the furcation. They were integrated into the existing restoration (telescopic-crown overdenture). This patient requested an implant-supported restoration of the maxilla. The third patient (IMPL-PERIO, male, 60 years old) presented after multiple extractions of maxillary teeth due to advanced periodontal disease. Teeth number 6 and 11 were present, with class II mobility. The patient requested a palate-free, implantsupported restoration of the maxilla and periodontal treatment of the remaining dentition. All existing mandibular teeth of the 3 patients were preserved, and a partial removable denture was not necessary for mandible restoration in any of the patients. Initial treatment The full-mouth initial periodontal treatment involved oral hygiene instructions, supragin-

Zafiropoulos et al

gival tooth cleaning and polishing, and subgingival scaling and root planing. Surgical and implant treatment In all 3 cases, subgingival scaling and root planing was followed by access flap surgery.8 Six cylindrical screw-type implants (RN, length 10 mm, 04.1 mm, SLA, Straumann, Waldenburg, Switzerland) were placed in the maxilla of the IMPL patient and 4 cylindrical screw-type implants (Straumann) were placed in the maxilla of the IMPL-PERIO patient, using a 1-stage surgical approach. Following full-thickness flap elevation, osteotomy preparation was performed at 875 rpm, and implants were manually placed at a torque of 35 Ncm (046.119/046.049 Straumann) in positions number 4, 5, 6, 11, 12, and 13 and in positions number 4, 5, 12, and 13 (IMPL and IMPL-PERIO patients, respectively). Postoperative care Both IMPL and IMPL-PERIO patients were prescribed a systemic antibiotic (clindamycin, Ratiopharm, Ulm-Donautal, Germany; 600 mg/d) to be taken once a day for 6 days and the oral analgesic diclofenac (Voltaren, Novartis Pharma, Nuremberg, Germany; 100 mg/d for 4 days), starting 1 day prior to surgery and implant placement. All 3 patients were instructed to rinse twice daily with 0.1% chlorhexidine (Chlorhexamed Fluid, GlaxoSmithKline, Buehl, Germany) for 3 weeks, also starting 1 day before periodontal surgery and implant placement. Sutures were removed 8 days postoperatively. Follow-up appointments were scheduled twice a month during the first 2 months after surgery, and once a month thereafter until loading. Temporaries The IMPL patient was provided with a provisional full denture for the maxilla. Teeth number 2 and 15, which were given

telescopic crowns, were preserved to provide the denture with greater retention. The PERIO and IMPL-PERIO patients were given temporary removable partial prostheses. Rehabilitation Four months after implant placement (IMPL and IMPL-PERIO patients) and 3 months after periodontal treatment (PERIO patient), maxillae were restored with telescopic crownretained palate-free removable dentures. Impressions were taken with individual acrylic trays (the open-tray impression technique was used for implant cases) using a polyether impression material (Impregum Penta Soft, 3M ESPE, Seefeld, Germany). Casts were mounted on a semi-adjustable articulator (SAM 2P, SAM Praezisionstechnik, Gauting, Germany), using the face-bow technique and check-bite registration. A wax-up was created and used as an orientation tool for the patient and surgeon as well as for further planning of rehabilitation. After the esthetic and functional try-in with the wax-up, a matrix of C-silicone (Zetalabor, Zhermack SpA, Badia Polesine, Italy) was manufactured. The direction of insertion and planned tooth position were determined by this silicone key (Figure 1A). In addition, it can be used to create a mockup. Primary telescopic crowns Implants Customizable abutments were used (RN synOcta 048.642, Straumann) to fabricate the individual zirconia implant abutments. These abutments consist of a prefabricated cast-on base and a residue-free burn-out plastic channel (Figure 1a). The plastic channels of the 6 abutments were patterned with resin (Pattern Resin, GC Dental Products Corp, Leuven, Belgium) (Figure 1b). The patterns were scanned and milled in a CAD/CAM (M4820, I-MES, Eiterfeld, Germany). After scanning, the zirconia implantJournal of Oral Implantology 457

Zirconia Telescopic Dentures for Maxilla Rehabilitation

FIGURE 1. (a) Creation of implant abutments using C-silicon matrix as orientation. (b) Wax-up of an implant abutment before scanning. (c) Zirconia implant abutments were fixed on the synOcta titan parts. (d) Zirconia implant abutmen