Clinical study on the success of posterior monolithic zirconia crowns and fixed dental prostheses: preliminary report

DOI: http://dx.doi.org/10.17214/gaziaot.286916 Short communication Clinical study on the success of posterior monolithic zirconia crowns and fixed dental prostheses: preliminary report Merve Bankoğlu Güngör,1* Seçil Karakoca Nemli,1 Alper Çağlar,2 Cemal Aydın,1 Handan Yılmaz1 Department of Prosthodontics, Faculty of Dentistry, Gazi University, 2Department of Prosthodontics, Faculty of Dentistry, Başkent University, Ankara, Turkey 1 ABSTRACT OBJECTIVE: The purpose of this report was to present preliminary clinical results regarding the success rates and technical outcomes of posterior monolithic zirconia single tooth crowns (STs) and fixed dental prostheses (FDPs). MATERIALS AND METHOD: Thirty-four patients received 43 posterior monolithic zirconia restorations as single tooth crowns (STs) and/or fixed dental prostheses (FDPs), which were fabricated using a CAD-CAM (Computer Aided Design - Computer Aided Manufacturing) system. At baseline and every 6 months, the restorations were examined for survival and technical outcomes. Success of the restorations was defined as the restoration remaining in situ, with no need for removal or replacement at followup visits. Technical outcomes were evaluated with a modified version of the United States Public Health Services criteria. Survival of restorations was estimated by using the Kaplan-Meier survival analysis. For each restoration, duration of follow-up was calculated from the time of placement to the date of its first failure. RESULTS: After a mean observation period of 18.6 ± 3.9 months (between 8-24 months), cumulative survival rates were 86.7% and 92.3% for STs and FDPs, respectively. Technical evaluation revealed good marginal adaptation and crown contours; however, modifications were needed for shade and occlusion of restorations. CONCLUSION: These preliminary results revealed high survival rate and generally successful technical outcomes for posterior monolithic zirconia STs and FDPs. Received: June 26, 2016; Accepted: January 21, 2017 *Corresponding author: Dr. Merve Bankoğlu Güngör, Department of Prosthodontics, Faculty of Dentistry, Gazi University, Emek, Ankara, Turkey; E-mail: © 2017 Bankoğlu Güngör et al. KEYWORDS: CAD-CAM; survival analysis; yttria stabilized tetragonal zirconia CITATION: Bankoğlu Güngör M, Karakoca Nemli S, Çağlar A, Aydın C, Yılmaz H. Clinical study on the success of posterior monolithic zirconia crowns and fixed dental prostheses: preliminary report. Acta Odontol Turc 2017;34(3):104-8 EDITOR: Güven Kayaoğlu, Gazi University, Ankara, Turkey COPYRIGHT: © 2017 Bankoğlu Güngör et al. This work is licensed under a Creative Commons Attribution License. Unrestricted use, distribution and reproduction in any medium is permitted provided the original author and source are credited. INTRODUCTION Zirconia-based ceramics which have superior mechanical properties are used as substructure material, veneered with glass ceramics because of its opacity. In clinical applications, chipping of the veneer is the most frequent complication, thereby reducing the success rate of zirconia fixed dental prostheses (FDPs).1,2 In order to overcome this problem, translucent or monolithic zirconia is needed, which enables the fabrication of monolithic restorations without veneering porcelain. Advantages of monolithic zirconia restorations include increased material quality with presintered homogeneous blocks used in the CAD-CAM (Computer Aided Design - Computer Aided Manufacturing) technique and a reduced production time/cost. In addition, permitting for material thickness of 0.5 mm, due to high mechanical strength, contributes to the preservation of tooth substance and the use of all-ceramic restorations in case the interocclusal space is limited.3 However, information is lacking on clinical results of monolithic zirconia restorations.4,5 Few clinical studies focused on enamel wear caused by monolithic zirconia restorations. However, they reported comparable or lower antagonist enamel wear than that caused by other ceramic materials.4,5 The purpose of this report was to represent preliminary clinical results, including success rates, technical and esthetic evaluations of posterior monolithic zirconia crowns, and FDPs. Acta Odontol Turc 2017;34(3):104-8 105 M Bankoğlu Güngör et al. MATERIALS AND METHOD This study consisted of patients who received monolithic zirconia single tooth crowns (STs) and/or fixed dental prostheses (FDPs) supported by teeth at the Department of Prosthodontics, Faculty of Dentistry, Gazi University, Ankara, Turkey. The Ethics Committee of Ankara University approved the study (No. 36290600/21), with all participants providing informed consent for clinical procedures. Thirty-four patients were treated with 43 posterior monolithic restorations. The inclusion criteria consisted of having vital or adequately endodontically-treated abutment teeth and good general health, without severe medical or psychological conditions. Exclusion criteria were signs of bruxism, severe periodontal disease, and being less than 18 years old. All teeth were prepared according to a standardized protocol for zirconia-based restorations (Figure 1).1 In addition, all preparations were standardized: occlusal thickness of the restorations was at least 1.5 mm at the lowest point of the central fossa, and axial reduction was approximately 1-1.5 mm. Also, 1 mm rounded shoulder margins and internal line angles were provided. Digital impressions were taken by using an intraoral scanner (CEREC Omnicam, Sirona, Bensheim, Germany) by an experienced dentist. Restorations were designed using CAD software (InLab SW 4.2, Sirona). The connectors for FDPs were designed with a mini- mum of a 12 mm2 area. Restorations were milled from a partially-sintered translucent zirconia block, and colored by being dipped in a staining liquid (InCoris TZI, Sirona), then fully-sintered under the required conditions of the manufacturer. All restorations were checked for marginal fit, inter-proximal contact, and occlusion before cementation; they were steam cleaned, dried, glaze pasted (Ivoclar Vivadent, Schaan, Liechtenstein) and applied according to the manufacturer’s recommendations. The restorations were cemented with adhesive resin cement (Panavia 21, Kuraray, Osaka, Japan). No pretreatment of the zirconia surface was done (Figure 2). At baseline (within 2 weeks after cementation), and then every 6 months, the restorations were examined clinically and radiologically by two calibrated clinicians, who were not involved in the treatment. Success of the restorations was assessed and defined as the restorations remaining in situ, with no need for removal or replacement at follow-up visits. Technical outcomes were evaluated by a modified version of the United StatesPublic Health Services (USPHS) criteria.6 The longevity of restorations was estimated with the Kaplan-Meier survival analysis, using a software package (SPSS 18.0, SPSS Inc, Chicago, IL, U (...truncated)