Twenty-Four-Month Clinical Evaluation of A Newly Developed Zinc- Reinforced Conventional-Ionomer Cement in Primary Molars: Preliminary Study Figen Eren Giray, Basak Durmus, Sertac Peker, Betül Kargül Department of Pediatric Dentistry, School of Dentistry, Marmara University, Istanbul, Turkey Abstract Purpose: To evaluate the 2-year clinical results of a newly developed zinc-containing conventional glass-ionomer cement (ChemFil Rock, Dentsply) when used in occlusal and approximal restorations in primary molars with caries. Materials and Methods: Following caries removal and cavity preparation, the teeth were restored with ChemFil Rock. The restorations were evaluated at baseline and at 6, 12, 18, and 24 months according to the modified US Public Health Service (USPHS) criteria. Data obtained were analysed using the Mann-Whitney U-test and the Friedman test. Results: At the end of 24 months, the success rates of the occlusal and approximal restorations of the primary molars restored with ChemFil Rock were 100% and 69%, respectively. No post- operative sensitivity was reported in any restored tooth at any patient assessment time. Conclusion: These results suggest that this material is suitable for occlusal and approximal restorations in primary teeth and it demonstrated acceptable clinical results. Key Words: Zinc-containing glass-ionomer, Primary molar, Clinical evaluation Introduction Tooth decay (caries) among children continues to be a major public health problem in both developed and developing countries globally [1]. Commonly used dental restoratives in paediatric dentistry today include glass-ionomer cements, polyacid-modified resin composites and resin composites. These materials are suitable for the preparation of tooth- substance-saving cavities [2]. Glass-ionomer cements (GICs) were developed by Wilson and McLean at the Laboratory of the Government Chemist in England in 1965. Fluoride ion release and uptake and the chemical adhesion to both enamel and dentin are the main advantages of GICs and have made them increasingly popular [3]. Other clinical advantages, such as biocompatibility and the low coefficient of thermal expansion, support their use in daily dental practice. Disadvantages of conventional materials included poor tensile and flexural strengths, which was precluded the use of these materials in load-bearing cavities, moisture sensitivity, and poor aesthetics, because of their opacity [4,5]. Since the introduction of GICs by Wilson and Kent, many modifications of these materials have been made over the years [3]. Today, a new generation of glass-ionomers may be able to provide better aesthetics, stronger bonding, and longer-term results, lasting years rather than months. GICs have been improved considerably in their aesthetic and mechanical properties. The development of GICs has been the subject of several studies due to the many advantages they provide [1,5-7]. Classical GIC powder consists of silica, alumina, calcium fluoride as the flux, cryolite, sodium fluoride, and/or aluminium phosphate [8]. One of the recently developed reinforced glass-ionomer material is ChemFil Rock (Dentsply DeTrey GmbH, Konstanz, Germany). According to the manufacturer, this new GIC has an enhanced setting reaction due to the zinc content as part of its glass particles, leading to higher strength, with similar working time and application comfort to regular GICs. Its zinc-modified reactive glass fillers achieve an earlier toughness build-up and superior fracture and wear resistance. The manufacturer also claims that this new restorative material requires significantly fewer steps than many competitive products (no cavity conditioning or surface coat needed). A simpler procedure can be a significant advantage in treating uncooperative or emergency patients or other challenging clinical situations (such as isolation). The manufacturers of ChemFil Rock also suggest that this material is suitable for occlusal and approximal restorations in permanent and primary teeth [9]. In primary molars, several studies have shown that GICs are not recommendable for approximal cavities due to unacceptably high fracture rates. However, occlusal cavities may be restored [10-16]. Reviewing the literature, no reported study has addressed the clinical performance of the new GIC, ChemFil Rock for restorations in primary teeth. Thus, the purpose of this study was to evaluate the 24- month clinical performance of the newly developed encapsulated zinc-containing glass-ionomer cement, ChemFil Rock, in occlusal and approximal cavities in primary molars. The hypothesis tested was that material would have acceptable effectiveness after 24 months of clinical service. Materials and Methods This study was conducted in the Department of Pediatric Dentistry, Faculty of Dentistry, Marmara University, Turkey. The study received ethical approval from Yeditepe University Human Ethics Committee (267⁄2012). The procedures and the risks and benefits of the study were explained to the child and the parents. Written informed consent was obtained from parents before proceeding with the study. The investigator was trained to perform the dental restorations under the supervision of an expert professor. Corresponding author: Dr Figen Eren Giray, Marmara University, Dentistry Faculty, Department of Pediatric Dentistry, Buyuk ciftlik Sok. No: 6 Kat: 434365 Nisantasi, Istanbul, Turkey, Tel: +902122319120-109; Fax: +902122465247; E-mail: erenfigen@yahoo.com 1