European Journal of Prosthodontics and Restorative Dentistry (2018) 26, 1–9 ejprd.org - Published by Dennis Barber Journals. Copyright ©2018 by Dennis Barber Ltd. All rights reserved. ARTICLE IN PRESS •••••••••••••••••••••••••••••••• EJPRD Clinical Evaluation of Sonic- Activated High Viscosity Bulk-Fill Nanohybrid Resin Composite Restorations in Class II Cavities: A Prospective Clinical Study up to 2 Years ABSTRACT This study evaluated the clinical performance of a bulk-fill resin composite in class II cavities for up to 2 years. Class II restorations (N=111) were made using a nanohybrid bulk-fill resin composite (SonicFill, Kerr Corp.) and evaluated following 1 week after placement, at 6 months, and thereafter annually up to 2 years using the United States Public Health Service (USPHS) criteria. The changes were analyzed using the McNemar test and the Kaplan-Meier method. No secondary caries was observed until the final recall. One restoration underwent endodontic treatment after 2 months following the restorative procedure and was deemed a failure. The overall success rate was 99.1%. Colour match deteriorated from a score of 0 to 1 in eight restorations from baseline to 6 months and six restorations showed marginal staining at final recall. Bulk-fill resin com- posite (SonicFill) showed acceptable clinical performance through 2 years of service but colour match to the tooth started to show some deterioration within the first 6 months. INTRODUCTION The traditional restorative material for posterior teeth, amalgam, is in- creasingly being replaced in favour of resin composite materials for direct restorations. This may be explained by the increasing concern over pos- sible mercury intoxication, especially after the reports of the World Health Organization (WHO) about health risks associated with the use of mercury in dental amalgam and vaccines. 1 Improvements in adhesive restorative dentistry, and increases in patient demands for tooth coloured restora- tions also increased the use of adhesive technology in dentistry. Adhesive restorative materials meet the requirements of minimally inva- sive dentistry and allow the clinicians to prevent the sound dental tissues. 2 Due to considerable improvements since their introduction in dentistry, the use of adhesive restorative materials has been extended to larger cavi- ties with different prognoses. In such large restorations, due to the limited depth of polymerization and the possibility of polymerization shrinkage, Keywords Clinical Study Resin Composite Bulk-Fill Composite SonicFill USPHS Adhesion Class I and II Restorations Authors Dr. Tuğba Toz Akalın * (DDS, PhD) Dr. Funda Öztürk Bozkurt * (DDS, PhD) Dr. Mahmut Kusdemir * (DDS, PhD) Dr. Alev Özsoy * (DDS, PhD) Mutlu Özcan ‡ (DDS, Dr.Med.Dent, PhD) Address for Correspondence Dr. Tugba Toz Akalın * Email: ttoz@medipol.edu.tr * Istanbul Medipol University, School of Dentistry, Department of Restorative Dentistry, Ataturk Bulvarı 27, 34083, Fatih, Unkapanı, Istanbul, Turkey ‡ University of Zurich, Dental Materials Unit, Center for Dental and Oral Medicine, Clinic for Fixed and Removable Prosthodontics and Dental Materials Science, Zurich, Switzerland Received: 27.10.2017 Accepted: 13.06.2018 doi: 10.1922/EJPRD_01620Akalin09