Hellenic Dent J 2006, 16:11-16 11 The elimination of marginal microlea- kage of composite resin restorations is an important parameter for clinical success. This marginal leakage due to polymerization shrinkage of the compo- site resin remains a problem in opera- tive dentistry. The properties of the materials as well as the clinician’s ability to control the development of detri- mental polymerization shrinkage stres- ses govern the quality and behavior of direct composite restorations in po- sterior teeth. Throughout its lifetime, the interface between a composite resin and the restored tooth is subjected to SEALING EFFECTIVENESS OF TWO LINERS AND ONE FLOWABLE COMPOSITE RESIN IN VIVO IN CLASS V RESTORATIONS* Received: 19.11.2005 Accepted: 16.03.2006 Hellenic Dental Journal 2006, 16:11-16 Key words: microleakage, glass ionomer cement, flowable composite resin. The purpose of this study was to evaluate, in vivo, the bonding to dentin of two liners and one flowable composite resin. Microleakage at the liner or flowable resin / dentine interface was recorded to evaluate the bonding of the materials. Two young adults dogs were selected as experimental animals and thirty- two class V cavities were prepared. The cavities were randomly assigned into four experimental groups of 8 teeth, representing the different treatment systems to be tested and restored with the adhesive resin system Prompt L Pop and the composite resin P-60. Three of the groups were treated with one of the following cavity liners: calcium hydroxide (Dycal), resin modified glass ionomer cement (Vitrebond) and flowable composite resin (Filtek flow), while the fourth group (control) was treated with only the adhesive resin system Prompt L Pop. The data was analyzed using ANOVA with Student-Newman-Keuls and Wilcoxon matched pairs signed ranked tests. Scanning electron microscopy was also used to examine features of the tooth/restoration interfaces. One-way ANOVA indicated significant differences (p<0.001) in microleakage among the groups tested. Vitrebond revealed the least microleakage of all the materials tested, although it was not significantly different from Filtek flow. Dycal exhibited significantly more leakage than the other liner cement, and was significantly different from the control. The Wilcoxon Signed Rank Test indicated insignificant differences (p>0.05) between the occlusal and gingival microleakage scores for each group. INTRODUCTION E. Koliniotou-Koumpia Assistant Professor, Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki P. Dionysopoulos Associate Professor, Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki S. Papadimitriou Assistant Professor, Department of Clinical Sciences, Veterinary School, University of Thessalia, Karditsa, Greece E. Koumpia, DDS, Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki D. Dionysopoulos, DDS, Department of Operative Dentistry, School of Dentistry, Aristotle University of Thessaloniki *Original paper (OP) 11-16 SEL. ñ DIONYSOPOULOS 21-02-07 14:02 ™ÂÏ›‰· 11