Journal of Biomaterials and Nanobiotechnology, 2011, 2, 329-334 doi:10.4236/jbnb.2011.23040 Published Online July 2011 (http://www.SciRP.org/journal/jbnb) Copyright © 2011 SciRes. JBNB 329 Microleakage of Nanofilled Composite Resin Restorative Material Ibrahim M. Hamouda 1* , Hagag Abd Elkader 1 , Manal F. Badawi 1 Dental Biomaterials Department, Faculty of Dentistry, Mansoura University, Mansoura, Egypt. Email: * imh100@hotmail.com Received November 11 th , 2010; revised March 30 th 2011; accepted May 28 th , 2011. ABSTRACT The role of nanofillers in reducing the microleakage of dental composite resins has not been previously investigated. So this study was designed to evaluate microleakage of nanofilled composite resin in comparison to the conventional hy- brid composite. Twenty extracted sound molars were selected. Class II cavities were prepared. All cavities were etched (enamel and dentin) with 37% phosphoric acid. Dentin bonding agents were applied to etched tooth surfaces and re- stored with nanofilled and hybrid composite restorative materials. The restored teeth were thermocycled. Specimens were immersed in 2% methylene blue dye, sectioned along the mesio-distal direction; dye penetration of occlusal and gingival margins of each section was evaluated using a stereo-microscope. No significant difference was found between the microleakage of nanofilled and hybrid composite restorations at occlusal/enamel and at gingival/dentin margins. Also, there were no significant differences for nanofilled composite restorations at occlusal/enamel margins and gingi- val/dentin margins. On the other hand, there were a significant differences for hybrid composite restorations at occlu- sal/enamel margins and gingival/dentin margins. Keywords: Microleakage, Nanofilled Composite Resin, Hybrid Composite Resin 1. Introduction Resin composites are increasingly used for restorative purposes because of good esthetic and the capability of establishing a bond to enamel and dentin [1]. However, like all dental materials, composites have their own limi- tations, such as the gap formation caused by polymeriza- tion contraction during setting, leading to marginal dis- coloration and leakage [2]. Improvements of mechanical properties of the composite have permitted its use in posterior teeth with greater reliability than was the case some years ago. This improvement included; development of smaller particle sizes of filler, better bonding systems, curing refinements and sealing systems [3]. Composite resin materials have progressed from mac- rofills to microfills and from hybrids to microhybrids, and new materials such as packable and nanofilled com- posites have been introduced to the dental market [4,5]. Each type of composite resin has certain advantages and limitations. The universal hybrid composites provide the best general blend of good material properties and clini- cal performance for routine anterior and posterior resto- rations [6]. A new brand of composite resins called nan- ofilled composites has been introduced to the dental mar- ket, which has been produced with nanofiller technology and formulated with nanomer and nanocluster filler par- ticles. Nanomers are discrete nanoagglomerated particles of 20 - 75 nm in size, and nanoclusters are loosely bound agglomerates of nano-sized particles. The combination of nanomer-sized particles and nanocluster formulations reduces the interstitial spacing of the filler particles and, therefore, provides increased filler loading, better physi- cal properties, and improved polish retention [3]. This investigation was designed to evaluate enamel and dentin microleakage of a nanofilled composite resin in comparison with conventional hybrid composite re- storative materials. 2. Materials and Methods The materials used in this study are presented in Table 1. A total of 20 specimens were prepared from both nano- filled and conventional hybrid composite resins. Speci- mens were cured with a light curing device (Chromalux E, Germany) according to the manufacturer’s instruc- tions. Twenty freshly extracted sound (non-carious and non- restored) mandibular human molars were selected and