الفهرس 
IntroductionOnly 14 pages are availabe for public view
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Abstract
Microleakage is defined as the penetration of bacteria, fluids, molecules, or ions into the spaces between the cavity walls and the restorative material, resulting in sensitivity, recurrent caries, discoloration of the margins, irritation of the pulp and restoration failure. The cavity design can affect the clinical success of the restoration by increasing or limiting the microleakage. Stresses generated by a composite bonded within a cavity depend not only on the C-Factor but also on the mass or volume of resin composite involved. Therefore, a handful of studies have measured microleakage in composite restored teeth. Purpose: The aim of this study was to compare the effect of the cavity design and the location of the gingival wall, on enamel and cementum on the microleakage of Class V composite resin restorations in primary molars. Materials and Methods: Class V cavity was made in the buccal surface of sixty sound primary mandibular second molar in this study. The teeth were divided into two main groups: group A (Kidney shaped cavity) and group B (Rectangle shaped cavity). Each group was also subdivided into two subgroups, Subgroup A1; Kidney shape with gingival margin on enamel, Subgroup A2;Kidney shape with gingival margin on cementum, Subgroup B1; Rectangle shape with gingival margin on enamel and Subgroup B2; Rectangle shape with gingival margin on cementum. After restoring all cavities with 3M™ Single Bond Universal Adhesive and Filtek™ Z250 XT (3M ESPE) composite, dye penetration test was performed to evaluate the microleakage of occlusal and gingival margins. Results: Regarding to the cavity design, the rectangle shaped cavity design (1.1±1.09) represented more microleakage than the kidney design (0.733±0.94). Regarding to the location of the gingival margin, those margins below Cemento-enamel junction (2.30±0.98) exhibit more microleakage than those above (1.20±1.13). Conclusion: More conservative cavity preparation, lowering the surface area of the cavity, as in the Kidney shape, helps greatly in minimizing the microleakage of composite restorations. Moreover, keeping the cervical margin in enamel as possible aids in the reduction of microleakage and saving the marginal integrity.