Effect of different shades of flow able composite on micro leakage of posterior restorations Dr. Khoroushi M., 1 Dr. Naeimavi M.2 1 Associate Professor, Department of Operativ Dentistry and Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran. 2Dentist, Private Practice, Isfahan, Iran. Abstract Background and Aim : Due to perfect adaptability, the flow able composite has been recommended to be used as the first layer of restoration in the gingival floor of the proximal cavities restored with composite filling materials. The objective of this in-vitro study was to evaluate the effect of using different shades of flow able composite as gingival increment on the micro leakage of posterior composite restorations. Materials and Methods : Total of thirty-six freshly extracted human sound premolar teeth were used in this laboratory investigation. Standard class II box-shaped cavities were prepared with proportional size and shape (3mm width, 2mm depth) with 1mm apical extension to CEJ. The teeth were randomly divided into 6 groups. Five shades of flow able composite resin A1,A2,A3.5,C2,D3, (Aeliteflow, Bisco, USA) were used as the first layer in the gingival portion of groups 2-6 respectively. All the rest of cavities were restored with hybrid composite A3 (Aelite, Bisco, USA), incrementally, and light cured through the proximal surface. After 24 hours of immersion in distilled water, the specimens were thermocycled (500 cycles, at 5-55 º C, with 30 seconds dwell time), sealed with nail varnish and immersed in 2% basic fushin solution for 24 hours. The restorations were sectioned longitudinally parallel to mesiodistal tooth dimension. Micro leakage status was evaluated using a 0-3 scoring scale. Data analysis was conducted using Kruskal-Wallis test at 0.05 significance level. Results : No statistically significant differences were observed between the study groups (p>0.05) under investigation. The least and the most micro leakage values were related to group 1 and 6 respectively. All specimens restored with A1 demonstrated zero score for dye penetration. Conclusion: The use of flow able composite with A1 shade as gingival increment may decrease the gingival micro leakage compared with control group. It may be advisable to use flow able composite with lower chroma in posterior composite restorations. Key words : micro leakage - flow able composite - posterior composite - shade. Corresponding Author: Dr. Khoroushi M., Department of Operativ Dentistry and Torabinejad Dental Research Center, School of Dentistry, Isfahan University of Medical Sciences, Isfahan, Iran. e.mail: khoroushi@dnt.mui.ac.ir | 
