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-37-everXPosterior0753 Effect of Light Curing Distance on Three Bulk-Fill Resin CompositesPoster Presentation11:00 AM–12:15 PM Mar 23, 2017CC, First Floor Authors:Authors:Lamia Metwally(Presenter)AinShams Universitymokhtaribrahim, AinShams Universityomaimaghallab, AinShams UniversityAbstract: Objectives: To evaluate the effect of light curing distance on miniflexuralstrength (FS) and relative microhardness(RMH) of three different bulk-fill composite resins used as base material.relative microhardness(RMH) of three different bulk-fill composite resins used as base material.Methods: For miniflexuralstrength testing; 120 bar shaped composite resin specimens of 5mm thickness, 12mm length, 2mm width were prepared . Specimens were stored in distilled water for 24 hours then loaded until failure using a universal testing machine with cross head speed of 0.5mm/min and then placed on a three points bending device. FS was then calculated using a specific formula.For relative microhardness; 60 cylindrical specimens with 4mm thickness and 4mm diameter. After 24 hours of storage in distilled water they were subjecyedto Vickers RMH test with load of 500 g and dwell timeof15 seconds. Five indentations were performed on each surface (top & 500 g and dwell timeof15 seconds. Five indentations were performed on each surface (top & bottom), average mean was calculated for each surface, the ratio between bottom and top of each surface was then calculated,Results: For FS testing; Two way anovashowed significant effect of material ( P= 0.0001). The Average mean for material was EverXPosterior (GC) 143.8±20.7, Xtrabase(VOCO) 124.6±17.8, FiltekBulk-Fill (3M) 115.8±19.9. There was no effect for the light curing distance or the interaction between the material and the light curing distance(0.26-0.86) respectively.For RMH testing: Two way anovashowed no significant difference of the material ( P=0.32). The average mean of the material was EverXPosterior (GC) 0.9 ±0.5 = Xtrabase(VOCO) 0.95 ±0.5 average mean of the material was EverXPosterior (GC) 0.9 ±0.5 = Xtrabase(VOCO) 0.95 ±0.5 =FiltekBulk-Fill (3M) 0.93 ±0.7 . There was no effect for the light curing distance or the interaction between the material and the light curing distance(0.9-0.36).Conclusions: Under the limitations of this study; the addition of fibers to the monomer system in EverXPosterior (GC) could have a valuable effect regarding miniflrexuralstrength. Variations in the light curing distance had no negative effect on the properties of the three tested bulk-fill resin composite base materials.Reprinted with permission from the Journal of Dental Research, J Dent Res 96 (Spec Iss A):-37-abstract number 0753, https://iadr2017.zerista.com/poster/member/76261, 2017