Tehran University of Medical Sciences Frontiers in Dentistry 2676-296X 10 5 2013 10 15 417 25 Hassan Torabzadeh Associate Professor, Iranian Center for Endodontic Research, Research Institute of Dental Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Amir Ghasemi Associate Professor, Dental Research Center, Research Institute of Dental Sciences of Shahid Beheshti University of Medical Sciences, Tehran,Iran. Atoosa Dabestani Private Practice, Preventive Dentistry Research Center, Research Institute of Dental Sciences of, Shahid Beheshti University of Medical Sciences, Tehran, Iran. Sara Razmavar Reseach Fellow, Preventive Dentistry Research Center, Research Institute of Dental Sciences of, Shahid Beheshti University of Medical Sciences, Tehran, Iran. 2015 10 16 Tooth fracture is a common dental problem. By extension of cavity dimensions, the remaining tooth structure weakens and occlusal forces may cause tooth fracture. The aim of this study was to evaluate and compare the fracture resistance of teeth restored with direct and indirect composite restorations.Sixty-five sound maxillary premolar teeth were chosen and randomly divided into five groups each comprising thirteen. Fifty-two teeth received mesio-occluso-distal (MOD) cavities with 4.5mm bucco-lingual width, 4mm pulpal depth and 3mm gingival depth and were divided into the following four groups. G-1: restored with direct composite (Z-250, 3M/ESPE) with cusp coverage, G-2: restored with direct composite (Z-250) without cusp coverage, G-3: restored with direct composite (Gradia, GC-international) with cusp coverage, G-4: restored with indirect composite (Gradia, GC-International) with cusp coverage. Intact teeth were used in G-5 as control. The teeth were subjected to a compressive axial loading using a 4 mm diameter rod in a universal testing machine with 1 mm/min speed. Data were analyzed using one-way ANOVA and Tukey tests.THE MEAN FRACTURE STRENGTH RECORDED WAS: G-1: 1148.46N±262, G-2: 791.54N±235, G-3: 880.00N±123, G-4: 800.00N±187, G-5: 1051.54N±345. ANOVA revealed significant differences between groups (p https://fid.tums.ac.ir/index.php/fid/article/view/615 https://fid.tums.ac.ir/index.php/fid/article/download/615/590