Tooth wear has a multi-factorial etiology involving the interplay of attrition, erosion and abrasion. When two-body abrasion occurs in the mouth whenever there is tooth-to-tooth contact, this is what most dentists call attrition. Abrasion wear may also occur when there is an abrasive slurry interposed between two surfaces, such that the two solid surfaces are not actually in contact, this is called three-body abrasion, with food acting as the abrasive agent, and occurs in the mouth during mastication.The aim of the present study are studying the effect of abrasives of toothpaste on the mechanical wear of teeth and reaching to the proper size and shape for the particle of these abrasives which can give a proper degree of polishing without more wear for enamel of the teeth.

received B.Sc., M. Sc., Ph.D. degree in Mech. Eng.from Minia Univ., Egypt,in 2002, 2007 and 2010,respectively. He is currently working as assistantprofessor at the University of Carlos III in Madrid,Spain. His permanent work is lecturer in the facultyof Engineering in Helwan, Helwan University, Egypt.