Good mechanical retention between metal and resin or luting agent can be obtained by roughening the metal surface with lost crystal salts. The relationship of metal-resin bond strength to the shape and size of the crystals ws studied. The results indicated that cuboid crystal salts provided the best roughening among the tested crystal shapes (cube, irregular, spherical, and cuboid). There was no relationship between the tensile bond strength and the size of the crystals. Furthermore, the bending strength of metal coated with resin was improved by the roughening of the metal surface.