Atomic force microscopy study of tooth surfaces

Atomic force microscopy (AFM) was used to study tooth surfaces in order to compare the pattern of particle distribution in the outermost layer of the tooth surfaces, Human teeth and teeth from a rodent (Golden hamster), from a fish (piranha), and from a grazing mollusk (chiton) with distinct feeding habits were analyzed in terms of particle arrangement, packing, and size d istribution. Scanning electron microscopy and transmission electron microsc opy were used for comparison. It was found that AFM gives high-contrast, hi gh-resolution images and is an important tool as a source of complementary and/or new structural information, All teeth were cleaned and some were etc hed with acidic solutions before analysis. It was observed that human ename l (permanent teeth) presents particles tightly packed in the outer surface, whereas enamel from the hamster (continuously growing teeth) shows particl es of less dense packing. The piranha teeth have a thin cuticle covering th e long apatite crystals of the underlying enameloid, This cuticle has a rou gh surface of particles that have a globular appearance after the brief aci dic treatment. The similar appearance of the in vivo naturally etched tooth surface suggests that the pattern of globule distribution may be due to th e presence of an organic material. Elemental analysis of this cuticle indic ated that calcium, phosphorus, and iron are the main components of the stru cture while electron microdiffraction of pulverized cuticle particles showe d a pattern consistent with hydroxyapatite, The chiton mineralized tooth cu sp had a smooth surface in an unabraded region and a very rough structure w ith the magnetite crystals (already knows to make part of the structure) pr otruding from the surface. It was concluded that the structures analyzed ar e optimized for efficiency in feeding mechanism and life span of the teeth. (C) 1999 Academic Press.