Tooth Matrix Formation and Mineralization in Extant Fishes

Abstract

Three highly mineralized apatitic tissues cover dentin of fish teeth: (A) Osteichthian enameloid with matrix containing collagen [1] that, in some teleosts, is secreted by inner dental epithelial cells [2] and is degraded during the mineralization process [3, 4]. Therefore, this enameloid is different from enamel, dentin and bone. (B) Chondrichthian enameloid with matrix that is a unique non-collagenous product of odontoblasts to which IDE cells secrete carbohydrate [5,6]. (C) A non-collagenous, ectodermally derived, enamel-like matrix which is found on crossopterygian [7], dipnoan [8] and holostean [9] teeth. We research tooth development in diverse fish species to elucidate homology with mammalian odontogenesis and to characterize structural features of tooth formation which modulate the levels of fluoride (F) in the enameloid [10]. Here we report ultrastructural and biochemical parameters of several fish species illustrating various strategies used to form highly mineralized tooth structures.