Ultrastructural organization and micromechanical properties of shark tooth enameloid

Textured and hierarchically structured calcium phosphate ceramic blocks through hydrothermal treatment

“…9). It has to be noticed that the crystals observed by Enax et al [57] in enamel of shark teeth were about 5 times thinner (Fig. 8d and e) than the crystals observed in the present study (Fig.…”

“…Even if the crystal phases and chemistry are different, elongated primary crystals are densely packed and aligned within domains in those three materials. Like in enamel of shark teeth [57], the obtained structures exhibit 5 levels of hierarchy: (i) hydroxyapatite crystalline structure, (ii) in the form of needle-like crystals, (iii) aligned in bundles, Table 1 Parameters n and K for the Avrami fits of the phase conversions at different temperatures with the according correlation coefficients, R2. The activation energy Ea for each phase can then be obtained with the Arrhenius equation.…”

Calcium orthophosphates (CaPO 4 ): Occurrence and properties

“…Shark enameloid is an intermediate form bridging enamel and dentine. It has enamel-like crystals of fluoridated biological apatite associated with collagen fibrils (Lowenstam and Weiner 1989;Rey et al 2006;Prostak et al 1993;Dahm and Risnes 1999;Carr et al 2006;Enax et al 2014). Due to the presence of fluorides, biological apatite of shark enameloid shows both higher crystal sizes and a more regular hexagonal symmetry if compared to non-fluoridated biological apatite of bones and teeth (Daculsi et al 1997).…”

“…F). Enameloid of shark teeth (Lowenstam and Weiner 1989;Daculsi et al 1997;Prostak et al 1993;Dahm and Risnes 1999;Carr et al 2006;Enax et al 2014) and some exoskeletons of mollusks (Leveque et al 2004) seem to be the only exclusions because they contain substantial amounts of fluoride, with is presented there as ion-substituted, nonstoichiometric FHA or HFA. Among all normal calcified tissues of humans, the highest concentration of fluorides is found in dentine and cementum, while the lowest-in dental enamel (Table 3).…”

Histological Observation of the Jaws and Teeth of the Green Spotted Pufferfish<i> (Tetraodon Nigroviridis)</i>

“…The dermal tooth (placoid scale) covering the body surface of sharks, cartilaginous fish, is considered to be the origin of the teeth of mammals including humans 1) , and many reports on the evolutionary process connecting sharks and humans have been published [2][3][4][5][6] . The crown surface of mammalian teeth contains epithelial enamel, whereas the teeth of most fish contain enameloid, which is structurally different from enamel, and studies to investigate fish teeth to clarify the evolution of enamel are considered necessary [7][8][9][10] . On the other hand, fish are used for genetic and embryological studies because they are easy to maintain compared to mammals, the time to reach sexual maturity is short, they are prolific and many samples can be collected at one time, and embryos are transparent throughout the course from eggs to hatching, making observation and experiments easy.…”