Comparative qualitative and quantitative assessment of biomineralization of tooth development in man and zebrafish...

It was the aim of this study to investigate the distribution of Ca, P, and C in predentin, mineralizing dentin, and mature dentin of human tooth buds and compare these results with those of zebrafish (Danio rerio) teeth using energy dispersive X-ray analysis (EDX) element analysis. The mandible of a 16-week-old human fetus containing 6 mineralizing tooth buds and three complete heads of zebrafish were fixed in formaldehyde and embedded in Technovit 9100. Serial sections of 80-microm thickness were cut in frontal-dorsal direction, and from these sections, polarized light micrographs were taken. The sections with tooth buds were then investigated with scanning electron microscopy, and EDX element analysis was performed with a Philips XL 30 FEG scanning microscope and an EDAX energy-dispersive X-ray system using spot measurements, EDX line-scans and element mapping. Quantitative measurements were made in predentin, mineralizing dentin adjacent to predentin, and mature dentin. The Ca and P content increased rapidly from outer predentin toward mineralizing dentin in human tooth buds and in zebrafish teeth. The Ca/P ratio was different for predentin and dentin areas, reflecting different calcium phosphate compositions in predentin and fully mineralized dentin. Because of the similarities between human tooth buds and zebrafish teeth, it can be concluded that the zebrafish tooth development may be an excellent model for studying biomineralization processes during odontogenesis.