9. Histogenesis of the dentin (dentinogenesis) · Preclinical Paediatrics · MU Sofia

HISTOGENESIS OF DENTIN (DENTINOGENESIS)

Dentin is formed by odontoblasts that differentiate from the ectomesenchyme cells of the dental papilla.

Dental Papilla is the formative organ of dentin and will eventually become the pulp of the tooth
For Dentinogenesis and Amelogenesis to take place, differentiating odontoblasts and ameloblasts will receive signals from each other known as reciprocal induction

There are two types of cells involved in dentin formation: odontoblasts and subodontoblasts (fibroblasts)

Start of Dentinogenesis begisn after the final differentiation of the odontoblasts and subodontoblasts
In the Cap Stage of dental embryo and in stage of early bell, ectomesenchyme cells in signalling molecules to the basal membrane still decimate
When the inner epithelial layer of enamel bell outlines the shape of the future crown, the two adjacent layers around the basal lamina stop their division and begin their differentiation
Innards of inner enamel epithelium differentiate and begin to emit signalling molecules to the ectomesenchyme below the basal lamina

Layer under basal lamina differentiated to preodontoblasts
Daughter cells below them are called the Hall Layer. Arranged in several layers. Not reached by ectodermal stimuli, but only by the mesoderm after their differentiation lower from the adjacent zones
They differentiate into Fibroblasts
Cells located below the odontoblasts and above the fibroblasts are called subodontoblasts are involved in Dentin-fibrillogenesis
They produce major collagen fibres during dentin fibrillogenesis called van Korf’s fibres

Odontoblasts extend their processes. They are freeing a space under the basement membrane
First place where this happens is in the growth centre. This is the space where the secretion of organic matrix and then its mineralization will begin
When One dentin layer is formed, odontoblasts drawn to the pulp, odontoblastic process is increased, new space is freeing. Process is repeated, matrix is then secreted and then mineralizaed
Process continues until dentin is formed

Continued growth of tooth germ leads to bell stage. Continuation of histodifferentiation and beginning of morpho-differentiation as the tooth crown assumes its final shape
Dentinogenesis begins after final differentiation of odontoblasts and subodontoblasts
Odontoblast formation is influenced by cells of inner dental epithelium and outer epithelium organize a network of capillaries to bring nutrition to ameloblasts