8 - morphology of tooth dentin. Classification and layers in dentin. Dentin physiology - metabolism. sensitivity and functions. Characteristics of the dentin in primary and permanent teeth in childhood

classification of dentin

1. primary physiologic dentin - mantle, circumpulpal, peritubular, intertubular, pre-dentin

2. Secondary physiologic dentin

3. Tertiary dentin / reactionary dentin / irregular secondary dentin

Layers of dentin

• Mantle dentin - most superficial layer, most highly mineralised, similar in degree of mineralisation to enamel, situated just below DEJ

• Circumpulpal dentin - thickest layer, less mineralised than mantle, less Korff’s fibres, thinner collagen fibres than mantle dentin 

• Intertubular dentin - between mantle and circumpulpal dentin, mineralised globule does not merge therefore its also known as the globular layer 

• Predentin - a band of newly formed un-mineralised matrix of dentin at the pulpal border of the dentin 

Metabolism of dentin

• ensured by the pulp 

• performed by odontoblast processes

sensitivity of dentin 

• nerve endings of the odontoblasts are in the predentin

functions of dentin

1. during dentinogenesis

• synthesising - proteins, matrix, macromolecules and collagen

• Secreting - beta fibres (collagen), amorphous organic and inorganic matter

• structure and mineralise dentin matrix

2. during functional phase

• continued formative function 

• ensure exchange of dentin 

• provide link between enamel, dentin and dental pulp 

• provide sensitivity of the dentin 

• protective function 

characteristics of dentin in primary and permanent teeth in childhood?

• thinner with larger and wider tubules

• closer proximity to pulp

• high sensitivity and lower mineralisation

function of dentin during dentogenesis

1. during dentinogenesis

• synthesising - proteins, matrix, macromolecules and collagen

• Secreting - beta fibres (collagen), amorphous organic and inorganic matter

• structure and mineralise dentin matrix

function of dentin during functional phase

2. during functional phase

• continued formative function 

• ensure exchange of dentin 

• provide link between enamel, dentin and dental pulp 

• provide sensitivity of the dentin 

• protective function