10 - Histomorpholoy of dental pulp . Pulp layers, physiology and functions of pulp: characteristics of the pulp in primary and permanent teeth in childhood

what are the pulpal layers?

• peripheral zone

• pulp core

• odontoblastic layer

describe the peripheral zone

• occupies periphery of both the coronal and radicular zones 

• Consists of:

1. a layer of odontoblastic cells located immediately below the dentin 

2. cell-free zone located below the odontoblasts or also called Weil’s cell-free layer

3. cell-rich zone 

4. parietal nerve layer or Rashkov’s nerve plexus 

• Peripheral zone is also called odontogenic, because it contains the cells odontoblasts, which build dentin 

• Acellular layer of Weil serves as a reservoir of nutrients required for odontoblast function. The cell-rich layer contains densely packed cells - mainly fibroblasts 

How do odontoblasts obtain the nutrients required for its function?

• Acellular layer of Weil serves as a reservoir of nutrients required for odontoblast function. The cell-rich layer contains densely packed cells - mainly fibroblasts 

what is the peripheral zone also known as and why?

• Peripheral zone is also called odontogenic, because it contains the cells odontoblasts, which build dentin 

describe the pulp core

• the central pulp areas contains:

• cells

• fibers

• blood vessels

• nerves

• lymph

• intercellular substances

describe the odontoblastic layer

• outermost layer of pulp, adjacent to dentin

• contains odontoblasts, which are responsible for dentin formation

• These cells extend their processes into the dentinal tubules, contributing to the maintenance and repair of dentin

Physiology of odontoblastic layer

1. Embryonic period

• begins from moment of initiation of tooth germ and ends several years after the eruption of the tooth with the completion of its root development

2. Functional period

• period begins after completion of root development and closure of the apex. The dental pulp has active exchange and protection

3. Regressive period

• with advancing age, the volume of dental pulp decreases due to formation of secondary dentin

pulp tissue becomes fibrous due to the continuous formation of fibers 

when does pulp tissue become fibrous ?

• due to continuous formation of fibers 

function of odontoblastic layer

• inductive - induces the cells producing dentin and enamel organ 

• formative 

• nutritive 

• protective  - sensory nerves respond with pain b 

• defensive - responds to irritation by producing reparative dentin 

characteristics of pulp in primary and permanent teeth in childhood

• large pulp chamber and root canal

• more fragile, disease gets complicated more quickly

• better trophicity - protection

• better sensory and regenerative functions