9 - histogenesis of dental pulp - origin and development. development of the dental papilla - cells, blood vessels and nerves. Anatomy of dental pulp

origin of dental pulp

• derived from mesenchyme and ectomesenchyme 

development of dental pulp

• beginning of pulp histogenesis is at the bud stage of the tooth and the end is at the completion of the tooth root

• The pulp chamber narrows with deposition of dentin and finally forms a canal containing blood vessels and nerves of the tooth

cells involved in the development of the dental papilla

• odontoblasts

• fibroblasts 

• undifferentiated mesenchymal cells 

• immunocompetent cells 

odontoblast in development of dental papilla

• outermost part of pulp is a layer of odontoblasts

• they form single layer, with cell body in pulp and long cytoplasmic odontoblastic processes extending into the dentinal tubules

fibroblasts in development of dental papilla

• most numerous connective tissue cells in the pulp 

• can synthesise and maintain connective tissue matrix 

• main function in pulp is to synthesise type 1 and 3 collagen 

undifferentiated mesenchymal cells in development of dental papilla

• distributed throughout the cell rich zone and pulp core, they are stellate shaped cells

• after receiving stimuli they can give rise to fibroblasts or to odontoblasts

immunocompetent cells in development of dental papilla

• these cells are recruited from bloodstream

• are an active participant in host defence (lymphocytes, macrophages, dendritic cells, neutrophils, plasma cells and mast cells)

blood vessels role in pulp

• it is microcirculatory system due to lack of true arteries and veins 

• Largest vessels observed in pulp are arterioles and venules 

• Pulpal blood flow is more rapid than in most areas in body 

• Pulpal pressure is amongst highest of all tissues 

• Walls of pulpal vessels are very thin as the pulp is protected by a hard underlying sheath of dentin 

• One or more small arterioles enter the pulp via apical foramen and ascend through radicular pulp of root canal, once they reach the pulp chamber they branch out peripherally to form a dense capillary layer 

• Circulatory system of pulp has a number of structures regulating amount of blood recquired for its function 

• Such as sphincters, shunts or arterio-venous anastomoses, collaterals, fenestrated capillaries and microcirculatory system 

• TA - terminal arterioles 

• PC precapillary sphincters 

• PCV - postcapillary venules 

• AVA  - arterio-venous anastomoses 

• LC - lymphatic capillaries 

what are some structures of the circulatory system that help regulate the amount of blood required for the functions of the pulp?

• Such as sphincters, shunts or arterio-venous anastomoses, collaterals, fenestrated capillaries and microcirculatory system 

why are the walls of pulpal vessels very thin?

as the pulp is protected by a hard underlying sheath of dentin

is pulpal pressure amongst the lowest or highest of all tissues ?

amongst the highest

is pulpal blood flow more or less rapid than that in most areas of the body?

more rapid 

what is the primary function of the blood vessels ?

• Primary function - regulate local interstitial environment via transport of hormones, nutrients, gases and removal of metabolic waste products

what are the largest vessels observed in pulp?

arterioles and venules 

Nerves in development of dental papilla

• enter pulp via apical foramen along with afferent blood vessels and form a neurovascular bundle

• Once in pulp chamber they ascend through radicular pulp of root canal, once they reach the pulp chamber they branch out

• Each nerve fibre may provide at least 8 terminal branches forming a plexus known as plexus of Raschkow

• The nerve entering the pulp consists of sensory afferents of the trigeminal nerve and sympathetic branches

• Delta fibres - unmyelinated fast conducting are associated with a sharp localised pain

• Myelinated fibres - slower in conducting and are associated with a dull diffuse pain

what is the sensory afferents nerves that enter the pulp?

• Delta fibres - unmyelinated fast conducting are associated with a sharp localised pain

• Myelinated fibres - slower in conducting and are associated with a dull diffuse pain

how do nerves enter the pulp?

• enter pulp via apical foramen along with afferent blood vessels and form a neurovascular bundle

anatomy of dental pulp

• dental pulp in crown is surrounded by hard shell made of enamel and dentin and in root - by dentin and cementum

• pulp has a peripheral and central zone: peripheral zone consists mainly of cells - odontoblasts and fibroblasts, as well as the peripheral branches of vessels and nerves

• Central zone mainly contains arteries, veins, nerves, collagen fibers located from the apex to the periphery of the pulp

• anatomically, the pulp is divided into coronal and radicular

anatomically what is the pulp divided into?

• coronal and radicular 

describe the coronal and radicular pulp

• coronal pulp - larger and contains many more elements than root pulp 

• Radicular pulp - acts as a conducting tube to carry blood to and from the coronal area to the apical canal 

• Both pulpal areas contain the same elements although the cells, fibres, blood vessels and nerves are more numerous in coronal pulp 

what are the zones of the pulp/

• pulp has a peripheral and central zone:

• peripheral zone consists mainly of cells - odontoblasts and fibroblasts, as well as the peripheral branches of vessels and nerves

• Central zone mainly contains arteries, veins, nerves, collagen fibers located from the apex to the periphery of the pulp