PULP REVIEW AND AGE CHANGES OF PULP

WHAT IS PULP? Pulp is a delicate, specialized connective tissue containing thin-walled blood vessels, nerves, and nerve endings enclosed within dentin.

How does the pulp form? At the beginig we need to know that the pulp occupy the roots and some part of the crown. So again how the pulp form?(How the root form?) The enamel organ form epithelial root sheet of hertwigs.  Hertwig epithelial root sheath initiates the formation of dentin in the root of a tooth by causing the differentiation of odontoblasts from the dental papilla.  The root sheath eventually disintegrates. As the root is completely formed leaving an opening (witch is the apical foramen) the dental papilla become the pulp.

As we see enamel organ witch consist of OEE(outer enamel epithelium) and IEE(inner enamel epithelium) will move apicaly in form of epithelial root sheet. When dental papilla touchs the epithelial root will differentiate into osteoblast forming dentine of the root.

After the complete closure of the root (except at the apical foramen where the blood vessel and nerve enters ) The dental papilla which was present her will be called the pulp

Anatomy of pulp

PULP SPACE the entire internal space of tooth which contains the pulp.

PULP SPACE CONSISTS OF: A_PULP CHAMBER B_PULP HORN C_ROOT CANALS D_LATERAL CANALS E_APICAL FORAMEN

Pulp Chamber or coronal pulp, located in the crown of the tooth Root canal or radicular pulp, is the portion of the pulp located in the root area.

Accessory canals or lateral canal, extra canal located on the lateral portion of the root The apical foramen is the opening from the pulp at the apex of the tooth to be continuous with the periapical tissue

Histology of the pulp

HISTOLOGY When the pulp is examined microscopically four distinct zones can be distinguished. The odontogenic zone composed of odontoblasts (at the periphery). The cell free zone or Weil’s zone. The cell rich zone. The central region or zone containing large nerves and blood vessels.

CELL FREE ZONE It is also called weil’s zone 40 microns wide & relatively free of cells, Traversed by 1. blood vessels 2. unmyelinated nerves 3. cytoplasmic process of fibroblasts This zone is found below the odontoblastic zone Represents the space into which odontoblasts move during tooth development.

CELL RICH ZONE subodontoblastic layer Contains more proportions of fibroblast and undifferentiated mesenchyml cells. Also contains macrophages, dendritic cells and lymphocytes. Formed due to migration of cells from pulp proper Mitosis seen when dead odontoblasts are replaced Also contain young collagen fibres during early dentinogenis.

PULP CORE The central connective tissue mass from the cell rich zone inward It contains blood vessels and nerves embedded in the pulp matrix together with fibroblasts. In young pulps, the cell population is greater while in older pulps fibre density is higher. The neurovascular bundles enter / exit this core through the apical foramen

UNDIFFERENTIATED CELLS CELLS OF PULP ODONTOBLASTS FIBROBLASTS UNDIFFERENTIATED CELLS DEFENSE CELLS

Age changes of the pulp

Age changes of dental pulp 1-reduction in size and volum of the pulp The most conspicuous changes is decreasing volume of the pulp chamber and root canal due to continuous dentin deposition.

Age changes of dental pulp 2-decreasing in cellular components With increasing age the pulp tissue shows a reduction in the number of the cellular elements specially progenitor cells, leading to reduction in regenerative potential of the pulp. Young pulp Old pulp

Age changes of dental pulp 3- actual fibrosis The collagen fibers increase in number and density which becomes more evident with the decrease in pulp size, so it produce an actual fibrosis.

Age changes of dental pulp 4- nerves and blood vessels a:nerve BV,minieralization b: blood vessels - arteriosclerosis - hyperplasia of intima - hyperplasia of elastic fiber .

Pulp calcification

What is pulp calcification? Pulp calcification : is rather common phenomenon that occurs with increasing age for no apparent cause.

Types of pulp calcification There is two types of pulp calcification :- A. Diffuse pulp calcification: these are amorphous, unorganized calcified masses and are typically formed within the radicular and coronal pulp.

B. Pulp stones (denticles): I. True denticle II. False denticle

True pulp stone: are composed predominantly of dentin and have dentinal tubules. So, How does it form?

False pulp stone : is composed of concentric layers of calcified material around a central nidus of necrotic cell or thrombi. with no dentinal tubules. Same question, How does it form?

According to there location pulp stones are classified into: I. free pulp stone II. Attached pulp stones III. Embedded pulp stones

References James k. avery and Daniel j. chiego, jr. essentials of oral biology and embryology. Essentials of Oral Pathology - Jaypee Brothers; 3 edition. Oral Pathology- Clinical Pathologic Correlations - 6th.ed