The dental pulp is the soft connective tissue inside teeth that supports dentin. It has four zones - the odontoblastic zone near the dentin, a cell-free zone beneath it, a cell-rich zone with many cells, and a pulp core containing major blood vessels and nerves. Odontoblasts are distinctive cells that form dentin, with about 60,000 per square millimeter. The pulp also contains fibroblasts that form collagen matrix, undifferentiated cells that give rise to connective tissues, macrophages that eliminate dead cells, lymphocytes, dendritic cells, nerves, and occasionally calcified pulp stones.

1. Pulp

2. The dental pulp is the soft connected tissue that supports the dentin.

3. Four distinct zone in pulp Odontoblastic zone- at the pulp periphery Cell free zone of Weil – beneath the odontoblast Cell-rich zone – where the cell density is high - seen easily in coronal pulp adjacent to the cell free zone Pulp core – characterized by the major vessels and nerves of the pulp

5. Odontoblast The most distinctive cell of the pulp and the most easily to recognized. The number of odontoblast is estimated in a range of 59,000 to 76,000 per square millimeters in coronal dentin

8. The cervical loop area: (1) dental follicle cells, (2) dental mesenchyme, (3) Odontoblasts, (4) Dentin, (5) stellate reticulum, (6) outer enamel epithelium, (7)inner enamel epithelium, (8) ameloblasts, (9) enamel.

9. Fibroblast The cells occuring in greatest number in the pulp Particularly numerous in coronal portion of the pulp, wherethey form the cell rich zone. The function of fibroblast is to form and maintain the pulp matrix, which consist of collagen and ground substance. Appear as flattened spindle-shaped cell with dense nuclei.

11. Undifferentiated ectomesenchymal cells Represents the pool from which connective tissue cell of the pulp are derived. This cell are found throughout the cell-rich area and the pulp core and often are related to blood vessels Appear as large polyhedral cell possessing a large, lightly stained centrally placed nucleus.

13. Macrophages Tend to be located in the pulp center. Appear as a large oval or spindled shaped cells. Pulp macrophages are involved in the eliminations of dead cells

15. Lymphocytes In normal pulps, T lymphocytes are found, but B lymphocytes are scarce.

16. Dendritic cells Are found in and around the odontoblast layer in nonerupted teeth and in erupted teeth beneath the odontoblast layer. Same function as Langerhans’ cells found in epithelium

18. Matrix and ground substance The extracellular compartment of the pulp or matrix, consist of collagen fibers and ground substance. The fibers are principally type I and type III collagen. In young pulps, single fibrils of collagen are found scattered between the pulp cell.

19. Innervation of dentin-pulp complex The dental pulp is innervated richly. Nerves enter the pulp through the apical foramen, along with the afferent blood vessels, and together with the neurovascular bundles.

21. Dentin sensitivity On of the unusual features of the pulp-dentin complex is the sensitivity. The extreme sensitivity of this complex is difficult to explain, because this characteristics provides apparent evolutionary benefit.

22. Pulp stones Pulp stone, or denticles, frequently found in pulp tissue They are discrete calcified masses calcium-phosphorus rations comparable to that of dentin. May contain tubules and may be surrounded by cells resembling odontoblast.