Pulp Histology Flashcards
Definition of Endodontics
Branch of dentistry concerned with the morphology, physiology, and pathology of the human dental pulp and periradicular tissues
Dental Pulp
Located in center of crown and root Loose Connective Tissue Enclosed in hard walls (dentin) Poor collateral circulation Connective tissue held together by ground substance Structure reinforced by collagen fibers
Pulp Embryology
Derived from neural crest cells (ectomesenchymal)
Forms dental papilla - mature pulp derives
Enamel Organ - Development
Enamel
Dental Papilla - Development
Pulp & Dentin
Dental Sac - Development
Cementum & PDL
Tooth development
Papilla -> IEE -> ameloblasts
Ameloblasts -> papilla -> odontoblasts -> predentin
Predentin -> ameloblasts -> enamel
Epithelial Diaphragm
AKA - cervical loop
Junction of IEE and OEE
Future CEJ
*Hertwig’s Epithelial Root Sheath
*Proliferation forms root
When ruptured, exposes dentin to connective tissue
Exposed dentin stimulates cementum deposition
Cell Rests of Malasseze’s
Epithelial remnants from root sheath
Remain dormant
If activated by inflammation, can proliferate providing lining of radicular cysts
Lateral Canal
communication b/n pulp and periodontum
Primary: formed if root sheath breaks down before dentin can be laid
Secondary: form if bv are not displaced
*Morphologic Zones of the Pulp
Core, Cell Rich, Cell Free, Odontoblast
*Odontoblastic Zone
Free nerve ends penetrate this layer, communicate via gap junctions, palisade arrangement (tight picket fence)
Cell Free Zone
zone of Weil, nerve fibers present, *diminish in size or temporarily disappear during rapid dentin formation
Cell Rich Zone
contains undifferentiated mesenchymal cells and fibroblasts
serves as reservoir for destroyed odontoblasts
Central Zone or Core
core of loose connective tissue
contains larger nerves and blood vessels
Dental Pulp Components
Cells, intercellular components, nerves, blood vessels, lymphatics
Cells of pulp
Odontoblasts, fibroblasts, undifferentiated mesenchymal cells, inflammatory cells
Odontoblast
Cell body and Odontoblastic process
Rough endoplasmic reticulum, golgi complex, mitochondria
Odontoblastic functions
synthesizing (cell body), secretory (odontoblastic process), mineralizing
Fibroblasts
Most abundant cell in pulp
Abundant in cell rich zone, synthesizes collagen matrix, secretes ground substance matrix
Undifferentiated mesenchymal cells
abundant in cell rich zone, can differentiate into different cells, reservoir for lost cells
Acute vs. Chronic Inflammatory Cells
Acute - neutrophils
Chronic - lymphocytes, plasma cells, macrophages
Intercellular Components
Intercellular fluid, ground substance, collagen fibers, blood vessels and nerves
Intercellular Fluid
derived from pulpal capillaries, vehicle for nutrients and waste removal
Ground Substance
sol-like, made of glycosaminoglycans, glycoproteins (complex protein-carbohydrate molecules) and water, supports cells, *composition altered by age and disease (shrink as older)
Helps regulate overall intrapulpal pressure, acts as a barrier against spread of microbes
Collagen Fibers
Type 1 found in dentin, both 1 and 2 found in pulp
Odontoblast - type 1
Fibroblasts - type 1 and 2
Collagen fibers - polypeptide chains, immature fibers called reticular fibers, fibrils aggregate to form bundles which in turn form fibers
