Periodontium Flashcards
Periodontium consists of…
- Cementum
- Periodontal ligament
- Bone that lines alveolus socket
Cementum
Functions
Composition
General
Function
- Seals tubules of root dentin
- Attachment for periodontum fibers to keep tooth in socket
Composition
- Inorganic
- 50% Calcium hydroxyapatite
- Organic
- 50% type I collagen, water, proteins
Generally thickest at root apex and interradicular areas of teeth w/ multiple roots
Thinest near CEJ
Limited to root of teeth
Acellular (primary) Cementum
Thin layer that surrounds the root next to dentin
Cellular (secondary) Cementum
Less mineralized
Thicker
Prevalent around apical root and interradicular areas
Intermediate Cementum Formation
Initially called intermedium cementum or cementoid
Formed by inner enamel epithelial root sheath cells during root dentin formation
Made of enamelin, hard
Acellular Cementum formation
Function
After intermedium cementum
Thin layer of acellular cementum is formed and attaches to intermedium
All of the cementoblasts in the acellular cementum migrate to periodontal ligament
Function: Provide attachment for tooth
Cellular Cementum Formation
Function
Forms when cementoblasts become embeded in the matrix as cementocytes
Function
- Adaptive role in response to tooth wear and movement
- Helps repair periodontal ligament
Cementocytes
Development
Features
Cementoblasts enclosed in a self-generated matrix
Matrix mineralizes and cementoblasts lose thier secretory ability and become cementocytes
Features
- Have cytoplasmic process within a canaliculi
- Canaliculi- small fingers extend from lacunae
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Root Development
Cervical loop brings about development
- Consists of IEE and OEE
Hertwigs Epithelial Root Sheath is formed by
- Growth of cervical loop deep into mesenchyme of dental sac
- Encloses more dental papilla
- Cementum forms on root after HERS disintegrates
Epithelial Rests of Malassez
Clusters of residual cells from HERS
Enamel Pearl
Defect in HERS
Cementoenamel Junction Varoation
Enamel and cementum overlap
Edge to edge
Enamel and cementum do not meet
Periodontal Ligament Formation
Formed from ectomesenchyme
Present within Dental follicle
Differentiate into fibroblasts
- Create collagen fibers
- Sharpey’s fibers (type I collagen)
- Form the PDL
Periodontum Ligament Function
Nutritive
- pdl has blood vessels to supply nutrients to
- itself, alveolar bone, cementum
Maitenance
- pdl heals rapidly
Sensory
- Receptors to detect movement and pressure
Supports tooth during occlusal movement
Cells of periodontum Ligament
- Fibroblasts
- Most abundant
- pdl has high collagen content
- provide rapid replacement of fibers
- Macrophages, mast cells, eosinophils
- Osteoclasts
- Imp in orthodontic movement
- Bone resorption in periodontal disease
- Undifferentiated Mesenchyme
- Cementoblasts, cementoclasts