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| PERIODONTIUM |
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TEETH IN-SITU
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Periodontium (forms a specialized fibrous joint called Gomphosis)
• Cementum
• Periodontal Ligament
• Alveolar bone
• Gingiva facing the tooth
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| Histology of periodontium |
It is a hard avascular connective tissue that covers the roots of teeth
Role of Cementum
1. It covers and protects the root dentin (covers the opening of dentinal tubules)
2. It provides attachment of the periodontal fibers
3. It reverses tooth resorption
Varies in thickness: thickest in the apex and In the inter-radicular areas of multirooted teeth, and thinnest in the cervical area 10 to 15 mm in the cervical areas to 50 to 200 mm (can exceed > 600 mm) apically
Cementum simulates bone
• Organic fibrous framework, ground substance, crystal type, development
• Lacunae
• Canaliculi
• Cellular component
• Incremental lines (also known as “resting” lines; they are produced by continuous but phasic, deposition of cementum)
Differences between cementum and bone
• Not vascularized – a reason for it being resistant to resorption
• Minor ability to remodel
• More resistant to resorption compared to bone
• Lacks neural component – so no pain
• 70% of bone is made by inorganic salts (cementum only 45-50%)
• 2 unique cementum molecules: Cementum attachment protein (CAP) and IGF
Clinical Correlation
Cementum is more resistant to resorption: Important in permitting orthodontic tooth movement
Development of Cementum
- Cementum formation occurs along the entire tooth
- Hertwig’s epithelial root sheath (HERS) –Extension of the inner and outer dentalepithelium
- HERS sends inductive signal to ectomesenchymal pulp cells to secrete predentin by differentiating into odontoblasts
- HERS becomes interrupted
- Ectomesenchymal cells from the inner portion of the dental follicle come in with predentin by differentiating into cementoblasts
- Cementoblasts lay down cementum
PowerPoint presentation on Cementum
click here
ReplyDeletegreat visuals and excellent power point presentation