Periodontium Flashcards
What is the periodontium
Tissues surrounding and supporting the teeth
What is the purpose of the periodontium
Retain tooth in socket
Resist masticatory loads
Defensive barrier, protecting tissues against threats from the oral environment
What separates the body tissues from the oral environment
Junctional epithelium
What are the two divisions of periodontal diseases
Diseases of the gingiva alone
Diseases of all the periodontal tissues
What are the periodontal tissues
Cementum
Gingiva
Periodontal ligament
Alveolar bone
What are the properties of cementum
Covers root dentine
Very similar in structure to bone
-Collagen matrix
-Lamellar arrangement
Provides attachment for some periodontal fibres
Two types:
-Cellular cementum
-Acellular cementum
Laid down by cementocytes
What makes cementum
Cementocytes
What is the differnece between acellular and cellular cementum
Acellular cementum
-No cells within
-Usually adjacent to dentine
-First formed (primary cementum)
Cellular cementum
-Contains cementocytes
-Later formed (secondary cementum)
-Present in apical part of root and in furcation regions
What happens to alveolar bone when teeth are lost
The alveolar process is resorbed leaving the ‘residual ridge’
What is the periodontal ligament
A connective tissue containing cells, extracellular matrix, fibres, nerves and blood vessels
What makes up the PDL matrix (ground substance)
Hyaluronate GAGs
Glycoproteins
-Fibronectin
Proteoglycans
-proteodermatan sulphate
-chondroitin/dermatan SO4 hybrid
What behaves like a viscoelastic gel
Ground substance
What cells are found in the PDL
Fibroblasts
Cementoblasts
Osteoclasts & Cementoclasts
Epithelial cells (cell rests of malassez)
Defence cells
What is the breakdown of the nerves within the PDL
Sensory
-Mechanoreceptors (A and Aδ fibres)
Rapidly or slowly adapting
Proprioception; chewing control
-Nociceptors (Aδ and C fibres)
Protective reflexes;
inhibit jaw elevator motor neurons
Autonomic (sympathetic)
-blood vessels control - vasoconstriction
What is the blood supply of the PDL
From inferior and superior alveolar arteries, passing into PDL from alveolar bone
From lingual and palatine arteries, supplying gingivae