Periodontium- Anatomy And Function Flashcards
What are the 4 main structures making up the periodontium?
Gingiva
Periodontal ligament
Alveolar bone
Cementum
What is the function of the periodontium?
Attachment of teeth to jaws
Support during mastication
Shock absorbs during mastication
What are the two classifications of gingiva?
Free- coronal to epithelial attachment
Attached- tightly bound to underlying bone ( muco periosteum)
What is the function of the gingivae?
Attachment between oral mucosa and teeth
Prevents bacterial invasion of underlying tissues
Where is the gingival attached to the teeth?
At or just coronal to the ACJ
What is the gingivae made up of?
Fibrous connective tissue covered by epithelium
Describe the basic structure of the oral epithelium
Stratified squamous epithelium
Made up of 2 groups of cells
1- keratinocytes
2- non keratinocytes
What cells make up non keratinocytes?
Langerhan cells- antigen presenting
Melanocytes- produce melanin
Lymphocytes- provide immunity
Merkel cells- sensory touch receptor
What are the 4 layers of non keratinised sites?
Basal cell layer
Prickle cell layer
Intermediate layer
Surface layer
What are the 4 layers to keratinised sites
Basal cell layer
Prickle cell layer
Granular layer
Keratinised layer
What are MCGs and where are they synthesised?
Contain lipids which are discharged into Intracellular spaces
Forming an incomplete barrier to free permeability of water
Synthesised in granular layer and prickle layers
Describe the three regions of gingival epithelium
Oral gingival epithelium- free and attached gingiva
Oral soul ulnar epithelium- face tooth. Not attached
Junctional epithelium- in contact with tooth
Describe feature of the oral gingival epithelium
Stratified squamous epithelium
Usually orthokeratinised
The junction between gingival epithelium and underlying gingival connective tissue
Features connective tissue papillae and rete pegs
Describe features of oral sulcular epithelium
Lines gingival sulcus and crevice
Faces tooth surface
Non keratinised
Shallow rete peg formation
Describe features of the junctional epithelium
Form epithelial attachment to the tooth
Hemidesmosones anchor basal keratinocytes to the basement membranes
Formed by fusion of reduced enamel epithelium and oral epithelium on tooth eruption
Moves apically as tooth reaches occlusion
Stabilises at ACJ
cells turnover every 14-21 days
Readily permeable due to large intercellular spaces
Small number of neutrophils pass through JE to enter crevice
What are the two main components of the gingival connective tissues?
Collagen fibres
Extra cellular matrix
Both produced by fibroblasts
What cells are commonly found in gingival connective tissues
Fibroblasts
Macrophages
Polymorphs/ neutrophils
Lymphocytes and plasma cells
Describe the groups of fibres which collagen is arranged in
Circular fibres
Trans septal fibres- embedded in cementum
Dentino gingival fibres
Dento periosteal fibres
Crestal fibres- fan out of alveolar bone into attached gingiva
Describes features of the extra cellular matrix
Network of polysaccharides and proteins Serves as structural element in tissues Synthesised by fibroblasts Includes gylcosaminoglycans GAG proteoglycans Glycoproteins
What is GAG
Gylcosaminoglycans
Bind h2o
Act as hydrostatic cushion- resists compressive forces
Describe features of the periodontal ligament
Derived from dental follicle Specialised vascular connective tissue Inserts into cementum and alveolar bone Made up of: Principal fibres Loose connective tissues Blast and clast cells Oxytalan fibres Cell rests of molasses
What is the function of the periodontal ligament?
Attachment of teeth to jaws
Absorbs forces
Role in tooth movement
Describe the principle fibres of the PDL
Sharpey fibres- attach cementum to bone
Arranged in groups: Oblique Apical Horizontal Alveolar crest Inter radicular
What is collagen formed and broken down by?
Fibroblasts cells
