The periodontium describes the tissues that surround and support the teeth
- Gingiva
- Periodontal Ligament (PDL)
- Cementum
- Alveolar Bone
Together they form a specialised fibrous joint also called a gomphosis.
This dento-alveolar joint is connected via the fibres of the periodonta ligament.
Periodontal Ligament (PDL)
The PDL is the dense, fibrous connective tissue that connect the tooth to the alveolar bone and forms from the Hertwig epithelial root sheath. Approx 0.2mm thick
SUPPORT – provides support to the tooth during mastication/loading.
SENSORY – is highly innervated giving mecahnoreceptive, nociceptive and reflex sensory feedback.
NUTRITIVE – due to a good blood supply the PDL maintains the vitality of the surrounding tissues and may play a factor in remodeling of alveolar bone
Principal Fibres
- Alveolar Crest – insert just below the CEJ(cemento-enamel junction) to the alveolar bone
- Horizontal – these are apical to alveolar crest fibres – run perpendicular to the tooth
- Oblique – run from cementum to alveolar bone in an oblique coronal direction
- Apical – radiate from the apex of the root
- Interradicular – run from the cementum to the interradicular alveolar bone in multirooted teeth
Sharpeys Fibres – smaller numerous fibres at the end of principal fibres which embed in cementum or bone and gives anchorage
Lamina Dura – a thin dense layer of cortical bone that forms the wall of the alveolar bone facing the tooth. Radiographically, appears as a white line beside a dark line which represents the PDL.
Cementum
Covers the root of the tooth; it is a hard, avascular connective tissue providing attachment to the PDL
50-200micrometers at its thickest (apex + intraradicular areas of multirooted teeth)
10-15micrometers at is thinnest (cervical areas)
Can be classed as acellular, cellular or mixed
dentalsmackers 