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Definition
It is that portion of the maxilla and mandible that forms and supports
the tooth socket (alveoli). It is formed when the tooth erupts, in order
to provide osseous attachment to the forming periodontal ligament and
gradually disappears after the tooth is lost
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Parts of Alveolar Bone
Alveolar bone consists of the following:
1. Inner and outer cortical plate.
2. The bone lining the socket.
3. An interior portion of cancellous bone
The cortical plates and the bone lining the socket meet at the alveolar
crest, usually 2 mm below the CEJ.
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The bone lining the socket is also compact bone and can be known as
any of the following:
1. Bundle bone,
since bundles of Sharpey’s fibers from the periodontal ligament are
embedded in it.
2. The cribriform plate
because it is perforated by numerous vascular channels.
3. Alveolar bone proper
as it provides direct bony support for the teeth.
4. Lamina dura
which is radiographically seen as a dense plate.
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chemical composition of bone.
A. Inorganic: 67% Hydroxyapatite
B. Organic: 33%
• Collagen – 28%
• Non-collagenous protein – 5%
Types Of Collagen Are Present In The Alveolar Bone
Type I - Mainly
Type III, V, XII, XIV – Traces.
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Various Non-collagenous proteins in Bone Matrix.
(i) Osteocalcin
(ii) Osteonectin
(iii) Osteopontin
(iv) Bone sialoprotein
(v) Bone proteoglycan biglycan
(vi) Bone proteoglycan II decorin
(vii) Thrombospondin
(viii) Bone morphogenetic proteins (BMPs).
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Coupling
It is interdependency of osteoblasts and osteoclasts in remodeling of
the bone.
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Fenestration And Dehiscence
Fenestration
Isolated areas in which root is denuded of bone and root surface is
covered by gingiva and periosteum, where marginal bone is intact.
Dehiscence
When the denuded areas extend through the marginal bone, the defect
is called dehiscence.
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Bone Modeling And Bone Remodeling
Bone modeling:
The process by which the overall size and shape of bone is established is
called as bone modeling. It extends from embryonic bone development
to the pre-adult period of human growth, which is continuous and
covers a large surface.
Bone remodeling:
The replacement of old bone by new is called bone turnover
remodeling. It does not stop when adulthood is reached, although its
rate slows down, which is cyclical and usually covers a small area.