Date post: | 01-Jun-2015 |
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Health & Medicine |
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Alveolar bone
Structure of bone • Bone is a specialized form of
connective tissue.• It consists of : Bone matrix
Cells
Periosteum
Endosteum
1. Bone matrix
Inorganic
OrganicWater
60% by weightIn the form of
apatite crystalsCalcium
PhosphorusMagnesiumPotasiumSodium
25% by weight
90% Type I collagen.Ground substance of
glycoproteins and proteoglycans with
small amount of proteins and lipids.
15% by weight
Bones Cells a) Ostoprogenator cells.b) Osteoblasts .c) Osteocytes .d) Osteoclasts .e) Bone lining cells.
Osteoblast • Bone forming cells• Extensive endoplasmic reticulum • Numerous mitochondria and vesicle• Active in collagen and ground substance formation • Produce intercellular substance called osteoid
tissue
Osteoclasts• Large multinucleated cells• Responsible for resorbtion of bone• Found in depressions in the bone called
Howship’s lacunae
Osteocytes• An osteocyte, a star shaped cells is the most
commonly found cell in mature bone • Osteocytes have an average half life of 25
years, they do not divide• Occupy a space called lacuna• Few organelles• Play role in calcium homeostasis
Osteoprogenitor cells• Mesenchymal fibroblast like cells• Form stem cell population to generate
Osteoblast.
Bone lining cells• Undifferentiated flattened cells• Line the surface of bone when there is no
deposition or resorbtion
Periosteum and endosteum
• Layers of bone forming cells and connective tissue cover the external and internal surface
• Provide nutrition to bone tissue• supply new osteoblasts
Types of bone1. Mature (Lamellar) bone:
Collagen fibers within each lamella are parallel
Osteocytes are evenly distributeda) compact bone
b) Spongy (Cancellous) bone
2. Immature (woven) bone
3. Bundle bone
Compact bone • Denser than cancellous bone.• Thick and solid• Lamellae are organized in the form of concentric
cylinder surrounding a narrow canal • 5-20 lamellae surround each canal
(circumferential lamellae). • The central vascular canal called Haversian
canal• Haversian canals are connected by transversely
running Volkmann’s canals
Haversian system
Spongy bone • Sponge-like found in the
head of a long bone• Has large marrow spaces• Surrounded by thin
trabeculae.
Bone Trabeculae
Bone Marrow Spaces
Woven bone • Bony tissue characteristic
of the embryonic skeleton in which the collagen fibers of the matrix are arranged irregularly in the form of interlacing networks.
• Less ground substance and less calcified
• Healing sockets after teeth extraction
Bundle Bone • Collagen fibers of PDL
(Sharpey’s fibers) are embedded in it
• More calcified• Restricted to alveolar
bone proper
Alveolar boneThe alveolar bone ( process )
• The part of maxilla or mandible which
supports and protect teeth.
• Dependent on the presence of teeth .
Functions • Forms the bony socket to hold the root of tooth
and attach it through the PDL• It gives attachment to muscle• Framework for bone marrow• Reservoir for calcium
Jaw bones
Basal boneAlveolar process
Alveolar bone proper
Supporting alveolar
bone
Cortical plates buccal ,lingual
Spongy bone
Alveolar process
Alveolar process
Alveolar bone proper • Forms the socket inner wall• Gives attachment to periodontal ligament• Perforated by many openings that carry
branches of interalveolar nerves and blood vessels into PDL
• Consists of lamellated and bundle bone
Supporting alveolar bone • Compact bone• Thinner in the maxilla• Thickest in molar and premolar region
Consist of cortical plate lingual plate (inner plate) labial plate (outer plate) supporting spongy bone (Cancellous bone
between cortical plates and alveolar bone proper)