Questions and Answers
What type of bone fills the space between the outer and inner plates and the alveolar bone proper?
What is the characteristic of Type 1 trabeculae in spongy bone?
What is the approximate percentage of inorganic component in bone composition?
What is the primary function of bone marrow in the alveolar bone?
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What is the composition of bone marrow in young bone?
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What is the term for isolated areas where the root is denuded of bone and covered only by periosteum and overlying gingiva?
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Which of the following is NOT a predisposing factor for fenestrations and dehiscences?
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What is the interdental septum composed of?
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During which type of ossification is alveolar bone formed?
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What is the process of replacing old bone with new bone?
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What is the type of collagen found in bone?
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What is the function of canaliculi in alveolar bone?
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What is the component of bone that provides structure and strength?
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At what stage of fetal development do mandible and maxilla form a groove that is opened toward the surface of the oral cavity?
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What consists of compact bone and forms the outer and inner plates of the alveolar process?
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What is the characteristic of the outer cortical plate in the maxilla?
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What type of bone is found in the spongy bone structure?
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What is the function of the bundle bone?
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What is the characteristic of the lamina dura?
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What is the region where the cortical plate is fused with the alveolar bone proper?
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What is the difference between the cortical plates in the maxilla and mandible?
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What is the characteristic of the buccal plates?
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Study Notes
Alveolar Bone
- Covered by periosteum
- Filled with spongy bone, which consists of heavy trabeculae with bone marrow spaces
- Trabeculae are of two main types:
- Type 1: regular and horizontal in a ladder-like arrangement, commonly seen in the mandible
- Type 2: irregularly arranged, numerous, and delicate, more common in the maxilla
Bone Marrow
- Red in young bone and yellow in old bone
- Consists of:
- Blood-forming elements
- Osteogenic cells
- Adipose tissue
Interdental Septum
- Consists of cancellous bone bordered by the socket walls of approximating teeth and facial and lingual cortical plates
- Can have irregular windows appear in the bone adjacent to roots if they are too close together
Embryology of Alveolar Bone
- Forms near the end of the 2nd month of fetal life
- Mandible and maxilla form a groove that opens towards the surface of the oral cavity
- Bony septa form gradually as tooth germs develop
Osteogenesis
- Process of bone formation
- Alveolar bone is formed during fetal growth by intramembranous ossification
- Consists of a calcified matrix with osteocytes enclosed within spaces called lacunae
- Osteocytes extend processes into canaliculi that radiate from the lacunae
Bone Composition
- 67% inorganic (hydroxyapatite crystals, calcium, phosphates, hydroxyl, carbonate, sodium, magnesium, and fluorine)
- 33% organic (non-collagenous proteins, collagen type I, osteocalcin, osteonectin, phosphoproteins, and bone morphogenic protein)
Fenestrations and Dehiscences
- Isolated areas where the root is denuded of bone and covered only by periosteum and overlying gingiva are termed fenestrations
- When the denuded area extends through the marginal bone, it is called a dehiscence
- Predisposing factors:
- Prominent root contour
- Malposition
- Labial portion of the root combined with a thin bony plate
- More common on facial bone than on lingual bone
- More common anteriorly than posteriorly
- Often occurs bilaterally
Bone Turnover (Remodeling)
- Replacement of old bone by new bone
- Occurs in physiologic growth movements
Alveolar Process
- Defined as the parts of the maxilla and mandible that form and support the sockets of the teeth
- Forms when the tooth erupts to provide osseous attachment to the forming periodontal ligament
- Disappears gradually after the tooth is lost
Alveolar Bone Proper
- Surrounds the roots of the tooth and gives attachment to the principal fibers of the periodontal ligament
- Histologically, it is bundle bone and lamellared bone
Bundle Bone
- The bone that lines the socket in which Sharpey's fibers are embedded
- Perforated with many small foramina for blood vessels and nerves
- Contains more calcium salts per unit area than other bone
- Also known as lamina dura due to its radiopacity
Supporting Alveolar Bone
- The bone that surrounds the alveolar bone proper and gives support to the socket
- Consists of cortical plates and spongy bone (cancellous bone)
Cortical Plates
- Consists of compact bone and forms the outer and inner plates of the alveolar process
- Thinner in maxilla than in mandible
- Thickest in the premolar and molar region of the mandible
- Buccal plates are thin, but lingual plates are heavy
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Description
This quiz covers the structure and types of spongy bone, including the arrangement of trabeculae and their characteristics. It's an important concept in anatomy and bone biology.
