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Flashcards in Alveolar Bone Deck (64):
1

Specialized mineralized CT. Composed of intercellular substance and osteocytes

Alveolar bone

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67%

Inorganic; hydroxyapatite

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33%

Organic

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28%

Collagenous

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5%

Non collagenous

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Alveolar bone can best resist

1. Compressive forces
2. Forces directed along long axis of the tooth

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Alveolar bone can least resist

1. Tensile strength
2. Shear stresses

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Function of alveolar bone

1. Support and protection
2. Attachment of muscles
3. Reservoir of minerals
4. Hemopoiesis- formation of blood cells

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- Portion of jaw bone that contains the teeth

Alveolar process

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- Rest on basal bone

Alveolar process

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- Proper development of alveolar process is dependent on tooth eruption and its maintenance of
tooth retention(residual ridge- no teeth process)

Alveolar process

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Composed of an outer and inner cortical plate of compact bone that enclose the spongiosa-
compartment of spongy bone also called as TRABECULAR or CANCELLOUS BONE

Alveolar process

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- Lines the alveolus
- Thin plate of cortical bone with perforations (cribriform plate)

Alveolar bone proper

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- Surrounds each tooth as continuous thin plate of compact bone
- Becomes fused with indistinguishable from the cortical plate of the Alveolar process in
some areas

Alveolar bone proper

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- The coronal rim of the alveolar bone
- parallel to CEJ at a distance of 1-2mm apical to it

Alveolar crest

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- corresponds to alveolar bone proper
- thin white line that is parallel to the outline of the roots of the teeth - radiographic representation of alveolar bone proper

Lamina dura

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- Active mononucleated nucleus
- Function: formation of cells
- Derived from mesenchymal stem cells

Osteoblast

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Osteoblast synthesize what

a. Type I and IV collagen
b. Cytokines and growth factors – BMP “bone morphogenic factor”

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- Entrapped osteoblast in the lacunae
- Number varies depending on the capacity of bone formation - Active in bone remodeling
- Found within matrix of bone
- Surviving cells and functional
- Function: to prevent hyper mineralization of bone

Osteocytes

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limited resorption in lacuna and canals

Osteolysis

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secondary rebuilding of perilacunar bone mineral

** after bone formation: it loses its ability to form matrix and becomes smaller
** occupies osteocytic lacuna and 2 canaliculi- maintain contact with adjacent osteocytes
and osteoblast/ lining cells
** nutrition is not a problem

Osteoplasia

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Big multinucleated cells found inside the howships lacuna
- Migration to PDL is not normal

Osteoclast

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- Can be seen at the surface attached to bone
- where acid and proteolytic enzymes( acids destroy inorganic component) exit
- Organelle- poor brush-like cytoplastic border w/c demarcates the zone of resorption

Ruffled border

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Sequence of resorption events

1.Attachment of osteoclast to bone
2.Create sealed environment
3.Releases acids to demineralized the hard tissue
4. Organic matrix is degradated by secretion of proteolytic enzymes

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Dense outer sheet of bone with closely packed layers

Compact bone

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Encloses the entire bone forming its outer and inner perimeter

Circumferential lamellae

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Makes up the bulk of compact bone
- Form the basic metabolic unit of bone – osteon

Concentric lamellae

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wide haversian canals, relatively young

Osteon HS1

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small haversian canal, more mature
** more mature, becomes smaller

Osteon HS2

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Between concentric lamellae
- Fragments of pre-existing concentric lamel-
lae from osteons mature during remodeling

Interstital lamellae

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connective membrane sur- rounding compact bone

Periosteon

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next to the bone surface, w/ bone cells and precursors

Inner layer

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more fibrous, gives rise to sharpey’s fiber

Outer layer

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covers the internal surface of compact and
spongy bone.
- Not well demarcated
- Loose CT with osteogenic cells
- Physically separates the bone surface from
the marrow w/n

Endosteon

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3 spongy bone

1. Trabecular- cancellous bone
2. Lamellae of bone arranged in flattened PAPILLA
3. Surrounds narrow spaces containing bone marrow- fat cells, RBC

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- Outside wall of mandibular and maxillary
- Continuous with alveolar bone proper at alveolar crest
- More pronounced, thicker in areas of mandible than maxilla
- Generally greater on lingual

Cortical plate

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- contains osteons and interstitial lamellae
- with bundle bone ➡ with several layers of bone parallel to the surface of the bone penetrated by
sharpey's fibers
- found in areas of recent bone apposition - with lines of rest

Alveolar bone

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spongy bone between : 2 bony plates
- alveolar bone proper of adjacent teeth/roots
- more in maxillary than mandible
- trajectories represents planes or lines of stress

Spongiosa

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maxilllary tuberosity - angle of mandible **thick lingual surface

Hematopietic marrow

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3 mechanism of bine formation

1.Endochondral/Intracartilaginous bone formation
2.Intramembranous bone formation
3.Sutural bone growth

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cartilage formation➡ cartilage removed➡ substituted by bone

Occurs by substitution rather than transformation (resorption of cartilage than bone deposition)

Occurs in the condyle

Endochondral bone formation

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bone develops directly from fibrous tissue

Mesenchymal cells differentiates into osteoblasts

Maxilla, body of mandible and cranium

Intramembranous ossification

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Function of sutures: accommodates growth of organs such as brain and eyes

Structural bone growth

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- cartilage of the first branchial arch
- Supports the developing mandible but does not con-
tribute to it
- 2 bilateral cartilages from the otic capsule to midline
but do not meet (mesial to developing mandible -
rod)
- (Area of canine)

Meckel’s cartilage

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intramembranous ossification begins here, form- ing the first bone of the mandible (embryonic period)

7th week

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rudimentary mandible is formed by in- tramembranous ossification

10th week

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Fate of meckel’s cartilage

1. Incus of inner ear
2. Malleus of inner ear
3. Sphenomalleolar ligament
4. Sphenomandibular ligament

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12th week

Condylar cartilage

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- 4th month; transient

Coronoid cartilage

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between meckel's cartilage; obliterated within 1st year after birth

Symphysial cartilage

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incremental lines (parallel)

Cementing lines

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new bone layer and resorption (scalloped)

Reversal line

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basophilic substance on surface of inactive bone.

Aplastic line

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bone layer from inactive old bone

Resting line

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thicker trabeculae, smaller marrow spaces.

Increased function

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thin trabeculae, wider marrow spaces.

Decreased function

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Tooth movement

1. Pressure side -
2. Tension side -

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resorption of bone

Pressure side

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deposition of bone

Tension side

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After tooth extraction, embryonic bone forms within the socket.

Residual ridge

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important diagnostic landmark
- Radiographic presentation

Lamina dura

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bone resorbs locally, creating a window through which the root can be seen.

Fenestration (hole)

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- the rim of bone between the fenestration and the alveolar crest disappears altogether.

Dehiscence

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Hyperfunction of the pituitary gland.
Disturbance in condylar growth

Acromegaly