Alveolar Bone and Tooth Eruption/Exfoliation Flashcards by Michael McMahan

The ______ is formed as a result of
attachment of the PDL fibers and passage of
vessels and nerves into and out of the PDL.

cribriform plate

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The term ______ refers to that bone in

which Sharpey’s fibers (PDL) are embedded.

bundle bone

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Immature bone in which the collagen fiber matrix is
randomly oriented. This type of bone is generally newly
formed (embryologic development) or associated with
healing wounds.

Woven bone

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Trabecular bone that lies between the cortical plates and

within the marrow spaces.

Spongiosa (a.k.a. Cancellous)

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The following cells are cells associated with \_\_\_\_
Ø Osteoblasts
Ø Osteocytes
Ø Osteoclasts
Ø Bone Lining Cells
Ø Chondroblasts
Ø Chondrocytes
Ø Mesenchymal Cells

Bone

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_______ is an osteoblast that has been entrapped by it’s own osteoid matrix

Osteocyte

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_____ – radiate in all directions, and allow diffusion of substances
throughout bone. Processes of the osteocytes travel within these
and connect to other osteocytes/osteoblasts, allowing cell-to-cell
communication. May have some mechanoreception properties, as well

Canaliculi

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A dense connective tissue, bound to bone by Sharpey’s fibers,
that contains blood vessels, nerves, and three cell layers

Periosteum

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Peripheral cell layer of periosteum contains ______

fibroblasts

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Intermediate cell layer of periosteum contains ______

undifferentiated mesenchymal cells

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Proximal cell layer of periosteum contains ______

osteoblasts

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Lines the medullary cavity and cancellous bone (trabeculae). Generally has the same composition as periosteum but is significantly thinner

Endosteum

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Which type of collagen in bone is ubiquitous in distribution?

Type 1 collagen

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Which type of collagen in bone is primarily a cartilage protein?

Type 2 collagen

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Which type of collagen in bone contains granulation and mesenchymal tissues; necessary for healing?

Type 3 collagen

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Which type of collagen in bone contains stromal connective tissue and promotes cellular attachment and migration?

Type 5 collagen

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Which type of collagen in bone facilitates conversion of cartilage to bone?

Type 10 collagen

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Non-collagenous proteins associated
with \_\_\_\_\_ include:
Ø Osteonectin
Ø Osteopontin
Ø Osteocalcin
Ø Sialoprotein
Ø Phosphoprotein
Ø Glycoprotein
Ø Proteoglycan
Ø Bone Specific Protein
Ø Bone morphogenetic protein (BMP)
Ø Carboxyglutamic acid containing protein

bone matrix

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The non-collagenous matrix proteins of bone

are characterized by what 3 things?

Ø highly acidic nature
Ø high aggregation tendencies
Ø calcium binding properties

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A process of osteoclast resorption, and bone
replacement by osteoblast activity. Mostly seen in
areas of alveolar bone affected by orthodontics.

In-Situ Remodelling

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Bone formation within or between connective tissue
membranes consisting of Type I collagen. Bone does
not replace cartilage as does endochondral bone.

Intramembranous Bone Formation

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Bone formation within hyaline cartilage that involves a
concomitant replacement of the cartilage framework by
bone

Endochondral Bone Formation

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This type of bone formation is found in the inner
spongy layers of bone, as well as sutures. It is an
extremely rapid and disorganized method of bone
deposition, and allows for growth of the tissues
surrounding it.

Intramembranous bone growth

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Woven bone is an example of

_____ bone growth.

intramembranous

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In intramembranous bone growth, _____ secrete matrix vesicles that mineralize surrounding collagen fibres

Osteoblasts

The osteoblasts usually become trapped themselves, becoming ______

osteocytes.

What are the 5 contents of the matrix vesicles secreted by osteoblasts in intramembranous bone formation?

``` Ø Pyrophosphatase Ø Alkaline phosphatase Ø Glycoproteins Ø Phosphoproteins Ø Phospholipids ```

____ bone growth is Mostly seen in the vertebrae, long bones, base of the skull, and head of the mandible.

Endochondral

In ____ bone growth, Mesenchymal cells make the general outline of the final bone shape. The cells differentiate into cartilage cells (chondroblasts), which increase in size, secrete collagen and mineralize it with matrix vesicles. The newly formed chondrocytes eventually die. Vascular tissue from the surrounding perichondrium invades the cartilage, allowing chondrocytes and mesenchymal cells to enter the area. The chondrocytes eat away the cartilage, and newly differentiated osteoblasts deposit osteoid onto the cartilage. The osteoid is mineralized by osteocytes, and bone is made.

Endochondral bone growth

The growth of the bones in endochondral bone formation is dependant on the growth of the _____, and stops once it is been completely removed

cartilage

``` The Zones of Cellular Activity are found in ____ bone formation Ø Reserve or resting chondrocytes Ø Proliferation Ø Maturation Ø Hypertrophy and calcification Ø Cartilage degeneration Ø Osteogenesis ```

Endochondral bone formation

Bone _____ is controlled systemically by hormones and locally by mechanical factors, growth factors, and cytokines.

metabolism

Hormones important to bone | metabolism include what 5 hormones?

``` Ø Parathyroid hormone (PTH) Ø 1,25-dihydroxyvitamin D Ø Calcitonin Ø Estrogen Ø Glucocorticoids ```

What are the cytokines and growth factors important to bone metabolism include what 7 things?

``` Ø Interlukin-1 (IL-1) Ø Interlukin-6 (IL-6) Ø BMP-2 and BMP-7 Ø Transforming Growth Factor (TGF-) Ø Insulin-like growth factor (IGF-I and IGF-II) Ø Platelet-derived growth factor (PDGF) Ø Fibroblast growth factor-beta (FGF-) ```

Under conditions that favor bone resorption, osteoblasts can be stimulated by cytokines and hormones to produce ____ which, in turn, promotes differentiation of osteoclasts

IL-6

What are the 5 cytokines that promotes differentiation of osteoclasts?

``` Ø Interleukin-11 (IL-11) Ø Tumor necrosis factor-alpha (TNF-) Ø Prostaglandins E2 (PGE2) Ø Parathyroid hormone (PTH) Ø 1,25-dihydroxyvitamin D ```

Osteoclastic resorption of bone involves the creation of a localized _____ pH to demineralize hydroxyapatite, and a variety of enzymes that degrade the organic bone matrix

acidic pH

What are the 7 things secreted by osteoclasts to degrade organic bone matrix?

``` Ø Lactic acid Ø Citric acid Ø Free protons (H+) Ø Acid phosphatase Ø Aryl sulfatase Ø Collagenase (MMP) Ø Gelatinase (MMP) ```

The reaction of osteoclasts is catalyzed by ____

carbonic anhydrase

``` Architecture (shape) of the tooth-associated ______ cortical bone is dictated by: Ø Facial-lingual alignment of teeth Ø Mesial to distal contour of the CEJ Ø Facial-lingual width of teeth Ø Presence of enamel pearls or cervical enamel projections ```

facial and lingual

``` Architecture (shape) of the _______ alveolar bone is dictated by: Ø Facial to lingual contour of the CEJ Ø Mesial or distal tilt of the tooth Ø Root proximity Ø Presence of enamel pearls Ø State of tooth eruption ```

interproximal

An isolated “port-hole” in the cortical bone that | allows exposure of the underlying root surface

Fenestration

A denuded area of cortical bone that extends through the marginal bone creating a “cleft-like” defect

Dehiscence

An area of bone formation that exceeds the average for a given anatomical area. The term is generally used in reference to the maxillary facial and lingual and mandibular facial

Exostosis

An area of bone formation that exceeds the average for a given anatomical area. The term is used in reference to the mandibular lingual or midline of the palate

Torus /Tori

Ø Generally asymptomatic causing a painless expansion of bone Ø Usually a single lesion that can be either unilocular or multilocular Ø Often confused with ameloblastoma or periapical granuloma or periapical cyst Ø Histology characterized by presence of numerous multinucleated giant cells in a stroma of ovoid & spindle shaped mesenchymal cells

Giant Cell Tumor

Ø Malignancy of plasma cell origin that accounts for nearly 50% of all malignancies involving bone Ø The abnormal plasma cells are typically monoclonal (arise from a single cell) Ø Patients frequently suffer kidney failure due to overload of circulating light chain protein (Bence Jones Protein) produced by the abnormal plasma cells

Multiple Myeloma

Ø Histology shows monotonous sheets of neoplastic, variably differentiated, plasmacytoid cells that invade and replace normal host tissue Ø Radiographically, patients may exhibit “punched out” areas in the cranium. Such areas are filled with the neoplastic plasmacytoid cells

Multiple Myeloma

Ø A malignancy of mesenchymal cells that have the ability to produce osteoid or immature bone Ø Excluding hematopoietic neoplasms, it is the most common type of malignancy to originate within bone Ø Pain and swelling are the most common symptoms Ø Radiographic findings vary from dense sclerosis to a mixed sclerotic-radiolucent lesion. About 25% of lesions exhibit a “sunburst” pattern

Osteogenic Sarcoma

______ is the most common type of | malignancy to originate within bone

osteogenic sarcoma

The primary and permanent dentitions develop ______ as the jaws increase in size from infancy to adolescence.

simultaneously

Jaws of the infant accommodate development of ____ | deciduous teeth

At 4-5 yrs of age, the jaws accommodate 20 erupted | teeth and _____ developing teeth

The mixed dentition stage, __-__ yrs of age, involves the concomitant exfoliation of deciduous teeth and eruption of permanent teeth

8-12 yrs

_______ is defined as the movement of a tooth from its site of development within the alveolar process to its functional position in the oral cavity.

Tooth eruption

Tooth eruption is divided into | what three developmental stages?

 Pre-eruptive phase  Pre-functional eruptive phase  Functional phase (post-eruptive phase)

Which phase of tooth eruption includes the following:  Growth of jaws  Growth of tooth buds  Remodeling of the walls of the bony crypt

Pre-eruptive phase

______ results when there is resorption of the mesial wall with concomitant apposition of bone on the distal wall

mesial migration

Over time, the jaws increase in what 4 ways?

 Length of jaw (anterior-posterior)  Width of jaw (coronal plane)  Alveolar ridge height  Buccal-lingual width of the alveolus

As the jaws increase in length, the crowding is alleviated by migration of teeth _____ which allows a more even distribution.

distally

With increased jaw size, the developing teeth move ______ and _______

outward (facially); towards the oral cavity (upward or downward).

Because of jaw length, the permanent developing ____ have angled inclinations prior to and during eruption and achieve vertical alignment only when jaw length is sufficient to allow it.

molars

Theories of Tooth Eruption:  Elongation of the roots in relation to stability of the fundus of the socket

Root Growth

Theories of Tooth Eruption:  Increased hydrostatic pressures in the apical dental sac or periodontal ligament

Vascular Pressure

Theories of Tooth Eruption:  Coronal bone resorption concomitant with bone apposition in the fundus area

Selective Bone Deposition and Resorption

Theories of Tooth Eruption:  Tissue pressure differential in the pulp compared to the PDL

Pulpal Pressure

Theories of Tooth Eruption:  Cells (myofibroblasts) exert traction on the tooth through the collagen network and cell-to-cell contacts

Periodontal and Gingival Fiber Ligaments

Of the numerous causes of tooth eruption, the | most frequently theories cited are what 3 theories?

root growth, alveolar bone remodeling, and periodontal ligament formation

______ (influences mineralization and | resorption of roots)

Parathyroid hormone

____ produced by fibroblasts, osteoclasts, macrophages

MMPs

A strand of connective tissue that contains remnants of dental lamina epithelium (derived from the successional lamina)  The rate of eruption is not constant but best described as a “burst of eruption” that averages about 3 mm every 3 months

Gubernacular canal/ eruptive pathway

The rate of eruption is not constant but best described as a “burst of eruption” that averages about ____ mm every 3 months

3 mm

 Oblique fiber groups of the PDL continually pull the tooth into occlusion as enamel is abraded.  Apical cementum deposition also serves as a compensatory eruptive mechanism to continual occlusal abrasion.

Occlusal Surface Wear:

 Mesial inclination of teeth in full contact will yield an | anterior force vector and when coupled with the pull of the transseptal fibers,

Proximal Wear (Mesial Drift):

Cell mediated tooth resorption involves the | ______

“odontoclast”

Derived from monocytes that exit capillaries to become connective tissue macrophages which, in turn, fuse together to form a (syncytium) large multinucleated giant cell that functions like an osteoclast. _______ degrade both the collagenous and non-collagenous matrix of cementum and dentin (lysosomal enzymes) and the hydroxyapatite mineral phase (acids).

Odontoclasts

Odontoclasts degrade both the collagenous and non-collagenous matrix of _____ and ______ (lysosomal enzymes) and the hydroxyapatite mineral phase (acids).

cementum and dentin

 Specialized fibroblast-like cells are thought to destroy the collagen fibers of the PDL associated with the resorbing tooth root.

Fibroclast

The finding of apoptotic cell death in the resorbing PDL suggests that shedding of teeth is a _______

programmed event.