9 Periodontium Flashcards
T/F: Primary cementum contains cells.
False. As primary cementum is secreted, the cementoblasts retreat toward the location of the future PDL. They are out of the way when mineralization of the cementum occurs.
T/F: Primary cementum is deposited as the tooth is erupting into the mouth.
True. Primary cementum is the first-deposited. It is initiated soon after that root dentin begins to be laid down and occurs simultaneously with the elongation of the root and eruption into the oral cavity (ie simultaneous with the pre-functional stage of eruption).
Identify location where primary cementum is most abundant.
Top: No, this is enamel.
Middle: Yes, primary cementum is more abundant in the cervical part of the tooth, reflecting the fact that it’s laid down first, and that cementogenesis proceeds from the CEJ to the root apex.
Bottom: No, this is the lcoation where secondary cementum is most abundant. Cementogenesis proceeds from the CEJ to the root apex, and primary cementum is secreted before secondary cementum.
Explain the mechanism responsible for the development of a secure attachment between dentin and cementum.
The initial organic matrix of cementum is composed of collagen fibers which intermingle with the adjacent unmineralized dentin amtrix prior to the mineralization of both these tissues.
Identify tissues.
L: acellular cementum
R: dentin/root
Identify tissues.
L: aceullar cementum
M: Tomes’ granular layer = hypomineralized regions in mantle dentin of the root
R: dentin, tubules organized at right angles to CEJ
Identify tissues.
L: Cellular cementum, dark areas are trapped cells called cementocytes, much thicker than previous acellular cementum
R: dentin
Identify.
Sharpey’s fibers.
Identify. Name an analogous structure in the dental pulp.
Cementicle. Pulp stones
Identify.
Alveolar crest.
Identify.
Red: horizontal
Blue: alveolar crest
Identify.
Both are oblique.
Identify.
Interradicular
Which represents cancellous/trabecular bone and which represents the cortical plate?
Orange: cancellous/trabecular
Blue: cortical platecomprised of lamellar and compact haversion system bone
Identify alveolar crest bundles.
Top: alveolar crest fiber bundles
Bottom: oblique fiber bundle
Identify.
- gingiva 2. PDL 3. alveolar bone 4. cementum
Identify
Both are periodontal ligament.
Identify.
- Periodontal ligament 2. Lamina dura 3. Cementum
Identify.
- Periodontal ligament (radiolucent)
- Lamina dura (opaque)
Identify.
- cementum
- periodtondal ligament
- alveolar bone
Identify.
- cementum
- periodontal ligament
- lamina dura
- trabecular bone
- bone marrow
Identify.
- cementum
- principal fiber bundles of PDL
- interstial space (site of larger vessels and nerves)
- alveolar bone
Identify.
- alveolar crest
- horizontal
- oblque
- apical
- interradicular
Most numerous cell type of PDL.
Fibroblast.
Identify.
A: cementicle
B: epithelial rest of Malassez
Identify the most numerous cell type of the periodontal ligament.
fibroblast
Label.
- lamina propria
- acellular cementum
- alveolar bone proper
- interstitial space
Identify.
- Acellular cementum
- cementoblast
- epithelial rest of Malassez
- fibroblast
Identify PDL.
Left.
Which of the following peridontium sites are vascularized?
A. cementum
B. periodontal ligament
C. cribriform plate
D. lamina propria of gingiva
- *B.** It is highly vascular. Larger vessels are located within clear areas called “interstitial spaces.”
- *C.** Vascualr canals are scattered throguhout the cribriform plate (socket wall). The main blood supply to the PDL come by way of these canals.
- *D.** This area is highly vascular.
The osteoclasts found in the PDL, like elsewhere in the body, arise from which of the following sites?
A. Haversian canal
B. periosteum
C. endosteum
D. bone marrow
D. This is where stem cells become osteoclasts and from where they are distributed throughout the body.
Label.
- acellular cementum
- PDL
- alveolar bone
- bone marrow
Which of the following rangse of numbers is the width of the PDL?
A .50 - 1.00 mm
B .20 - .30 mm
C .12 - .33 mm
C
Which of the following terms is used for the ends of the principal fiber bundles embedded in cementum and alveolar bone?
A. Tomes’ fiber
B. Hertwig’s fiber
C. Sharpey’s fiber
D. Korff’s fiber
C; he described them as “fibers that join together the lamellae of bone.” The fibers are not confined to the alveolar process. They exist where ends of tendons or ligaments are embedded in bone.
T/F: Sharpey’s fibers are located in cellular or secondary cementum, but do not exist in aceullar or primary cementum.
False, they are found in both types of cementum.
Which collagen types comprise the principal bundles of the periodontal ligament?
Type I: it’s the most abundant type of collagen; also found in bone, cementum, dentin, and bundle groups of the free ginigiva; provides tensile strength to tissues.
The PDL and pulp tissues have which of the following similar structures?
A. collagen fibrils
B. tissue fluid
C. abundant nerve and blood vessel networks
D. proprioceptive sense
A, B, C in both.
D Proprioceptive sense is found only in PDL’s nerve supply (not pulp).
Which of the following are function sof the PDL?
A. supportive
B. sensory
C. nutritive
D. formative E. resorptive
ALL!
A. Suspenses and supports the tooth by way of its collagen fiber bundles.
B. Abundant nerve supply.
C. Served by vast blood supply.
D. 3 blast cells (fibroblast, cementoblast, and osteoblast)
E. Carried out by osteoclast and odontoclast.
Identify cementicle.
Top: epithelial rest of Malassez (remnants of epithelial cells involved in tooth development). Bottom: Yes, ectopic mineralization in PDL.
Identify osteoclast.
Top: osteoclast
Bottom: epithelial rest of Malassez
Label.
- Fibroblast
- Sharpey’s fibers
- Cementoblast
D. Cementocyte
Label.
- Cementoblast
- Osteoblast
- Cementocyte
The formative function of the PDL is carried-out by which of the following cells?
A. Cemtoblast
B. Macrophage
C. Fibroblast
D. Osteoblast
A. Yes, formed cementum.
B. No, defense cell.
C. Yes, forms ligament’s extracellular substance.
D. Forms alveolar bone.
Which of the following cells are found in the PDL, but not in the pulp tissue?
A. osteoclast
B. fibroblast
C. osteoblast
D. macrophage
A, C PDL only.
B, D both tissues.
Which of the following are sometimes found in the PDL?
A. epithelial cells
B. osteoclast
C. cementicles
D. elastic fiber bundles
A. Yes, epithelial rest of Malassez, remnants of epithlium invlved in tooth development.
B. Yes, present int he ligament during normal alveolar bone remodeling and may appear in repsonse to local trauma.
C. Yes, ectopic mineralizations in the ligament, common in older ligaments.
D. No, elastic fibers of the ligament are associated with blood vessels and are not arrnaged in bundles.
Which of the following are found in the PDL?
A. denticles
B. lymphatic vessels
C. blood vessels
D. nerves
B, C, D Yes
A. No, pulp stones are ectopic mineralization in pulp tissue.
Which of the following cells are in the PDL?
A. odontoblast
B. cementoblast
C. fibroblast
D. osteoblast
A. Found in pulp and dentin, not ligament. B. Yes, in PDL next to cementoid layer. C. Yes, most numerous. D. Yes, next to lamina dura of alveolar process.
T/F: Cementoblasts lie within th eperiodontal ligament along the cementoid layer.
True, located in PDL adjacent to cementoid layer.
When collagen fiber bundles of the PDL extend from the interradicular septum or bone to the cementum in the furcation of multirooted teeth?
Interradicular
Which collagen fiber bundles of the PDL are attached to the cementum somwhat apically from their attachment to the bone?
Oblique, they are the most numerous and constitute the main attachment of the tooth.
Label.
Acellular cementum.
Periodontal ligament.
Alveolar bone.
What specific name is given to strands of epithelial cells located in the PDL?
Rest of Malassez, remnants of epithelium of Hertwig’s epithelial root sheath.
The majority of the fibers of the PDL is which of the following types?
A. reticular
B. elastic
C. collagen
D. oxytalan
C, the prinipal fiber bundle groups of the PDL are comprised of collagen fibers.
Most numerous type of the periodontal ligament?
A. cementoblast
B. fibroblast
C. undifferentiated or stem cell
D. macrophage
B
What cell has the capacity to resorb and synthesize the extracellular or intercellular substance of the PDL?
A. cementoblast
B. odontoclast
C. osteoblast
D. fibroblast
A. No, synthesizes cementum and has not resorption capacity.
B. No, it resorbs the mineralized tissue of a tooth, but does not resorb the substance of the PDL and does not have the capacity to synthesize.
C. No, forms bone, no resorptive capacity.
D. Yes, has capacity to both syntehsize and resorb the intercellular stubstance of the PDL.
Identify cementum.
Top: No, lamina dura or socket wall.
Bottom: Yes (apical cellular cementum).
Identify aceullar cementum.
Left: yes, primary or acellular cementum
Right: acellular cementum.
identify marked cells.
- Cementocyte (within cementum)
- Cementoblast (positioned in PDL).
Identify A.
cementum
Identify.
- cellular (secondary) cementum
- acellular (primary) cementum 3. dentin.
Identify.
- PDL
- Cementum
- Lamina dura
Identify.
- Cementum
- PDL
- Alveolar bone
Identify.
- Junctional epithelium
- Acellular cementum
Identify.
A. Acellular cementum
B. PDL
C. Alveolar bone
Identify.
- Alveolar bone
- PDL
- Acellular cementum
Identify.
A. Cementoid layer (unmineralized)
- Cementoblast
- Cementocyte
Identify.
A. PDL
B. alveolar bone
C. acellular (primary) cementum Tomes’ granular layer in outer surface of root dentin (dark area net to cementum)
Identify.
A. acellular cementum
B. cellular cementum
1. cementocyte.
Identify.
- Secondary/cellular cementum
- Primary/acellular cementum
- pulp cavity
- dentin
- enamel
Identify most common CEJ.
Most common: cementum overlaps enamel.
Next common: cementum meets enamel
Least common: cementum does not meet enamel
Identify.
- enamel
- dentin
- acellular (primary) cementum
Identify.
Left: PDL
Right: Cementum
Note tissue damage caused by calculus.
Identify.
Primary cementum.
Note: Junctional epithelium has moved onto and is attached to cementum surface by basal lamina.
Identify.
- Acellular primary cementum.
- PDL
Identify.
- Acellular cementum
- PDL
Identify.
- cementoblast
- osteocyte
- osteoblast
- cementocyte
Identify.
- cementoid (unmineralized)
- cementoblast
- acellular cementum (mineralized)
identify.
Left: cementoid (unmineralized)
Right: cementoblast
Identify.
Right/1. Acellular cementum (next to dark Tomes’ granular layer).
Left/2. PDL
Note: When tooth was removed a piece of alveolar bone remained attached to cementum by periodontal ligament fibers.
Identify.
- Acellular (primary) cementum
- Cellular (secondary) cementum, note presence of cementocytes.
Identify.
- Lacuna (site of cementocyte cell body)
- Canaliculi (site of cementocyte process)
Identify.
Top: Cementoblast
Bottom left: cementocyte
Bottom right: Sharpey’s fiber
Identify.
Sharpey’s fiber, collagen fiber bundle of PDL passes into cementum.
Identify.
Sharpey’s fiber.
Identify.
Sharpey’s fiber.
Identify.
Acellular cementum.
Note: the main route of blood supply to the PDL is from the surrounding alveolar bone (as depicted).
Identify marked line.
Appositional growth lines.
Identify the depicted condition.
Excessive cementum is called hypercementosis.
T/F: The percent of organic substance in cementum is higher than the percent in both enamel and dentin.
True. Cementum has a higher percent organic substance than enamel and dentin. Cementum-35%, enamel-1%, dentin-20%.
Which of the following is true for the cementoid layer of the cementum?
A. hypermineralized.
B. hypomineralized
C. unmineralized
D. mineralized.
C. Also true for the predentin and osteoid layers.
T/F: Sharpey’s fibers are found within cementum, but do not exist within any of the other mineralized tissues.
False. Sharpey’s fibers also exist within compact bone tissues, such as the lamina dura of the alveolar process.
What percentage of cementum is composed of inorganic substance?
50%. Less than enamel-50%, and dentin-70%
Label.
Alveolar bone.
PDL
Acellular cementum.
Dentin
What percentage of cementum is composed of organic substance?
35% organic (higher than enamel-1% and dentin-20%).
The cementoid layer of cementum contacts or abuts which of the following?
A. dentin
B. enamel
C. PDL
D. pulp
C. The cementoid or newly formed layer of cementum abuts the PDL. It’s connected to the PDL by Sharpey’s fibers.
Label.
Alveolar bone.
Periodontal ligament
Acellular cementum.
The cell processes of a cementocyte are located in which of the following sites?
A. lacuna
B. PDL
C. tubule
D. canaliculi
D. Cell process in canaliculi. Cell body in lacuna.
Label.
Acellular cementum.
Periodontal ligament.
Alveolar bone.
T/F: Sharpey’s fibers are found in cellular cementum but not acellular cementum.
False, Sharpey’s fibers are found in both cellular and acellular types of cementum.
The cell body of cementocytes is located in which of the following sites?
A. PDL
B. lacuna
C. Tomes’ granular layer
D. cancliculus
B, Lacuna is also the site of the cementoblast’s cell body. Its processes are in canaliculi. Lacunae and canaliculi are also found in bone tissues, sites of an osteocyte.
T/F: Sharpey’s fibers connect cementum to dentin.
False, Sharpey’s fibers connect cementum to PDL.
What percentage of cementum is water?
15%, (higher than enamel-3% and dentin-10%).
Identify acellular cementum.
Note Tomes’ granular layer (between dentin and cementum)
L: acellular cementum
R: cellular cementum.
What specific cell is located in secondary or cellular cementum?
cementocyte
Identify cementoblast.
- Cementoblast, secretes cementum from its location within the PDL.
- Cementocyte, a cementoblast that encloses itself within its own secretion. The cementocyte or cell of cementum serves a metabolism function rather than continuing its previous formative function.
T/F: Unlike enamel and dentin, cementum has blood vessels within its volume.
False. Cementum (like enamel and dentin) is avascular. Pulp is the only vascularized part of a tooth.
The highest percentage of the organic substance of cementum is composed of which of the following?
A. Hydroxyapatite
B. Glycosaminoglycans
C. Collagen
D. Amelogenin
C. Highest percentage of organic substance of cementum is collagen. Also true for dentin and bone, but not enamel. Enamel is the only mineralized tissue that does not contain collagen.
T/F: The inorgnaic substance of cementum is composed of hydroxyapatite crystals.
True. HA crystals in all mineralized tissues. The percentage, size, and density of crystals differs.
