Eruption and Shedding Flashcards
The movements a tooth makes to attain and maintain its position in the jaw is known as ___.
eruption
What direction does a tooth not move during eruption?
apically
T/F. Tooth movement occurs throughout life.
True.
The movements of eruption are a ___ activity involving different cell types of the ___ ___.
cellular; periodontal ligament
What cells are involved in movements of eruption?
cementoblast
osteoblast
osteoclast
fibroblast
What is the most numerous cell type of the periodontal ligament?
fibroblast
What are the 3 functions of fibroblasts?
- secretes extracellular substance (fibroblast)
- lysis extracellular substance (fibroclast)
- may become a contracting cell (fibromyocyte)
What is a contracting cell called?
a ‘fibromyocyte’ myofibroblast
A fibromyocyte or myofibroblast is a cell that is connected to principal ___ fiber bundles that connect the tooth to ___ bone, when it contracts the collagen fibers ___ moving the tooth.
collagen; alveolar; contract
What are the 3 stages of eruption?
- preemergence
- prefunctional
- functional
What is the main direction of movement during the preemergence stage?
facially
What is the main direction of movement during the prefunctional stage?
occlusially
What is the main direction of movement during the functional stage?
mesially
The preemergence stage starts with the appearance of the ___ ___ and continue to the appearance of the ___ ___ ___ and ___ root sheath, just prior to the start of root ___ formation.
dental lamina; reduced enamel epithelium; Hertwig’s; dentin
After enamel formation is complete, what do the four cell layers of the enamel organ form?
the reduced enamel epithelium
The cervical loop is where the ___ and ___ layers of the enamel organ come together to form ___ ___ ___ ___.
outer; inner; Hertwig’s epithelial root sheath
How is the reduced enamel epithelium attached to the completed enamel surface?
by a basal lamina
During demineralization of a forming crown of an extracted tooth, the reduced enamel epithelium is attached to ___ enamel.
immature
What are the two main functions of Hertwig’s epithelial root sheath?
- determines the number of root canals of tooth
2. determines the root dentin outline
T/F. The preemergence stage starts after root formation.
False, it starts BEFORE root formation
In what stage are the number of root canals determined?
Preemergence
The openings in the Hertwig’s ___ indicate the number of root ___ before the start of root formation.
diaphragm; canals
The ___ stage starts with root dentin formation and ends when the tooth reaches occlusial plane.
prefunctional
The apical end of Hertwig’s epithelial root sheath continues as the ___ and determines the number of root ___.
diaphragm; canals
When the HERS breaks up, what process occurs cervically?
cemetogenesis
The first step in the fate of HERS is the ___/___ stage. Here the number of root ___ is determined and the tooth erupts ___ from this level.
sheath/diaphragm; canals; occlusially
During the second step of the fate of HERS, the ___ elongates to determine the root ___ outline. The ___ remains at relatively the same level.
sheath; dentin; diaphragm
Finally, the root ___ forms when the sheath breaks-up in the last step of the fate of HERS. ___ forms on exposed dentin. This sequence continues ___ until root dentin is completed.
dentin; Cementum; apically
T/F. Remnants of epithelial cells from HERS in the periodontal ligament appear during the functional stage of eruption. This is known as the epithelial rest of Malassez.
False. Remnants of epithelial cells from HERS in the periodontal ligament appear during the PREFUNCTIONAL stage of eruption. This is known as the epithelial rest of Malassez.
During the prefunctional stage of eruption, what merges with the reduced enamel epithelium and undergoes cell death?
oral epithelium. The allows the coronal most part of the tooth to emerge into the oral cavity
Once the tooth emerges into the oral cavity, what does the reduced enamel epithelium become?
the junctional epithelium
What attaches the junctional epithelium to the tooth surface?
basal lamina
The basal lamina can be found along the surfaces of the ___ and ___ and it continues to the ___ tissue (lamina propria) side of the free gingival junctional epithelium.
enamel; cementum; connective
T/F. There are two basal lamina associated with the junctional epithelium.
True.
Which eruption stage begins with the occlusal plane and physiologically continues throughout life?
functional stage
What positions can you find junctional epithelium as it changes throughout life?
A. Attached to enamel
B. Attached to enamel and cementum
C. Attached to cementum
What stage of eruption does the functional arrangement of principal fibers of PDL occur?
functional stage
T/F. Attrition, dead tracts, and reparative (teritary) dentin can lead to changes during functional eruption.
True.
Continued ___ formation, reduced ___ tissue volume and ___ mineralization are all examples of changes that can occur during the functional stage of eruption.
dentin; pulp; ectopic
A bone ___ can be seen on radiograph surrounding the ___ molar during the preemergence stage.
crypt; third
___ is defines as the physiologic elimination of ___ teeth by the resorptive action of ___.
Shedding; primary; odontoclasts
Where do odontoclast originate from? How does it get to its target site?
bone marrow; via lood vessels
T/F. Odontoclast resorb the 4 mineralized tissues of teeth.
three
What must remain intact on the enamel of permanent premolars if they wish to avoid damage during shedding?
reduced enamel epithelium
