eruption & shedding Flashcards
the movements a tooth makes to attain and maintain its position in the jaw
eruption
the movements of eruption are a cellular activity involving different cell types of the _____
periodontal ligament (PDL)
different cell types of the PDL
cementoblasts, osteoblasts, osteoclasts, and fibroblasts
most numerous cell type of the PDL that is thought to play a key role in tooth movement
fibroblast
functions of the fibroblast within the PDL:
- secretes extracellular substance
- lysis the extracellular substance
- may become a contracting cell called a fibromyocyte myofibroblast
a glycoprotein that exhibits elastic properties and serves as an integrin (similar to cell integrins) that binds to extracellular components such as collagen
fibronectin
stages of eruption and main direction of movement
- preemergence stage (facially)
- prefunctional stage (occlusally)
- functional (mesially)
the preemergence stage starts with the appearance of the _____ and continues to the appearance of ____ and ____, just prior to the start of root dentin formation
dental lamina; reduced enamel epithelium; Hertwig’s root sheath diaphragm
the number of ____ a tooth will have is determined during the preemergence stage
root canals
the cervical loop is where outer and inner layers of enamel organ come together to form ____ during the preemergence stage
Hertwig’s epithelial root sheath
the reduced enamel epithelium is attached to the completed enamel surface by a ____, the last secretion of ameloblasts
basal lamina
2 main functions of Hertwig’s epithelial root sheath
- determines the number of root canals of the tooth
2. determines the root dentin outline
Hertwig’s root sheath determines ____ before the start of root dentin formation and _____ at the start of root dentin formation
number of root canals; root dentin outline
the prefunctional stage of eruption starts with _____ and ends when tooth reaches _____
root dentin formation; occlusal plane
Hertwig’s epithelial root sheath breaks up and _____ begins at cervical most part of root dentin
cementogenesis
remnants of epithelial cells from Hertwig’s root sheath in the periodontal ligament; appear during prefunctional stage of eruption
epithelial rest of Malassez
during the prefunctional stage of eruption, the merged _____ and _____ undergo cell death
oral epithelium; reduced enamel epithelium
upon emergence into the oral cavity, the reduced enamel epithelium becomes the _____
junctional epithelium
the functional stage of eruption starts at the ____ and physiologically continues _____; main movement is mesially, called _____
occlusal plane; throughout life; physiologic mesial drift
____ attachment position changes during functional eruption
junctional epithelium
functional arrangement of the _____ of the PDL occurs during the functional stage of eruption
principal fiber bundles
changes during functional eruption:
attrition dead tracts reparative (tertiary dentin) continued dentin formation reduced pulp tissue volume ectopic mineralization
during the functional stage of eruption, ____ occurs between the junctional epithelium and adjacent connective tissue (lamina propria)
reciprocal induction
shedding is caused by physiologic _____ activity
odontoclastic
the odontoclast, like the osteoclast, originates in the ____ and is conveyed to the site of activity by ____ (odontoclasts resorb the 3 mineralized tissues of teeth)
bone marrow; blood vessels
openings in the bone located lingual to the primary anterior teeth are called _____
gubernaculum canals
