Flashcards in Eruption and Shedding Deck (52):
1
Eruption definition
The movement a tooth makes to attain and maintain its position in the jaw
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T/F - Tooth movement only occurs as it is erupting
False - Tooth movement occurs throughout life
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What direction(s) does a tooth move to attain and maintain its position in the jaw?
All directions, except apically
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Why type of activity is involved in movements of eruption?
Cellular activity involving different cell types of the periodontal ligament (PDL)
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What is the most numerous cell type of the PDL contributing to tooth movements?
Fibroblast
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What are the functions of a fibroblast within the PDL?
Secrete extracellular substance (fibroblast)
Lysis extracellular substance (fibroclast)
Contracting cell (fibromyocyte)
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What is a fibromyocyte myofibroblast?
A cell connected o collagen fiber bundles that connect the tooth to the alveolar bone
When it contracts, the collagen fibers contract, moving the tooth
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What are the stages of eruption?
Preemergence
Prefunctional
Functional
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When does the Preemergence occur?
Before the start of root formation
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What is the main tooth movement direction during the Preemergence stage?
Facially (however, they move in all different directions, but the net movement is facial)
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What appears during the preemergence stage?
Reduced enamel epithelium
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What attaches the reduced enamel epithelium to the enamel?
Basal lamina
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Cervical loop
Outer and inner epithelial layers coming together to form Hertwig's epithelial root sheath
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Functions of Hertwig's epithelial root sheath
Determines how many root canals
Determines the root-dentin outline
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What about Herwig's epithelial root sheath determines root canals?
The number of openings in Hertwig's diaphragm
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When does the prefunctional stage occur?
Begins with root dentin formation and ends when the tooth reaches the occlusal plane
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What is the main tooth movement direction of the Prefunctional stage?
Occlusally
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What happens to Hertwig's epithelial root sheath during the Prefunctional stage
The sheath covers the root dentin, the apical end continues as the diaphragm, and the sheath breaks up
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Epithelial rest of Malassez
Remnants of epithelial cells from Hertwig's epithelial root sheath in the PDL
Appear during prefunctional stage of eruption
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What happens to reduced enamel epithelium during the prefunctional stage?
The merged oral epithelium and reduced enamel epithelium undergo cell death
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When does functional stage of eruption occur?
When the tooth reaches the occlusal plane and continues throughout life
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What is the main tooth movement direction during the Functional stage?
Mesially
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What happens to the PDL during the funcitonal stage?
Functional arrangement of principal fiber bundles occurs
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What happens to junctional epithelium during the functional stage?
It changes position
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Shedding
The physiologic elimination of primary teeth caused by the resorptive action of odontoclasts
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What causes shedding
Odontoclastic activity
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Odontoclasts origin
Bone marrow and goes to the site of activity via blood vessels
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Odontoclasts
Resorb the 3 mineralized tissues of teeth
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What stage does odontogenesis begin?
Preemergence
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What stage do Ameloblasts, odontobalsts, and fibroblasts differentiate?
Preemergence
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What stage does the crown dentin appear?
Preemergence
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What stage does enamel formation and maturation begin?
Preemergence
33
What stage is the DEJ established?
Preemergence
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What stage does the reduced enamel epithelium appear?
Preemergence
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What stage does the pulp chamber appear?
Preemergence
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What stage is Hertwig's epithelial root sheath form?
Preemergence
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What stage is the number of root canals determined?
Preemergence
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What stage does the bone crypt form?
Preemergence
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Bone crypt
Undergoes remodeling and becomes the alveolar process
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What stage does the root dentin form?
Prefuncitonal
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What stage does Hertwig's epithelial root sheath break up?
Prefunctional
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What stage does the Epithelial rest of Malassez form?
Prefunctional
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What stage do cementoblasts differentiate and cementogenesis occur?
Prefunctional
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What stage does the PDL and alveolar process form?
Prefuncitonal
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What stage are the collagen fiber bundles of the PDL arranged obliquely?
Prefunctional
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What stage does the reduced enamel epithelium merge with the oral epithelium?
Prefuncitonal
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What stage does the tooth emerge into the oral cavity?
Prefunctional
48
What stage does the reduced enamel epithelium become the junctional epithelium of the free gingiva?
Prefunctional
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What stage are the principal fiber bundles of the PDL functionally arranged?
Functional stage
50
What stage is the alveolar process preserved?
Functional stage
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What stage is secondary and tertiary dentin formed?
Functional stage
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