Eruption and Shedding Flashcards
what is eruption
The movements of a tooth from its formative stages within the jaws to its functional stage in the oral cavity
why does a tooth move physiologically
moves in all directions except apically and continues to move throughout its existence in the oral cavity
Stages of Eruption
Preemergences
Prefunctional
Functional
Main direction of movement in the Preemergence phase
Facially
Main direction of movement in the prefunctional stage
Occlusially
Main direction of movement during the functional stage
Mesially
when does the tooth move into the functional stage
Once it reaches the occlusal plane
what is the early bone that surrounds the tooth
Boney Crypt
what occures priot to root dentin formation
Appearance of dental lamina and continues to the appearances of reduced enamel epitheliuma nd Hertwig’s root sheath
what is the main movement in the Preemergeces stages
Facially
what does the 4 layesr of the enamel organ become after enamel formation is complete
Reduced enamel epithelium
where is the cervical loop
Outer and inner layers of enamel organ come together
where the outer and inner layers of the enamel organ come together
Hertwig’s epithelial root sheath
what does the reduced enamel epithelium attach to
Attached to completed enamel surface via a basal lamina
what is the last secretion of the ameloblasts
Basal lamina
what is enamel made out of if it stains well
out of mostly organic matterial
what are the functions of Hertwig’s epithelial root sheath
Determines root detnin outline
Determines number of root canals of the tooth
does the roots form during the preemergences stages
Preemergences is before the start of root formation
when does Hertwig’s root sheath determines number of root canals
Before the start of root dentin formation
when does Hertwig’s root sheath determine root dentin outline
At the start of root dentin formation
during what stage does Odonotogenesis begin
During the preemergences stage
what cells differenciate during preemergence stage
Ameloblasts, odontoblasts, and fibroblasts
what parts of the tooth form during preemergence
Apearance of crown dentin Enamel formation begins Appearances of pulp change DEJ forms Reduced enamel epithelium forms Formation of HErtwigs epithelial root sheath Root canal number forms Bone crypt remodelled
what parts of tooth formation occure in the preemergence stage
Epithelial stages and tooth germ apearances
How does the Prefunction stages begin
with root dentin formation
when does the prefunctional stage end
when the tooth reaches the occlusial plane
Parts of the prefunctional stages
Root formation
Merger
Emergence
how is Reduced enamel epithelium attached to the enamel surface
Via a basal lamina
How does Cementum begin to form around the tooth
The Hertwig’s epithelial root sheath begins to break up below the enamel to form the cementum
what are the apical ends of HERS
area of diaphragm part during prefunctional stage of reuption
what covers the Root dentin along the prefunctional stage
Hertwig’s sheath over the root dentin surface
what happens to the root sheath during the diafragm stage
number of root canal determines and the tooth erupts occlusially from this level
what happens as the Root sheath elongates
Determines the root dentin outline
diaphragm remains at relatively the same level
what happens to the root sheath as root dentin forms
Sheath breaks up
Cementum forms on exposed dentin
how long does the process of Root dentin forming, sheath breaking up and cememntum forming occure for
Continues apically until root dentin outline is completed
what are epthelial rest of Malassez
Remanents of epithelial cells from Hertwigs root sheath in the periodontal ligament
when does Epithelial rest of Malassez
During prefunctional stage of eruption
what happens to the tooth right before eruption
The merged oral epithelium and reduced enamel epithelium undergo cell death (then the most coronal part emerges into the oral cavity)
why does a baby cry during teething
Not cut the tooth is moving through the oral epithelium, but because food can get caught and infect ( cells die on their own)
What does the Reduced enamel epithelium become
The junctional epithelium
where does the junctional epithelium exist
Between the enamel and the gingiva
how does the Junctional epithelium attach to the enamel and the lamina propria of the free gingiva
the basal lamina
what begins being formed in the prefunctional stage
Root dentin
Epithelial rest of Malassex
Cementoblasts and cementum
Periodontal ligament site (collagen fibers bunfle)
changing of reudced enamel epithelium to junction epithelium of free jingiva
what breaks up during the prefuctional stage
Hertwig’s epithelial root sheath
How are collagen fiber bundles of the PDL arranged in the prefunctional stage
Not functionall (arranged obliquely
How is the junctional epithelium attached to the tooth during the prefunctional stage
Via the basal lamina
why does the tooth move mesially during the functional stage of eruption
Physiologic mesial drift
when does the functional stage of eruption end
continues throughout life
how does the junctional epithelium change during functional eruption
attached to enamel
attached to enamel and cementum
attached to cementum
what happens to the principle fibers bundles of the PDL during the functional stage of eruptions
Functional arrangement of principle fibers
what changes occur during funcation eruption
attrition Dead tracts reparative (teritary) dentin continued dentin formation reduced pulp tissue volume ectopic mineralizion
what happens to the alveolar process during the functional stage
Maintenance (preservation) of alveolar process (remodeled bone crypt
where does reciprocal induction occur during the functional stage
between the junctional epithelium and adjacent connective tissue (lamina propria
what is shedding
The phsiologic elimination of primary teeth caused by the resorptive action of odontoblasts
what causes shedding
physiologic odontoblastic activity
where does the odonotoclast originate
in the bone marrow
how does the odontoclast get to the site of activty
by blood vessels
What do Odontoclasts do
Resorb the 3 mineralized tissues of the tooth
what do odontoclasts look like
like osteoclasts (multinucleated giant cell made in the bone marrow)
what side does the permanat dentition come from under the tooth
Via the lingual side
what happens if the reduced enamel epithelium breaks down
the enamel is subject to damage
the openings in the bone located lingual to the primary anterior teeth
Gubernaculum canals
what passes through the gubernaculum canal
A gubernaculum ligament
what is the roll of the gubernaculum ligmanet
passes through the canal to the dental follicle of a succeedaneous tooth and guide it to the oral cavity
