This document discusses tooth shedding, or the process by which primary teeth are replaced by permanent teeth. It defines shedding as the physiological process by which deciduous teeth are resorbed and lost to make way for successor teeth. Key points covered include the factors affecting shedding like pressure from erupting permanent teeth and genetic factors; the histology of shedding involving resorption of dental hard and soft tissues; the typical pattern of shedding from anterior to posterior teeth; and potential abnormalities in shedding like retained, submerged, or residual primary teeth.
3. Definition
ď To give off, discharge, or expel from the body of a plant or
animal, slough off, or lose as part of the normal processes of
life.
ďIt is a physiological process
for elimination of deciduous
teeth by resorption of their
roots prior to eruption of their
permanent successors.
4. Factor affecting shedding
1. Local factors
ďPressure from the erupting successional tooth plays
an important role in shedding.
ďGrowth of the face and jaws and Enlargement of
the masticatory muscles probably increase the forces
applied over the deciduous teeth.
ďPressure + Enlargement = Loss of
Supporting Tissue Tooth Exfoliation
Accelerated.
5. Factor affecting shedding
2. Genetic factors
ďApoptosis in the periodontal ligament fibers.
ďThe initiation of root resorption may be inherent
developmental process.
8. Histology of shedding
ODONTOCLASTS
ďDerived from blood
monocytes, migrate to the
resorption site and fuse to form
multinucleated cells.
ďAre cells with same histological
nature of osteocalsts.
ďThey have ruffled border and
sealing zone.
ďThey have the ability to resorb
the pre-dentine.
10. Histology of shedding
PULP response.
ďWhile the root is being resorped; coronal
pulp appears normal with odontoblasts line
the pre-dentine.
ďOnce the root resorption is almost
completed the odontoblasts degenerate,
mononuclear cells migrate form pulpal bl. v.
and fuse forming odontoclasts.
11. Histology of shedding
PULP response.
ďJust before exfoliation, the odontocalsts
migrate away from the dentine surface and the
remaining pulp tissue secreats cement like
tissue.
ďThe tooth is shed with some pulpal tissue
intact.
12. Histology of shedding
PERIODONTAL LIGAMENT response.
ďFibroblasts of the P L exhibit sings of interface
with cytotoxic alteration as well as apoptosis.
ďThese changes leads to abrupt loss of the P L.
14. Pattern of shedding
ďźThe pattern of shedding is
symmetric in both Rt and Lt sides.
ďźThe lower E shed before the
upper E.
ďźGirls teeth shed before that of
boys.
ďźSequence of shedding in the
mandible follows anterior to
posterior order; while in the
maxilla the 1st molar shed before
the canine.
16. Pattern of shedding
Anterior teeth
ďFor all deciduous anterior teeth
resorption initiated at the
lingual side of the root.
ďWith subsequent movement
and relocation of the teeth in
the growing jaws, the growing
permanent tooth becomes
directly below the deciduous
one.
ďThe resorption become
apically.
18. Pattern of shedding
Posterior teeth
ď For deciduous molars, root
resorption initiated on the inner
surface where the permanent
premolars initially developed.
ď Later the premolars come to lie
beneath the deciduous molars.
ď Farther resorption at the apices
then occur.
ďThe shift in position may account
for the intermittent nature of the
resorption.
22. Abnormalities of shedding
1. Retained deciduous teeth.
ďDeciduous teeth that persist beyond
their shedding time is known as
retained deciduous teeth.
ďMost common in upper B and lower
E.
ďUsually due to congenital missing or
impaction of permanent ones
ankylosis due to trauma.
ďAppears normal and persist for a
while till resorption occurs due to
heavy masticatory forces.
24. Abnormalities of shedding
2. Submerged deciduous teeth.
ďAnkylosed deciduous teeth
mostly due to trauma.
ďNo active eruption and become
at a lower level than the other
teeth âSUBMERGEDâ.
ďMostly in lower E.
ďThe permanent become either
impacted or out of alignment.
ďSubmerged tooth should be
removed allowing the
permanent one to erupt
27. Abnormalities of shedding
3. Remnants of deciduous teeth.
ďRoots of the deciduous
teeth specially molars which
interfere with the eruption
path .
ďUsually due to more
diverged roots of the
deciduous teeth and the
smaller the premolar size .
28. Abnormalities of shedding
4. Pre-deciduous teeth.
ďKnown as rootless or natal
teeth.
ďRare condition in the newborn
infants.
ďIt is dangerous cause it may be
inhaled as it is rootless so not
fixed to the body.
ďMay cause eruption cyst.
ďCause discomfort to the
mother during lactation.