The document discusses tooth eruption and shedding. It defines tooth eruption and describes the various stages of eruption including pre-eruptive, eruptive, and posteruptive movements. It discusses the patterns, histology, and theories of tooth eruption. Key stages include pre-eruptive tooth movements within the jaw, eruption through the bone and oral mucosa, and posteruptive movements to maintain position. Theories discussed include bone remodeling, root growth, hydrostatic pressure, and periodontal ligament traction.

1. DEPARTMENT OF
CONSERVATIVE
DENTIST
AND
ENDODONTICS
PRESENTED BY:-
DR. ADITYA SHINDE
GUIDED BY:-
DR.LALITAGUARI MANDKE
TOOTH
ERUPTION
&
SHEDDING

2. CONTENTS
 DEFINITION
 PHYSIOLOGIC
TOOTH MOVEMENTS
 STAGES OF
ERUPTION
 PATTERN AND
HISTOLOGY
 THEORIES OF
ERUPTION
 CHRONOLOGY OF
ERUPTION
 CONTINUOUS TOOTH
ERUPTION
 CLINICAL
CONSIDERATIONS
 SHEDDING OF
PRIMARY TEETH

3. TTOOOOTTHH EERRUUPPTTIIOONN
DEFINITION:-
It is the axial or occlusal movement of
the tooth from its developmental position
within the jaws to functional position in
the occlusal plane.- (orban’s)
Eruption is the movement of the
developing teeth within and through the
bone and the overlying mucosa of the jaws
to appear in the oral cavity and reach the
occlusal plane.-(james k. avery)

4. PPHHYYSSIIOOLLOOGGIICC TTOOOOTTHH
MMOOVVEEMMEENNTTSS
These are of various types :-
1) Axial or vertical
2) Drifting
3) Torsion
4) Tipping

5. SSTTAAGGEESS OOFF TTOOOOTTHH
EERRUUPPTTIIOONN
1) Pre – eruptive tooth
movements.
1) Eruptive / Prefunctional tooth
movements
2) Posteruptive tooth movements

6. PPAATTTTEERRNN AANNDD HHIISSTTOOLLOOGGYY OOFF
VVAARRIIOOUUSS SSTTAAGGEESS OOFF EERRUUPPTTIIOONN
PRE – ERUPTIVE
TOOTH MOVEMENT
These are the
movements made by
the deciduous and
permanent tooth
germs within the
tissues of jaws before
they begin to erupt.
AA –– eennaammeell oorrggaann
BB –– ddeennttaall llaammiinnaa
CC –– bbaassaall bboonnee

7. DDeecciidduuoouuss TTeeeetthh
WWhheenn ddeecciidduuoouuss ttooootthh ggeerrmmss ddiiffffeerreennttiiaattee ,, tthheerree iiss
ggoooodd ddeeaall ooff ssppaaccee bbeettwweeeenn tthheemm..
AAss TTooootthh ggeerrmmss ggrrooww mmoorree rraappiiddllyy tthhaann bboonnee –– tthhiiss
aavvaaiillaabbllee ssppaaccee iiss uuttiilliizzeedd aanndd ddeevveellooppiinngg tteeeetthh
bbeeccoommee ccrroowwddeedd ttooggeetthheerr eessppeecciiaallllyy iinn tthhee iinncciissoorr
aanndd ccaanniinnee rreeggiioonn..
TThhiiss ccrroowwddiinngg iiss rreelliieevveedd bbyy ::--
-- ggrroowwtthh iinn lleennggtthh ooff iinnffaanntt jjaaww
-- iinnccrreeaassee iinn wwiiddtthh
-- iinnccrreeaassee iinn hheeiigghhtt

8. PPeerrmmaanneenntt TTeeeetthh
 PPeerrmmaanneenntt tteeeetthh wwiitthh ddeecciidduuoouuss pprreeddeecceessssoorrss aallssoo
uunnddeerrggoo ccoommpplleexx mmoovveemmeennttss bbeeffoorree tthheeyy rreeaacchh tthhee
ffiinnaall ppoossiittiioonn ffrroomm wwhhiicchh tthheeyy wwiillll eerruupptt..
TThheessee cchhaannggeess iinn tthhee rreellaattiivvee ppoossiittiioonn aarree bbaassiiccaallllyy
bbeeccaauussee ooff ggrroowwtthh ooff tthhee ppeerrmmaanneenntt ttooootthh ggeerrmmss aanndd
eerruuppttiivvee mmoovveemmeenntt ooff tthhee ddeecciidduuoouuss ttooootthh..

9. Labio-lingual sections on mmaannddiibbllee tthhrroouugghh cceennttrraall iinncciissoorrss
AA –– aatt bbiirrtthh BB –– aatt 44tthh mmoonntthh CC –– aatt 1100tthh mmoonntthh DD –– aatt 2255tthh mmoonntthh

10. Unerupted ddeecciidduuoouuss ccaanniinnee aanndd iittss
ppeerrmmaanneenntt ssuucccceessssoorr llooccaatteedd lliinngguuaallllyy
aanndd aappiiccaallllyy ttoo iitt ,, iinn aa sseeccttiioonn ooff
mmaannddiibbllee aatt tthhee aaggee ooff 66 mmnntthhss..

11. Deciduous first molar showing germ of
permanent first premolar between its
roots at the age of about 6 yrs.

12.  Permanent maxillary molar
in tuberosity
 Dentition shows the erupted
deciduous teeth and partially
developed crown of permanent
teeth at the age of 2 years

13. HISTOLOGY OF TOOTH
MOVEMENT
Bone remodelling occurs within the crypt
wall during physiologic tooth
movement. At right , osteoblasts are
present for bone deposition and are
seen as a continuous row of minute
spots. At left , osteoclasts are
present for bone resorption and are
seen as dark spots.

14. Bone remodelling – selective deposition and removal
of bone by osteoblastic and osteoclastic activity.
These movements of both deciduous and permanent
tooth germs are a combination of 2 factors :-
1)Total bodily movement
2)Eccentric growth
Presence of dental follicle.

15.  Bodily movement of crown during
pre-eruptive phase

16. 2)ERUPTIVE / PREFUNCTIONAL
TOOTH MOVEMENT
PATTERN OF TOOTH MOVEMENT
The tooth moves from its position within the bone of the jaw
to its functional position in occlusion , and the principal
direction of movement is occlusal or axial.
However , it is important to recognize that jaw growth is
normally occurring while most teeth are erupting , so that
movements in planes other than axial are superimposed on
eruptive movement.

17. HISTOLOGY OF TOOTH
MOVEMENT
55 mmaajjoorr eevveennttss ttaakkeess ppllaaccee ::--
1) The secretory phase of amelogenesis is
completed just before the onset of root
formation and prefunctional eruption.
There is a relation between the cessation of
mineralisation and activation of the
epithelial cells beyond the enamel – forming
area.

18.  22))TThhee iinnttrraaoosssseeoouuss ssttaaggee ooccccuurrss
wwhheenn rroooott ffoorrmmaattiioonn bbeeggiinnss aass
aa rreessuulltt ooff tthhee pprroolliiffeerraattiioonn ooff
bbootthh tthhee eeppiitthheelliiaall rroooott sshheeaatthh
aanndd tthhee mmeesseenncchhyymmaall ttiissssuuee ooff
tthhee ddeennttaall ppaappiillllaa aanndd ddeennttaall
ffoolllliiccllee..
Prefunctional eruptive stage in formation of
root

19.  3)The supraosseous stage begins when the erupting tooth
moves occlusally through the bone of the crypt and the
connective tissue of the oral mucosa , so that the reduced
enamel epithelium covering the crown comes into contact
with the oral epithelium.
Crown tip aapppprrooaacchhiinngg oorraall eeppiitthheelliiuumm

20.  As this occurs , the reduced enamel epithelium of the crown
proliferates and forms a firm attachment with the oral
epithelium. A fused , double layer over the erupting crown is
then formed.
Contact and fusion of REE and oral mucosa

21. 4)The tip of the crown eenntteerrss tthhee oorraall ccaavviittyy bbyy
bbrreeaakkiinngg tthhrroouugghh tthhee cceenntteerr ooff tthhee ddoouubbllee –– llaayyeerreedd
eeppiitthheelliiaall cceellllss..
 tthhee ccuusspp ttiipp ccaauusseess ddeeggeenneerraattiioonn ooff tthhee mmeemmbbrraannee ––
bbeeggiinnnniinngg ssttaaggee ooff cclliinniiccaall eerruuppttiioonn..
 -- DDeennttooggiinnggiivvaall jjuunnccttiioonn –– llaatteerraall bboorrddeerrss ooff oorraall
mmuuccoossaa
 -- JJuunnccttiioonnaall oorr aattttaacchhmmeenntt eeppiitthheelliiuumm –– RREEEE--rreesstt ooff
eennaammeell eeppiitthheelliiuumm
 -- OOnnee -- hhaallff ttoo ttwwoo -- tthhiirrddss ooff tthhee rroooottss aarree ffoorrmmeedd..

22. Clinical appearance of crown

23. 5)The erupting
tooth continues to
move occlusally at
a maximum rate ,
and there is
gradual exposure
of more of the
clinical crown.
PPrriimmaarryy ttooootthh aatt tthhee eenndd ooff
eerruuppttiivvee pphhaassee ..PPeerrmmaanneenntt
ssuucccceessssoorr
iinn pprreeeerruuppttiivvee pphhaassee

24. Significant changes also occur in :-
- the tissues overlying the teeth
- the tissues around the teeth
- the tissues underlying the teeth
CHANGES IN TISSUES OVERLYING TEETH
Initial change – alteration of the connective tissue of
the dental follicle – forms pathway for eruption.

25.  Influx of monocytes and
osteoclasts.
 Future eruption pathway
appears as a zone in which :-
 connective tissue fibers have
disappeared
 Cells have degenerated and
in number
 decrease number of blood
vessels
 Terminal nerves have broken
up and degenerated.
 These changes are due to loss
of blood supply to that area
and release of enzymes.
DDeevveellooppmmeenntt ooff eerruuppttiivvee
ppaatthhwwaayy oovveerrllyyiinngg tthhee
ccrroowwnn..

26.  Resorption ooff tthhee oovveerrllyyiinngg bboonnyy ccrryypptt..
DDeevveellooppiinngg eerruuppttiioonn ppaatthhwwaayy aanndd gguubbeerrnnaaccuulluumm ddeennttiiss

27.  REE comes in contact with oral mucosa – they proliferate
and fuse into one membrane
Fusion and rupture of REE and oral epithelium

28. Gubernacular canals

29. CHANGES IN TTIISSSSUUEESS AARROOUUNNDD TTHHEE TTEEEETTHH
DDeevveellooppmmeenntt ooff PPDDLL ffiibbeerrss aanndd
mmooddiiffiiccaattiioonn ooff aallvveeoollaarr bboonnee
AA--eeaarrllyy ffiibbeerr ffoorrmmaattiioonn
BB--bboonnee cchhaannggeess
CC--ffuurrtthhuurr ffiibbeerr ddeevveellooppmmeenntt
nneeaarr oocccclluussiioonn ,, wwiitthh ffiibbeerrss
mmoorree ddeennssee..

30. CHANGES IN TISSUES UNDERLYING THE TEETH
CChhaannggeess iinn ffuunnddiicc bboonnee dduurriinngg
eerruuppttiivvee mmoovveemmeenntt..
FFoorrmmaattiioonn ooff bboonnee llaaddddeerr iinn tthhee
ffuunnddiicc rreeggiioonn..

31. 3)POST-ERUPTIVE /
PREFUNCTIONAL TOOTH
MOVEMENT
PATTERN OF TOOTH MOVEMENT
Are those that :-
1) Maintain the
position of erupted tooth while the
jaw continues to grow. 2)
compensates for occlusal and
proximal wear.

32. HISTOLOGY OF TOOTH
MOVEMENT
IInnccrreeaasseedd ddeennssiittyy ooff PPDDLL
ffiibbeerrss
VVaassccuullaarriissaattiioonn ooff ppuullpp aanndd
PPDDLL ffiibbeerrss

33. aabboovvee ddiiaaggrraamm sshhoowwss MMyyeelliinnaatteedd nneerrvveess aatt lleefftt aanndd bblloooodd
vveesssseellss aatt rriigghhtt ssiiddee
UUllttrraassttrruuccttuurree ooff
iinntteerrssttiittiiaall ssppaaccee iinn PPDDLL
aalloonngg wwiitthh nneerrvveess && bblloooodd
vveesssseellss
Posteruptive changes : attrition
and compensative formation of
cementum

34. FFoorrmmaattiioonn ooff jjuunnccttiioonnaall
eeppiitthheelliiuumm..
AA ,, BB –– pprreeeerruuppttiivvee
CC –– pprreeffuunnccttiioonnaall eerruuppttiivvee
DD--EE--FF--ffuunnccttiioonnaall oocccclluussiioonn

35. THEORIES OOFF TTOOOOTTHH MMOOVVEEMMEENNTT
THEORIES
BONE
REMODELLING`
ROOT GROWTH
HYDROSTATIC
PRESSURE
PERIODONTAL LIGAMENT
TRACTION

36. BBOONNEE RREEMMOODDEELLLLIINNGG
 Selective deposition and resorption of bone brings about
eruption.
 Bone remodelling of the crypt wall , clearly is important to
achieve tooth eruption.
 The intense metabolic activity in the alveolar bone taking
place around the moving tooth requires the presence of
dental follicle.
 Experiments have shown that when tooth germ is removed
but the follicle is left in position , the eruptive pathway still
forms in bone indicating dental follicle and not bone as the
major determinant in tooth eruption.

37. determines position of tooth
Thus , dental follicle plays important role in bone
remodelling by stimulating
osteoclasts & osteoblast
coordinates bony changes
This theory is still recognized , as the persons
genetically lacking in osteoclasts have retarded
tooth eruption.

38. RROOOOTT GGRROOWWTTHH
 Root growth theory considers growth in root
length to be responsible for tooth eruption , as
the growing root presses against the socket
base & opposite force pushes the tooth to erupt.
 Although at first glance this may seem an
obvious mechanism , root formation is
unlikely to be the cause of tooth eruption.

39. the basis of this theory is questionable due to
certain facts :-
Some teeth move a greater distance than the length
of their fully formed roots.
Some teeth still erupt after root formation has been
completed.
Rootless teeth also erupt.
If root formation is responsible for eruption , it
would be expected that the onset of root formation and
eruptive movement would coincide.

40. If root formation results in an eruptive force , there
is the requirement of a fixed base , but the bone at
the base of the root cannot act as a fixed base as
pressure on the bone results in its resorption.
Presence of CUSHION – HAMMOCK LIGAMENT.
Root growth theory is now considered to be
unimportant for tooth eruption , but it is true that
root growth is necessary for eruption as it gives
attachment to periodontal fibers.

41. HYDROSTATIC // VVAASSCCUULLAARR PPRREESSSSUURREE
This theory is based on the fact that dental papilla is highly
vascular.
It is known that teeth move in synchrony with the arterial pulse
, so local volume changes can produce limited tooth movement.
Ground substance can swell upto 50% with the addition of water
, and a differential pressure sufficient to cause tooth movement
between the tissues above and below the erupting tooth has been
reported in the dog.
Again, whether such pressures are the prime movers of teeth is
debatable because surgical excision of the root , and therefore the
local vasculature , does not prevent tooth eruption.

42. PPEERRIIOODDNNTTAALL LLIIGGAAMMEENNTT
TTRRAACCTTIIOONN
 AAmmoonnggsstt aallll 4 tthheeoorriieess PPDDLL ttrraaccttiioonn tthheeoorryy hhaass
ssttrroonnggeesstt eevviiddeennccee iinn iittss ffaavvoorr..
 TThhee ttrraannsssseeppttaall ffiibbeerrss rruunnnniinngg bbeettwweeeenn aaddjjaacceenntt tteeeetthh
aaccrroossss tthhee aallvveeoollaarr pprroocceessss ddrraaww nneeiigghhbboorriinngg tteeeetthh
ttooggeetthheerr && mmaaiinnttaaiinn tthheemm iinn ccoonnttaacctt..
 AAss lloonngg aass PPDDLL iiss vviiaabbllee ttooootthh mmoovveemmeenntt ooccccuurrss..
 SSppeecciiaalliizzeedd ffiibbrroobbllaassttss pprreesseenntt iinn PPDDLL –– mmyyooffiibbrroobbllaassttss..
 TThheessee bbyy vviirrttuuee ooff tthheeiirr ccoonnttrraaccttiillee ffoorrcceess eexxhhiibbiitt
ffiibbrroonneexxuuss..

43. Through fibronexus they transmit forces to the
collagen bundles.
These collagen bundles apart from undergoing
remodelling are also inclined at the correct angle to
bring about eruptive movement – basic requirement
for tooth movement
It is concluded that the force for tooth eruption is
most probably generated by the contractile property
of fibroblast of ligament along with other
conditions (presence of follicle) which must be
present so that this contraction can be used for tooth
eruption.
Hence eruption is a multifactorial phenomenon.

44. AA ––ffiibbrroobbllaassttss
BB ––aaddhheerreennccee ttyyppee iinntteerrcceelllluullaarr
jjuunnccttiioonnss
CC –– ffiibbrroonneexxuuss,, aattttaacchheedd ttoo ccoollllaaggeenn
bbyy ffiibbrroonneeccttiinn
DD –– ddeeppoossiittiioonn ooff ccoollllaaggeenn
EE –– rreessoorrppttiioonn ooff ccoollllaaggeenn

45. CHRONOLOGY OOFF PPRRIIMMAARRYY
TTEEEETTHH

46. CCHHRROONNOOLLOOGGYY OOFF PPEERRMMAANNEENNTT TTEEEETTHH

48. CHRONOLOGY OF PRIMARY DENTITION

49. CHRONOLOGY OF PERMANENT
DENTITION

50. CCLLIINNIICCAALL AAPPPPLLIICCAATTIIOONN
 tthhee ““ssiixx//ffoouurr”” rruullee ffoorr pprriimmaarryy ttooootthh eemmeerrggeennccee
mmeeaannss tthhaatt 4 tteeeetthh wwiillll eemmeerrggee ffoorr eeaacchh 66
mmoonntthhss ooff aaggee..
 TThhuuss ,, aaggee ooff 66 mmoonntthhss == 4 tteeeetthh
1122 mmoonntthhss == 88 tteeeetthh
1188 mmoonntthhss == 1122 tteeeetthh
224 mmoonntthhss == 1166 tteeeetthh
3300 mmoonntthhss == 2200 tteeeetthh..

51. CCOONNTTIINNUUOOUUSS TTOOOOTTHH
EERRUUPPTTOONN
 Eruption does not cease when teeth meet their
antagonists but continues throughout life.
 It consists of :-
1)active eruption
2)passive eruption
Active eruption – is the movement of teeth in the
direction of the occlusal plane.
Passive eruption – is the exposure of the teeth by
apical migration of the gingiva.

52. Anatomic crown – the portion of the tooth covered by enamel.
Anatomic root – the portion of the tooth covered by cementum.
Clinical crown – the part of the tooth that has been denuded of its
gingiva and projects into the oral cavity.
Clinical root – the portion of the tooth covered by periodontal
tissues.
When the teeth reach their functional antagonists , the gingival
sulcus and junctional epithelium are still on enamel and the
clinical crown is approximately 2/3rds of the anatomic crown.
“Gottlieb” believed that active and passive eruption proceed
together.
Active eruption is coordinated with attrition

53. CLINICAL CONSIDERATION
1) DEFICIENCY OF VITAMIN C
Necessary for the formation of collagen
fibers
& Cross – linkages between collagen fibers.
Deficiency – collagen fibers poorly formed in
the pdl and tooth fails to erupt or
erupts slowly and very late.

54. 2) TEETHING PROBLEMS
Gum adjacent to erupting teeth shows acute
reaction and pain – acute inflammatory
response
Systemic manifestations – as general malaise
, fever , and sometimes diarrhea.

55. PPRREEMMAATTUURREE EERRUUPPTTIIOONN
PPRRIIMMAARRYY TTEEEETTHH
Occurs infrequently
1)Natal teeth & Neonatal teeth – ( Massler and
Savara 1950)-
Taking only time of eruption as
reference , natal teeth are those observed in the
oral cavity at birth. Neonatal teeth are those that
erupt during the first 30 days of life.

56. 22)) OOsstteeppbbllaassttiicc aaccttiivviittiieess iinnssiiddee tthhee ttooootthh ggeerrmm
aarreeaa rreellaatteedd ttoo bboonnee rreemmooddeelllliinngg pphheennoommeennaa
33)) HHyyppoovviittaammiinnoossiiss
44))SSyysstteemmiicc ccoonnddiittiioonnss oorr ssyynnddrroommeess ssuucchh aass ––
EElllliiss –– VVaann CCrreevveelldd ssyynnddrroommee
HHaalllleemmaannnn –– SStteerriiffff ssyynnddrroommee
CClleefftt ppaallaattee
55)) EEnnvviirrnnmmeennttaall ffaaccttoorrss eegg ppoollyycchhlloorriinnaatteedd
bbiipphheennyyllss

57. DIAGNOSIS –is important ffoorr mmaaiinntteennaannccee
ooff nnaattaall aanndd nneeoonnaattaall tteeeetthh ooff tthhee nnoorrmmaall
ddeennttiittiioonn..
PPrreemmaattuurree lloossss ooff pprriimmaarryy ddeennttiittiioonn mmaayy
ccaauussee lloossss ooff ssppaaccee aanndd ccoollllaappssee ooff ddeevveellooppiinngg
mmaannddiibbuullaarr aarrcchh wwiitthh ccoonnsseeqquueenntt
mmaalloocccclluussiioonn iinn ppeerrmmaanneenntt ddeennttiittiioonn..

58. PPEERRMMAANNEENNTT TTEEEETTHH
 PPrreemmaattuurree eerruuppttiioonn ooff ppeerrmmaanneenntt tteeeetthh iiss
uussuuaallllyy aa sseeqquueell ooff pprreemmaattuurree lloossss ooff
ddeecciidduuoouuss ttooootthh..
 OOccccaassiioonnaallllyy ,,ccaasseess ooccccuurr iinnvvoollvviinngg tthhee
eennttiirree ddeennttiittiioonn –– ppoossssiibbiilliittyy ooff aann eennddooccrriinnee
ddyyssffuunnccttiioonn –– hhyyppeerrtthhyyrrooiiddiissmm..

59. DELAYED ERUPTION
Associated with systemic conditions like rickets , cretinism ,
endocrine deficiencies and cleidocranial dysplasia or may be
genetic
Sometimes local factors – act as barrier
Retained deciduous tooth-ankylosed due to trauma
Fibrosis of gingiva
Loss of deciduous tooth and drifting of adjacent teeth

60. PREMATURE LOSS
WWiitthhoouutt cclloossuurree –– eeaarrllyy eerruuppttiioonn ooff iittss ssuucccceessssoorr..
CClloossuurree dduuee ttoo ddrriiffttiinngg ooff aaddjjaacceenntt tteeeetthh –– ddeellaayyeedd
oorr nnoo eerruuppttiioonn..
IMPACTED TEETH
33rrdd mmoollaarrss dduuee ttoo llaacckk ooff ssppaaccee
ccaanniinneess dduuee ttoo tthheeiirr llaattee eerruuppttiioonn ttiimmee..

61. ERUPTION CYST
 It is a form of dentigerous ccyysstt && iiss
ffrreeqquueennttllyy aassssoocciiaatteedd wwiitthh eerruuppttiinngg
ddeecciidduuoouuss oorr ppeerrmmaanneenntt tteeeetthh iinn cchhiillddrreenn
 IItt iiss eesssseennttiiaallllyy aa ddiillaattaattiioonn ooff tthhee nnoorrmmaall
ffoolllliiccuullaarr ssppaaccee aabboouutt tthhee ccrroowwnn ooff tthhee
eerruuppttiinngg ttooootthh –– ccoonnttaaiinnss ttiissssuuee fflluuiidd oorr
bblloooodd
 CClliinniiccaallllyy –– aappppeeaarrss aass aa cciirrccuummssccrriibbeedd ,,
fflluuccttuuaanntt ,, oofftteenn ttrraannsslluucceenntt sswweelllliinngg ooff tthhee
aallvveeoollaarr rriiddggee oovveerr tthhee ssiittee ooff eerruuppttiinngg ttooootthh..
EERRUUPPTTIIOONN HHEEMMAATTOOMMAA
Blood – appears purple or deep blue - referred to as
eruption hematoma.Cause of development is not known
Requires no treatment – tooth generally erupts into the
oral cavity without significant delay – sometimes a
small portion of tissue overlying the tooth is removed
to facilitate eruption.

63. SHEDDING OF PRIMARY
TEETH
Definition :
Shedding is the exfoliation of the primary
teeth caused by physiological resorption
of their roots.(James k. Avery)
Causes :
1.Loss of root
2.Loss of bone
3.Increased force

64. 1. Loss of root :
Pressure from growing and
erupting permanent
teeth induces the
differentiation of osteoclast
which results in resorption of
the primary root.
Resorption shortens the
root and causes loss of
attachment fibers of the
periodontal ligament.

65. 2. Loss of bone :
Weakening of the supporting tissues of the primary
teeth occurs as a result of root resorption and
modifications of the alveolar bone.
Supporting structures are weakened also by facial
growth of the alveolar bone , which occurs to provide
sufficient space for positioning of the permanent teeth.

66. 3. Increased force :
Increased
masticatory forces on
the weakened teeth
are a result of muscular
growth , this amplifies
compression of the
periodontal ligaments
and promotes resoption
of the teeth and
alveolar bone.

67. CONCLUSION
 Eruption is the movement of the teeth through the bone of the jaw
and the overlying mucosa, to appear and functional in the oral
cavity.
 Active eruption is the result of occlusal movement of the tooth.
 Clinical eruption begins with the appearance of the crown tip in
the oral cavity and continues until the tooth comes into occlusion.
 The periodontal fibers are organizing to stabilize the erupting
tooth, the root dentinogenesis follows as the bone in the fundic
region organizes in response to the change in root length.
 Shedding of the primary teeth is the result of progressive resorption
of their root through the activity of the osteoclast or odontoclast.
 Disturbance of the resorption process results in abnormal behavior
of the primary teeth, some primary teeth may be retained
because of the absence or impaction of their permanent
successors, others may be ankylosed and submerged.
 In rare cases, teeth may appear in the oral cavity of newborn or
neonatal infants, and are called preprimary teeth.

68. REFERENCES
1 – Oral development and histology, James k Avery ,
thieme publications (3rd edition) .
2 - Oral Histology – A.R. Ten Cate, Mosby
Publications (3rd edition).
3 - Orban’s Oral Histology and Embryology – Mosby
Publications(10th edition).
4 - Principles of Anatomy and Oral Anatomy for
Dental Students – M.E. Atkinson and F.H. White (1st
edition) Churchill Livingstone Publishers.