Dr. Jamal Giri presented on the development of dentition and tooth eruption. The presentation covered the stages of tooth development from the bud stage through root formation and eruption. It discussed the various theories of tooth eruption including the roles of root formation, bone remodeling, the periodontal ligament, hydrostatic pressure, and the dental follicle. It also summarized Proffit's contributions regarding the mechanism and control of tooth eruption, including maintaining an eruptive force and clearing the eruption path.

1. Presenter:
Dr. Jamal Giri
Resident (1st Year)
Development of dentition

2. Contents
1. Development of dentition and
supporting structures.
2. Mechanism of tooth eruption.
3. Proffit’s contributions regarding
eruption.
4. Clinical implications.
2Dept. of dentistry-PG section, IOM (2011)

3. 4th week of Intra uterine life (IUL)
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4. Development of Branchial arch
 Neural crest cells migrate into the head and neck
region (4th week)
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5. 5Dept. of dentistry-PG section, IOM (2011)

6. 6th week of Intra uterine life(IUL)
 Basal cells of oral
epithelium proliferate at a
rapid rate.
 Condensation of
underlying connective
tissue.
 Formation of primary
epithelial band. 6Dept. of dentistry-PG section, IOM (2011)

7. 7th week of Intra uterine life(IUL)
 Primary epithelial band
divides into 2 processes:
 1) Vestibular lamina.
Oral vestibule
 2) Dental lamina.
Tooth bud
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8. Dental lamina
 8th-10th week of IUL: Series of swellings
corresponding future deciduous teeth.
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9.  Directly from Dental
lamina.
 Deciduous teeth
 Lingual extension of
Dental lamina
 Successional teeth
 Distal extension of
Dental lamina.
 accessional teeth
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10. 10Dept. of dentistry-PG section, IOM (2011)

11. Stages of tooth development
 1)Bud stage.
 2)Cap stage.
 3)Bell stage.
 4)Stage of apposition.
 5)Stage of root formation and eruption.
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12. Bud stage
 Stage of initiation.
 Formation of Bud shaped
enamel (dental) organ.
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13. Age Tooth Bud formation
8-10 weeks (IUL) All the deciduous teeth.
4th month (IUL) Permanent first molar.
5th month (IUL) Permanent central incisor to
first premolar.
10th month Permanent second premolar.
1 year Permanent second molar.
4-5 years Permanent third molar.
13Dept. of dentistry-PG section, IOM (2011)

14. Cap stage
 Stage of proliferation.
 Differential growth
(more towards
periphery).
 Formation of tooth germ. Dental
papillaDental sac
Enamel
organ
Tooth germ
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15.  First signs of cellular
arrangement.
 Enamel organ :Enamel.
 Dental papilla : Dentin & pulp
 Dental sac : Cementum &
periodontal ligament.
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16. Bell stage
 Stage of histo-
morphodifferentiation.
 4 distinct cell types
present in enamel organ.
 The dental lamina
disintegrates.
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18. Formation of ameloblast
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19. Appositional stage
 Reciprocal interaction.
 Dentin and enamel
formation.
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21. Reduced enamel epithelium
 Formed by outer and
inner enamel
epithelium.
 Protect the enamel
before eruption.
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22. Stage of root formation and eruption.
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24. Stages of tooth development
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25. Genetic basis of tooth development.
 More than 200 genes
involved.
 Homeobox genes.
 (http://bite-it.helsinki.fi)
Oral Biosci Med 2/2004, S. 77-91
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26. Patterning of Dentition
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27. Oral Biosci Med 2/2004, S. 77-91
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28. Defective initiation
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29. Defective Proliferation
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30. Defective histodifferentiation
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31. Defective morphodifferentiation
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32. Defective apposition
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33. Tooth eruption
 Greek word:
 Erumpere- to break out
 The process whereby a tooth moves from its
developmental position within the jaws to
emerge in the oral cavity.
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34. Theories of tooth eruption.
 Role of root formation.
 Role of bone remodeling.
 Role of periodontal ligament.
 Role of hydrostatic pressure.
 Role of dental follicle.
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35. Role of root formation.
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36.  Pitfalls:
 Rootless teeth also erupt
(Dentin dysplasia).
 Hammock ligament
hypothesis.
 Root length is not equal to
distance of path of
eruption. 36Dept. of dentistry-PG section, IOM (2011)

37. Role of bone remodelling.
 Selective deposition
and resorption of bone.
 Marks and Cahill
studies: when the tooth
germ is wired to bone,
the bony eruption
pathway is still formed.
37Dept. of dentistry-PG section, IOM (2011)

38. Role of periodontal ligament.
 Formation & renewal of
the PDL has been
considered a factor.
 Pitfalls:
 1) dentin dysplasia.
 2) Primary failure of
eruption.
38Dept. of dentistry-PG section, IOM (2011)

39. Role of hydrostatic pressure.
 Van Hassel and McMinn
(1972)
 Hydrostatic pressure
gradient apico-occlusally.
 Pitfall:
 Relatively small study (6
dogs).
39Dept. of dentistry-PG section, IOM (2011)

40. Role of dental follicle.
 Marks and Cahill.
 a pattern of cellular activity
involving the reduced enamel
epithelium (REE) and the
follicles.
 Recruitment of osteoclasts &
release of proteases.
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41. Wise et al, CROBM July 2002 vol. 13 no. 4 323-335
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42.  Study on dog’s premolar.
 Removal of the follicle from the unerupted tooth
prevented the tooth from erupting (Cahill and
Marks, 1980).
 Leaving the follicle intact and substituting an
inert object for the tooth resulted in eruption of
the inert object (Marks and Cahill, 1984).
42Dept. of dentistry-PG section, IOM (2011)

43. Proffit’s contribution
 Mechanism and control of tooth eruption:
overview and clinical implications, Orthod
Craniofac Res 2009;12:59–66.
 Tooth eruption is difficult to study:
 1) erupt slowly.
 2) Inaccessible for clinical examination.
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44. For eruptive movements.
Eruptive force. Clearance of eruption
path.
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45. Eruptive force.
 Remains elusive.
E
R
U
P
T
I
O
N
Root
formation
Bone
remodelling
Dental
follicle
Hydrostatic
pressure
Periodontal
ligament
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46. Clearance of eruption path.
 Pressure from the eruptive force
causes resorption.
 An eruption path is cleared and the
tooth follows along it.
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47. Resorption-Eruption uncoupling
Ankylosis
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48. Primary failure of eruption
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49. The daily rhythm of tooth eruption
 AJODO, Volume 107, Issue 1, January 1995, Pages
38-47.
 17 subjects ( 10 boys, 7 girls)
 41 hour video microscopic observation.
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50. Results
 Mean daily eruption: 71um/day
 Small amount of intrusion during Daytime.
 Net eruption at night.
 Transient intrusion associated with breakfast,
lunch, dinner.
50Dept. of dentistry-PG section, IOM (2011)

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