This document discusses dental anatomy and histology, specifically focusing on tooth eruption. It begins with an introduction and overview of the mechanisms and chronology of eruption. It then discusses the sequence of emergence for primary and permanent teeth. Potential disorders of eruption are also reviewed, including impaction caused by obstacles like supernumerary teeth, odontomas, or arch length deficiencies. Treatment options for various eruption disorders include surgical exposure, attachment of impacted teeth for orthodontic alignment, and removal of hard tissue obstacles blocking eruption.

1. Dental anatomy and histology
Dr.sinu jayaprakash

2. contents
• Introduction
• Mechanism of eruption
• Chronology of eruption
• Eruption disorders

3. introduction

4. eruption
• It is the developmental process responsible
for moving a tooth from its crypt position
through the alveolar process into the oral
cavity to its final position of occlusion with its
antagonist.

5. emergence
• It should be reserved for describing
the moment of appearance of any part
of the cusp or crown through the
gingiva.emergence is synonymous with
moment of eruption,which is often used
as a clinical marker for eruption.

6. Tooth movements
Pre eruptive tooth movement
made by the deciduous
and permanent tooth germ within tissues of
the jaw before they begin to erupt.
Eruptive tooth movement
made by tooth to move from its position
within the bone of the jaws to its functional
position in occlusion.it is divided into
intraosseous and extraosseous components.

7. Posteruptive tooth movement
maintaining the position of
the erupted tooth in occlusion while the
jaws continue to grow and compensate for
occlusal and proximal tooth wear

8. Mechanisms of eruption

9. Mechanisms of eruption
• Root formation
• Hydrostatic pressure
• Bone remodelling
• Periodontal ligament

10. • Root formation
Root formation appears to be an obvious
cause of tooth eruption because it undoubtedly
causes an overall increase in the length of the
tooth that must be accommodated by the
growth of the root into bone of the jaw, by an
increase in jaw height, or by the occlusal
movement of the crown.

11. • Root formation is accomodated during
tooth eruption
• It is not cause of eruption but may
accelerate tooth eruption

12. Chronology of eruption

13. DEFINITION
• Chronos –time
• Logos-study
• Chronology is defined as the study which deals with
the timing of various stages of tooth development.
Starting with the initiation of first dental tissue laid
down to the emergence of tooth in the oral cavity and
its completion of calcification.

15. Age of attainment
• It is based upon tooth emergence
• It is used clinically to avoid damage to
developing tooth during treatment

16. Age of prediction
• It is based on the average age of the
subjects in a stage of development
• Age prediction are used for assessing
unknown age of patients and forensic
archealogical appearance

17. Maturity assessment
• Here the stages are averaged rather
then subject ages
• Such scales are useful when maturity is
assessed of known age

19. Sequence of emergence of primary teeth
• The predominant sequence of eruption of
primary teeth in the individual jaw is
central incisor
Lateral incisor
first molar
Canine
Second molar

20. Sequale of eruption

21. Generally

22. Primary teeth
• Primary teeth are smaller in overall size and
dimension
• More prominent cervical ridges
• narrower at their ‘necks’
• Lighter in colour
• Roots are more widely flared
• Buccolingual diameter is less than permanent
teeth

23. Primary teeth
• The teeth function an average of 8 yrs for
maxillary teeth
• Teeth function an average of 7.6 yrs for
mandibular teeth
• Hold an important role in reserving space for
permanent teeth

24. Important functions of sound primary teeth

25. Mixed dentition period
• First mixed dentition begins with the
emergence and eruption of mandibular first
permanent molar.
• It ends with the loss of last primary tooth
which usually occurs at 11-12yrs.

27. PERMANENT TEETH
At birth,1st per molar is the only per
tooth which shows evidence of
calicfication
Dates of eruption per incisor is same as
primary incisor but in years
Premolar start calicification b/w 1-2yrs

28. Permanent teeth
Lower teeth sequence of eruption 6 1 2 3 4 5
Upper teeth sequence of eruption 6 1 2 4 3 5
Lower teeth erupts before upper
opposing teeth
• 1st,2nd 3rd molar erupt at age of 6,12,18
yrs resp.

29. Difference b/w primary and permanent teeth

30. enamel

31. dentin

32. The pulp

33. Periodontal Ligament

34. Eruption disorders

35. Etiology of eruption problems
• Disturbance occur in any phases of
eruption
• 3 main causes of eruption disturbance
1.Ectopic position of the tooth germ

36. Etiology of eruption problems
2.Obstacles in eruption path
-lack of space
-follicular collision
-presence of compact bone
-supernumerary teeth
-Odontomas
-scar tissue
-non –attached mucosa
-giant cell fibromatosis
-odontogenic tumour or cyst

37. Etiology of eruption problems
3.Failures in the eruption mechanisms
follicle or pdl defects according to
the stage of eruption due to trauma ,
surgery, congenital diseases or other
causes

38. Etiology of eruption problems
• 1st ,2nd conditions lead to impaction
• 3rd according to stage in which eruption
disturbance occurs will lead to primary
teeth disorders or secondary
retention(aftr emergence)

39. Etiology of eruption problems
• So its necessary to develop a rational
treatment approach inorder to diagnose
which of the prerequisites for eruption
have been violated and to what extent

40. Supernumerary teeth
• cause crowding, displacement, rotation,
impaction, delayed eruption.
• Most common- mesiodens 4th molar
in max arch

41. Supernumerary teeth
• Different forms assosiated with
different effects on dentition-
tuberculate type is most common with
delayed tooth eruption
. Conical form is associated with
displacement
Treatment
• Removal of hard tissue obstacle

42. Regional odontodysplasia
• Also called ghost teeth
• Unusual anomaly that result from somatic
mutation or latent virus in odontogenic
epithelium
• Affected teeth-delay or failure in eruption
• Shapes are very irregular,defective
mineralization

43. Regional odontodysplasia
• Central incisor, lateral incisor, canine –
most frequently affected
• Abnormality in tooth structure can also
be responsible for the eruptive
disorders

44. IMPACTED TEETH
Condition of being firmly lodged
(impacted in alveolar bone) or wedged by a
physical barrier ,usually other teeth,so it
is prevented from erupting.

45. impaction

46. Etilogy of impaction

48. impaction
Treatment
• Surgical exposure
• Attachment to the teeth
• Orthodontic correction to bring the
teeth into the arch

49. ankylosis
• Resulting from fusion of cementum or
dentin in the alveolar bone
• Most common cause-delayed deciduous
exfoliation
• Common in mandibular molars

50. odontomas
.Odontomas occur in maxilla than mandible
• More than half is combined with
impacted teeth-lead to impacted teeth

51. odontomas
• Treatment
Removal of odontoma
So 3 out of 4 impacted teeth can be
expected to erupt subsequent to removal of
odontomas

52. Scar tissue
• Seen after cleft palate surgery and
trauma
• Apparently obstruct the collagenolytic
capacity of the follicle
• Treatment of choice is uncovering
procedure, including enamel exposure.

53. Mucosal barrier
Any failure of the follicle of an erupting
tooth to unite with the mucosa will entail
in a delay in the breakdown of the mucosa
and constitute a barrier to emergence

54. Gingival hyperplasia
• It results from various causes
(hormonal or hereditary causes ,vitamin
c deficiency, drugs such as phenytoin)
might causes an abundance of dense
connective tissue or acellular collagen
that can be an impediment to tooth
eruption

55. Arch length deficiency
• Often an etiological factor for crowding
and impaction.
• In a recent study of the relationship
between formation and eruption of the
maxillary teeth and the skeletal pattern of
the maxilla, a shortened palatal length was
found to delay the eruption of the
maxillary 2nd molar, although no delay in
tooth formation was observed

56. X-radiation
• X-ray also has been shown to impair tooth
eruption.
• Ankylosis of bone to tooth was the most
relevant finding in irradiated animals.
• Root formation impairment, periodontal cell
damage and insufficient mandibular growth
also seem to be linked to tooth eruption
disturbances due to x-radiation

57. THANK YOU