Dr Sherif Hassan associate prof oral biology

2. Definition of eruption:
Eruption is the movement of tooth germ from its original site
until appear into the oral cavity, and come to occlusion , and
still to move throughout live.
Terminology:
ACTIVE ERUPTION: It is the actual movement of the tooth
from its developmental site to its position in the dental arch.
PASSIVE ERUPTION: Occurs due to apical recession of
gingival tissue exposing more tooth structure into the oral
cavity.
ANATOMICAL CROWN: It is part of the tooth that covered
by enamel.
CLINICAL CROWN: is the part of the tooth that seen in the
oral cavity.

3. Types of movements:
1. Axial movement: Movements of the tooth to incisal or
occlusal direction.
2. Drift movement: movement of the tooth into mesial
direction.
3. Tilt movement: Movement of the tooth around
horizontal axis.
4. Rotation movement: Movement of the tooth around
longitudinal axis.
5. Bodily movement: Movement of the tooth as all into any
direction.
6. Eccentric growth: One end (crown) of the developing
tooth move toward eruption whereas, other end (growing
root) remain stable.

4. Types of physiologic tooth movements:
1. Pre-eruptive tooth movement Movements of the tooth
from its origin until appear into the oral cavity.
2. Eruptive pre-functional movement: movement of the
tooth from the appearance in the oral cavity until reaches
the occlusion.
3. Eruptive post-functional movement: the tooth has
been reached to the occlusion and still move throughout
its life span .

5. I. Pre-eruptive tooth movements

6. 1. Growth of teeth firstly:
The five deciduous tooth germs grow at a faster rate than
jaw growth, and so the tooth germs become crowded.
2. Growth of jaw:
A. Growth of the jaw in length allow:
✴Anterior deciduous tooth germs to move toward the midline.
✴Second deciduous molar to move distally.
B. Growth of the jaw in width allow:
✴All deciduous teeth germs to move outward (facially).
C. Growth of the jaw in height allow:
✴All deciduous teeth germs to make axial movement .
1. Movement of deciduous tooth germs

7. 1.Firstly:
The deciduous and permanent tooth germs develop at the same
level in the same bony crypt and the permanent anterior tooth
germs are located lingual to the deciduous one.
2. By axial movement of deciduous tooth germs:
both permanent and deciduous tooth germs become located in a
separate crypt.
3. Then the deciduous teeth erupt by axial movement:
The permanent anterior teeth become located in an apicolingual
position.
4.Lastly:
The deciduous tooth root begin to resorb and the permanent
become located apical to the deciduous one.
2. Movement of permanent anterior tooth germs

8. 1.Firstly,
Both deciduous and permanent tooth germs are at the same level in
the same bony crypt, while premolar tooth germs are located lingual to
the deciduous one..
2. Then
By axial movement of deciduous teeth for eruption, Premolar germs
move to become situated within the deciduous roots.
3. Movement of premolar tooth germs

9. 1.Maxillary molars:
• Maxillary molars are found in
the maxillary tuberosity facing
distally.
• Growth of maxilla in length
leads to tilting of the maxillary
molars to become facing
downward.
2.Mandibular molars:
• Mandibular molars are found
in the ramus of mandible
facing mesially.
• Distal growth of mandible
leading to tilting to the
mandibular molars to become
facing upward.
4. Movement of permanent molar tooth germs

10. Types of movements in pre-eruptive stage:
1.Bodily movement:
Bone resorption occure in the surface toward which tooth moves.
Bone deposition occurs on the crypt wall behind it.
2.Eccentric growth:
One end (crown) of the developing tooth move toward eruption.
The other end (growing root) remain stable.
Gobernacular canal:
• The crypts of both deciduous and permanent successor are
connected together by a canal termed: Gobernacular canal.
• This canal may act as a key for eruption of permanent successor
into its proper position.
• Gobernacular canal contain a cord that connect between
deciduous and permanent successor termed Gobernacular cord.
Histology of pre-eruptive tooth movements

11. Eccentric growth

12. II. Eruptive pre-functional tooth movements

13. Types of movements in
eruptive pre-function
stage:
1. Axial occlusal or incisal: in
the direction of the long axis.
It is the principal one.
2. Bodily movement: in distal,
mesial, lingual or buccal
direction.
3. Tilting movement: around
the horizontal axis as in case
of molars.
4. Rotation movement:
around long axis as in case
of lower central incisors or
canine.
Histology of eruptive pre-function tooth movements

14. Clinically:
Tooth eruption may be accompanied by:
1-Discomfort or pain.
2- Irritability.
3- Slight temperature increase.
4- There is also increased salivation.
But
No Bleeding.

15. III. Eruptive post-functional tooth
movements

16. Accommodation of jaw growth:
Completed at the end of the second decade when the jaw growth stop.
Achieved by the formation of new bone at the alveolar crest and at the
socket floor to keep place with the increasing height of the jaws.
This readjustment occurs between 14-18y.
This movement occurs earlier in girls than in boys.
Compensation for Occlusal wear.
Attrition of occlusal surface make open space of the occlusion.
These axial post-eruptive movements are made to compensate this
attrition.
occurred by continuous cementum deposition around the apex of the
tooth.
Compensation for proximal wear.
By forces causing mesial drift . This force move the teeth in a mesial
direction to keep proximal contact.
Mechanism of Eruption

17. Mechanism of Eruption ( theories of eruption):
1.Root formation theory.
2.Bone remodeling theory.
3.Vascular pressure theory.
4.Periodontal ligament traction theory.

18. Periodontal ligament traction theory
Fibroblast has a contractile
function.
Fibronexus is a Connection
between fibroblasts together.
Fibronectin is a Connection
between fibroblast and collagen
fibers.
Contraction of all these structures
make the movement of tooth.

20. Eruption Hematoma

21. Impaction