tooth eruption theories, peridontal ligament theory, hydrostatic pressure theory etc

1. Sri Aurobindo college of dentistry
Department of pedodontics and
preventive dentistry

2.  Guided By:-
Dr. Bharat Bhushan Sir
Dr. Khushboo Barjatya Mam
Dr. Binti Rani Chand Mam
Dr. Abhilasha Tripathi Mam
Dr. Hariom Meena Sir
Submitted By :-
Shailendra Hamad
Roll No. 62 Batch- G
BDS 3rd year(2017-18)

3. Theories Of Tooth Eruption
Contents
-Root elongation theory
-Bone remodelling theory
-Periodontal ligament contraction theory
-Hydrostatic pressure theory
-Pulp constriction theory
-Dental follicle theory

4. Phases of Tooth Eruption
 Pre eruptive phase
 Eruptive phase
 Post eruptive phase

5. Pre eruptive phase
 This phase includes all the movements from
the time of early initiation and formation of
crown for primary and permanent teeth.
 This phase is ended with early initiation of
root formation.

6. Eruptive phase
 This phase starts with initiation of root
formation and ends by reaching at the level of
occlusal contacts.

7. Post eruptive phase
 This phase remains till teeth are functional
and present in oral cavity.
 Compensate for masticatory wear

8. Factors necessary for tooth to
erupt intraosseously.
 The overlying tissue (Bone, primary root and
gingiva) must resorb to provide an eruptive
path.
 A force must be generated to move the tooth
vertically.

9. Root elongation theory
 The apical growth of root results in an axially
directed force that brings about the eruption of
the teeth.
 These theory is although not widely accepted
because teeth move greater distance during
eruption than the increase in root length.
 Teeth that are malformed and lack roots also
erupts in no of cases.

10. Bone Remodelling theory
 It is believed that an inherent growth pattern
present in maxilla and mandible which moves
teeth by selective deposition and resorption of
bone.
 This is also not accepted as bone deposition
and resorption both are seen as a result of
eruptive forces applied by the tooth over the
bone.

11. Role of dental follicle
 Marks (1980) and Cohill(1984) demonstrated the
role of dental follicle in tooth eruption on an animal
study.
 Intercellular changes occurs in dental follicle and
recruitment of osteoclast and bone forming cells
near dental follicle leads to eruption of tooth.
 Dental follicle before it forms periodontal ligament
also plays a role in the eruption even though it
might not provide the actual eruptive force.

12. Periodontal Ligament Traction
Theory
 It is said to be the most accepted theory.
 This theory states that periodontal ligament
are rich in fibroblast which contain contractile
elements.
 This fibroblasts contracts and transmit the
forces to collagen bundle fibres of PDL which
leads to application of axially directed force
which causes eruption of tooth.

13. Hydrostatic pressure theory
 This theory states that the hydrostatic pressure
difference between the tissue around the erupting
crown and its apical extent is responsible for tooth
eruption.
 It was observed (Hassel Mc Minn, 1972) that the
tissue pressure apically was greater than
occlusally which theoritically generates an
eruptive force.
 No association was found between the pressure
gradient and the rate of eruption.

14. Pulp Constriction Theory
 This theory states that growth of root dentin
and constriction of pulp causes sufficient
pressure to move the tooth in axial direction.
 This theory is not accepted because in some
cases pulp less teeth also erupts.
 After premature extraction of decidous molar
The premolar erupts without any growth of
dentin or pulp constriction.

15.  Tooth eruption is definitely a multifactorial
process which includes few or all the factors
explained in the theories or some other
factors like
 Control of endocrine glands
 Pressure from muscular action
 Effect of nutrition
 Inherent tendency of teeth to erupt

16. THANK YOU