contains theories of tooth eruption

1. THERORIES OF TOOTH
ERUPTION
Resource Faculty
Prabhat Ranjan Pokharel
Head of department
Rajesh Gyawali
Assistant professor
Jamal Giri
Assistant professor
DEPARTMENT OF ORTHODONTICS
PRESENTER
Nabin Chaudhary

2. Contents
• Root elongation theory(Hammock ligament theory)
• Bone remodeling
• Periodontal ligament contraction theory
• Vascular pressure theory
• Pulp constriction theory
• Dental follicle theory

3. Physiologic tooth movement
• Tooth eruption
• Migration or drift of tooth
• Changes in tooth position during
mastication
• Active eruption
• Passive eruption
• Anatomical crown
• Clinical crown

4. Phases of tooth eruption
• Pre-eruptive phase
• Eruptive phase(4 stages:root form-
ation,penetration,movement,occlusal
contact)
• Post-eruptive phase

5. Patterns of tooth movement
• Pre-eruptive phase
1. Bodily(drifting) movement
2. Eccentric growth
• Eruptive phase
1. Axial(occlusal) movement
2. Drifting(bodily) movement
3. Tilting(tipping) movement
4. Rotating movement
• Post-eruptive phase
1. axial

6. ROOT ELONGATION THEORY
 proliferating root impinges on a fixed base, thus converting an apically directed force of the
tooth into occlusal movement
 Fallacies
o rootless tooth erupts
o Some teeth erupt more than the total length of the roots
o Teeth erupt even after the complete formation of the root
Therefore root formation is accommodated during tooth eruption and is a consequence,
not a cause, of the eruption process.

7. • According to Harry Sicher, a band of fibrous tissue(cushion hammock
ligament) exists below the root apex spanning from one side of
alveolar wall to another.
Ligament was never found histologically

8. BONE REMODELING
• The end result of bone remodeling is a considerable bone deposition
at the bottom of the socket
• selective formation and resorption of bone brings about eruption.
• Fallacies :
• alveolar bone remodeling which occurs around the root,endby bone
deposition, is the outcome and not the cause of axial tooth
movement

9. PERIODONTAL LIGAMENT
CONTRACTION THEORY
• CONTRACTILE ELEMENTS - COLLAGEN AND FIBROBLASTS
CONSTRICTION
Force initiated by fibroblast
Transmitted to extracellular compartment via fibronexus and
collagen bundles by root formation
ERUPTION

10. • Fallacies
• Examples of PDL being present but tooth not erupting and rootless
teeth erupting have been reported.

11. • Fallacies
• Examples of PDL being
present but tooth not
erupting and rootless
teeth erupting have
been reported.
A –fibroblasts
B –adherence type
intercellular junctions
C – fibronexus, attached
to collagen by
fibronectin
D – deposition of
collagen
E – resorption of collagen

12. PULP CONSTRICTION THEORY
• Growth of root dentin and constriction of pulp --- sufficient pressure
to move tooth occlusally
• Fallacies
• Pulpless teeth erupt at same rate as normal teeth
• Premature extraction of deciduous molar: premolar do erupt
without any growth of dentin or pulp constriction

13. VASCULAR PRESSURE THEORY
• THE VASCULAR PRESSURES are present in pulpal tissues as well as in the
periodontal ligament
• The pressure exerted by the blood vessels at the apex of the tooth help
in eruption of teeth
• Fallacies
• The pressure exerted is not enough to help in eruption of teeth
• Teeth erupt even when the vascular supply is cut

14. DENTAL FOLLICLE THEORY
• Specific cellular changes occur in and around the follicle when a
tooth erupts.
• Source for new bone-forming cells and osteoclasts
• Teeth eruption is delayed or absent in animal models and human
diseases that cause a defect in osteoclast differentiation

15. • Tooth eruption is definitely a multifactorial process involving all
• or few factors of the above or other factors like
 Control of Endocrine Glands
 Pressure from muscular action
 Effect of Nutrition
 Inherent tendency of teeth to erupt

16. Facts
• Rate of eruption
• Intraosseous=1-10µm/day
• Extraosseous=75 μm/day
• Root formation ( tomes 1872 )
• Bone remodeling ( brash 1928 )
• Dental follicle ( marks and cahill 1984)
• Periodontal ligament ( thomas 1967 )
• Hydrostatic pressure ( sutton and graze 1985 )
• Pulpal pressure ( v . Korff 1935 )