DEFINE ERUPTION &DESCCRIBE ITS PHASES AMJAD AL_BLEAHID

Tooth Eruption Eruption is the axial or occlusal

movement of the developing teeth, in order to appear in the oral cavity & reach the occlusal plane

The onset of eruptive movement begins in the bell-stage

Axial movement begins with the onset of root formation & continues throughout the life span of the teeth

Eruption of tooth Axial or occlusal movement of teeth

(or teeth germs) From : Their developmental position

in the jaw To : Their functional position in the

oral cavity

Phases of Eruption Pre-

eruptive phase

Eruptive phase

Post-eruptive phase

Pre-Eruptive Phase STARTE : End of early bell ENDS : Beginning of root formation EVENTS : Jaw growth In length ,

width and height TYPES OF MOVEMENTS : 1-Bodily movement 2-Eccentric growth

Histological Changes During this phase, movements are achieved

in two ways :

1-bodily movement resorption occurs on the surface of the crypt wall in advance to the movement direction ,

while bone apposition by osteoblastic activity occurs on the crypt wall behind it.

2-Eccentric growth During root growth, there is only bone resorption on the surface of the crypt that faces the growing direction of the tooth germ

Eruptive Phase (Pre-Functional Eruptive Phase ) STARTS : at the time of root

formation ENDS : when the tooth has reached

the occlusal plane.

The Eruptive Stages 1- Intraosseous

stage

The eruptive movement occurs within the bony crypt

2- Supraosseous stage

The eruptive movement occurs within the connective tissue of the oral mucosa.

The movement is faster than before

Histological Changes Intraosseous stage Root Formation Periodontal Ligament Formation Alveolar Bone Formation Supraosseous stage Dentogingival Junction Formation Gubernacular Cord and Canal Formation

Post-eruptive Phase (Functional Eruptive Phase ) STARTS : when the teeth reach

occlusal plane & continues as long as they remain in the oral cavity

Histological Changes In this stage, the root, the periodontal

ligament & The alveolar bone continue their formation.

The teeth are subjected to 2 movements Occlusally & Mesially The erupting teeth is influenced by the

surrounding environmental factors that help in to determine the final position in the oral cavity (e.g. muscles forces & childhood habits) (Thumb suckling habits)

References Antonio Nanci: Ten cat`s Oral

Histology: Development, Structure, and Function, 8th ed. Elsevier Health Sciences, Mosby, 20`3

Bhasker, S.N.: Orban’s Oral Histology and Embryology, Edition By G.S. Kumar, Mosby 13th ed. 2011

Any question?