Tooth eruption is defined as T he movement

Tooth eruption is defined as “T he movement of a tooth from its s ite of dev elopm ent w ithin the alveolar proces s to its functional p o s i ti o n i n o r a l c a v i ty ”, Massier and Schour, 1941

Active Eruption & Passive Eruption

Stage of tooth eruption • Pre-eruptive • Intraosseous movement • Eruptive mucosal penetration preocclusal eruption • Post-eruptive

Pre-eruptive stage • Deciduous teeth • Permanent teeth

Eruptive stage

Post-eruptive stage 1. accommodation for growth 2. c o m p e n s a t e f o r o c c l u s a l & interproximal wear (m e s i a l d r i f t( 3. s u p r a e r u p t i o n

����� � attrition abrasion erosion

Factors consideration in tooth eruption • development of periodontium, root, pulp, alveolar bone • speed of eruption • events during eruption – eruptive pathway: gubernacular canal – 3 D movement – inheritable position

Development of Dental Follicle • cementoblasts • periodontal ligament • alveolar bone

Reduced Enamel Epithelium

Gubernacular canal Gubernacular cord Eruptive Pathway

FORCES of Tooth Eruption • Root Formation • Pressure ( Pulp and Hydrostatic( • Periodontal Ligament • Bone Remodeling and Dental Follicle

Root growth • relation of root growth and eruptive movement: Carlson (1944( • remove HERS • supraeruption • rootless tooth : Gowgiel 1961, 1967

Pulp growth • Antimitotic drugs inhibit mitotic activity of pulp cell : Sicher (1962)Ness & Smale (1959( • Vitamin D deficiency & overdose: Bryer

Hydrostatic pressure • King & Bryer -> sympathetectomy • Main (1961) -> Hypotensive drugs • Hassel & Mc. Minn (1972) -> measure fluid pressure

Periodontal Ligament -> root resection Michaeli et al (1982) -> degenerate PDL Ness (1967) -> PLF Bellows et al (1983) -> PLF • Berkovitz & Thomas (1969) • • •

dental follicle • Control resorption and formation of bone around tooth germ: Cahill & Mark 1974, 1980, 1983, 1987 • no dental follicle, no eruption • PDL , alveolar bone and cementum are derivative of Dental Follicle

Bone remodeling • Apposition & resorption of bone • Vit A and D def. Bone growth • Metal and Acrylic replica: Marks & Cahill (1984(

Molecular biology of Bone Remodeling • Influx of monocytes at the onset of eruption • appearance of osteoclasts • signaling molecules

signaling molecules • • • CSF-1 EGF IL-1 TGF alpha TGF beta-1

Problem? ? ? • In vitro / in vivo • nature of experimental animal ……extrapolation • experimental design…isolate single system

Conclusion of FORCES of Tooth Eruption Multifactorial )However, “Dental Follicle” Activity & Bone Remodeling have the Highest Potential(

. 1 Timing of Eruption. 2 Unerupted Tooth (Embedded(. 3 Tooth Impaction. 4 Position of newly Erupted Successors. 5 Dental Treatment Consideration on Newly Erupted Tooth. 6 Denture and Supra-Erupted Tooth

)Of Deciduous Teeth(

Mono-Phyodontism Di-Phyodontism Poly-Phyodontism

Pattern of Shedding • Resorption of roots – anterior/posterior • Shedding of crown

Cause of shedding • Pressure from permanent teeth • loss of bone…weakening of supporter • trauma and inflammation…occlusal stress, caries. . Etc.

Histology of Sheding -Gubernacular Canal -Osteoclasts -Odontoclasts -Perio. Dontal Ligament

Clinical Application • Remnants of Deciduous Teeth • Retained Deciduous Teeth • Submerged Deciduous Teeth