Tooth eruption is defined as “ The movement of a tooth from its site of development within the alveolar process to its functional position in oral cavity,” Massier and Schour, 1941

Active Eruption & Passive Eruption

S tage of tooth eruption Pre-eruptive Intraosseous movement Eruptive mucosal penetration preocclusal eruption Post-eruptive

P re-eruptive stage D eciduous teeth P ermanent teeth

E ruptive stage

P ost-eruptive stage 1. accommodation for growth 2. compensate for occlusal & interproximal wear (mesial drift) 3. supraeruption

ฟันสึก a ttrition a brasion e rosion

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

D evelopment of D ental F ollicle cementoblasts periodontal ligament alveolar bone

Reduced Enamel Epithelium

G ubernacular canal G ubernacular cord Eruptive Pathway

FORCES of T ooth E ruption R oot F ormation P ressure ( Pulp and Hydrostatic ) P eriodontal L igament B one R emodeling and D ental F ollicle

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

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

H ydrostatic pressure King & Bryer -> sympathetectomy Main (1961) -> Hypotensive drugs Hassel & McMinn (1972) -> measure fluid pressure

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

d ental f ollicle 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

B one 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

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

Multifactorial Conclusion of FORCES of Tooth Eruption (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

P attern of S hedding R esorption of roots –anterior/posterior S hedding of crown

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

- Gubernacular Canal - Osteoclasts - Odontoclasts - PerioDontal Ligament Histology of Sheding

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