PHYSIOLOGIC TOOTH MOVEMENT─ ERUPTION AND SHEDDING

高雄醫學大學 兒童牙科陳弘森

07-3121101-7008, 7020hosech@kmu.edu.tw

Eruption

Movement of a tooth through the jaw into the oral cavity.

Pattern of tooth movement

1. preeruptive movement

2. eruptive movement

3. posteruptive movement

Histology of tooth movement

Preeruptive phase Eruptive phase Posteruptive phase

Preeruptive phase

Bodily movement Excentric growth bony remodeling osteoclast

Eruptive phase

Root formation Periodontal ligament Dento-gingival juction

Posteruptive phase

Condylar growth Jaw bone growth

Direction of tooth movement

Axial Drifting Tilting Rotating

Tooth eruption mechanism

The push mechanism The pull mechanism

Push mechanism

Root growth (Pierce 1887) Vascular pressure (Constant 1900) Bone growth (Brash 1928) Cellular proliferation (Eidmann 1923) Dental follicle

Pull mechanism

Collagen maturation (Thomas 1967) Fibroblasts (Ness 1967)

Eruption rates

Mouse Guinea pig 200-1100 μ m/day Rabbit Human 140 μ m/day

(5 μ m/day)

Clinical consideration

Early eruption Delayed eruption Impacted

Shedding(exfoliation)

Gradual removal of roots and alveplar bone

Shedding of teeth

odontoclasts pressure

odontoclasts

Cementoclas Dentinoclast

Histology of shedding

Odontoclasts

Large multinucleated cell

Cytoplasm of vacuole

Dense mitochondria

Brush border surface

Acid phosphatase

Odontoclasts

resorption bay (Howship’s lacunae)

brush border (ruffled border ; microvilli )

acid phosphatase

Root resorption

resorption period rest period repair period

Clincal consideration

Remnants of deciduous tooth Retained deciduous tooth Submerged deciduous tooth

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