Tooth Movement Flashcards
Tooth movement define ?
Occurs as consequence the bone has to remodel as specified coupled sequences of resorption and formation events to replace existing bone.
Or
Physiological I.e. in response to muscular or orthodontic forces leads to bone being laid down in tension sites and bone being resorbed at pressure sites.
Optimal forces for tooth movement
- Ideal forces in orthodontic tooth movement are those which over come capillary blood pressure.
What happens if excessive pressure?
Excessive pressure result in Hyalinisation where cellular component of periodontal ligament disappears
Ground glass appearance define ?
-Hyalinised zone assume “ground glass “ appearance but returns to normal once pressure is reduced and periodontal ligament repopulated with normal cells.
-in this case osteoclast appear to “undermine” bone rather than resorbing at frontal edge.
Tendency of forces should be use ?
- low constant force
light and low levels of forces That are capable of moving teeth.
-intermittent forces generate more bone turnover than continuous forces
Pressure side - ideal tooth movement
- Pressure side of tooth being moved in the direction
- Osteclasts all lined up resorbing bone known as Frontal resorption
- Osteoclast comes from monocytes in the blood.
Tension side - ideal tooth movement
- No osteoclast, Pale pink new bone has been laid down by Osteoblast
Hyalinisation ( Sterile Necrosis)
- Excessive pressure cause “ ground glass appearance “ of cells called hyalinisation
Tooth movement - Optmimum Force
Pressure side
- Cell proliferation occurs within the periodontal ligament in area of compression and osteoclasts in from surrounding blood vessels
- Resorption occurs adjacent to the area of pressure within days (osteoclast)
Tension side
- On tension side periodontal fibres are stretched and there is proliferation of fibroblasts and osteoblast. Osteoid is deposited on socket wall and remodelled into mature bone.
Tooth movement Excessive Force
- If excessive force is applied direct resorption of the bone doesn’t occur due to compression of blood vessels
- Sterile necrosis ( Hyalinisation ) structure less microscopic appearance
- After few days indirect resorption occurs then tooth moves (undermining resorption)
Tooth movement how much optimal Force?
- Below capillary pressure (20 -25 g/cm2)
- Depends on Root surface area
- Type of tooth movement (tipping or bodily movement)
What are consequences of excessive force?
- Delay in tooth movement
- Increased risk of Anchorage loss
- greater discomfort of tooth being moved
- Increased tooth mobility
- Greater risk of root resorption
Duration of force
- Clinical tooth movement : 6 hours per day
- Optimal tooth movement - continuous 24 hours per day
-Due to irregularity of tooth socket walls forces are not even and there may be pockets of excessive force
Root resorption
- Minimal 1mm usually-
- ## varies from tooth to tooth U2s’ lose 2.5mm Molars 1mm
Factors increase Risk of root resorption?
- Moving teeth against buccal and lingual bone
- Torqueing teeth (3rd order movement)
- maxillary and mandibular surgery for jaw correction
- Treament with Xtns are part of plan
