Rates of Tooth Movement - 1

Application of Continuous Light Force

• Blood flow is altered & oxygen tension begins to change. Prostaglandins and cytokines are released.
• Metabolic changes occur. Chemical messengers affect cellular activity. Enzyme levels change.
• Increased cyclic adenosine monophosphate levels are detectable & cellular differentiation begins within PDL (Periodontal Ligament)
• Tooth movement begins as osteoclasts & osteoblasts remodel the bony socket.
• Result of continuous light force Osteoclasts initiate resorption of lamina dura from the side of PDL The osteoclasts arrive in 2 waves:

1.  TheIst wave derived from the PDL itself
2. 2nd the wave (larger) from distant areas via blood flow 

All these events lead to FRONTAL RESORPTION

Application of Continuous Heavy Force

• Blood flow gets cut off to the compressed PDL area.
• Cell death in the compressed area.
• Cell differentiation in adjacent marrow spaces: undermining resorption begins.
• Undermining resorption removes lamina dura adjacent to compressed PDL.
• Tooth movement occurs. (In contrast to the tooth movement occurring within 2 days with continuous light forces)