Lecture 7 Flashcards
Ortho tx uses prolonged pressure applied to the tooth where resorption and deposition occur. This bony response is mediated by what?
the PDL
If the PDL is destroyed during ortho (or other tx), what happens?
ankylosis
Under normal circumstances what is the size of space the PDL occupies?
.5 mm
What 2 things remodel the collagen of the PDL?
fibroblasts and fibroclasts
T/F the PLD is highly vascular
False; though it does contain some blood vessels and cells
What kind of nerve endings are in the PDL?
myelinated and unmyelinated free nerve endings
*sense perception of pain and proprioception
T/F the PDL space is filled with fluid
True
*same fluid found in other vascular areas
When is PDL fluid expelled?
When pressure is maintained
*after 3-5 seconds tooth is compressed against PDL and bone
T/F resting pressures of lips, cheeks, and tongue are balanced
False;
Mand ant: greater tongue pressure
Max incisor: Lip pressure is greater
what is the threshold for ortho force?
5-10 grams/square cm
What is the lip bumper?
removable appliance used in kids to create and save space necessary to accommodate adult teeth without extraction.
Harnesses the natural forces of the muscles surrounding the lower teeth to broaden the length of the dental arch
*tongue pushes teeth forward and out
Can the PDL itself generate forces to move a tooth?
yes. Eruption
what two things can cause chemical messengers that lead to remodeling of alveolar bone and tooth movement to be released?
1-Mechanical Compression of tissues
2- changes in the blood flow
*cytokines and prostaglandins
When is blood flow increased in an area of the tooth?
spaces where there is tension
*decreased blood flow in areas of compression
Decreased blood flow to the PDL increases what chemical messengers?
prostaglandins and IL-1 beta
*cAMP is the 2nd messenger