exam 3 Flashcards
true or false
maxillary molar has higher ratio of trabecular to cortical bone
true
root resorption may result from
accumulate of catabolic cytokines in the pDL
Fatigue cracks or defects in cementum covering the dentin of the root.
Dental extrusion may result in prematuries and occlusal trauma
what is the heritability estimate for external apical root resorption
70%
pulp death can result from
application of heavy forces if apex of teeth is closed = Pulp Death
true or false
the anchorage value for mandibular molars is greater than for maxillary molars
true
more bone in mandible higher anchorage.
External apical root resorption (EARR)
the loss of root structure involving the apical region to the extent that it can be seen I. standard radiographs
in the context of bone modeling and remodeling
Cortical bone
has frontal resorption(catabolic modeling) within the PDL and remodeling sites ahead of the moving tooth (0.3-0.5mm/mo)
in the context of bone modeling and remodeling
Trabecular bone
resorption occurs on all sides of exposed trabeculae, resulting in high rate of movement…(.6-1mm/mo
true or false
mandibular molars move twice as fast as maxillary molar
false
maxillary molars move twice as fast as mandibular molars
Leading roots______ _____ bone and trailing roots resorb_______ bone
leading=trabecular bone
trailing roots= cortical bone
class 2 problems are more prevalent in
whites of norther European decent
in McNamara’s study he found class2 was mostly due to
Mandibular skeletal retrusion.
true maxillary protrusion was rare
true or false
early treatment is more effective than later treatment I chilndren
according to profit
false no difference
order of growth
width then length then finally height
what are the best appliance for control of vertical dimension
Bionators
Increase vertical dimension results in
elongation and increase activity of stomatognathic muscles
Bionators to maintain vertical dimension are what size
3-4 mm of posterior opening
Bionator to decrease the vertical dimension
5-6 mm of posterior opening
closes a skeletal open bit
Bionator to increase the vertical dimension
4-5 mm of posterior opening for posterior eruption grooves to guide eruption(open the bite)
Twin Block appliance
tooth born appliance
used in minimum to moderate crowding
early and mixed dentition or permanent dentition
Maxillary and or mandibular constriction
Frankel appliance
tissue born appliance
importance of the Hertwig shealth
I n developing tooth bud induces neural cells to form periodontal ligament
When do supracrestal fibers form
as teeth erupt they ar made of collagen fibers inserted into cementum
Biioelectric theory
Relates tooth movement in part to change in bone metabolism
states that metabolism is controlled by the electric signals produced when alveolar bone flexes and bends
in bioelectric theory electric signals are
piezoelectric
Arch integrity
important function of the supracrestal fiber network
PDL is filled with _____ derived from where?
fluid derived from vascular system
acts as shock absorber
osteoclasts are derived from
circulating preosteoclasts that are formed in the marrow
osteoblasts are derived from
oerivascular cells
what is the electric potential in osteoclastic vs osteogenic areas
Electric potential more negative in osteogenic areas
More positive+= osteoclastic+
eruption mechanisms depend on
metabolic events = formation cross- linkage and shortening of collagen fibers
