Lecture 10 Flashcards
when extraoral force is applied to the maxillary teeth, where is the force effective?
sutures of maxilla
What does occipital pull head gear do to growth?
restricts max growth in anterior-posterior and vertical demensions
in what class would restriction of growth in the maxilla be beneficial?
class II
what are the two general philosophies for implementing max. expansion?
1-fixed expansion
2- removable expansion
4 negative effects from using removable expansion appliances
1-apical and crestal stress in anchor teeth is higher
2-higher stress in cortical and spongy bone from forces produced against hard palate and alv. bone
3-vertical displacement (crown tipping) of molar cusps
4-poor patient compliance
what are the 2 internal rotations of the mandible?
1- rotation around the condyle (matrix rotation)
2-rotations centered within body (intra matrix rotation)
T/F over time mandibular plane increases
False. body of mandible rotates (up anteriorly, down posteriorly)
*rotation of around condyle or centered within mand. body
What makes the mandible more challenging to expand?
there is no mandibular suture
T/F moving lower incisors is problematic for stabilty
True.
*lip pressure increases too much
What area of the mandible is the only one that can be expanded and maintain stability?
expansion across the premolars
expansion for canines and maintain stability
0-1mm
expansion for premolars and maintain stability
1st premolars: 2mm
2nd premolars: 2-3mm
expansion for molars and maintain stability
3 mm
T/F the mandible can be pushed and pulled the same way the maxilla can to alter growth
False. The TMJ is difficult to transfer force through
what is the main problem for the cupping device?
it has to be worn 24/7 and kids just wont do that.
It also runs the risk of tilting incisors lingually
what is the purpose of the delaire-type facemask, AKA reverse pull headgear?
enhance A-P maxillary growth in a class III px
mechanism the Delaire-type facemask works
1-pulls maxilla while pushes mandible
3 effects of Delaire-type face mask
1-some forward max. movement
2-forward movment of max. teeth
3-downward and back rotation of mandible
it is easier to restrain or stimulate mandibular growth?
stimulate
*mandible can be pulled into protrusion and held for long duration with moderate force
when do you know true stimulation of mandibular growth has occurred?
when on the growth chart you see faster than normal growth that continues thereafter
how do functional appliances move the dentition? (2)
1-repositioning the skeletal bases, placing force on teeth by stretching the muscles and tissues
2-changing occlusion relationships and therefore occlusal forces on teeth
what is the threshold needed to move a tooth?
6 hours
*may or may not also apply to sutures
when is the best time to wear functional appliances?
sleeping hours
*longer than 6 hours and HGH is being released
Treating a deficient mandible can be treated in what 3 ways
1-modify growth
2-ortho camouflage
3-surgery
*teach px the pros/cons of each and that they may yield slightly different resutls
in phase 1 ortho, what area is one of the most actively adaptable areas of bone growth?
alveolar process
- between primary and adult dentition
- idea for ortho
what are the 2 aspects of the mixed dentition stage?
1-utilize arch perimeter
2-the adaptive changes in occlusion that occur during transition of one dentition to another
what makes phase 1 ortho limited?
it can only occur in the presence of at least 1 primary tooth
how long does phase 1 ortho usually last?
6-12 months
what 3 things does phase 1 ortho do?
1-corrects existing abnormalities
2-creates conditions where the dentition can function and developing normal
3-final primary teeth are lost and perm. erupt
When does the American Association of Ortho recommend every child receive ortho eval and pano?
before age 8
when can a pt move on to phase 2 ortho?
after phase 1 and after all primary teeth are lost
*around 11 or 12
what are 4 reasons to refer your patient for early ortho?
1-crowding
2-abnormal growth and development
3-ectopic eruption and impactions
4-traumatic occlusion/crossbites
phase 1 (early) ortho can help correct what 3 things?
1-abnormal growth
2-abnormal habits
3-fix things that may result in trauma
what 3 things can phase 1 ortho help correct regarding possibility for trauma
1-severe deep bites
2-cross bites
3-protruded maxillary incisors
T/F anterior crossbites in primary dentition is common
False. Anterior cross bites in primary dentition indicates a skeletal growth problem
- same with class III
- mandibular growth lags
what types of abnormal habits can phase 1 ortho help?
mouth breathing, finger sucking, tongue position posture
What is the most basic sign of future crowding?
Lack of inter-dental spacing in the primary dentition
the maxillary anterior primary teeth are what % smaller than their perm. successors?
75% smaller
mandibular anterior primary teeth combine to be how many mm smaller mesio-distally than their successors?
6 mm smaller
T/F arch perimeter does increase after eruption, however it is a small increase in the maxilla and essentially non-existent in the mandible
TRUE
T/F because of arch growth, it can be relied upon for further dental alignment to alleviate crowding
FALSE
*arch growth is not sufficient for that
what 3 things are used to create space in mandible for mild crowding?
1-increase arch width across canines
2-labial positioning of the central and lateral incisors
3-distal shift of perm. canines when primary molars are lost
what is leeway space?
size differential between primary molars and perm premolars
*AKA E space
how big is mandibular leeway space on each side?
2.5 mm
how big is maxillary leeway space on each side?
1.5 mm
what is the mesial distal diameter of the maxillary perm. teeth?
128 mm
what is the mesial distal diameter of the mandibular teeth?
126mm
the maxillary arch is aprox. how many mm larger than the mandibular arch?
2 mm
flared maxillary incisors (ugly duckling stage) may cause waht?
impacted canines
what percent of 11 year olds have diastemas?
49%
what 4 things can cause a diastema?
1-tooth size discrepancy
2- mesiodens
3-abnormal frenum
4-a normal stage of deveopment
what event may cause a diastema to close on its own?
eruption of perm. canines
what size of diastema has the greatest chance of closing on its own?
less than 2mm
what does premature loss of the primary canines reflect?
insufficient arch size in the anterior region
During eruption sometimes the lateral incisors impinge on _______ causing them to ______ and be lost
canines, resorb
what happens if only 1 canine is missin?
the midline will shift
what are 3 options for maxillary crowding?
1-expansion
2-limited ortho on 1st molars and incisors
3- extract primary canines to create space
when can palatal expansion be done?
any time prior to the end of the adolescent growth spurt
what are the 4 reason for early palatal expansion?
1-stop mand. shifts on closure
2- space of erupting max. teeth
3-lessen arch distortion and tooth abrasion interferences on anterior teeth
4- reduce mandibular skeletal asymmetry
what 3 options are available for mandibular crowding?
1-expansion (no suture to expand, but lip bumpers/schwarz may help)
2-limited ortho on mand. perm. teeth
3-extract primary canines to create space
T/F class III are easy to control
False
*limited ortho, reverse pull head gear
T/F early treatment is really helpful for class II
FALSE. early tx is no more helpful than just regular phase 1
ectopic eruption of the perm. 1st molar can cause resorption of the primary 2nd molar and requires _________
active intervention
- impacted molar is susceptible to decay
- may need to extract primary tooth
if ectopic eruption of 1st molar occurs what 2 options besides extraction might be called for?
1-spacer between them
2-active ortho
permanent teeth often erupt in abnormal positions due to _____________
over retained primary teeth
perm. teeth normally move in what 2 directions while erupting?
occlusally an buccally
_____ is when 2 tooth buds fuse together to make one large crown
Fusion
- 2 independent pulp chambers and roots
- count teeth 1 less than normal
__________ is when one tooth bud tries to divide into 2 teeth
gemination
- normal tooth count
- 2 pulp chambers, 1 root
