Biomechanics, Techniques and Appliances 25% 16Q Flashcards
How many grams of force do you need to intrude a maxillary central?
25g
How many grams of force do you need to intrude a maxillary central + lateral?
50g
How many grams of force do you need to intrude a maxillary central + lateral + canine?
100g
How many grams of force do you need to intrude a maxillary canine?
50g
How many grams of force do you need to intrude a mandibular central + lateral?
40g
How many grams of force do you need to intrude a maxillary central?
20g
How many grams of force do you need to intrude a maxillary central + lateral + canine?
80g
How many grams of force do you need to intrude a maxillary canine?
40g
Moment = ________ x _________
moment = foce x distance
tendency for force to produce rotation
moment
what is created when a line of force does not go through the of resistance?
a moment
A higher moment to force ratio produces more ( crown / root ) movement than ( crown / root ) movement
`root
crown
What are placed in areas of largest bending movement so it can create the most gentle force
helices
parallel forces in opposite direction
couple
___________ movements require a force and a moment
bodily
what movement is created when Mc/MF = 0
Pure tipping or uncontrolled tipping
what movement is created when 0 < Mc/MF < 1 ?
Controlled tipping
what movement is created when Mc/MF = 1 ?
bodily movement
what movement is created when Mc/MF > 1 ?
torque
the center of rotation of a tooth is approximately
⅓ down the root in bone
the center of resistance of a tooth is approximately
the midpoint of the root
which appliance can create controlled incisor tipping with CR at the apex
lip bumper
force requirement (in g) for intrusion
15-25g
force requirement (in g) for tipping, rotation and extrusion?
50-75k
force requirement (in g) for translation?
100-125g
force requirement (in g) for canine retraction?
100-150g
a 0:1 - 5:1 moment to force ratio will produce which type of tooth movement?
uncontrolled tipping
a 7:1 moment to force ratio will produce which type of tooth movement?
controlled tipping
a 10:1 moment to force ratio will produce which type of tooth movement?
translaiton
a 12:1 moment to force ratio will produce which type of tooth movement?
tooth movement
Force = (1/Distance)2
This means that if the distance decreases by ½, force increases by ___x
4x
Force = (1/Distance)2
This means that if the distance increases by ½, force decreases by ___%
44%
the duration threshold for light force to produce movements is ___ - ___ hours
4 - 6hrs
In a physiologic response to sustained pressure, movement begins after ___ hours
48hrs
on average, RPE treatment will move the A point 2.5mm ____________ and 3.5mm ___________
- 5mm downward
- 5mm forward
to determine that a crossbite is skeletal, you will see dental compensations. upper molars will have ______ crown torque and lower molars will have _________ crown torque
buccal
lingual
the limit
the limit to expansion is the
zygomatic arch or pterygoid plates
the mandibular limit to expansion is the
coronoid process of the mandible
After RPE, stabilization is needed for ___ - ___ months to re-establish the suture
4 - 6months
the maxillary mid-palatal suture is _________ tissue that is mainly __________ with osteogenic surfaces on each side.
fibrous
collagen
can RPE reduce nocturnal enuresis (involuntary urination)?
yes
in RPE, the dental:skeletal effects of expansion are ___ : ___
1 : 1
During bonding we use ___% ________________ acid as etch. This removes ___ - ___ microns of enamel.
37% phosphoric acid
3-10 microns
Omission of air-dispersion step ( increases / decreases ) shear bond strength in self-etching primer system
decreases
Porcelain etch for bonding is made of ___% _________
10% HCl
Bracket adhesive with Fl- releasing etching gel has significantly ( higher / lower) bond strength
higher
Fl- applied to teeth before bonding ( increases / decreases ) bond strength
decreases
Fl- prevents dental caries by decreasing enamel _____________
solubility
1st order wire bends are
in / out
rotation and BL thickness
2nd order wire bends are:
up / down – align marginal ridges
3rd order wire bend are:
torque
When pt has steep premolar cusps: finish with ( increased / decreased ) OB
increased
reorganization of the PDL occurs in ___ - ___ months
3 - 4 months
the class II div 2 characteristic that is most prone to relapse is:
deep bite
Case: rotated incisors, deep bite, large overjet. Most likely to relapse?
Rotation
which periodontal fibers most important in stability / relapse?
supracrestal fibers
After orthodontic treatment, these things can happen:
- Reduction in root _______
- Reduced _______ support
- Crowding
- Rotation
- length
- alveolar bone
In Little’s post-tx relapse study he found that ___/___ of mandibular incisors relapse
⅔
Burstone stated that the upper occlusal plane should be relatively ______ and not allow more than ___mm of incisal show at rest
flat
3mm
Soft tissue thicknesses increase more in ( females / males )
females
The incidence of canine impactions is ___ - ___%
1 - 2%
With canine impaction cases, the incidence of the impaction being bilateral is ___%
8%
The 3 options for labially positioned impactions are:
closed eruption, apically positioned flap, excisional
For labially positioned impacted canines, choose (closed eruption / apically positioned flap ) for a better esthetic outcome
closed eruption
For labially positioned impacted canines, an apically positioned flap is good when:
when the canine is angles mesiodistally
and when there is an inadequate amount of gingiva
For labially positioned impacted canines, excisional technique is good when there is ___mm or more of attached gingiva and the tooth is below the _____________
3mm
mucogingival junction
Palatal impactions are ___x more likely than labial impaction
2x
If tip is distal to lateral root, removal of C will resolve ___% of cases
91%
If tip is past midline of lateral root: removal of C resolves ___% of cases
64%
When a mesiodens causes the impaction of a central incisor, the _____________ technique should be used to bring it into the arch
closed eruption
T/F: Functional appliances accelerate Mn growth, but treated pts do not have larger mandibles
True
According to Bancceti’s articles, with the use of a twin block appliance, overall changes are ___% dental and ___% skeletal
45%
55%
with the use of a twin block appliance, which parts of the mandible show and increase in size?
body
ramus length
With a twin block appliance, the lower incisors are capped to prevent:
proclination and extrusion
The twin block appliance allows you the ability to increase VDO by:
removing acrylic from lower part of appliance so mandibular teeth will erupt