Ortho Flashcards
All of the following are advantages of the indirect method of bonding brackets to a tooth over the direct method EXCEPT one. Which one is the EXCEPTION?
• reduced chair-side time
• more precise location of brackets possible in the laboratory
• controlled thickness of the resin between the tooth and the bracket interface
• less technique sensitive
• easier clean-up during bonding and de-bonding
• better visualization in lab (especially for lingual brackets)
less technique sensitive
Which of the following are considered functional appliances? Select all that apply. • frankel • bionator • dark's twin block • herbst • activator • quad-helix
- frankel
- bionator
- dark’s twin block
- herbst
- activator
A headgear appliance is used for: • anchorage • traction • both anchorage and traction • neither anchorage or traction
both anchorage and traction
Anchorage is used to maintain space. Traction is used to create space.
Optimal usage of headgear:
- Worn regularly for 10-12 hours per day, minimum is 8 hours per day
- Normally, orthodontists suggest 14 hours/day
- Growth hormone released in the early evening
- Ideal to place headgear after dinner not before bedtime
Doubling the length of a wire decrease its strength by ?, makes it ? times less stiff, and gives it ? times the range
• half
• 8
• 4 (Strength = Stiffness x Range)
1/2=1/8*4
when the diameter of a wire is doubled, its strength is increased by ? times, its stiffness by ? times, and its working range is decreased by ?
• 8
• 16
• half (Strength = Stiffness x Range)
8=16*1/2
? teeth are more prone to root resorption when orthodontically moved.
Endodontically treated
first-order bends ?
faciolingual bends (Horizontal control)
second-order bends ?
angled bends (tip control)
third-order bends ?
torque control
The Hawley retainer is the most common retainer in orthodontics because it can use the palate for anchorage
• both the statement and the reason are correct and related
• both the statement and the reason are correct but not related
• the statement is correct, but the reason is not
• the statement is not correct, but the reason is correct
• neither the statement nor the reason is correct
both the statement and the reason are correct but not related
Maxillary incisor rotation is best treated after ?
all permanent teeth have erupted (not commonly treated during the stage of mixed dentition)
hyalinization of the PDL means?
necrosis
Anchorage means?
resistance to displacement
Stationary anchorage: displacement of anchor teeth can be minimized by arranging the force system so that anchor teeth must move ?
bodily (translation) if at all, while movement teeth are allowed to tip
Orthodontic forces can be treated mathematically as vectors.
Forces produce either translation (bodily movement), rotation, or a combination of translation and rotation, depending upon the relationship of the line of action of the force to the center of resistance of the tooth.
• both statements are true
• both statements are false
• the first statement is true, the second is false
• the first statement is false, the second is true
both statements are true
Center of resistance?
a point at which resistance to movement can be concentrated for mathematic analysis
- In single-rooted teeth, the center of resistance is on the long axis of the tooth ? the way from the alveolar crest to the apex.
- In multirooted teeth it is ?
- one-third to one-half
* just apically to the furcation
Side effects of reverse-pull headgear include ?
downward and backward rotation of the mandible
Side Effects of Headgear?
- (typically found with cervical headgear) will cause the mandible to move inferiorly and posteriorly
- Negates Class II correction
- May cause distal tipping of molars
Which condition is appropriately treated at an early age?
• deviated midline in the absence of a functional shift
• mild crowding of lower permanent incisors
• two deciduous molars nearly in crossbite
• posterior crossbite with a functional shift
posterior crossbite with a functional shift
A skeletal crossbite, as contrasted with a functional crossbite, usually demonstrates ?
a smooth closure to centric occlusion
Displaced teeth related to functional shifts occur in which of the following situations? Select all that apply. • posterior crossbite after prolonged thumb sucking • class II, division I malocclusion • anterior crossbite in mildly prognathic children • an anterior open bite after prolonged thumb sucking
- posterior crossbite after prolonged thumb sucking
* anterior crossbite in mildly prognathic children
A functional crossbite is usually caused by ?
thumbsucking and does not demonstrate smooth closure into CO
Maxillary expansion is often done to correct crossbites.
Tongue thrusting often causes crossbite.
• both statements are true
• both statements are false
• the first statement is true, the statement is false
• the first statement is false, the second is true
the first statement is true, the statement is false (often causes open bite)
Which of the following are not classic symptoms of a sucking habit? Select all that apply.
• anterior open bite
• crossbite
• expanded maxillary arch
• proclination of the maxillary incisors
• retroclination of the mandibular incisors
• a Class II malocclusion
expanded maxillary arch (Increased pressure exerted by the buccinator muscles during sucking, on the maxillary arch, results in its constriction)
The most essential factor related to correction of anterior crossbite is ?
the space available mesiodistally
A "Poor man's Cephalometric Analysis" is performed via • dental cast analysis • facial profile analysis • photographic analysis • full face analysis
facial profile analysis
Which of the following correlate with a steep mandibular plane? Select all that apply.
• long anterior facial vertical dimension
• anterior open bite
• tendency toward a Class III malocclusion
• greater maxillary-mandibular plane angle
tendency toward a Class III malocclusion
What is needed so that soft tissues are clearly visible on a lateral cephalometric radiograph?
• adjustment in kilovoltage
• adjustment in milliamperage
• a soft tissue shield
• a hard tissue shield
• nothing must be done to make soft tissues visible
a soft tissue shield
Mandibular growth stops (before/after) ? maxillary growth
after
In predicting the time of the pubertal growth spurt, while treating jaw mal-relationships in a growing child, the orthodontist can get the most valuable information from:
• wrist-hand radiograph
• height-weight tables
• presence of secondary sex characteristics
• stage of dental development
wrist-hand radiograph (less useful in evaluating whether growth has stopped or is continuing (patient’s position on growth curve). Serial Cephalometric radiographs are used for this purpose)