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

Ortho Flashcards by B -

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

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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

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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.

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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

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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

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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

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? teeth are more prone to root resorption when orthodontically moved.

Endodontically treated

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first-order bends ?

faciolingual bends (Horizontal control)

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second-order bends ?

angled bends (tip control)

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third-order bends ?

torque control

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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

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Maxillary incisor rotation is best treated after ?

all permanent teeth have erupted (not commonly treated during the stage of mixed dentition)

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hyalinization of the PDL means?

necrosis

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Anchorage means?

resistance to displacement

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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

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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

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Center of resistance?

a point at which resistance to movement can be concentrated for mathematic analysis

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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

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Side effects of reverse-pull headgear include ?

downward and backward rotation of the mandible

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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

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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

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A skeletal crossbite, as contrasted with a functional crossbite, usually demonstrates ?

a smooth closure to centric occlusion

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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

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A functional crossbite is usually caused by ?

thumbsucking and does not demonstrate smooth closure into CO

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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)

Oligodontia/absence of one or more teeth, is more common in which gender?

females (often associated with smaller than average tooth-size ratio)

Conditions associated with multiple supernumerary teeth:

* Gardener's syndrome * Down's syndrome * Cleidocranial dysplasia * Sturge-Weber syndrome

``` During a serial extraction case, which teeth are NOT typically removed? • primary canines • primary first molars • permanent first premolars • primary second molars ```

primary second molars

``` At age 9, young Jimmy needs his tooth #30 extracted due to caries. What is the proper space maintenance treatment? • distal shoe on "T" • band and loop on "T" • removable partial denture • no space maintenance is needed ```

no space maintenance is needed — #31 has not erupted yet and it will tend to erupt close to the area of where # 30 had been

The most rapid losses in the A-P distance of the arch is usually due to ?

a mesial tipping and rotation of the permanent first molar after removal of the primary second molar

Which of the following are part of the rationale for retention in orthodontics (accomplished with fixed or removable retainers)? Select all that apply? • allow for reorganization of the gingival and periodontal tissues • minimize changes due to growth • maintain teeth in unstable conditions

all of them

The cranial vault is made up of a number of flat bones that are formed by ?, ?cartilaginous precursors. • endochondral bone formation; with • intramembranous bone formation; without • both endochondral and intramembranous bone formation; with • both endochondral and intramembranous bone formation; without

intramembranous bone formation; without

The bones of the cranial base are not affected to a great degree by growth of the brain since ?

they are endochondral bones

The condyle of the mandible grows by ?

proliferation of cartilage

The chief factor in the formation of the alveolar process is ?

the eruption of teeth

After a tooth has been moved from one position to another, the resulting bone is ? bone

transitional

Growth of the cranial base generally ? growth of the jaws

precedes

Once bone is formed, it grows by: • interstitial growth only • appositional growth only • both appositional and interstitial growth • degenerative changes into bony structures

appositional growth only

The greatest period of cranial growth occurs ?

between birth and 5 years of age

Remodeling of bone results in the histologic structures called ?

osteons

``` Cartilage differs from bone in that cartilage can increase in size by: • apposition • sutural expansion • interstitial growth • endosteal remodeling ```

interstitial growth

Cartilage tissue is pressure tolerant and able to provide flexible support because it is ? and contains ?

* avascular | * an intracellular matrix of proteoglycans

The body of the mandible grows longer by ? of bone on its posterior surface, while the ramus grows higher by ? at the condyle accompanied by surface remodeling

* periosteal apposition | * endochondral replacement

``` Bone deposition in the ? region is responsible for the lengthening of the maxillary arch. • palate • tuberosity • incisor • zygomatic ```

tuberosity

Since there is no cartilage replacement, maxillary growth occurs in two ways?

(1) by apposition of bone at the sutures that connect the maxilla to the cranium and cranial base (2) by surface remodeling

* The maxilla migrates ? * surface remodeling includes resorption of bone ? and apposition of bone ? * Much of the anterior movement of the maxilla is ? by anterior resorption, and downward migration is ? by inferior apposition of bone

* downward and forward * anteriorly - inferiorly * negated - augmented

``` An 18-year-old patient presents back to you complaining of crowding of his lower anterior incisors. You explain that this is because of: • late mandibular growth • pressure from third molars • maxillary tooth-size excess • trauma • an oral habit he must have ```

late mandibular growth

* Generally speaking, the earlier the growth spurt, the ? the duration of the growth spurt and the ? overall the growth will be. * Girls will generally start growth sooner, grow for a shorter amount of time, and will grow less than boys

shorter - less

``` What percentage of 6-year-old children have a median (maxillary) diastema? • 78% • 98% • 49% • less than 25% ```

98% (It is prevalent in 49% of 11-year-old children)

total closure of a diastema initially greater than ? mm is unlikely

The grand design of the human face is the result of ? which interact to produce the final result

remodeling and displacement (occur in opposite directions)

The most commonly impacted tooth is the mandibular canine. The longer a tooth has been impacted, the more likely it is to be ankylosed. • 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

the first statement is false, the second is true (The maxillary canine is the most commonly impacted tooth)

If a permanent maxillary first molar has erupted ectopically against the distal root surface of a primary second molar, what would be the treatment of choice? • disking the distal of the primary first molar • an appliance incorporating a finger spring to move the primary second molar mesially • a brass wire placed between the primary second molar and permanent first molar • extraction of the primary second molar

a brass wire placed between the primary second molar and permanent first molar (this problem often associated with a developing skeletal Class II pattern)

1. The time required to upright a molar can vary from: 2. The time required to stabilize the molar can vary from: • 2-3 weeks • 1-2 months • 2-6 months • 6-12 months • 2-3 years

1. 6-12 months | 2. 2-6 months

Slow progress in molar uprighting in an adult patient is most likely due to ?

occlusal interferences

activity of both osteoclasts and osteoblasts are important but the timing of ? is critical

osteoclastic, not osteoblastic, activity

Which of the following are signs of incipient malocclusion? Select all that apply. • lack of spacing in primary dentition • crowding of permanent incisors in mixed dentition • premature loss of mandibular primary canines • larger than normal primary teeth

* lack of spacing in primary dentition * crowding of permanent incisors in mixed dentition * premature loss of mandibular primary canines

* The maxillary anterior primary teeth are about ? of the size of their permanent successors. * The mandibular anterior primary teeth are, on average, about ? narrower mesiodistally than their successors

* 75% | * 6 mm

``` Angle's Class I occlusion represents ?% of the population. Angle's Class II occlusion represents ?%. While Angle's Class III occlusion represents the remainder. • 40; 55 • 50; 45 • 60; 35 • 70; 25 ```

70; 25

The nasolabial angle is the angle between the base of the nose and the upper lip, it should be ?

perpendicular or slightly obtuse

the incidence of malocclusion in a homogeneous population generally is ?, relative to a heterogeneous population.

lower

what is the other name of pseudo in pseudo class III malocclusions?

functional or apparent

The "Sunday bite" is a term given to ?

the forward postural position of the mandible which is adopted by people with Class II profiles in an effort to improve their esthetics

The most common cause of Class I malocclusion is: • an abnormal frenum • uneven growth of the arches • mandibular incisor crowding • discrepancy between tooth size and supporting bone

discrepancy between tooth size and supporting bone

``` Which of the following is/are generalized causes of failure of tooth eruption or delayed tooth eruption? Select all that apply. • hereditary gingival fibromatosis • down syndrome • rickets • hyperparathyroidism ```

* hereditary gingival fibromatosis * down syndrome * rickets

One or more of the following statements regarding the effect of environmental influences during growth and development of the face, jaws and teeth are true. Select all that apply. • patients who have excessive overbite or anterior open bite usually have posterior teeth that are infra- or supra-erupted respectively • a non-nutritive sucking habit leads to malocclusion only if it continues during the mixed dentition stage • negative pressure created within the mouth during sucking is not considered a cause of constriction of the maxillary arch • "adenoids" which lead to mouth breathing, cannot be indicted with certainty as an etiologic agent of a long-face pattern of malocclusion because studies show that the majority of the long-face population have no nasal obstruction

All of them 1. A sucking habit that is stopped prior to mixed dentition has not been shown to lead to malocclusion. 2. The negative pressure created within the mouth during sucking is not what causes the maxillary constriction. It is the force from the buccinator muscles that does

when space closure in the case of a lost permanent incisor occurs rapidly ?

no difference if spacing is present or not prior to the loss (there is a possibility that drifting of the adjacent teeth will occur if there is a loss of a primary incisor, if there is no space then space closure occurs even in primary dentition)

Boys precede girls in total number of teeth erupted until ? months, then girls surpass boys and remain ahead throughout completion of the primary dentition

``` A periapical radiograph of primary tooth M shows tooth #22 overlapping half of the root. The patient is not in the chair, so you cannot palpate to determine on which side tooth #22 is erupting. What would you presume? • tooth #22 is erupting distally • tooth #22 is erupting mesially • tooth #22 is erupting lingually • tooth #22 is erupting facially ```

tooth #22 is erupting facially

In ? arches, the permanent incisor tooth buds lie lingual to the primary incisors

both the maxillary and mandibular

Leeway space is a calculated difference between primary and permanent tooth size. There is typically more leeway space in the maxillary arch. • 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

the first statement is true, the second is false

During the canine-premolar transition period, the permanent first molars generally move mesially into the leeway space after the primary second molars are shed, thus causing a loss in arch length. This is referred to as

"the late mesial shift of a permanent first molar"

Increases in the vertical height of the jaws and face continue until ? in girls and in ? in boys

* 17 or 18 | * the early twenties

``` Which of the following teeth are required for a dentist to perform a Moyers' mixed dentition analysis? • mandibular first molars • maxillary first molars • mandibular incisors • maxillary incisors ```

mandibular incisors

Which of the following is false concerning a mixed dentition analysis? (Moyers analysis) Select all that apply. • it is used to predict the amount of crowding after the permanent teeth erupt • it determines space available vs. space required • the analysis is based on a correlation of tooth size • it is performed during the mixed dentition • it is performed with a boley gauge, study models and a prediction table • analysis is done for each quadrant

analysis is done for each quadrant (analysis is done for each arch)