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Ortho > Lecture 10 > Flashcards

Lecture 10 Flashcards

1
Q

the ___ is one of the most actively adaptable areas of bone growth during the period of transition between the adult and primary dentitions, which is therefore an ideal time for most major orthodontic interventions

A

alveolar process

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2
Q

from a clinical point of view, there are two very important aspects to the mixed dentition period. what are they?

A
  • the utilization of the arch perimeter
  • the adaptive changes in occlusion that occur during the transition from one dentition to another
  • therefore, supervision of a child’s development of occlusion is most critical during this mixed dentition stage
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3
Q

phase I orthodontic treatment is ___ treatment performed on a patient before ___

A
  • limited

- all primary teeth are lost

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4
Q

how long does phase I treatment typically last?

A

6-12 months

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5
Q

after phase I treatment is complete, all braces and ortho appliances are removed and the patient is placed into ___

A

retainers

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6
Q

phase I treatment is oriented to correct ___ early before the can cause additional problems or damage existing permanent teeth due to ___

A
  • abnormalities

- traumatic occlusal relationships

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7
Q

phase I treatment ideally corrects ___ and places the patient in a position where the dentition can function and develop normally while the remaining primary teeth are lost and the rest of the permanent teeth erupt

A

-abnormalities

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8
Q

the american association of orthodontists recommends that every child receive an orthodontic evaluation and panoramic x-ray before the age of ___ to identify early orthodontic problems

A

8

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9
Q

patients who have undergone phase I treatment will typically undergo phase II treatment (full ortho treatment) later when the primary dentition is lost, typically around age ___

A

11 or 12

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10
Q

what are 4 reasons to refer your patient early for orthodontic treatment and intervention?

A
  • crowding
  • abnormal growth and development
  • ectopic eruption and impactions
  • traumatic occlusal relationships/crossbites
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11
Q

early orthodontic treatment and intervention can help correct what 3 things?

A
  • possibility of trauma from severe deep bites, anterior/posterior crossbites, or protruded maxillary incisors
  • abnormal growth (class III occlusion/anterior crossbites)
  • abnormal habits (mouth breathing, thumb and finger habits, tongue posture position)
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12
Q

a young child who has a tendency toward a class III malocclusion will have end to end contact of the ___

A

primary incisors

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13
Q

a true anterior crossbite in the primary dentition is rare because ___

A

mandibular growth lags behind maxillary growth

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14
Q

an anterior crossbite in the primary dentition is often indicative of a ___ and a ___

A
  • skeletal growth problem and a developing class III malocclusion
  • remember: an anterior crossbite in a primary dentition usually indicates a skeletal growth problem
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15
Q

orthodontic treatment typically isn’t started until the eruption of the permanent teeth around ___ years old

A

7-8

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16
Q

what are 2 major signs that a patient could have crowding problems?

A
  • lack of interdental spacing in the primary dentition

- crowding of the permanent incisors in the mixed dentition, alleviation through skeletal growth

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17
Q

the maxillary anterior primary teeth are about ___% the size of their permanent successors

A

75%

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18
Q

the mandibular anterior primary teeth (total) are, on average, about ___mm narrower mesiodistally than their successors

A

6mm

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19
Q

does arch perimeter increase after eruption of permanent incisors?

A
  • yes, however it is a small increase in the maxilla, and essentially non-existent in the mandible
  • therefore, arch growth cannot be relied upon to contribute to further dental alignment, and alleviate dental crowding
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20
Q

in the mandibular arch in both sexes, the amount of space for the mandibular incisors is negative (1-2mm) for about 2 years after their eruption, meaning what?

A

a small amount of crowding in the mandibular arch at this time is normal

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21
Q

the additional space to align mandibular incisors, after the period of mild normal crowding, is derived from what 3 sources?

A
  • a slight increase in arch width across the canines
  • slight labial positioning of the central and lateral incisors
  • a distal shift of the permanent canines when the primary first molars are exfoliated
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22
Q

the primary molars are significantly larger than the premolars that replace them, and the ___ provided by this difference offers an excellent opportunity for natural or orthodontic adjustment of occlusal relationships at the end of the dental transition

A

“leeway space” or “E space”

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23
Q

what is the average mandibular and maxillary leeway space?

A
  • mandibular leeway space averages about 2.5mm on each side

- maxillary leeway space averages about 1.5mm on each side

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24
Q

both ___ and ___ tend to decrease during the transition from primary to permanent dentition (ie. some of the leeway space is used by mesial movement of the ___)

A
  • arch length (distance from a line perpendicular to the mesial surface of the permanent first molars to the central incisors) to arch circumference
  • molars
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25
Q

the maxillary arch is slightly longer in arch length compared to the mandibular arch. the mesial-distal diameter of the maxillary permanent teeth is approximately ___mm, whereas the sum of the mesial-distal diameter of the mandibular permanent teeth is approximately ___mm. maxillary dental arch is typically ___mm larger than the mandibular dental arch.

A
  • 128mm
  • 126mm
  • 2mm
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26
Q

some spacing between the primary incisors is normal in the late primary dentition and is necessary to ___

A

provide enough room for alignment of the permanent incisors when they erupt

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27
Q

at age ___, a gap-toothed smile is what you would like to see

A

6

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28
Q

what denotes the “ugly ducking” stage, and what age does it occur?

A
  • in some children, the maxillary incisors flare laterally and are widely spaced when they first erupt
  • age 9
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29
Q

towards the end of the ugly duckling stage, the position of the incisors tends to improve when the ___ erupt, but this condition increases the possibility that the ___ will become impacted, and these patients should be referred to an orthodontist for evaluation

A
  • permanent canines

- canines

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30
Q

about ___% of 11 year old children have a maxillary diastema between their maxillary central incisors

A

49%

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31
Q

what are diastemas possibly caused by?

A
  • tooth size discrepancy
  • mesiodens
  • abnormal frenum
  • normal stage of development
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32
Q

the diastema space in a child tends to close as the ___ erupt, but the greater the amount of space, the less likelihood ___

A
  • canines

- the less likelihood it will close on its own

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33
Q

as a general guideline, a maxillary central diastema of ___mm or less will sometimes close on its own

A
  • 2mm

- anything greater than this, and closure is unlikely

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34
Q

premature loss of the primary canines reflects insufficient ___. the crowns of the lateral incisors, during eruption, impinge on the roots of the primary canines, causing them to resorb and they are lost

A

-arch size in the anterior region

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35
Q

if only one mandibular canine is prematurely lost, the midline will shift in the direction of the lost tooth, with ___ and ___ migration of the mandibular incisors

A

lateral and lingual

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36
Q

what are possible phase I treatment options for maxillary crowding?

A
  • expansion
  • limited orthodontics on maxillary first molars and incisors
  • extraction of primary canines (or others as needed) to create space for erupting permanent teeth
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37
Q

T or F:

palatal expansion can be done at any time prior to the end of the adolescent growth spurt

A

true

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38
Q

what are 4 major reasons for doing early expansion?

A
  • to eliminate mandibular shifts on closure
  • provide more space for the erupting maxillary teeth
  • lessen dental arch distortion and potential tooth abrasion from interferences of anterior teeth
  • reduce the possibility of mandibular skeletal asymmetry
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39
Q

what are 4 appliances that often leave indentations in the superior surface of the tongue? how long do the indentations typically last after removal of the appliance? what is the treatment?

A
  • W-arches, quad helixes, expanders, and habit appliances
  • up to 1 year
  • no treatment is recommended, but patients and parents should be warned of this possibility
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40
Q

what are possible phase I mandibular crowding treatment options?

A
  • expansion - schwartz, lip bumper
  • limited orthodontics on mandibular permanent teeth
  • extraction of primary canines (or others as needed) to create space for erupting permanent teeth
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41
Q

patients with a class III skeletal growth pattern are typically in a ___ crossbite with ___ constriction, and can be in full posterior crossbite

A
  • anterior

- maxillary

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42
Q

class III growth patterns are very difficult to control, especially in ___, and referral to an orthodontist should be initiated as soon as possible

A

males

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43
Q

treatment for class III patients typically consists of ___

A

-limited orthodontic treatment on the permanent dentition in association with expansion and reverse pull head gear

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44
Q

when treating a class III patient, what might happen if forward traction is applied at an early age?

A

it is possible to produce displacement of the maxilla rather than just displacement of the maxillary teeth

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45
Q

is phase I treatment more common for skeletal class II or class III patients?

A

class III

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46
Q 
T or F:
in class II phase I treatment, skeletal changes are not likely to be produced by early treatment with headgear or a functional appliance but tend to be diminished or eliminated by subsequent growth and later treatment
A
  • false

- changes are likely

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47
Q 
T or F:
in class II phase I treatment, skeletal changes account for only a portion of the treatment effect, even when an effort is made to minimize tooth movement
A

true

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48
Q 
T or F:
in class II phase I treatment, after later comprehensive treatment, alignment and occlusion are very different in children who did and those who did not have early treatment
A
  • false

- alignment and occlusion are very similar

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49
Q 
T or F:
in class II phase I treatment, early treatment reduces the number of children who require extractions during a second phase of treatment or the number who eventually require orthognathic surgery
A
  • false

- it does not reduce the number

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50
Q 
T or F:
in class II phase I treatment, the duration of phase II treatment (full ortho treatment) is quite similar in those who had a first phase of early treatment aimed at growth modification and those who did not
A

true

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51
Q 
T or F:
based on research results, it seems clear that for most class II children with a skeletal class II relationship, early treatment is no more effective than just one phase of later treatment
A
  • true
  • however, that isn’t to say there aren’t certain dental situations that a class II patient could benefit from phase I treatment (crossbite, traumatic deep bite, crowding, etc.)
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52
Q

thumb sucking and finger sucking are very difficult habits for some patients to break on their own, and often patients require help though ___

A

removable and fixed appliances

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53
Q

T or F:
the need to suck a finger or thumb can be very subconscious, and some patients suck their thumb without even realizing they are doing it

A

true

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54
Q

to break thumb/finger sucking habits, orthodontic appliances work to make the experience ___ or ___, and is intended to remind the patient, who may be doing it subconsciously, that they want to stop, and that they need to make the conscious decision to take their thumb out of their mouth

A

weird or painful

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55
Q

sucking habits often produce a ___ maxillary arch, and tendency toward bilateral ___ crossbite

A
  • narrow

- posterior

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56
Q

children who thumb/finger suck may sometimes shift the mandible to one side on closure, termed ___, which can guide permanent molars and premolars into a crossbite relationship. this can cause ___

A
  • functional crossbite

- this can cause damage to the dentition and can influence how the patient grows

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57
Q

with patients with thumb and finger sucking habits, the maxillary incisors are typically flared ___, and the mandibular incisors are reclined ___ causing a ___. also, as the hand rests on the chin, it can retard growth of the mandible, resulting in a class ___ profile.

A
  • bucally
  • lingually
  • anterior open bite
  • II
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58
Q

___ is a descriptive term for the appearance of the tongue when there are indentations along the lateral borders of the tongue

A

crenated tongue (or scalloped tongue)

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59
Q

what is crenated tongue caused by?

A
  • compression of the tongue against the adjacent teeth
  • this usually results from habits where the tongue is pressed against the lingual surfaces of the dental arches, or could be due to macroglossia
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60
Q

pressure from the tongue against the teeth can move the teeth into abnormal positions and can prevent the teeth from coming together through ___ or through ___, which can cause open bites on both ___ and ___

A
  • impeding eruption
  • orthodontic movement of the teeth
  • lateral
  • anterior
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61
Q

___ habits are very difficult for orthodontists to manage, and if patients are not willing to cooperate, a high tendency for orthodontic relapse will occur once the braces are removed

A

tongue

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62
Q

___ and ___ can be associated with tongue pressure parafunctional habits, which place the teeth in a situation comparable to a traumatic occlusion

A
  • root resorption and bone and gingival loss
  • the tongue continues on and off pressures, creating mobility in the tooth, which creates a constant inflammatory response in the dentoalveolar complex
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63
Q

in younger patients, ___ and ___ is a key element in orthodontic treatment planning

A

growth and the potential for growth

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64
Q

many orthodontic options are only available during periods of growth, and once growth is complete, ___ is often the only alternative for these patients

A
  • orthognathic
  • unfortunately, even with the best early intervention, some patients growth cannot be corrected and the patient will require surgery once their growth is complete
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65
Q

___ is a difficult, complex problem and an orthodontist must complete a full ortho analysis and treatment plan before initiating any ___ treatment

A
  • growth modification

- growth modification

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66
Q

for the growth of the maxilla and mandible, growth in the ___ is completed first, then growth in the ___, and then growth in the ___ direction

A
  • width
  • vertical
  • anterior-posterior
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67
Q

orthodontic force applied to teeth has the potential to radiate outward and affect ___ locations

A
  • distant skeletal

- it is now possible to apply force to implants or temporary anchorage devices to affect a patients growth

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68
Q

since the downward and forward growth of either the maxilla or the mandible is influenced by the growth of adjacent soft tissues, what two things would seem reasonable?

A
  • pressures resisting the downward and forward movement of either jaw, would decrease the amount of growth of bone
  • while adding to the forces that pull the maxilla or mandible downward and forward should increase their growth
69
Q

typically during normal growth, the maxilla undergoes a small amount of forward rotation, which rotations the maxilla up and ___ and down ___. this rotation tends to tip the maxillary incisors ___ which increases their prominence

A
  • anteriorly
  • posteriorly
  • forward
  • a small amount of forward rotation is the usual pattern, but backward rotation also frequently occurs
70
Q

extraoral force to the maxilla has been used for class ___ correction since the late 1800s

A

II

71
Q

extraoral force applied to the maxillary teeth radiates to the ___, where it can affect the pattern of skeletal maxillary growth

A

sutures of the maxilla

72
Q

depending on the direction of pull of the force with an occipital pull head gear, the maxilla can be restricted in its growth in which two directions?

A
  • anterior-posterior

- vertical

73
Q

___ of the maxilla in a class II patient allows the mandible to catch up as it grows normally in the anterior-posterior and vertical dimensions, which corrects the patients class II relationship

A

restriction of growth

74
Q

what are the 2 components of head gear?

A
  • outer bow - different lengths

- inner bow - must be sized to fit into the maxillary first molars

75
Q

what is considered optimal for head gear wear?

A

worn regularly for 10-12 hours per day, minimal for 8 hours per day

76
Q

with head gear, what is the ideal amount of force for orthopedic changes?

A

250-450g per side

77
Q

with head gear, what is the ideal amount of force for tooth movement?

A

100-200g per side

78
Q

what is the greatest advantage of suing extraoral anchorage (head gear)?

A

it permits the posterior movement of teeth in one arch without adversely disturbing the opposite arch

79
Q

what are the 3 “pull” types offered with head gear?

A
  • occipital pull
  • cervical pull
  • combination pull
80
Q

___ pull restricts inferior and anterior maxillary growth

A

occipital

81
Q

___ pull restricts superior and anterior maxillary growth, which can extrude maxillary molars and cause an open bite

A

cervical

82
Q

___ pull restricts anterior maxillary growth

A

combination

83
Q

like other sutures of the facial skeleton, the ___ becomes increasingly tortuous and interdigitated with increasing age

A

midpalatal suture

84
Q

in childhood (early mixed dentition), sutural expansion can be accomplished with ___

A

almost any type of expansion device

85
Q

by early adolescence, interdigitation of spicules in the midpalatal suture has reached the point that a ___ with considerable force is required to create microfractures before the suture can open

A

jackscrew

86
Q

by the late teens, interdigitation and areas of bony bridging across the suture develop to the point that ___ becomes impossible

A

skeletal maxillary expansion

87
Q

T or F:
crossbites can occur either anteriorly or posteriorly and should be corrected as soon as possible to eliminate potential damage through traumatic occlusion

A

true

88
Q

crossbites should be thoroughly diagnosed and usually fall into 1 of which 3 different categories?

A
  1. dental (teeth have erupted into a crossbite position)
  2. functional (the cusp tips of the teeth require the patient to shift to one side or the other in order to achieve maximal intercuspation)
  3. skeletal (dentition is normal, but the skeletal growth has developed asymmetrically causing the crossbite)
89
Q

a ___ crossbite, as contrasted with a functional crossbite, usually demonstrates a smooth closure to centric occlusion

A

skeletal

90
Q

what are 6 methods of crossbite correction?

A

hyrax appliance, haas appliance, hawley removable expansion, quad-helix, W arch, transpalatal arch

91
Q

a ___ is a condition where the maxillary and the mandibular teeth move past each other like a pair of scissors

A
  • scissor bite

- the occlusal surfaces of the teeth are not in occlusion

92
Q

scissor bites can be dental, skeletal, or functional in nature and can be very damaging to the surrounding bone and gingiva due to what two things?

A
  • teeth may occlude on the opposing gingiva and bone

- teeth are displaced buccally and lingually causing thinning of bone and gingiva

93
Q

T or F:

scissor bites are easy to correct orthodontically

A

false

94
Q

transverse force across the maxilla in children and adolescents can open the ___

A

midpalatal suture

95
Q

the midpalatal suture expansion force is usually delivered with a ___ mechanism, which is fixed to the maxillary teeth

A

jackscrew

96
Q

during midpalatal suture expansion, the maxilla opens as if on a hinge, with its apex at the ___

A

bridge of the nose

97
Q

during midpalatal suture expansion, the suture also opens on a hinge anterioposteriorly, separating more ___ than ___

A

more anteriorly than posteriorly

98
Q

maxillary expansion is typically between ___ and ___

A

5-15mm

99
Q

after palatal expansion, you will typically see what two things?

A
  • diastema formation between the central incisors

- expansion of the nasal floor

100
Q

what are the two general philosophies for implementing maxillary expansion?

A
  • fixed expansion

- removable expansion

101
Q

what are 4 negative effects from suing removable expansion appliances?

A
  • the overall apical and crestal stress in the periodontium of anchor teeth is higher in a removable appliance compared to a fixed appliance
  • removable appliances also produce higher stress in both cortical and spongy bone from forces produced against the hard palate and alveolar bone
  • the vertical displacement (crown tipping) of molar cusps is higher in removable appliances than fixed
  • patient compliance is worse for removable appliances
102
Q

for maxillary expansion, generally a ___ appliance is superior to a ___ appliance

A
  • fixed bonded palatal expansion

- removable

103
Q

rapid maxillary expansion is considered to be at a rate of ___mm per week

A

3-7mm

104
Q

slow maxillary expansion is considered to be at a rate of ___mm per week

A

1-2mm

105
Q

T or F:
rapid maxillary expansion was recommended when the technique was reintroduced int he 1960s because it was thought that this produced more skeletal than dental change, though recent research has shown this not to be true

A
  • true
  • although it initially produces more skeletal than dental changes, the teeth cannot respond to the quick heavy force produced through rapid expansion
  • during the time when bone is filling in, orthodontic tooth movement continues and allows skeletal relapse, so that although total expansion is maintained, the percentage due to tooth movement increases and the skeletal expansion decreases
106
Q

with slow expansion at a rate of 1mm per week, the total expansion is about half skeletal and half dental from the beginning. how does the outcome compare to rapid expansion at 2 weeks vs 10 weeks?

A
  • looks very different at 2 weeks

- very similar at 10 weeks

107
Q

what procedure is performed when maximum skeletal expansion and minimal dental expansion is desired?

A
  • implant supported expansion
  • the patient has a narrow maxillary arch with palatal screws (implants) for deliver of expansion force directly to the bone
  • the expansion device has a wire framework that clips over the exposed head of the bone screws
  • the expansion force is only against the screws
108
Q

T or F:
a study conducted comparing tooth-anchored maxillary expansion with bone-anchored maxillary expansion showed both expanders having similar results

A

true

109
Q

in a study conducted comparing tooth-anchored maxillary expansion with bone-anchored maxillary expansion, the greatest changes were seen in the ___ dimension; changes in ___ and ___ dimension were negligible

A
  • transverse

- vertical and anterior-posterior

110
Q

in a study conducted comparing tooth-anchored maxillary expansion with bone-anchored maxillary expansion, ___ expansion was greater than ___ expansion, and the authors of the study discovered similar tipping of the molars with both appliances

A
  • dental

- skeletal

111
Q

internal rotation of the mandible (rotation of the core relative to the cranial base) has what two components?

A
  • rotation around the condyle, or matrix rotation

- rotations centered within the body of the mandible, or intra-matrix rotation

112
Q

it can be observed that in most individuals, the body of the mandible rotates during growth in a way that would tend to decrease the ___ angle. what two ways can this occur?

A
  • mandibular plane angle (it would go up anteriorly and down posteriorly)
  • this can occur either by rotation around the condyle or rotation centered within the body of the mandible
113
Q

because the mandibular arch is more constrained, the limits of expansion for stability seem to be tighter for the mandible than the maxillary arch, due to there not being a ___ to expand skeletally

A

patent mandibular suture

114
Q

available data suggests that moving lower incisors forward more than ___mm is problematic for stability, probably because lip pressure seems to increase sharply at about that point

A

2mm

115
Q

T or F:

a considerable body of data shows that expansion across canines is stable

A
  • false

- it is not stable, even if the canines are retracted when they are expanded

116
Q

expansion across the ___ and ___ can be stable if it is not overdone

A

premolars and molars (this is dental expansion only, not skeletal expansion)

117
Q

how much expansion should canines, first premolars, second premolars, and molars be limited to?

A
  • canines = 0-1mm,
  • first premolars = 2mm
  • second premolars = 2-3mm
  • molars = 3mm
118
Q

since the mandible, like the maxilla, grows largely in response to growth of the surrounding soft tissues, it should be possible to alter its growth in somewhat the same was maxillary growth can be altered by ___ or ___

A
  • pushing back against it or pulling it forward
  • to some extent this is true, but the attachment of the mandible to the rest of the facial skeleton via the TMJ is very different from the sutural attachments of the maxilla
119
Q

T or F:
the response of the mandible to force transmitted to the TMJ is nearly the same as the response of the maxilla to force transmitted to sutures

A

false

120
Q

what is a chin cup device/appliance?

A
  • an extra-oral force used to control excess mandibular growth
  • it has been shown to remodel the TMJ and restrain mandibular growth on experimental animals but the appliance has to be worn on a full time or nearly full time basis, something that children simply won’t do
121
Q

what is the difference between a soft and hard chin cup appliance?

A

the soft chin cup appliance is more comfortable but increases the chance that the lower incisors will be tipped lingually, which is undesirable in skeletal class III patients

122
Q

one of the problems with the chin cup device is that the extraoral force aimed at the condyle of the mandible tends to ___

A

load only a small portion of the rounded surface

123
Q

T or F:

controllying excessive mandibular growth is an important unsolved problem in contemporary orthodontics

A

true

124
Q

what is a delaire-type facemask (reverse pull headgear)?

A
  • used to place forward traction against the maxilla and a restrictive force against the mandible
  • in class III patients, the maxilla is often deficient vertically, and antero-posteriorly
  • a downward and forward direction of force is usually needed, which can be provided by the delaire-type facemask
125
Q

forward traction against the maxilla by a reverse pull headgear typically has what 3 effects?

A
  • some forward movement of the maxilla
  • forward movement of the maxillary teeth
  • downward and backward rotation of the mandible
126
Q

T or F:

the mandible tends to respond well to restraining its growth

A

false

127
Q

how can growth stimulation be implemented in the mandible?

A

when the condyle translates forward away from the temporal bone during normal function, the mandible can be pulled into a protruded position and held there for long durations with moderate and tolerable force, which should stimulate force

128
Q

T or F:
if growth stimulation is defined as producing a larger mandible at the end of the total growth period than would have existed without treatment, then it is harder to demonstrate a positive effect

A

true

129
Q

T or F:

patients treated with mandibular growth stimulation tend to have larger mandibles than those not treated

A
  • false

- studies have shown that the ultimate size of the mandible in treated and untreated patients is remarkably similar

130
Q

the difference between growth acceleration in response to a functional appliance and true growth stimulation can be represented using a ___

A

growth chart

131
Q

if growth occurs at a faster-than-expected rate while a functional appliance is being worn and then continues at the expected rate thereafter so that the ultimate size of the jaw is larger, true ___ has occurred

A

stimulation

132
Q

if faster growth occurs while the appliance is being worn, but slower growth thereafter ultimately brings the patient back to the line of expected growth, there has been a ___, and not a ___

A

acceleration, and not a true stimulation

133
Q

although there is a great deal of individual variation, the response to a functional appliance will most often show what on a growth chart?

A

a solid line

134
Q

T or F:

the extent to which growth modification treatment can produce permanent skeletal change remains controversial

A

true

135
Q

a functional orthodontic appliance is either ___ or ___

A

bonded or removable

136
Q

how do functional orthodontic appliances move the dentition?

A
  • repositioning the skeletal bases, placing force on the teeth through stretching the musculature and soft tissues
  • and/or by changing the dental occlusal relationships thereby changing the occlusal forces placed on teeth
137
Q

what are 4 examples of functional orthodontic appliances?

A

frankel, bionator/activator, clark twin block, and herbst

138
Q

there is a definite threshold for the duration of force needed to move a tooth. what is this duration?

A
  • at least 6 hours

- whether a similar duration threshold exists for sutures in unknown

139
Q

is has been shown that addition of new bone at the epiphyseal plates of the long bones occurs mostly, perhaps entirely, at night. why?

A

during the evening and sleeping hours, more growth hormone is being released

140
Q

what are 3 treatment options for a patient with a deficient mandible?

A
  • modify growth
  • orthodontic camouflage (moving the teeth to camouflage a skeletal abnormality)
  • orthognathic surgery
  • it is important to realize these options could produce different results
141
Q

presenting a ___ of the post treatment profile can greatly help patients understand the differences between alternative treatment approaches

A
  • computer generated simulation
  • although showing patients these simulations heightens their esthetic awareness, some patients are not bothered by their profile and do not want to correct it
142
Q

permanent teeth often erupt in abnormal positions as a result of ___

A

over-retained primary teeth

143
Q

in circumstances where over-retained primary teeth have caused permanent teeth to erupt in abnormal positions, how can this be corrected?

A
  • removal of the over-retained primary tooth/teeth will allow some spontaneous alignment of the ectopically erupting permanent teeth
  • it is important to remember that permanent teeth normally move occlusally and buccally while erupting
144
Q

___ is when two tooth buds fuse together to make one large wide crown

A
  • tooth fusion
  • the fused tooth will have two independent pulp chambers and root canals
  • the fusion will start at the top of the crown and travel possibly to the apex of the root.
145
Q

___ is when one tooth bud tries to divide into two teeth

A
  • tooth gemination
  • the tooth count is normal with gemination
  • on a radiograph, the geminated tooth will have one pulp canal but two pulp chambers
146
Q

T or F:

treatment options for fused or gemination teeth are usually not good

A

true

147
Q

what are some treatment options for fused or gemination teeth?

A
  • extraction
  • RCT
  • recontoured crowns
  • sometimes ortho is needed
148
Q

T or F:

elastics are usually attached to brackets and archwires, but it is sometimes necessary to attach it to a naked tooth

A
  • false

- they should never be attached around a naked tooth

149
Q

elastics worn in a vertical direction with no anterior or posterior forces are used for which angles classification?

A

class I

150
Q

elastics worn from the anterior on the maxillary teeth to the posterior on the mandibular teeth are used for which angles classification?

A

class II

151
Q

elastics worn from the anterior on the mandibular teeth to the posterior on the maxillary teeth are used for which angles classification?

A

class III

152
Q

elastics worn from the lingual of one or more maxillary teeth to the buccal of one or more mandibular teeth are used for which malocclusion classification?

A

crossbite

153
Q

___ is the resistance to unwanted tooth movement

A

anchorage

154
Q

___ is used to create space (example is using headgear to distalize a tooth to create space

A
  • traction

- the skull is used as anchorage to distalize the tooth

155
Q

in orthodontics, for every desired action, there is an equal and opposite reaction. ___ forces move other teeth as well as cause movements that are unwanted. ___ is used to minimize unwanted tooth movement, while maximizing desired effects.

A
  • reaction forces

- anchorage

156
Q

T or F:

in orthodontics, it is possible to only consider the teeth whose movement is desired

A
  • false

- reciprocal effects throughout the dental arches must be carefully analyzed, evaluated, and controlled

157
Q

a major part of treatment planning is maximizing ___ and minimizing ___

A

maximizing the tooth movement that is desired, while minimizing undesirable side effects

158
Q

the goal of anchorage is to maintain the concentration of force on the tooth that movement is desired, while keeping the pressure in the ___ as low as possible, ideally below the threshold that tooth movement occurs

A

PDL of the anchor teeth

159
Q

the threshold of tooth movement is quite low, so ___ is often necessary to distribute forces

A

multiple anchorage teeth

160
Q

what is the “anchorage value” of any give tooth roughly equivalent to?

A

that tooth’s root surface area

161
Q

in each arch, the anchorage value of the first molar and second premolar are approximately equal in surface area to the ___ and ___

A

canine and two incisors

162
Q

what is the best example of reciprocal tooth movement?

A
  • closing a diastema between the central incisors
  • force applied to the teeth and the arch segment are equal and so is the force distribution in the PDL so only desired tooth movement occurs
163
Q

___ is accomplished by adding additional teeth to the unit to distribute the force over a larger root surfaced area in the anchorage unit (could also add an extraoral force such as headgear or interarch elastics)

A

reinforced anchorage

164
Q

___ describes minimizing displacement of anchor teeth by arranging the force system so that the anchor teeth must move bodily (translation ___g), if they move at all. the anterior teeth are allowed to tip ___g.

A
  • stationary anchorage
  • 70-120g
  • 35-60g
165
Q

two stage treatment with tipping followed by uprighting can be used as a means of controlling ___, by distributing the force over a larger PDL area of the anchor teeth, and thus reducing ___

A
  • anchorage

- pressure in that area

166
Q

how is anchorage accomplished with the palate?

A

acrylic plate in the roof of the mouth

167
Q

how is anchorage accomplished with the head/neck?

A

headgear

168
Q

how is cortical anchorage accomplished?

A

using the resistance of cortical bone to remodel

169
Q

what are some options for temporary anchorage?

A

devices (TADs), implants, and ankylosed teeth

Ortho (15 decks)

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