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Ortho > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

early loss of a primary tooth presents a potential alignment problem because ___

A

drift of the permanent or other primary teeth is likely unless it is prevented

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2
Q

space maintenance is appropriate only when ___, and when all unerupted teeth are in normal position and at the normal stage of development

A

adequate space is available

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3
Q

if there is not enough space for the permanent tooth or if the permanent tooth is missing, space maintenance alone is ___ and other treatment approaches are necessary

A

inadequate or inappropriate

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4
Q

the most rapid losses in the anterior-posterior distance of the arch is usually due to what?

A

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

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5
Q

T or F:
when the primary second molar is lost early, it is always necessary to maintain the space until the arrival of the second premolar

A

true

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6
Q

when can a space maintainer be removed?

A

once the tooth has erupted enough that the crown has emerged through the gingival tissues

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7
Q

which type of space maintainer should be restricted to holding the space of a single tooth and why?

A
  • band and loop

- the loop has limited strength and is not intended to accept the functional forces of chewing

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8
Q

about how long do band and loop space maintainers last, and what is the most frequent problem influencing this?

A
  • 18 months

- cement failure

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9
Q

whenever a space maintainer is used, it must be monitored carefully for what two things to be successful?

A

breakage and leakage

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10
Q

what is the purpose of placing a spur to rest on the distal marginal ridge of the first primary molar?

A

helps resist levering occlusal pressures placed on the band and loop space maintainer

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11
Q

when a second primary molar is lost prematurely, should you band the primary first molar or permanent first molar? what are some considerations?

A
  • typically the first permanent molar is the tooth of choice
  • risk of decay to permanent tooth
  • evaluate x-ray to determine when the first primary molar will be lost
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12
Q

when is a distal show space maintainer indicated?

A

when a primary second molar is lost before the eruption of the permanent first molar

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13
Q

to facilitate easier placement, the distal shoe space maintainer is usually placed at or very soon after ___

A

extraction of the primary molar

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14
Q

the distal shoe space maintainer has a loop portion, made of ___ wire, and the intra-alveolar blade, which are soldered to a band so that ___

A
  • 36mil stainless steel

- the whole appliance can be removed and replaced with another space maintainer after the permanent molar erupts

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15
Q

in the design of the distal shoe space maintainer, the loop portion must be contoured closely to the ridge because ___

A

the appliance cannot resist excessive occlusal forces from the opposing teeth

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16
Q

in the design of the distal shoe space maintainer, the blade portion must be positioned so that it extends ___mm below the mesial marginal ridge of the erupting permanent tooth in order to ___

A
  • 1mm

- guide its eruption

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17
Q

in the design of the distal shoe space maintainer, how can the position of the blade be measured?

A
  • from pretreatment radiographs and verified by a radiograph taken at try-in or post-cementation
  • an additional occlusal radiograph can be obtained if the faciolingual position is in doubt
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18
Q

a lingual holding arch is usually the best choice to maintain space for ___ after premature loss of the ___; what teeth MUST be erupted for this to work?

A
  • premolars
  • mandibular primary molar(s)
  • permanent incisors must be erupted
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19
Q

in the design of the lingual holding arch, it is stepped away from the premolar area to allow for their eruption without interference, which results in a ___ design; he wire is also ___mm away from the soft tissue at all points.

A
  • keyhole

- 1.5mm

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20
Q

in the design of the lingual holding arch, a spur can be used in the mixed dentition for either of what two purposes?

A
  • to maintain a correct midline when a primary canine is lost
  • or to retain an orthodontically corrected midline.
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21
Q

A maxillary lingual arch on the maxillary teeth can be used if ___.

A

the overbite is not excessive

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22
Q

what is a nance appliance?

A
  • a Nance arch with an acrylic button in the palatal vault is indicated if the overbite is excessive.
  • he palatal button must be monitored closely, because it may cause soft tissue irritation.
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23
Q

the transpalatal arch prevents ___

A
  • a molar from rotating mesially into a primary molar extraction space
  • prevents the first molars mesial migration, but it is necessary for the mesially positioned teeth to be present on the opposite side of the arch when a transpalatal arch design is employed as a sole space maintainer
24
Q

what can happen if the mesially positioned teeth are missing on both sides, and the TPA is used as a space maintainer?

A

-the entire TPA can drift mesially, thus loosing arch length.

25
Q

what is the reasoning behind the decision to replace maxillary anterior primary teeth in patients when more than one tooth is missing and when it will be more than 6 months before eruption of permanent central incisors?

A

the presence of replacement teeth will hold the tongue in a better position. In this way, the development of a tongue thrust is less likely, but there are no well validated empirical research which actually demonstrates an association between missing primary anterior teeth and the development of tongue thrust

26
Q

are there any identifiable serious risks to replacement of multiple missing primary maxillary incisors?

A

no

27
Q

what are the pros and cons for replacement of missing maxillary primary teeth?

A
  • pros: possible prevention of tongue thrust, esthetics

- cons: insurance companies rarely cover this procedure

28
Q

what are 3 removable space maintainers?

A
  • hawley (wire labial bow) retainer with tooth
  • removable essix with tooth
  • removable partial denture (replaces anterior teeth for esthetics)
29
Q

what are some considerations when making a removable partial denture?

A
  • multiple clasps, preferably adams’ clasps, are necessary for good retention
  • both the clasps and the acrylic need frequent adjustment to prevent interference with physiologic adjustment of primary teeth during eruption of permanent teeth
30
Q

removable space maintainers are dependent on ___

A

patient compliance

31
Q

removable space maintainers should be removed during ___ and ___

A

eating and brushing teeth

32
Q

why should removable retainers to replace one missing primary molar be avoided?

A

they are a choking hazard

33
Q

what are 3 other types of space maintainers?

A
  • lip bumper
  • bonded retainers
  • fixed prosthetics (maryland bridge, composite bridge)
34
Q

what is a lip bumper?

A

a bar that is typically connected to the mandibular first molars, and is held away from the teeth to preserve arch length

35
Q

What type of space maintainer would you use if both mandibular second primary molars are lost prematurely and the mandibular permanent incisors haven’t erupted?

A
  • a pair of band an loop space maintainers is recommended in this case instead of a lingual arch
  • on younger patients the primary incisors often erupt lingually, which would then interferer with their eruption
36
Q

if a patient needs to have the primary canine extracted, does space maintenance need to be used? why or why not?

A
  • yes, typically always
  • when one primary canine is extracted, the central and lateral incisors will drift into the missing canines space, causing a space deficiency for the permanent canine, as well as a midline discrepancy
  • if both primary canines are extracted, the central and lateral incisors tend to tip lingually, causing a space deficiency, and space maintenance should be used
37
Q

if a patient needs to have the primary canine extracted, what can a spur on a lingual arch be used for?

A
  • to maintain the midline and arch length, when a primary canine is lost
  • or to retain a orthodontically corrected midline
38
Q

what is the best choice for a space maintainer to prevent mesial movement of a second primary molar?

A

a band and loop space maintainer

39
Q

why is it important to start space maintenance therapy prior to the eruption phase of the permanent tooth?

A

since the force of eruption of the permanent tooth exerts pressure which can push the adjacent primary tooth forward

40
Q

the ___ phase of the permanent molar is the time of greatest forces exerted against the primary molar

A

eruption phase

41
Q

do you need space maintenance if the first primary molar is lost after the first permanent molar has fully erupted?

A

space maintenance should be considered on a case by case basis, and is not necessary in every case

42
Q

if a patient loses a primary molar unilaterally in the maxillary arch, what is the best choice for space maintenance?

A

band and loop space maintainer

43
Q

if a patient loses primary molars bilaterally, space maintenance should be employed to prevent ___; what are the best choices for space maintenance?

A
  • prevent the shifting of the maxillary second primary molars (if the first permanent molars haven’t erupted yet), or first permanent molars mesially
  • both a nance holding arch or a bilateral band and loop space maintainer; a lingual arch could be used if it doesn’t interfere with the patient’s anterior occlusion
44
Q

what are the pros and cons of a nance holding arch?

A
  • doesn’t come loose often
  • could cause palatal irritation
  • doesn’t prevent the distal shift of B and I
  • total arch length is still preserved
45
Q

what are the pros and cons of a bilateral band and loop space maintainer?

A
  • works well

- has a higher occurrence of breakage

46
Q

what are the pros and cons of a lingual arch?

A
  • similar to the nance

- cannot be used if a patient has a deep bite occlusion

47
Q

if a permanent first molar is extracted on a child before the eruption of the permanent second molar, does the patient require space maintenance?

A
  • no space maintenance is necessary, because the erupting second molar will drift in a mesial direction, and will typically fill the space of the first molar most of the time, although the second molar may be tipped mesial once it has fully erupted
  • this same situation can also be applied to third molars when second molars are lost
  • in both situations, the teeth that are moving mesially to close the space must be unerupted
48
Q

in some cases, the first permanent molar will erupt mesially and impact beneath the second primary molar. what are some possible treatment options in this case?

A
  • placement of a separator or brass wire to distalize the maxillary first molar
  • orthodontics to distalize the maxillary molar
  • extraction of the second primary molar with orthodontics to distalize the maxillary first molar (requires space management after treatment is complete)
49
Q

if a patient is missing a permanent tooth, the best space maintainer is ___

A
  • the primary tooth
  • as long as it doesn’t ankylose, it will work to function in occlusion, maintain space, and maintain alveolar bone for possible future implant
  • it is important to make sure the primary tooth remains healthy and caries-free
50
Q

when a primary tooth needs to be extracted and the permanent tooth is still erupting, do you need space maintenance?

A
  • if the permanent tooth will erupt within 6 months (ie. more than 1/2-2/3 of its root is formed), then space maintenance is unnecessary
  • judgement of the root length is tricky, so when in doubt, use a space maintainer
51
Q

what does the tanaka johnston mixed dentition analysis predict?

A

the size of the unerupted teeth

52
Q

using the tanaka johnston mixed dentition analysis, how would you calculate mandibular arch length?

A

MANDIBULAR ARCH: measure the M-D width of each of the mandibular incisors, add these widths together, then divide this total number by 2; add 10.5; this number will represent the estimated size of the M-D widths of the mandibular 1st and 2nd premolars and canine for one side; multiply this number by 2 to get the widths for both sides, then add this number to the total M-D width of the mand. incisors and you can calculate the estimated arch length

53
Q

using the tanaka johnston mixed dentition analysis, how would you calculate maxillary arch length?

A

MAXILLARY ARCH: measure the M-D width of each of the MANDIBULAR incisors (yes, mand. incisors are used to estimate maxillary arch too), add these widths together, then divide this total number by 2. add 11; this number represents the size of the M-D widths of the max. 1st and 2nd premolars and canines, for one side; calculate arch length by multiplying this number by 2 and adding it to the total M-D width of the 4 max. incisors

54
Q

using the tanaka johnston mixed dentition analysis, how would you calculate arch perimeter?

A
  • take segmental measurements around each arch, one arch at a time
  • measure from the M of the first permanent molar to the D of the lateral incisor
  • measure from the D surface of the lateral incisor to the M surface of the central incisor
  • repeat steps for the opposite side, then add all 4 segments together = arch perimeter
55
Q

using the tanaka johnston mixed dentition analysis, how would you calculate estimated crowding and spacing?

A
  • subtract the arch perimeter by the arch length
  • a negative number represents the amount in mm of crowding
  • a positive number represents the amount in mm of spacing

Ortho (15 decks)

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