Lecture 4 Flashcards
early loss of a primary tooth presents a potential alignment problem because ___
drift of the permanent or other primary teeth is likely unless it is prevented
space maintenance is appropriate only when ___, and when all unerupted teeth are in normal position and at the normal stage of development
adequate space is available
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
inadequate or inappropriate
the most rapid losses in the anterior-posterior distance of the arch is usually due to what?
a mesial tipping and rotation of the permanent first molar after removal of the primary second molar
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
true
when can a space maintainer be removed?
once the tooth has erupted enough that the crown has emerged through the gingival tissues
which type of space maintainer should be restricted to holding the space of a single tooth and why?
- band and loop
- the loop has limited strength and is not intended to accept the functional forces of chewing
about how long do band and loop space maintainers last, and what is the most frequent problem influencing this?
- 18 months
- cement failure
whenever a space maintainer is used, it must be monitored carefully for what two things to be successful?
breakage and leakage
what is the purpose of placing a spur to rest on the distal marginal ridge of the first primary molar?
helps resist levering occlusal pressures placed on the band and loop space maintainer
when a second primary molar is lost prematurely, should you band the primary first molar or permanent first molar? what are some considerations?
- 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
when is a distal show space maintainer indicated?
when a primary second molar is lost before the eruption of the permanent first molar
to facilitate easier placement, the distal shoe space maintainer is usually placed at or very soon after ___
extraction of the primary molar
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 ___
- 36mil stainless steel
- the whole appliance can be removed and replaced with another space maintainer after the permanent molar erupts
in the design of the distal shoe space maintainer, the loop portion must be contoured closely to the ridge because ___
the appliance cannot resist excessive occlusal forces from the opposing teeth
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 ___
- 1mm
- guide its eruption
in the design of the distal shoe space maintainer, how can the position of the blade be measured?
- 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
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?
- premolars
- mandibular primary molar(s)
- permanent incisors must be erupted
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.
- keyhole
- 1.5mm
in the design of the lingual holding arch, a spur can be used in the mixed dentition for either of what two purposes?
- to maintain a correct midline when a primary canine is lost
- or to retain an orthodontically corrected midline.
A maxillary lingual arch on the maxillary teeth can be used if ___.
the overbite is not excessive
what is a nance appliance?
- 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.
the transpalatal arch prevents ___
- 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
what can happen if the mesially positioned teeth are missing on both sides, and the TPA is used as a space maintainer?
-the entire TPA can drift mesially, thus loosing arch length.
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?
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
are there any identifiable serious risks to replacement of multiple missing primary maxillary incisors?
no
what are the pros and cons for replacement of missing maxillary primary teeth?
- pros: possible prevention of tongue thrust, esthetics
- cons: insurance companies rarely cover this procedure
what are 3 removable space maintainers?
- hawley (wire labial bow) retainer with tooth
- removable essix with tooth
- removable partial denture (replaces anterior teeth for esthetics)
what are some considerations when making a removable partial denture?
- 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
removable space maintainers are dependent on ___
patient compliance
removable space maintainers should be removed during ___ and ___
eating and brushing teeth
why should removable retainers to replace one missing primary molar be avoided?
they are a choking hazard
what are 3 other types of space maintainers?
- lip bumper
- bonded retainers
- fixed prosthetics (maryland bridge, composite bridge)
what is a lip bumper?
a bar that is typically connected to the mandibular first molars, and is held away from the teeth to preserve arch length
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 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
if a patient needs to have the primary canine extracted, does space maintenance need to be used? why or why not?
- 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
if a patient needs to have the primary canine extracted, what can a spur on a lingual arch be used for?
- to maintain the midline and arch length, when a primary canine is lost
- or to retain a orthodontically corrected midline
what is the best choice for a space maintainer to prevent mesial movement of a second primary molar?
a band and loop space maintainer
why is it important to start space maintenance therapy prior to the eruption phase of the permanent tooth?
since the force of eruption of the permanent tooth exerts pressure which can push the adjacent primary tooth forward
the ___ phase of the permanent molar is the time of greatest forces exerted against the primary molar
eruption phase
do you need space maintenance if the first primary molar is lost after the first permanent molar has fully erupted?
space maintenance should be considered on a case by case basis, and is not necessary in every case
if a patient loses a primary molar unilaterally in the maxillary arch, what is the best choice for space maintenance?
band and loop space maintainer
if a patient loses primary molars bilaterally, space maintenance should be employed to prevent ___; what are the best choices for space maintenance?
- 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
what are the pros and cons of a nance holding arch?
- 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
what are the pros and cons of a bilateral band and loop space maintainer?
- works well
- has a higher occurrence of breakage
what are the pros and cons of a lingual arch?
- similar to the nance
- cannot be used if a patient has a deep bite occlusion
if a permanent first molar is extracted on a child before the eruption of the permanent second molar, does the patient require space maintenance?
- 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
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?
- 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)
if a patient is missing a permanent tooth, the best space maintainer is ___
- 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
when a primary tooth needs to be extracted and the permanent tooth is still erupting, do you need space maintenance?
- 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
what does the tanaka johnston mixed dentition analysis predict?
the size of the unerupted teeth
using the tanaka johnston mixed dentition analysis, how would you calculate mandibular arch length?
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
using the tanaka johnston mixed dentition analysis, how would you calculate maxillary arch length?
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
using the tanaka johnston mixed dentition analysis, how would you calculate arch perimeter?
- 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
using the tanaka johnston mixed dentition analysis, how would you calculate estimated crowding and spacing?
- 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
