Orthodontics II Flashcards
DENTAL ARCH MEASUREMENTS nArch \_\_\_\_ n Arch \_\_\_\_ n Arch \_\_\_\_ n Arch \_\_\_\_ (Height)
• When we talk about dimensional measurements of the dental arch, we think about primarily arch circumference which is the measurement of the ____ and ____ of the arch itself.
length width circumference depth size shape
Arch Length
INTERCANINE DISTANCE
When we talk about measurements of arch length we talk about this measurement.
• Arch length- is the ____ line from the most anterior tooth in the mouth to the most
posterior tooth
◦ In the primary dentition- The most posterior tooth is the distal aspects of the
primary second molar.
◦ In a mixed dentition or permanent dentition- were talking about that same anterior position which is tangent across the ant surface of the teeth to the most posterior tooth which is the distal aspect of second premolar or the mesial aspect of the adult molar.
tangent
Arch Length Changes From Primary to Permanent
- increase?
- decrease?
In some respects, its arch length is going to stay the same!
• We see more consistencies in arch length in the ____ arch
• But actually for both arches, we see a ____ in the arch length measurements
◦ Decrease is seem more substantially in the ____ and only slightly in the
maxillary
• Therefore, we will have ____ space for teeth as we progress from a full
complement of primary teeth to a full complement of permanent teeth.
maxillary
decrease
mandible
less
Arch length
Mandibular, girls
• When looking at these graphs, its important to note the axis
◦ X axis- Age in ____
◦ Y axis- Changes in ____ (mm)
• These arch length changes will be ____ specific and ____ specific.
• We will see subtle changes in regards to gender specific issues. Like for most things
we’ve talked about in dental and growth and development so far.
• However we will see more dramatic difference when we compare changes in the max arch length vs mand arch
years
arch length measurement
arch
gender
Transition from Full Primary to Full Permanent Dentition
n 3 Stages of Development
n ____ Dentition
n ____ Period
n ____ Dentition
early mixed
intertransitional
late mixed
Early mixed dentition
• In the early mixed dentition we see a very slight ____ of our arch length measurement.
◦ Primary dentition - posterior tooth Is the ____ in the primary dentition.
◦ Mixed dentition- posterior tooth is the messiah aspect of the ____.
we originally see some early loss of spaces as we decrease from 25 to about 24. That initial downwards slope and loss of arch length is due to closure of ____.
The we see the emergence of the ____
◦ Remember this is the same sequence that we talked about last time.
◦ M1- perm first molar, I1- perm central , I2-perm lateral.
‣ In palmer notation M1, I1, I2 is 6,1,2 respectively
We see a slight slight uptick as we see the emergence of the incisors.
decease 2nd molar perm first molar primate space perm first molar
PRIMATE SPACE
n LOCATION
n TIMING of CLOSURE
There’s 2 main spaces that we talk about when we measure arch length differences.
A. Primate space- a ____ space closure or space loss
B. Loss of leeway space- ____ space closure or space loss
• These are important concepts to understand because these are typical questions that would be asked on the orthodontist/pedo section of the boards!
• So this is the substantial part of the dimensional change of the arch and they’re important spaces to understand.
• Where these spaces are ____ are gonna be important, the ____ and amount of closure is important to know as well.
minimal
major
located
timing
PRIMATE SPACE
n LOCATION
nMaxillary Arch > Between ____
nMandibular Arch > Between ____
• Primate space in the maxillary arch is located ____ to the primary canine.
• Primate space in the mandible is located ____ to the primary canine
primary lateral incisor and canine
primary canine and primary first molar
mesial
distal
n TIMING OF CLOSUREà Upon eruption of permanent ____ (especially mandibular)
◦ So when we see ____ emerge, we see the closure of primate space
Why would primate space be more affected in the mandibular arch than the maxillary arch?
• Yes, the mandibular teeth erupt first but what about the locations of the molar
related to the space?
◦ Its closer to the ____!
• So if you have a tooth emerging from the ____ aspect of the dentition the mandibular arch, the primate space is gonna be more directly affected than max arch primate space.
◦ Because its actually closer to the emergence of the permanent teeth.
◦ We have more closure of the primate space in ____ and as opposed to the max.
◦ Most of the primate space is maintained for the most part in the max arch.
There is some closure in the maxillary but it is not as substantial as the mandibular
first molars 6 space distal mandibular
Arch Length ____
Primary to Permanent
n Closure of ____
n Closure of Leeway Space
decrease
primate space
Transition from Primary to Permanent
n 3 Stages of Development
n ____ Dentition
n ____ Period
n ____ Dentition
- Early mixed dentition is from age ____.
- Intertransitional period is from age ____.
- Late mixed is ____ and a little beyond
early mixed intertransitional late mixed 6 to 8 8 to 10 10-12
Transition from Primary to Permanent
What occurs in this inter transitional period from a tooth emergece perspective?
• As we discussed the other day, during an early mixed dentition:
◦ We started with 20 primary teeth
◦ We see the emergence of the ____.
‣ Remember the early stage of mixed dentition we have a complement of 20 primary teeth with ____ adult teeth!
‣ Therefore we end up with a total of ____ teeth.
How many teeth do we have at the end stage of the early mixed dentition?
• ____ is correct! But what is our ratio?
• We still have the same complement of teeth but the ratio will be different 50% adult and 50%
primary = ____ primary and ____ permanent
◦ At the latest stage of the early mixed dentition we are gonna exfoliate our primary central and primary laterals in both the max and mandibular arch.
◦ So we’re gonna see the emergence of perm laterals, perm centrals perm at this point.
perm first molars
4
24
24
12
12
Intertransitional Period
What happens in the intertransitional period (age 8-10) from a tooth emergence perspective?
• There are no ____ changes.
• Theres a lot evolving in terms of tooth formation underlying the primary teeth.
• But purely looking at ____ pattern, we don’t see any changes. We see the emergence of 6, 1, 2, in the early mixed dentition
• In intertransitional phase (sometimes referred to middle mix transition)
◦ We see no ____ changes
◦ We see emergence in mand arch of perm first molars, perm central, perm lateral incisor. this plateau here is the inter transitional period
dental emergence
dental emergence
dental emergence
Transition from Primary to Permanent
n 3 Stages of Development
n Early Mixed Dentition
n Intertransitional Period
n Late Mixed Dentition
Then we move on in a late mixed dentition in mandibular arch
Whats the first event that occurs in the late mixed dentition in the Mandibular arch?
1. We see loss of ____
2. Emergence of ____
primary canine
perm canine
Late Mixed Dentition
• Quiz question: what would our first event be in the mixed late dentition in the max arch? ◦ Its ____. Remember the sequence is going to be different.
◦ The sequence in mixed late dentition is ____ in (palmer notation) for mandibular
◦ And ____ in maxillary
• We see emergence of perm canine and first second premolar.
• Dimensionally, we’ve gone from about 24 mm to the emergence of our perm second molar to about ____ mm.
• We lose ____ space. Which is the Mesial-Distance distance between the primary molars and PM
first premolar 3457 4537 22.5 leeway
LEEWAY SPACE
nLOCATION > Differential in ____ size between primary molars and premolars (possibly canines)
Of all of the teeth, if we include canines, primary first molar, primary 2nd molars, and compare max to Mandibular teeth. Which single tooth do you think contributes the most to leeway space?
◦ Answer: ____
◦ Think about the size and shape of primary 2nd molar.
‣ Remember from tooth anatomy, the primary second molar is almost as large MD as a perm first molar.
‣ If you picture the size and shape of a larger primary molar tooth and the second premolar substituting for that space, theres a substantial difference between the size and shape MD.
◦ Yes, a single primary 2nd molar will contribute the most to leeway space. This is why we have more leeway space in ____ than the max arch.
mesiodistal
mand second molar
mandibular
LEEWAY SPACE
nTIMING OF CLOSURE > Closes by loss of ____ (especially 2nd molar) upon eruption of ____, mostly from a ____ direction
primary molars
premolars
distal
Arch Length DECREASE Primary to Permanent
n Closure of Primate Spaces
n Closure of Leeway Spaces
- Closure of leeway space - major decrease
A. Reminder again this is from the emergence of the ____, first PM, 2nd PM, ultimately to the perm first molar - In the graph we can see that we started out at 25.5 mm and ended up ended up at ____ mm.
A. So we have quite a substantial closure or loss of arch length from that transition from primary teeth into perm teeth
perm canine
23
Changes in Arch Length Primary to Permanent Dentition
nEarly Mesial Shift =Closure of ____
nLate Mesial Shift =Closure of ____
primate space
leeway space
“Maintenance of the ____ is sufficient to align all of the permanent teeth within the arch in seventy percent of children.”
This means that we could conserve leeway space!
- If we start ____ before we lose primary second molars, we can preserve the leeway space
- We may be able to correct crowding issues using the extra posterior space to unravel anterior crowded and thus avoid having to consider extracting perm teeth
We try to do as much as we can to avoid ____ extractions.
◦ Sometimes its necessary but if we can preserve leeway space that gives us one advantage in that non extraction vs ext mode of treatment. Especially when we transition from late mixed dent to perm dentition. Which is for the most part around the time we usually begin a comp tx phase or what we called a stage/ phase 2 tx.
primary second molar
treatment
PM
ARCH LENGTH CHANGES
n ____ SPECIFIC
n ____ SPECIFIC
ARCH
GENDER
Arch Length Difference Mandibular; Girls v. Boys
- There are changes are really ____.
- The graphs are ____
- The biggest difference has to do with the maxillary as compared to the ____ graph. ◦ The reason why is because we see a lesser close of ____
subtle
analogies
mandibular
primate space
Arch Length Difference
Maxillary; girls v boys
• The biggest difference has to do with the max as compared to the Mandi graph.
• The reason why is because we see a lesser closure of ____ as upon the emergence of ____
• We see a larger uptick as we see emergence of perm Central and perm lateral incisors. And the middle
part of the mixed dentition is the inter transitional period. And then a loss of leeway space.
• We have our leeway space closure and the sequence of mergence is difference where instead we see 345 canine followed by 1st 2nd PM. In the max arch we see first PM, 2nd PM, canine and followed by
emergence of the perm 2nd molar.
primate space
perm first molar
Arch length difference
Maxillary; girls v boys
Why do we see this larger uptick when we have primate space closure and then really its off set substantially by increased arch length as we see emergence of perm central and perm lateral incisors.
Why does this occur?
We talked about this previously on weds. The eruption pattern of max incisors as opposed to Mandi incisors. Do yrhy have a tendency to erupt in the max arch in an identical spot to the psi incisors or do they have a tendency to erupt ina. More labial position compared to the primary incisors?
• ____. If you picture our arch length measurement from the most ant tooth to the most D aspect of the primary second molar or the M aspect to the second first molar. If you have incisors that will emerge slightly labial to the primary teeth they’re replacing this will actually ____ our arch length measurement.
Then we have our inter transitional period. And we have a lesser loss of space because again the difference in size between our primary molars compared to the PM in the max arch is ____ awn what we had in the mandibular arch
Overall is our net difference lesser or greater than the max arch?
• Its ____, substantially lesser. Started out with 28mm with our arch length measurement and we ended
about ____ so we have substantial amount of net difference from beginning to end in Mandi arch as
labial increase lesser lesser 27.5
Arch length difference
Max. v. mand; boys
• When we talk about our differences when we look at the graph for boys
◦ Maxillary- started at ____ mm and ended at ____
◦ Mandibular- started at ____ and ended at ____
• In maxillary graph- maxillary graph where we see the ____ of the incisors,
◦ which is going to offset our loss of ____
• In mandibular arch - we don’t have much labiality of the incisors because of the ____ pattern.
◦ so the loss of primate space added to our loss of leeway space isn’t really offset by much.
29 28 25.5 23 labiality leeway space eruption