space analysis and its interpretation Flashcards
how to determine if there is enough room for succideneous teeth in mixed detention
measure space within the arches after the permanent incisors and first molars have erupted
- compare to space needed to align unerrupted permanent teeth
what is the space available
Distance the arch circumference rom the mesial of 1 permanent first molar to the mesial of the other 1 permanent first molar
how to determine space available
strait line segments
- 2 lateral from mesial of 1st molar to alveolar process in canine
- 2 anterior from canine region to midline
what is the space required
the sum of the width of incisors that have erupted plus the width of the canines and premolars that have not erupted
how to measure for space required
incisors directly from dental casts
- measure unerupted on radiographs
- correlate width of erupted lower incisors
what type of radiograph should be used for estimating teeth size
periapical
not panoramic
how accurate is measuring magnification by comparing to a known tooth size
fair to good, depending on quality
pros and cons of measuring magnification by comparing to a known tooth size
useful for all ethnic groups
extra-radiation
how good is the correlationg between size of permanent lower incosor to unerupted canines and premolars
Good
what method for estimating tooth size uses proportionality tables
Moyers prediction
how to use the moyers method
Mesiodistal width of lower incisors are measured
- use table to predict both upper and lower
quality of the Tanaka-johnston prediction
good accuracy with small bias toward overestimating the unerupted tooth sizes
what does the Tanaka-john prediction predict
the size of the unerupted canines and premolars using the lower incisors
how to do the tanaka johnson prediction
uses two formulas from the mesiodistal width of the lower incors
what are the formulas for mandible canine and premolars in one quad
1/2MD width of 4 lower incors+10.5mm
what are the formulas for he maxillary canine and premolars in one quad
1/2 MD width of 4 lower incisors+11mm
what is the problem os using radiographic images
Getting a good canine view
what is the Hixon-oldfather prediction
combination of radiographic and proportionality table
what is done in the Hixon-oldfather prediction
size of permanent incisors measured from the dnetal casts and size of premolars measure from periapical radiographs to predict size of unerupted canines
what demographic does the Hixon-oldfather prediction show
norther europe
- not good for african or asia
problems with the Hixon-oldfather prediction
mandiular arch only
Needs periapical radiographs
what is the most practical way to do space analysis
Tanaka and Johnston method
why is the Tanaka_johnston prefered
No radiographs
No lengthy prediction tables, graphs or equations
Both arches
Reasonable prediction
what to consider when using Tanaka-Johnston method
The ethnicity of the children(caucasian was used to measure
what is the assumption of the Tanaka-Johnston
- corrrelation between size of erupted mandibular incisors and size of remaining unerupted max and mandibular canine
- patient must fit the caucasion population
- teeth are developing normally
what are the most variable teeth appart from 3rd molars
max lateral incisors
Mad second premolars
how to adust predictions if from a different population
- recongize limitation
- different table/formula for racial group
- use individualized periapical radiographs
what are some of the last teeth to show up
premolars
- may not be sure on the size
what does space analysis assume
- Arch dimensions do not increase during growth
- possition of the incisors will not change in a way that increases or decreases circumference and available space
- the mesial shift of 1st molars can be predicted accurately, at least with Class I
what classification tends to have the best space analysis
Class I
when can arch circumference and incisor stability be assumed
after the eruption of lateral incisors
why does class II cause problems with space analysis
- lower incisors tend to tip facially, increasing sapce in the lower arch
- upper incisor moves facial or lingual
why does class II cause problems with space analysis
lower incisors tip lingually, decreaseing space in the lower arch
- upper incisors move facial, increasing space
what is used to measure teeth
Boley gauge, sharpened to get interproximal
how acccurate should measurements be
down to the 10th millimeter
how to calc mandiular arch length
measure cont arch length over the contacts of the mandibular teeth between mesial of permanent 1st molar on the right to the left
what does section one measure
Space analysis (mandible)
what does section 2 measure
mesiodistal width of the lower incisors
what does section 3 measure
calc the maxillary arch length
what does section 4 measure
mesiodistal maxillary incisor width
what does section 5 measure
mandibuar space available
what is found in section 6
maxillary space available
what is included in section7-10
determine skeletal status of patient
determine if mesial molar shift can occurs
why determine skeltetla status of patient
mandibular incisors stabilit and space implication
where do you get the info for section 7
facial profile analysis on the reverse side of space analysis form
what does a jaw relationship of Class I and Class II molar relatoinship mean
maxilary space loss/shortage
what tooth is good for previous dental relationships, even when posterior teeth have drifted
Canine
what does a class III molar relationship with a class I skeletal pattern mean
mandibular space loss/shortage
when should you complete section 9
when a patient has a class I skeletal relationship and 1 or both molars in an end-to-end relationship or not quite class I
when can a class I molar releationship be achieved with a class I skeletal relationship with an end to end molar relatoinship
- shift mandibular 1st permanent molar mesially into leeway space
- more mand than maxillary growth
- combo
what is the leeway space
Difference in total width of primary molars and canine, compared to combine width of permant teeth that are replaced
what happens to arch lengthin the late mixed dentition
arch length decreases
how to determine shortening of available space due to mesial shift
draw vertical line at the mesiobuccal cuspt tip of permanent max first molar
another line in buccal groove of permanet mandibular first molar
= distance between 2 space required to achieve class I occlusion
what is shown in class I
lip posture of the patient
how to determine if protrusive or retrusive lips
Protrusive: infront of nose-chin line
Retrusive: behind nose-chin line
how do you account for the change in first permanent molar position that may occur during trasition to the permanent dentition
measure distance the lower molar would have to move to go to class I
