Mixed Dentition Analysis and Serial Extraction Flashcards
what are the 6 forms of tooth size arch length discrepancy manifestations
- lateral incisor eruption forcing premature exfoliation of temporary cuspids
- patients with severe crowding, the lateral incisor is in contact with the mesial surface of the deciduous first molar
- after a forced unilateral exfoliation of a deciduous cuspid
- labial or lingual eruption of permanent incisors
- premature loss of deciduous molars could lead to arch length deficiencies
- labial or lingual eruption of cuspids
how are the mesiodistal width of unerupted cuspids and bicuspids predicted
- non radiographic methods
- radiographic methods
what are the nonradiographic methods
- tanaka and johnston
- moyers
what is half the mesiodistal width of the four permenanent upper and lower incisors
- maxilla = +11.0mm
- mandible = +10.5mm
what is the moyers method
- measure the MD width of the four lower incisors
- determine the required space to align the four permanent incisors
- determine the available space
- predict the combined MD widths of the cuspid and two bicuspids
- determine the remaining space (subtracting the estimated widths of the cuspid and two bicuspids from the available space)
what are the radiographic methods
- Huckaba
- Hixon- Oldfather
what is the huckaba method
technique based in the assumption that the magnifciation degree of a ddeciduous tooth on an xray would be the same as the erupting permanent tooth on the same PA film
describe the moyer method
- minimum error and quickly done
- could be done by experts or novice
- no need for special equipment or XR
- could be done on study models or in mouth and both arches
what is the tanaka and johnston method
correlates the MD widths of the four permanent lower incisors with the widths of the cuspid, first, and second bicuspid of one side of the maxillary and mandibular arch
how do you do the huckaba analysis
- measure the MD width of the deciduous tooth on the XR (Y’)
- measure the MD width of the successor permanent tooth on the XR (X’)
- measure the MD width of the deciduous tooth on the study model (Y)
- the MD width of the permanent tooth is calculated by a mathematical proportion (X)
what is the formula for the huckaba analysis
X = X’Y/Y’
what is the hixon oldfather method
developed an equation to predict the MD widths of the unerupted cuspid and two bicuspids from children of the Iowa Facial Growth Study
- measuring only the teeth from the left side of each subject
- the estimated error was signifcantly reduced revewing the original equation
- measure the teeth on both sides of each subject
what are the steps to follow to predict tooth size in the hixon oldfather analysis
- measure the MD widths of the lower right central and lateral incisors on the study models
- measure the MD widths of the lower right first and second bicuspids on the PA XR
- add both measurements and take that number to the prediction graph to determine the MD widths of the cuspid and both bicuspids
- add one standard error to the estimated prediction
- do the same procedure for the left side
- add the predicted widths with the widths of the erupted lower incisors to obtain the required space from mesial of first molar to mesial of first molar
- measure the available space and subtract the required space
if the meixed dentition analysis predicts light crowing:
maintain the arch length with any appliance and examine the patient periodically probably will need future ortho tx
what is light crowding
1-4mm
