Mixed Dentition Analysis Methods

MIXED DENTITIONMIXED DENTITION
ANALYSISANALYSIS
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MOYERS MIXED DENTITIONMOYERS MIXED DENTITION
ANALYSISANALYSIS
 The purpose of a mixed dentition analysis is toThe purpose of a mixed dentition analysis is to
evalute the amount of space available in theevalute the amount of space available in the
arch for the erupting permanent canines andarch for the erupting permanent canines and
premolars. In this analysis the size of thepremolars. In this analysis the size of the
unerupted permanent cuspids and premolars areunerupted permanent cuspids and premolars are
predicted from the knowledge of the sizes ofpredicted from the knowledge of the sizes of
certain permanent teeth that are already eruptedcertain permanent teeth that are already erupted
in the mouth.in the mouth.

 The moyers analysis predicts the combinedThe moyers analysis predicts the combined
mesio-distal width of 3,4,5 based on the sum ofmesio-distal width of 3,4,5 based on the sum of
the widths of the four lower permanent incisors.the widths of the four lower permanent incisors.
 the mesio-distal width of the four lower incisorthe mesio-distal width of the four lower incisor
are measured and summed up.the amount ofare measured and summed up.the amount of
space available for the 3,4and 5 after incisorspace available for the 3,4and 5 after incisor
alignment is determined by measuring thealignment is determined by measuring the
distance between the distal surface of lateraldistance between the distal surface of lateral
incisor and the mesial surface of first permanentincisor and the mesial surface of first permanent
molarmolar..

 Based on the mesio-distal width of fourBased on the mesio-distal width of four
mandibular incisors, the expected width of themandibular incisors, the expected width of the
canines, first and second premolars arecanines, first and second premolars are
predicted by referring the probability chart. Whilepredicted by referring the probability chart. While
doing so,the 75%level of probability isdoing so,the 75%level of probability is
considered reliable.considered reliable.
 The predicted tooth size of 3,4,5 is comparedThe predicted tooth size of 3,4,5 is compared
with arch length available for them so as towith arch length available for them so as to
determine the discrepancy. If the predicted valuedetermine the discrepancy. If the predicted value
is greater than the available archis greater than the available arch
length,crowding of teeth can be expectedlength,crowding of teeth can be expected

 Total mandibular width of 345Total mandibular width of 345
incisor widthincisor width
19.5 20.6, 20.119.5 20.6, 20.1
20.0 20.9,20.420.0 20.9,20.4
20.5 21.2,20.720.5 21.2,20.7
21.0 21.3,21.021.0 21.3,21.0
21.5 21.8,21.321.5 21.8,21.3
22.0 22.0, 21.622.0 22.0, 21.6
22.5 22.3,21.922.5 22.3,21.9
23.0 22.6,22.223.0 22.6,22.2
23.5 22.9, 22.523.5 22.9, 22.5
24.0 23.1, 22.824.0 23.1, 22.8

HUCKABA’S ANALYSISHUCKABA’S ANALYSIS
 Here both study cast and radiographs areHere both study cast and radiographs are
used for determining the width ofused for determining the width of
unerupted tooth.unerupted tooth.
 PrinciplePrinciple
 with any type of radiograph, it iswith any type of radiograph, it is
necessary to compensate for enlargementnecessary to compensate for enlargement
of the radiographic image. This can beof the radiographic image. This can be
done by measuring an object that can bedone by measuring an object that can be
seen both in radiograph and on the cast.seen both in radiograph and on the cast.

 YI= X1 xY2/X2YI= X1 xY2/X2
 y1= width of unerupted tooth whose measurement is toy1= width of unerupted tooth whose measurement is to
be determinedbe determined ..
 y2= width of unerupted tooth on radiograph.y2= width of unerupted tooth on radiograph.
 X1=width of a tooth that has erupted measured on theX1=width of a tooth that has erupted measured on the
cast.cast.
 X2=Width of a tooth that has erupted,measured on theX2=Width of a tooth that has erupted,measured on the
radiographradiograph

 Accuracy of this method of determiningAccuracy of this method of determining
the width of the unerupted tooth is fair tothe width of the unerupted tooth is fair to
good, depending upon the quality of thegood, depending upon the quality of the
radiographs and their position in the archradiographs and their position in the arch
 this technique can be used in maxillarythis technique can be used in maxillary
and mandibular arches for all ethnicand mandibular arches for all ethnic
groups.groups.

HIXON AND OLD FATHER’SHIXON AND OLD FATHER’S
 The mesio-distal width of mandibularThe mesio-distal width of mandibular
central and lateral incisor is obtained fromcentral and lateral incisor is obtained from
the casts. Determine the width of thethe casts. Determine the width of the
premolars from the intraoral periapicalpremolars from the intraoral periapical
radiographs made using long coneradiographs made using long cone
technique. Sum up the width of centraltechnique. Sum up the width of central
and lateral incisor along with the width ofand lateral incisor along with the width of
unerupted premolars of that particularunerupted premolars of that particular
side.side.

 The estimated sum total width of theThe estimated sum total width of the
cuspids and bicuspids of that particularcuspids and bicuspids of that particular
side can be obtained from the chart. Everyside can be obtained from the chart. Every
measured sum width of incisor andmeasured sum width of incisor and
bicuspids has a corresponding sum widthbicuspids has a corresponding sum width
of the cuspids and bicuspids in the chart.of the cuspids and bicuspids in the chart.

 measured values estimated tooth sizemeasured values estimated tooth size
46 18.446 18.4
 47 18.747 18.7
 48 19.048 19.0
 49 19.449 19.4
 50 19.750 19.7
 51 20.051 20.0
 52 20.352 20.3
 53 20.753 20.7
 54 21.054 21.0
 55 21.355 21.3

56 21.656 21.6

Nance careys analysisNance careys analysis
This analysis is similar to arch perimeter analysisThis analysis is similar to arch perimeter analysis
of the permanent dentition.of the permanent dentition.
PROCEDUREPROCEDURE
measure the mesio-distal width of the eruptedmeasure the mesio-distal width of the erupted
permanent teeth.permanent teeth.
measure the width of each unerupted tooth,measure the width of each unerupted tooth,
cuspids and bicuspids (3,4,5) from the intra-oralcuspids and bicuspids (3,4,5) from the intra-oral
periapical radiographsperiapical radiographs..

 The total mesio-distal width of all the teeth inThe total mesio-distal width of all the teeth in
each quadarent will indicate space required toeach quadarent will indicate space required to
accommodate the permanent toothaccommodate the permanent tooth
..
 using brass wire measure the arch perimeter.using brass wire measure the arch perimeter.
 compare the space required and spacecompare the space required and space
available to arrive at the arch lengthavailable to arrive at the arch length
discrepancy.discrepancy.

Mixed Dentition Analysis Methods

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Mixed Dentition Analysis Methods