Diagnostic aids in orthodontics

Orthodontic study castThey are

accurate plaster reproductions of the teeth and their surrounding soft tissues

Orthodontic study cast

Orthodontic study castUses of study models:

1.Assist and record dental anatomy

2. Assist and record intercuspation3. Assist and record arch form4. Assist and record the curves of

occlusion 5. Calculate total space analysis6. Measure progress during

treatment7.Medico legal documentation

Orthodontic study castPont’s analysis:Measurement of the 4 maxillary

incisors automatically establish the width of the arch in the premolar and molar region by using :

Calculated premolar value= SI x 100 80 Calculated molar value = SI x 100 64Measured premolar and molar value

is obtained from the distance between distal end of the occlusal groove

(SI = the sum of incisors)

Orthodontic study castCarey’s analysis Is to discover the arch length –

tooth size discrepancy

Orthodontic study castAvailable

space required space

Spacing

Crowding

Normal

Orthodontic study castBolton AnalysisTo determine the

disproportion between the size of the maxillary and mandibular teeth

Overall ratio= sum of mand12 x 100

sum of maxOverall Ratio = 91.3%

Anterior ratio= sum of mand6x 100 sum of max

Anterior ratio = 77.2%

Orthodontic study castmixed dentiton analysis:Used to evaluate the amount of

space available in the arch for succeeding permanent teeth

Moyer’s mixed dentition analysis

By using prediction charts

Tanaka and Johnson analysis

Predicted width of canine and premolar

Maxillary= sum of mandibular incisors + 11 2

Mandibular= sum of mandibular incisors + 10.5 2

Orthodontic study cast

Unerupted tooth size =

Erupted tooth on cast X uneurpted on xray Erupted on x-

ray