Orthodontic Study Models

Arch perimeter analysis

Analysis used to assess the need for extraction in the maxillary arch

Nance Carey’s analysis

Analysis used to assess the need for extraction in the mandibular arch

• Pont’s analysis

• Linder Harth’s index

• Korkhaus analysis

• Ashley Howe analysis

Analyses used to assess the need of arch expansion

Bolton’s analysis

Analysis used to assess the tooth material excess

Mixed dentition analysis

Analysis used in mixed dentition

Arch perimeter analysis

• determination of arch length and total tooth material

• wire is placed contacting the mesial surface of the 1st M of one side and is passed over the buccal cusps of the premolars and along the anteriors and is continued on the opposite side in the same way up to the mesial surface of the opposite 1st M

Carey’s analysis

Similar to arch perimeter analysis, but performed on the mandibular cast

Mixed dentition analysis

• Evaluates space available for erupting permanent canines and premolars

• Estimates the size of unerupted permanent teeth

• Compares space available with space required

• Determines expected amount of crowding or spacing

• Radiographic method

• Prediction tables

• Combined method

According to Proffit and Ackerman, tooth size may be estimated using:

MD widths of the 4 permanent mandibular incisors

In Moyer’s Mixed Dentition analysis, prediction is based on the sum of the ?

Moyer’s Mixed Dentition Analysis

• Predicts the combined MD width of the unerupted canine and premolars (3, 4, 5)

• Uses a probability chart/table

• 75% probability level is commonly used

Radiographic method (Mixed dentition analysis)

• Estimates actual width of unerupted permanent teeth

• An erupted tooth is used as a reference to correct the radiographic measurement

Tanaka Johnston Method

• Non-radiographic mixed dentition analysis

• Used to predict the size of unerupted permanent canines and premolars (3,4,5)

• Used the MD width of 4 permanent mandibular incisors

• Does NOT require radiographs/probability tables

• Can be used to estimate tooth size in BOTH Mx and Md arches

Moyer uses a probability table; Tanaka-Johnston uses a formula

Differentiate Moyer’s vs. Tanaka-Johnston mixed dentition analysis

Tooth-to-tooth

Bolton’s analysis evaluates ? relationship

Bolton’s analysis

• Evaluates tooth-size discrepancy between the Mx and Md arches

• Uses the MD width of teeth

• Determines whether there is a relative Mx or Md tooth-size excess

• Important for achieving proper overjet, overbite, and occlusion

Pont’s analysis

• Determine whether the dental arch is narrow or wide

• Determine the need for lateral arch expansion

• Determine how much expansion is possible at the PM and M region