Mixed Dentition Analysis & Serial Extraction

Question 1

List the 6 forms of tooth size arch length discrepancy manifestations:

Answer 1

1. Lateral incisor eruption forcing premature exfoliation of temporary cuspids
2. Patients with severe crowding, the lateral incisor is in contact with the mesial surface of the deciduous first molar (no room for canines)
3. After a forced unilateral exfoliation of a deciduous cuspid
4. Labial or lingual eruption of permanent incisors
5. Premature loss of deciduous molars could lead to arch length deficiencies
6. Labial or lingual eruption of cuspids

Question 2

Prediction of the mesiodistal widths of unerupted cuspids and bicuspids can be done via:

Answer 2

1. non-radiographic methods
2. radiographic methods

Question 3

non-radiographic methods to predict mesiodistal widths of unerupted cuspids and bicuspids include:

Answer 3

1. tanaka & johnston
2. moyers

Question 4

The prediction of the size of unerupted canines and premolars in a contemporary orthodontic population is correlated to the MD widths of the four permanent lower incisors with the widths of the cuspids, first premolar and second premolar of one side of the maxillary and mandibular arch:

Answer 4

Tanaka & Johnston (non-radiographic method)

Question 5

For Tanaka & Johnston method, half of the mesiodistal widths of the four permanent lower incisors:

Answer 5

+11.0 = maxilla

+10.5 = mandible

Question 6

Tanaka & Johnston is performed:

Answer 6

by quadrant

Question 7

Method of prediction of the MD widths of unerupted canines and premolars-

• which could predicted with minimum error & quickly done
• could be performed by novices or experts
• no need for special equipment or xrays
• could be done on study models or in mouth
• could be done on both arches

Answer 7

Moyers

Question 8

List the steps to Moyers prediction of the MD widths of unerupted canines & premolars:

Answer 8

1. measure the MD width of the 4 lower incisors
2. determine the REQUIRED space to align the 4 permanent incisors
3. determine the AVAILABLE space
4. predict the combined MD widths of the canine and two premolars
5. determine the REMAINING space (subtracting the estimate widths of the canine and two premolars from the available space)

Question 9

Radiographic methods to determine the MD width of unerupted canines & premolars include:

Answer 9

1. Huckaba
2. Hixon-oldfather

Question 10

Radiographic method to predict the MD widths of unerupted canines & premolars via arch size analysis and tooth size prediction:

Answer 10

Huckaba

Question 11

The technique for Huckaba is based on the assumption that the magnification degree of a deciduous tooth on an x-ray would be the same as:

Answer 11

the erupting permanent tooth on the same PA film

Question 12

List the steps involved in Huckaba analysis:

Answer 12

1. Measure the MD width of the deciduous tooth on the x-ray (Y’)
2. Measure the MD width of the successor permanent tooth on the x-ray (X’)
3. Measure the MD width of the deciduous tooth on the study model (Y)
4. The MD width of the permanent tooth is calculated by a mathematical proportion (X)

Question 13

List two equations for Huckaba analysis and describe variables:

Answer 13

X: X’ = Y: Y’

X= X’Y/Y’

X: MD width of the permanent tooth (calculated)
X’: MD width of successor permanent tooth on xray
Y: MD width of deciduous tooth on study model
Y’: MD width of deciduous tooth on xray

Question 14

For Huckaba analysis- measuring the MD width of the deciduous tooth on the xray results in:

Answer 14

Y’

Question 15

For Huckaba analysis- measuring the MD width of the successor permanent tooth on the x-ray results in:

Answer 15

X’

Question 16

For Huckaba analysis- measuring the MD width of the deciduous tooth on the study model results in:

Answer 16

Y

Question 17

What does the Hixon-Oldfather analysis estimate?

Answer 17

estimation of the sizes of the unerupted canine and premolars (radiographically)

Question 18

Developed an equation to predict the MD widths of the unerupted canine and two premolars from children of the Iowa Facial Growth Study by measuring ONLY the teeth from the left size of each subject:

Answer 18

Hixon-Oldfather Analysis

Question 19

Hixon-Oldfather Analysis, only measure teeth from the:

Answer 19

LEFT side of each subject

Question 20

T/F: with the Hixon-Oldfather Analysis, the estimated error was significantly reduced reviewing the original equation. Measuring the teeth on BOTH sides of each subject.

Answer 20

True

Question 21

List the steps of the Hixon-Oldfather Analysis: (revised)

Answer 21

1. measure the MD widths of the lower right central and lateral incisors on the study models
2. measure the MD withs of the lower first and second right premolars on x-ray
3. Add both measurements and take that number to the prediction graph to determine the MD widths of the canine and both premolars
4. Add one standard error to the estimated prediction
5. Do same procedure for left side
6. Add the predicted widths of th erupted lower incisors to obtain the required space from mesial of first molar to mesial of first molar (crossed arch)
7. Measure the available space and subtract the required space

Question 22

If the mixed dentition analysis predicts that there is NOT a crowding problem, you should:

Answer 22

continue with periodic patient observation

Question 23

If the mixed dentition analysis predicts light crowding (1-4mm), you should:

Answer 23

1. maintain the arch length with any appliance
2. examination of patient periodically (probably will be a need for future ortho treatment)

Question 24

What is considered light crowding in mixed dentition analysis?

Answer 24

1-4 mm

Question 25

If the mixed dentition analysis predicts crowding of more than 4 mm, most probably the patient will:

Answer 25

develop crowing in the permanent dentition which will require ortho treatment after a thorough evaluation

Question 26

If the mixed dentition analysis predicts a crowding in excess of 6mm:

Answer 26

In the mandibular arch, the patient will benefit from serial extraction

Question 27

The orderly removal of deciduous and permanent teeth in a determined sequence:

Answer 27

Serial extraction

Question 28

Pre-requisites for serial extraction:

Answer 28

1. Skeletal Class I
2. Dental Class I
3. Bimax dental protrusion
4. Dental crowding in excess of 6 mm
5. Light of anterior open bite tendency
6. No congenitally missing second premolars

Question 29

List the main benefits of serial extraction:

Answer 29

1. naturally induced movement & alignment of severely crowded anterior teeth
2. health improvement of the adjacent tissues
3. psychological and cooperation improvement, due tot he incisor alignment
4. decrease on orthodontist workload and stress
5. less iatrogenic damage

Question 30

List the main disadvantages of serial extraction:

Answer 30

1. Increase of the overbite
2. Lingual inclination of the incisors
3. Scaring tissue on the extraction spaces
4. Diastemas
5. Alteration on the tongue function

Question 31

A cephalometric evaluation of the effects of class I serial extraction proceeds found a:

Answer 31

delay on mandibular growth

Question 32

Two types of serial extraction include:

Answer 32

1. conventional serial extraction
2. alternative serial extraction

Question 33

1. Premature extraction of the deciduous canines provides the space for the incisors to assume normal positions over supporting bone
2. Extraction of the first deciduous molars permits the desirable early eruption of the firm premolars
3. Final extraction of the first premolars makes it possible for the canines to erupt in favorable direction

Answer 33

Conventional serial extraction