Orthodontic Space Analysis

Question 1

Locations of Space Deficit/Excess (Crowding/Spacing)

Answer 1

Anterior (3-3)
Midarch (4-6)
Posterior (7-8)

Question 2

Determining available Posterior Space

Answer 2

Distal of 6 to Anterior border of ramus (along the occlusal plane)
Posterior limit: 2-3mm distal of anterior border of ramus

Question 3

Considerations for Posterior Space Deficiency in a growing patient (difficult to determine)

Answer 3

1. Rate of mesioocclusal migration of 6s
2. Rate of resorption of anterior border of ramus: 3mm increase per year in posterior dentition area (1.5mm per side) after complete eruption of 6s until 14(F) and 16(M)

Question 4

How to determine if patient has posterior space deficiency

Answer 4

Eruption of 7s is delayed

Question 5

How to correct posterior space deficiency

Answer 5

Removal of 8s

Question 6

Does Impaction = Posterior Space Deficiency?

Answer 6

No. Could be caused by ectopic position of tooth

Question 7

Quantifying Space relation issues

Answer 7

1. Direct measurement on Models
   Sum of Mesio-distal width of teeth (5-5) - Arch length (measuring from 6m-3m + 2d-1m + contralateral side) = Crowding (+ve) or Spacing (-ve)
2. Estimation
   a. Identify areas with crowding/spacing
   - Overlap of contact points
   - Displacement
   b. Estimate amount of space needed to align the teeth

Question 8

What causes non-apparent crowding

Answer 8

Correction of proclined teeth (requires space)

Question 9

What causes non-apparent spacing

Answer 9

Correction of retroclined teeth (creates space)

Question 10

Quantifying non-apparent spacing/crowding

Answer 10

1. Using formulas
   Every 1mm change in A-P postion of a tooth results in a 2mm space deficiency./excess
2. Estimation