Class 1

Question 1

What are key factors for crowding and malalignment?

Answer 1

• Facial & Dental estheetics
• Post-tx stability
• Dental Occlusion

Question 2

For Class 1 cases, when should you extract teeth?

Answer 2

• Facial Disharmony
• Jaw Discrepancy
• Lip incompetence due to protrusion

Question 3

Facial & Dental Esthetics: Incisors too protrusive vs too retrusive

Answer 3

Tooth Promince:
* Extraction: Less
* Expansion: More

Incisors too protrusive: Soft Tissue Relationships
* Lip Incompetence
* Thick full liipps look good w/more incisor promience, not in thin, tight lips

Incisors Too retrusive: Soft tissue relationships
* Size of nose & chin effects lip prominence
* Backward incline of upper lip=Upper incisors to lingual
* Best Esthetics: Low lip is at least as proinent as the chin
* Large chin and/or nose: tx options
1 no ext and move incisors forward: best if no lip incompetence
2 ext & retract incisors

Question 4

Stability:

Answer 4

Ability of the arch to hold its position when external forces are applied
* Tongue pushes arch buccal
* Liip pushes arch lingual

Lower Arch=tighter limits for expansion:
1 Lower incisors: 2 mm of forward movement
* Lip pressure=Limiting factor of forward
* Incisor tipped buccally & crowded=as protrusive as ST allows
* Incisor tippedl ingual can move farther vs upright incisor

2 K9: Not sable (0-1 mm)
* even if K9s are retracted

3 Premolars/Molars: Stable if not overdone
* 1st premolar: 2 mm
* 2nd premolar: 2-3 mm
* 3rd premolar: 3 mm

Question 5

Expansion:

Answer 5

• Less stable
• More lip prominence (Full lips)

Tranverse expansion:
* expand more than AP
* Only posterior to K9s
K9s never maintained; Not stable (0-1 mm)
* intercanine dimension Decreases as we age
* due to lip P at corner of mouth
Molar/Premolars: Maintain; Stable
* low cheek pressures

Excess Transverse Expansion Increase risk of:
1 gingival stripping–> Gingival recession
* critical variable: amt of attached gingiva, If questionable-perio consult, and gingival graft before tx
2 Fenestration of premolar and molar roots through alveolar bone
* Increase if > 3 mm

Question 6

Class 1 Extraction guidelines

Answer 6

1. ALD < 4:
   nonextraction
   * expansion
   * reduce m-d tooth width of selected teeth
   Extractoin:
   * severe incisor protrusion (7-10 mm)
   * severe vertical discrepancy
2. ALD: 5-9 mm
   Both possible depending on:
   * hard & soft tissue characteristics
   * How final incisor poistiion is controlled