Maxillary Expansion

Question 1

Diagnosis to expand

Answer 1

-narrow palatal vault (easily assessed using casts)
-transpalatal width of 31 mm or less is likely to require expansion
-Transverse deficiency

Question 2

Transverse deficiency

Answer 2

Crossbite, crowding, laterally flared posterior teeth, dark spaces at the corners of the mouth

Question 3

Etiology

Answer 3

-environmental and genetic factors
-airway difficulties
-digit habits

Question 4

Airway difficulties

Answer 4

Promote mouth breathing —> tongue in floor of mouth —> no pressure from tongue on maxilla to expand it

Question 5

Digit habits

Answer 5

Buccinator muscle creates inward force

Question 6

3 methods for expansion

Answer 6

-split removable plate with jack screw or heavy midling spring
-lingual arch —>quad helix, W-arch
-fixed palatal expander with jack screw

Question 7

Primary/early mixed dentition

Answer 7

-use quad helix (100g force)
-jack screws can accidentally be activated too rapidly and distort facial structures

Question 8

Late mixed dentition

Answer 8

4 band RPE
2 band RPE
Include as many teeth as possible
Exo case- delay extraction of premolars

Question 9

4 band RPE

Answer 9

Severe anterior crowding and a tapered arch form

Question 10

2 band RPE

Answer 10

Mixed dentition with mild crowding

Question 11

Rapid activation of jackscrews

Answer 11

0.5 mm per day
10-20 lbs of pressure

Question 12

Semi rapid activation of jackscrews

Answer 12

0.25 mm per day

Question 13

Slow activation of jackscrews

Answer 13

1 mm per week
2 lbs of pressure

Question 14

______ can provide same ultimate result over a 10-12 weeks as RPE with less trauma to teeth and bones

Answer 14

Slow

Question 15

Effects of palatal expansion

Answer 15

Separation of palatal suture is non parallel
Stresses are concentrated in the anterior and progress to the posterior (can get diastemas, posterior maxilla has more attachments)
Wedge shape separation from frontal view

Question 16

Effect on mandinle of palatal expansion

Answer 16

Mandibular teeth often upright
Inter molar and inter canine distances increase

Question 17

Expand until maxillary ______ cusps occlude with ________ inclines of buccal cusps of mandibular molars

Answer 17

Lingual, lingual

Question 18

Retain for _____ months using the appliance

Answer 18

4-6 months

Question 19

What to do when appliances arent enough

Answer 19

Suture closure
Treatment options - SARPE/SARMe, multiple piece Lefort I

Question 20

Sutural considerations

Answer 20

Major area of resistance to expansion is not just the midpalatal suture
-frontomaxillary, zygomaticofrontal, zygomaticomaxillary, zygomatic temporal sutures

Question 21

SARPE indications

Answer 21

-Transverse maxillary deficiencies > 5 mm in skeletally mature pt (<5 mm can be camouflaged by the ortho)
>-7 mm discrepancy —> SARPE definitely indicated (more stable and vascularity is not compromised as in segmentalized LeFort osteotomies
- if extractions are not desired prior to surgery
-pt with arch length discrepancies and maxillary incisors in an acceptable vertical and sagittal position are ideal

Question 22

SARPE vs Lefort I

Answer 22

-SARPE= more stable in transverse
-Risk of perio defects, relapse and compromised blood supply are reduced with SARPE
-Lefort require alignment of teeth/tipping of roots prior to surgery and often extractions