Week 1 Posterior crossbites

Question 1

Transverse skeletal problem?

Answer 1

True facial asymmetry (mainly mandible)

Maxillary constriction

Question 2

Transverse dental problem?

Answer 2

Posterior cross bite

Question 3

how much of population with a posterior crossbite?

Answer 3

9% of adults

6-10% of whole population

Question 4

True or false?

1) True midface asymmetry is common
2) True mandibular asymmetry treatment is very complicated

Answer 4

1) False, very rare

2) True

Question 5

What can cause facial asymmetry?

Answer 5

1. Post-trauma
2. Growth deficiency/excess
3. Mandibular shift (CR - CO)

Question 6

Most common cause of facial asymmetry?

Answer 6

Mandibular shift (CR - CO)

Question 7

True max skeletal constrictions results from changes in __________

Answer 7

changes in max transverse dimension

Question 8

Treatment options for Max skeletal constriction?

Answer 8

Near adolescents & adolescents (10-19yrs): RPE or SPE (heavy force device)

Preadolesent in the primary and mixed dentitions: Lingual arch type appliances (Double or Quad Helix)

Question 9

3 types of maxillary expanders

Answer 9

1. Jackscrew type
2. Spring type
3. Bonded with jackscrew type

Question 10

RPE vs SPE

Answer 10

RPE: 1-2 quarter turns/day (Tx time

Question 11

Problems with RPE or SPE?

Answer 11

Pain

Soft tissue irritation

Maxillary diastema (but will close)

Breakage

Debonding

Question 12

When do you use lingual arch type expanders?

Answer 12

For primary and mixed dentition

W arch or Quad helix

Treatment time: months
Retention: months

Question 13

RPE is not indicated in adults.. why?

Answer 13

Use banded and bonded fixed appliance if the case is very minor.

If bilateral and significant: surgery is indicated for expansion

Question 14

With palatal expansion there is _________ effects

Answer 14

50 dental

50 skeletal

Question 15

What causes the posterior cross bite?

Answer 15

1. Retained primary teeth

2. Crowding / tipped teeth

Question 16

Rationale for posterior dental crossbite correction?

Answer 16

Improve premolar position (if moving primary teeth)

Reduce abrasion (aso CR -> CO)

Increase arch perimeter (for more space)

Eliminate CR-CO shifts (simplify diagnosis and potential for asymmetric growth)

Question 17

True or False?

Lingual arch type does the same thing as RPE/SPEs

Answer 17

True

it is for Early mixed/mixed dentition

Question 18

W arch anchorage, configuration, wire type, retention?

Answer 18

anchorage: reciprocal

can be designed asymmetrically if the case has a true unilateral post cross bite.

W configuration increases length of wire and flexibility

Wire: 036 SS (other materials would not produce enough forces across the suture)

Retention: Cemented bands (also take away patient compliance problems)

Question 19

Biomechanics of W arch?

Answer 19

Force: applied near the palatal CEJ
(not through Cres, Cres located higher)

Type of movement: some bodily & some tipping

Where would the areas of compression be? : facial surfaces of molars

We want to limit tooth movement if there is no dental crossbite…. but (remember the final result is 50 skeletal and 50 dental…)

Question 20

Quad helix anchorage type, configuration, wire type, retention?

Answer 20

Biomechanically same as W arch…

Anchorage: reciprocal

Quad configuration: increases length wire and flexibility

Wire type: 0.038 SS

Retention: cemented bands

Question 21

When do we use Cross Elastics to fix posterior crossbite?

Answer 21

When both Maxillary and Mandibular in the wrong position.

Use cross elastics when you are only correcting the dental displacement.

Should take several weeks to fix the crossbite.

Question 22

Problems with cross elastics?

Answer 22

Compliance

Question 23

Retention period for Cross elastics?

Answer 23

retention period is really overcorrection, looking for rebound, and then removing the appliance

Question 24

True or False?

The patient must wear cross elastics at all time except when they eat

Answer 24

True