Week 1 Posterior crossbites Flashcards
Transverse skeletal problem?
True facial asymmetry (mainly mandible)
Maxillary constriction
Transverse dental problem?
Posterior cross bite
how much of population with a posterior crossbite?
9% of adults
6-10% of whole population
True or false?
1) True midface asymmetry is common
2) True mandibular asymmetry treatment is very complicated
1) False, very rare
2) True
What can cause facial asymmetry?
- Post-trauma
- Growth deficiency/excess
- Mandibular shift (CR - CO)
Most common cause of facial asymmetry?
Mandibular shift (CR - CO)
True max skeletal constrictions results from changes in __________
changes in max transverse dimension
Treatment options for Max skeletal constriction?
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)
3 types of maxillary expanders
- Jackscrew type
- Spring type
- Bonded with jackscrew type
RPE vs SPE
RPE: 1-2 quarter turns/day (Tx time
Problems with RPE or SPE?
Pain
Soft tissue irritation
Maxillary diastema (but will close)
Breakage
Debonding
When do you use lingual arch type expanders?
For primary and mixed dentition
W arch or Quad helix
Treatment time: months
Retention: months
RPE is not indicated in adults.. why?
Use banded and bonded fixed appliance if the case is very minor.
If bilateral and significant: surgery is indicated for expansion
With palatal expansion there is _________ effects
50 dental
50 skeletal
What causes the posterior cross bite?
- Retained primary teeth
2. Crowding / tipped teeth
Rationale for posterior dental crossbite correction?
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)
True or False?
Lingual arch type does the same thing as RPE/SPEs
True
it is for Early mixed/mixed dentition
W arch anchorage, configuration, wire type, retention?
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)
Biomechanics of W arch?
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…)
Quad helix anchorage type, configuration, wire type, retention?
Biomechanically same as W arch…
Anchorage: reciprocal
Quad configuration: increases length wire and flexibility
Wire type: 0.038 SS
Retention: cemented bands
When do we use Cross Elastics to fix posterior crossbite?
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.
Problems with cross elastics?
Compliance
Retention period for Cross elastics?
retention period is really overcorrection, looking for rebound, and then removing the appliance
True or False?
The patient must wear cross elastics at all time except when they eat
True
