Crossbites Flashcards
Crossbites definition
CROSSBITE IS APPARENT WHEN THE BUCCAL
CUSPS OF THE LOWER TEETH OCCLUDE LATERAL TO
THE BUCCAL CUSPS OF THE UPPER TEETH.
BUCCAL CROSSBITE:
- BUCCAL CUSPS OF
MANDIBULAR TEETH OCCLUDE BUCCAL TO THE
BUCCAL CUSPS OF THE MAXILLARY TEETH
LINGUAL CROSSBITE
(SCISSORS BITE):
BUCCAL
CUSPS OF MANDIBULAR TEETH OCCLUDE
LINGUAL TO THE LINGUAL CUSPS OF THE MAXILLARY TEETH
Can have
Unilateral
Bilateral crossbites
Bilateral lingual crossbite aka
Scissors bite
Prevalence of crossbites
Population ?
8-22 percent of pop
Percentage of orthodontic patients?
10 percent
What percentage are bilateral?
2 percent
In terms of pre-normal occlusions (class III)?
3 times more common
Classification?
- UNILATERAL BUCCAL CROSSBITE
- WITH DISPLACEMENT
- WITHOUT DISPLACEMENT
- BILATERAL BUCCAL CROSSBITE
- UNILATERAL LINGUAL CROSSBITE
- BILATERAL LINGUAL CROSSBITE (SCISSORS BITE)
FEATURES OF A BILATERAL CROSSBITE?
ALWAYS SKELETAL IN ORIGIN
* OFTEN COMBINED WITH A SKELETAL III
Unilateral crossbite without displacement is due to a
True asymmetry of the skeletal bases, usually pathological in origin
For example
Unilateral cleft palate
Condylar hyperplasia
Aetiology of crossbite
- HEREDITARY FACTORS …SKELETAL
- ENVIRONMENTAL FACTORS
I. DIGIT SUCKING
II. MOUTH BREATHING
Transverse anomalies like A-P anomalies can be (dentoalveolar/skeletal)
Dentoalveolar/skeletal or both
Why do we treat crossbites?
- SOME EVIDENCE THAT
DISPLACING CONTACTS MAY
PREDISPOSE A SUSCEPTIBLE INDIVIDUAL TO TMD.
- ALTHOUGH THIS EVIDENCE IS WEAK, …. IS THEREFORE A FUNCTIONAL
INDICATION FOR ORTHODONTIC TREATMENT.
A CROSSBITE WITH
A DISPLACEMENT
Therefore how to we treat crossbites
PREPARATION FOR BONE GRAFTING IN PATIENTS WITH CLP
Which crossbites should we treat
NOT UNILATERAL OR BILATERAL CROSSBITES
WITHOUT DISPLACEMENT.
Why?
THE MALOCCULSION IS OF MINOR IMPORTANCE.
THERE IS A CONSIDERABLE TENDENCY TOWARDS
RELAPSE – UP TO 40% WITH ALL FOR,SOF ACTIVE
EXPANSION
Timing of treatment of the deciduous dentition?
SOME RECOMMEND GRINDING
1. TO ELIMINATE THE DISPLACING CONTACTS.
2. TO FACILITATE SPONTANEOUS CORRECTION
NB BUT NOT RECOMMENDED!
TREATMENT OF CROSSBITES IN
THE MIXED DENTITION.
NO AND YES
NO
LEIGHTON (1986) – SPONTANEOUS
CORRECTION FREQUENTLY OCCURS.
YES
SCHRODER (1981) & PETREN (2003) – HIGH
FREQUENCY OF TRANSMITTANCE TO PERMANENT DENTITION