10 - Crossbite Flashcards
What is a Crossbite?
British Standard Glossary of Dental Terms:
• Crossbite - transverse discrepancy in tooth relationship
3 types of crossbite:
Buccal crossbite
Lingual crossbite
May be no occlusal contact
Tends to occur in premolar region as in below example
Tends to occur in class II relationship
Anterior crossbite (reverse overjet)
)One or more incisor teeth into a reverse overjet position as in a class III)
If one tooth or several teeth in reverse overjet -> anterior crossbite
If upper incisors all inside bite -> class III or reverse overjet
^unsure - clarify what she meant by that
Aetiology of cross bites
• Skeletal pattern
• Soft tissue pattern
• Dental effect
Aetiology of crossbite - Skeletal pattern:
- Majority result of discrepancy in width of dental bases
• upper dental arch narrower than lower -> buccal crossbite
• lower dental arch narrower than upper -> lingual crossbite - Gross ant-post discrepancy
• marked class III -> buccal crossbite
• marked class II -> lingual crossbite - Genuine asymmetry of dental base or arch -> could lead to unilateral crossbite without displacement
mandibular growth disturbance or abnormality (very rare) -> unilateral crossbite without displacement
Aetiology of crossbite - Soft tissue pattern
Posterior teeth are in a position of balance between cheeks and tongue
Alteration of balance:
a) Low tongue position possibly associated with:
• increased lower face height (Prof Moss)
• result of mouth breathing (Linder-Aronson)
• habits thumb sucking
b) Increase in cheek pressure
• habits thumb sucking
OR
Surgical repair in cleft palate - contraction of scar tissue - unilateral buccal crossbite
Aetiology of crossbite - Dental effects:
Treatment of buccal crossbite
How do we treat:
- unilateral crossbite with displacement
- unilateral crossbite without displacement
1- Unilateral crossbite with displacement - treat to avoid possible TMJ problems
2- Unilateral crossbite without displacement - must find cause:
- Dental asymmetry -> treat orthodontically
- Dental base asymmetry -> investigate - growth abnormality? Surgery needed?
Treatment of buccal crossbite
How do we treat:
- Bilateral crossbite aligned
- bilateral crossbite (needing alignment )
1- bilateral crossbite aligned -> accept as no displacement (no treatment needed)
2- bilateral crossbite (needing alignment):
- mild to moderate -> treat orthodontically
- severe -> cannot treat orthodontically
Treatment of buccal crossbite
When do we treat a buccal crossbite ?
Treatment methods for buccal crossbite:
Conventional methods for treating buccal crossbite
Removeable appliances
Most commonly would use midline screw plate
Conventional methods for buccal crossbite
Fixed appliances
- QUAD HELIX - Simplest form of fixed expansion device - consists of metal molar bands on the 6s
Technician has bent the quad helix and then is expanded before placed into mount, cemented onto 6s
Quad helix can be used for:
- bilateral expansion
- unilateral expansion
- differential expansion - can expand more in premolar or molar region
- Full upper and lower fixed appliance
In upper arch could expand the arch wire - put in gradually thicker and wider expanded arch wire
OR
Cross elastic - hook on lower 6 buccally to hook on upper 6
Rapid maxillary expansion method
How does this work?
What age should it be used?
Uses?
1- expansion by:
1. Maxilla moves apart by opening mid palatal suture
2. Teeth tilt buccally
2- Should be used around 12-14 - before mid palatal suture fuses ( 14 years old ) + permanent teeth have erupted
3-
Bilateral buccal expansion for bilateral buccal crossbite
1 or 2 turns a day - heavy force onto teeth
Describe what you can see
Narrow upper arch
Bilateral buccal crossbite
Narrow pointed shaped upper arch
Wide lower arch
Also have alignment issues- retained Cs , canines dont fit - buccally displaced
So needs correction of bilateral buccal crossbite and alignment of teeth
Pt in correct age group so rapid maxillary expansion
Need to retain expansion then switch to fixed appliance for alignment - retention with removable retainer
Localised crossbite treatment
If we have localised crossbite eg on a single tooth
Lingual crossbite treatment
Anterior crossbite
Consider whether we can proclaimers upper incisors over the bite to correct the anterior crossbite which depends on:
Crossbite diagnosis
If unilateral buccal crossbite
If due to asymmetry of arch or skeletal then would be without mandibular displacement - need unilateral expansion
If with mandibular displacement - the patient is closing cusp to cusp in buccal segment -and mandible is displacing to one side - need to expand bilaterally
