Underbites can be caused by misaligned teeth (dental crossbite) or disproportional development of the facial skeleton (skeletal underbite). Dental crossbites can lead to the development of a skeletal crossbite if not corrected early in a child's life.
In a growing child, the main objective of treatment is to prevent a permanent skeletal underbite from developing.
This is usually done with a combination of:
1) A fixed palatal expander
^ Expander on day of fitting. The central screw needs to be turned in the direction of the arrow to start expansion.
^ Expander after 2 months.
2) A facemask: This will provide skeletal traction to encourage bone growth in the upper jaw and development of the cheekbone area which is usually deficient in patients with skeletal underbites. The lower jaw and chin are restrained from growing forward simultaneously.
The facemask is worn after school and at night for at least 9-12 months.
3) Sectional braces: These are usually bonded on to the first permanent molars and permanent incisors which are present after the age of 7-8 years old.
These treatment modalities will not only correct the underbite, but also provide leeway for future growth during puberty.
^ Pre-treatment underbite from the front
^ Pre-treatment underbite from the side
^ Underbite in treatment. This is after 6 months of expander and sectional braces. Further traction with the facemask is required to create leeway for future growth.
Depending on the severity of the underbite, not all 3 modalities may be required to treat the issue.
Proper assessment and diagnosis is essential to identify the cause of the underbite and begin treatment at the appropriate time. Early detection and treatment may prevent or reduce the need for future orthognathic jaw surgery.
