Post-traumatic anterior
open bite can occur as a result of broken balance among the masticatory muscles. The superior hyoid muscle group retracts the mandible downward and contributes to the anterior
open bite.
Denervation of the digastric muscle by injection of
botulinum toxin type A (BTX-A) can reduce the power of the digastric muscle and help to resolve the post-traumatic anterior
open bite. A patient with a bilateral angle fracture had an anterior
open bite even after undergoing three operations under
general anesthesia and rubber
traction. Although the
open bite showed some improvement by the repeated operation, the occlusion was still unstable six weeks after the initial treatment. To eliminate the residual anterior
open bite, BTX-A was injected into the anterior belly of the digastric muscle. Following injection of BTX-A, the anterior
open bite showed immediate improvement. Complication and relapse were not observed during follow-up. Long-standing post-traumatic
open bite could be successfully corrected by injection of BTX-A into the anterior belly of the digastric muscle without complication.