Treacher Collins patients who have not undergone lengthening of the mandibular ramus will typically have a steep mandibular plane angle with or without malocclusion.
At skeletal maturity bimaxillary surgery to lengthen the posterior mandible and maxilla (counterclockwise rotation) and correct open bite deformities, retrognathia etc may be performed as described in the section on orthognathic surgery.
Additionally these patients may also profit from a genioplasty procedure.