A disproportionately grown upper or lower jaw causes dentofacial deformities. Chewing becomes problematic, and may also cause pain due to straining of the jaw muscle and bone. Deformities range from micrognathia, which is when the mandible doesn't grow far forward enough (over bite), and when the mandible grows too much, causing an under bite; all of which are uncomfortable. Also, a total maxilla osteotomy is used to treat the "long face syndrome," known as the skeptical open bite, idiopathic long face, hyper divergent face, total maxillary alveolar hyperplasia, and vertical maxillary excess. Prior to surgery, surgeons should take x-rays of the patient's jaw to determine the deformity, and to make a plan of procedures. Mandible osteotomies, or corrective jaw surgeries, benefit individuals who suffer from difficulty chewing, swallowing, TMJ pains, excessive wear of the teeth, open bites, overbites, underbites, or a receding chin. The deformities listed above can be perfected by an osteotomy surgery of either the maxilla or mandible (whichever the deformity calls for), which is performed by an oral surgeon who is specialized in the working with both the upper and lower jaws. Orthognathic surgery is also available as a very successful treatment (90–100%) for obstructive sleep apnea.