**6. Orthognathic surgery vs. telegnathic surgery**

Maxillomandibular advancement is considered a telegnathic surgery, which involves maxil‐ lary and mandibular osteotomies to enlarge posterior airway space. Telegnathic surgery is derived from the Greek words *tele,* which means "over a distance," and *gnathis,* which relates to the jaws, whereas orthognathic surgery is derived from the Greek words, ortho, which means, "to straighten," and *gnathis meaning "jaw".* OSA patients are usually middle age, obese, mostly males with significant comorbid medical conditions; on the other hand patients with dentofacial abnormalities are young with no sex prevalence (male or female) and usually in a good health.

There are no major differences in the surgical techniques although the goals of therapy are different. In orthognathic surgery the goal is to correct the occlusion and improve esthet‐ ics while in telegnathic surgery the optimal goal is to relieve upper airway obstruction. Orthodontic treatment is a must for all patients with dentofacial deformities who are going for orthognathic surgery. In OSA patients accepting the existing bite can be used if the patient does not want to go through the lengthy orthodontic treatment. Surgical move‐ ment in the orthognathic surgery patient are dependent upon the esthetic requirement as well as occlusion correction, whereas in OSA patients a larger surgical movement of the maxilla and mandible should be done (up to 10mm) with the main concern being open‐ ing the posterior airway space [25, 26].
