In conjunction with the lips, tongue, and oropharynx, the teeth play an important role in the articulation of consonants via airflow obstruction and modification. Therefore, along with these articulators, any orthodontic therapy that changes their position may play a role in speech disorders. This paper examines the relevant studies and discusses the difficulties of scientific investigation in this area. The ability of patients to adapt their speech to compensate for most handicapping occlusion and facial deformities is recognized, but the mechanism for this adaptation remains incompletely understood. The overall conclusion is that while certain malocclusions show a relationship with speech defects, this does not appear to correlate with the severity of the condition. There is no direct cause-and-effect relationship. Similarly, no guarantees of improvement can be given to patients undergoing orthodontic or orthognathic correction of malocclusion. ORTHODONTICS (CHIC) 2011;12:340–353.
Key words: cleft palate, hearing loss, malocclusion, orthognathic surgery, speech defect