Abnormal Swallowing Habits

N factors play a part in de­ termining the form and relationship on the dental arches. It is difficult, if not impossible, to determine the order of im­ portance of these factors, but the activity of the orofacial musculature must rank high if one considers the number of mal­ occlusions which may be attributed to an imbalance of these muscles. Perversion of the orofacial musculature may be the result of hypoactivity or hyper­ activity of the muscles which act on the outer surfaces of the teeth and alveolar processes or their counterparts which exert their influence on the inner aspect of the dental arches and associated bone. An imbalance of these muscles is usually the result of altered activity of both groups. Abnormal swallowing habits are always associated with a greater or lesser degree of muscular dysfunction. These habits are so frequently encountered that Strang (1958) states: “Without a doubt abnormal swallowing habits comprise one of the most common and influential muscular perver­ sions that the orthodontist encounters.” Rix (1946) states that the nature of the first stage of deglutition varies with the amount and type of material to be swal­ lowed. Fluid will evoke one type of swallowing pattern while the deglutition performed merely to aid drainage of the mouth and naso-pharvnx and to moisten the oral and pharyngeal mucous mem­ branes has other characteristics. The latter is termed the refreshing or basic swallow and is the more important because of its frequency throughout the day and night. The basic swallow is performed with the teeth in occlusion and the tongue closely adapted to and pressing on the palate and lingual surfaces of the maxil­ lary teeth. The lips and cheeks remain relatively inactive while deglutition is occurring. A common type of perversion of the basic swallow is described by Rix (1946). The tongue is placed either between the upper and lower incisors or between all the maxillary and mandibular teeth and deglutition is accompanied by a marked activity of the lips and often the cheeks. According to the author the muscular activity is secondary to the abnormal posi­ tion of the tongue and is an attempt to form a seal on its periphery. This swallow­ ing pattern also often evokes a more wide­ spread muscular activity which produces a movement of the head. This aberrant form of deglutition may be the result of a retention of the infantile type of swallow or initiated by recurrent infections of the upper respiratory tract (Rix, 1946). Moyers (1950) believes that