Masters Thesis

An investigation of the relationship among misarticulation, tongue thrust, and malocclusion

Until recently, there was little interest in the neuromuscular syndrome commonly called "tongue thrust." Though articles on tongue thrusting had been printed before the year I960, only in this last decade has tongue thrust caused much interest and come to the attention of those in the fields of dentistry and speech pathology. The features of the syndrome were given by Jon Eisenson (1965) who stated: a deviant swallowing pattern exists when (1) unusual tension exists in the mouth enclosing musculature, (2) perceptible contraction of swallowing muscles decreases or is absent, and, (3) the tongue is thrust forward causing it to protrude between the teeth. This definition is by no means the only one used to describe tongue thrusting—for a study of the literature reveals many definitions. Irwin Ronson (1965), in his studies of tongue thrusters, said that visceral swallowing may occur with or without masseter contraction, especially in anterior open bite cases. As a result of the tongue thrust syndrome, the oral cavity may be changed and dental irregularities produced. Associated with these modifications are sound production defects, especially of the sibilants. Jann (I960) has stated that the tongue thrust habit, associated with perverted swallowing, articulation defects, and open bite type of malocclusion, is a syndrome estimated to occur in approximately ten percent of the school age population. Fletcher (1961) stated that this syndrome focused attention on the emerging synergism in the orofacial region, especially as it pertained to speech and dental irregularities. This syndrome has been described by various names; among them are: tongue thrust, poor orofacial muscle habits, orofacial muscle-pressure imbalance, infantile swallowing, perverted swallow, and visceral swallow. Each of these terms is indicative of the condition in which the tongue is thrust against or through the anterior dentition; there is a tight labial seal indicating over-activity of the orbicularis oris and mentalis; and there is a lack of masseter contraction to bring the posterior teeth together.

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