In normal swallowing as described in the article "Radiographic Study of Movements of the Tongue in Swallowing" by G. M. Adrian et al. appearing in The Dental Practitioner, Vol. V No. 8, April, 1955 at pages 252-261, the tip of the tongue is positioned against the anterior curved surface of the palate just behind the upper anterior dentition. The superior surface of the tongue is then elevated upwards and backwards against the hard palate. When the front of the tongue is raised at the start of the swallow the arched dorsal surface is lowered and the forepart of the soft palate is depressed and bowed forward into the mouth cavity. A seal is thereby maintained between the tongue and palate. If the tongue tip is held too far forward and too low in the mouth as swallowing begins, it is thrust forward against or between the backs of the front teeth. The substantial force exerted on the teeth during poor swallowing often causes an abnormal repositioning of the front teeth and surrounding bone. An habitual incorrect placement of the tongue when swallowing, i.e., tongue thrust, may cause a serious problem such as anterior open bite.
U.S. Pat. No. 3,478,742 issued to E. H. Bohlmann Nov. 18, 1969 discloses an orthodontic multipurpose repositioner and oral habit conditioner comprising a molded plastic support, guard and barrier device fitted between the teeth of a patient for tooth, lip and tongue positioning. The device has sockets to receive the upper and lower teeth, extension parts for lip positioning and a barrier to prevent insertion of a thumb into the mouth and/or protrusion of the tongue between the teeth. A tongue guide extending upwardly along the roof of the mouth carries electrodes to repel the tongue downward by galvanic action which stimulates reflex tongue movement. The tongue tip, however, is deflected downward. But as stated in the aforementioned article, the ideal position is against the anterior bend of the hard palate behind the front teeth.
U.S. Pat. No. 3,871,370 issued to L. E. McDonald Mar. 18, 1975 discloses a tongue thrust correction appliance positionable in a patient's mouth. The appliance has an upper jaw engaging structure including two laterally spaced elements and a shelf-like plate. The plate is integrally molded with the laterally spaced elements for suspension across the interior of the mouth in spaced relationship to the roof of the mouth. Each of the laterally spaced elements is provided with surface conformations that enhance retentive engagement with the jaw. The lateral spaced elements maintain the plate in suspended relationship for support of the endmost portion of the tongue on the upper surface of the plate. Tongue movement is thereby and restricted to a predetermined position against the roof of the mouth during swallowing. The tongue tip, however, may fall below the shelf-like plate so that neither proper positioning nor proper physiologic posture is assured at the start of the swallow.
U.S. Pat. No. 4,718,662 issued to R. B. North Jan. 12, 1988 discloses a tongue positioning and exercising device having an outer marginal area for clenched retention between upper and lower teeth. Tongue supporting members extend inwardly and upwardly from the marginal area to position the tongue properly with the tongue tip in contact with the upper alveolar ridge of the gum. Openings permit passage of saliva through the device. Projections on a modified form of the device cause tongue discomfort if the tongue is improperly located below the device. The device, however, requires clenched retention so that normal mouth opening is not possible.
"Bone Remodeling Orthodontics by Jaw Repositioning and Alveolar Growth" by Leon Kussick Copyrighted 1987 by Quintessence Publishing Co. Inc., Chicago, Ill. discloses at page 244 an acrylic maxillary removable tongue thrust retraining appliance having an assembly of Adams clasps arranged for retention, a labial arch wire positioned to retract flared maxillary anteriors and a lingual strengthening wire adapted to the patient. The assembly is formed individually for each patient. Portions of the assembly that should not have acrylic are blocked out by an appropriate material. Acrylic is then poured to provide an anterior tongue channel so to direct the tongue to a hole cut in the anterior part of the palatal acrylic. In primary dentition, retention can be provided by occlusal acrylic extended around buccal teeth. Clasps as used in the aforementioned appliance are subject to deformation. In all cases, the devices are constructed from impressions made for individual patients.
In order to fabricate any of the foregoing tongue thrust retraining appliances for an individual patient, it is necessary to take impressions of and construct models of the individual patient's mouth. A mold for the appliance is then prepared from the models and the molded appliance is fitted to the mouth of the patient. The process is time consuming and requires expert care at each step. It is an object of the invention to provide an improved tongue thrust retraining device readily adapted to fit a wide range of patients without requiring impressions and models in its preparation. It is a further object of the invention to provide an improved tongue thrust retraining device which is adapted to simulate the physiological aspects of proper swallowing.