Tongue and Lip Forces Exerted during Deglutition in Subjects with and without an Anterior Open Bite

¹ Departments of Prosthodontics and Orthodontics, University of Washington School of Dentistry, Seattle, Washington

A technique was devised to measure the magnitude and duration of forces exerted on the dentition during deglutition. Pressures exerted on the area of the maxillary central incisors by the lip and tongue were measured in two groups of orthodontically treated subjects. The Group A, anterior open-bite cases, i.e., tongue thrusters, consisted of 6 subjects. The Group B or non-thrusters, consisted of 5 subjects who did not relapse to an anterior open bite. A pressure transducer was used to record pressure on the labial and lingual of the maxillary left central incisor.

The following results were observed: (1) The mean tongue pressure of the anterior open-bite sample was twice that of the controls. These differences were statistically significant. (2) Anterior open-bite subjects, i.e., tongue thrusters, exerted both tongue and lip pressures for a longer duration than did the non-open-bite subjects. (3) There was a lip-tongue synergy in the oral stage of swallowing for all subjects. The lip always applied pressure prior to the tongue. However, a difference did exist in duration of pressure and magnitude of pressure applied to the teeth by tongue and lip during swallowing. (4) The tongue did not protrude past the labial edge of the upper central incisors during swallowing among the anterior open-bite subjects, i.e., tongue thrusters, with the exception of 1 of the 6 subjects.

A basic difference between anterior open-bite subjects, i.e., tongue thrusters, and subjects without an anterior open bite was found in the duration of lip and tongue pressures applied to the anterior teeth. Anterior open-bite subjects, i.e., tongue thrusters, applied both tongue and lip pressure against the anterior teeth for a longer duration of time than did the subjects without an anterior open bite.