Effects of oral myofunctional therapy on swallowing and sibilant production.

This study investigated the effectiveness of oral myofunctional therapy in eliminating a 16 year-old girl's tongue thrust swallowing pattern and mild sibilant distortion. An ABC design was used where Phase A had eight baseline sessions (no treatment), Phase B had 14 oral myofunctional therapy sessions, and Phase C had four articulation treatment sessions. Dependent measures of swallowing and sibilant production were obtained in each session. A third dependent variable, labial diadochokinetic rate, was also measured each session and served as a control for maturation. Oral myofunctional therapy was shown to be effective in eliminating the tongue thrust swallowing pattern of this subject, but not her sibilant distortion. However, her sibilant distortion reduced after one articulation treatment session and was maintained at negligible levels over the next three treatment sessions. As expected, labial diadochokinetic rate remained stable across the three phases. At the conclusion of Phase C, two bi-weekly home visits revealed that the subject had maintained and generalized her new swallowing pattern. Measures obtained six months after completion of Phase C indicated that the subject had maintained her new swallowing and speech production behaviors. The subject's maximal tongue strength and endurance were below expected normal values at the initiation of the study and increased during the study. Her tongue endurance appeared more sensitive to the effects of oral myofunctional training than tongue strength and, unlike tongue strength, tongue endurance decreased in the six month period following completion of the study.