What effects do use of a pacifier and thumbsucking have on speech difficulties?
For most children, the use of a pacifier and/or thumb sucking occurs during the early years and is a relatively short-term practice. When of short duration, they typically do not have a significant effect on the development of the oral musculature, the relationship of the dentition and occlusion, or on speech development and production. However, such practices, if persistent across many years may result in a myofunctional condition. That is, the muscles in the front of the mouth (lips and surrounding area) are used, while other muscles (e.g., the masseter) are not as active. In addition, a forward carriage of the tongue may also exist at rest and during swallowing. These factors in combination may lead to a persistent tongue thrust which can further influence the oral muscle development, occlusion, and alignment of teeth.
Tongue thrust, which is a normal swallowing pattern in early childhood should be gradually replaced by a mature swallow. The upper limits of tongue thrust developmentally is age 9. Tongue thrust is often accompanied by occlusal and alignment problems and can also be associated with articulation errors. Sounds that are most often distorted by inaccurate tongue placement include tongue tip sounds /s, z, t, d, l, n/. Other sounds may be distorted if the oral structures are not in proper relationship, such as the case of a high and narrow palatal vault. Bunching of the tongue can effect palatal sounds, such as /S and dz/.
One should exhibit caution when counseling parents on the effects of pacifier and thumb sucking practices. Mild deviations in oral structures have not correlated strongly with speech production problems. A family dentist can determine if the use of the pacifier or thumb is causing structural problems in the dentition and/or occlusion. Tongue thrust behavior (and pacifier and thumb sucking) should decrease with age. If tongue thrust is present, referral to an SLP will result in careful analysis of its presence and how it directly effects speech production. The two problems respond well to intervention.
Kathleen Fahey, Ph.D., CCC-SLP is a professor and the chair of the Department of Communication Disorders at the University of Northern Colorado. She is the author of the text ''Language Development, Differences, and Disorders: A Perspective for General and Special Education Teachers and Classroom-Based Speech-Language Pathologists, as well as many articles and presentations. Kathleen teaches undergraduate and graduate courses in phonology and language.