The sublingual or lingual frenulum (LF) is a normal anatomical structure located in the oral cavity and attached to the lower part of the tongue and the floor of the mouth. It is formed by a central fold of the floor of mouth fascia, the overlying oral mucosa, and sometimes the extrinsic tongue muscle. A condition in which the LF is short and restricts tongue movement is called ankyloglossia and is more common in men. When tongue mobility is restricted, it can manifest in a variety of ways, including decreased tongue performance, changes in orofacial structures and abnormal speech production. Treatment of short LF and ankyloglossia requires a multidisciplinary approach, divided into surgical and nonsurgical approaches. The latter are often performed by a speech-language pathologist through individualised therapy that includes exercises for correct speech production, breathing, swallowing, and tongue mobility. With our research, we wanted to investigate how the length of LF affects the development of facial structures, speech, tongue mobility and related problems, and whether we can correctly identify a short LF by objective measurement.
In the empirical part, we studied 104 children aged 4.5 to 5.5 years who participated in a speech screening at the age of five. During the screening, clinical observation of the child's speech and orofacial structures, including LF, was performed. The child performed tongue mobility exercises, and the tongue's range of motion was measured indirectly with a caliper. Finally, an interview was conducted with the parents about current and past problems that the child may have had that could be related to a short LF. The results showed that between 5.2 % and 28.1 % of the children (depending on the method of assessment) had a short LF, and the ratio between boys and girls was 0,88-1.25:1.0. The tongue's tip range of motion upwards, which was less than 50 %, was significantly related to LF attachment to the alveolar ridge and the tip of the tongue, but had no effect on the shape of the tip of the tongue (heart shape). Distortion was more common with a short LF and was related to the tongue's range of motion in five-year-olds, which also affected the articulation of the /r/ sound. Speech sound disorders were associated with a heart-shaped tongue tip, tongue's range of motion of less than 60%, and difficulty extending the tongue straight forward and touching the upper lip with the tip of the tongue. The short form of LF had no effect on speech rate, voice quality, breathing, tongue position at rest, and hard palate shape. Out of the seven tongue mobility exercises, there was a significant relationship between performance on five exercises and tongue's range of motion. According to parents’ reports, the problems most likely to occur with short LF were related to sleep, feeding, and breastfeeding, but none of the associations were statistically significant. In three children in whom LF had already been operated, the results show that several problems persisted after surgery. By combining clinical observation with the indirect measurement of tongue range of motion and disordered oral functions, we concluded that functional changes and dysfunction of oral functions do not necessarily occur despite abnormalities in several areas.
Through our research, we have obtained information which can help speech-language pathologists to identify the potential consequences of a short LF when examining the child and assesing whether the child can better adopt appropriate speech and movement patterns through therapy. Speech-language pathologists should be involved in LF problem solving before the surgery and could reduce the number of unnecessary surgical procedures through therapy and appropriate diagnostics. They can provide appropriate advice and support to parents in a decision whether or not to treat a short LF.
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