Objective: Considering the documented increase in oral dysfunction in children with speech sound disorders, there is a lack of evidence on the effects of oromyofunctional therapy (OMT) for remediation. This study aimed to assess the effect of OMT on the accuracy of the /s/ phoneme in children aged between 8 and 12 with persistent interdental lisps. Method: Following dental referral for interdental lisps and tongue thrust patterns, four participants, ages 8;6 to 12;8 were recruited for this multiple baseline across participants investigation. The independent variable was the accuracy of /s/ in word-initial position, at the word level. The independent variable included the modified Australian Orofacial Myology Collaboration treatment protocol. Intervention was conducted for two 30-minute sessions and home practice was required. Additional information was collected pertaining to the participants’ compensatory behaviors and oral dysfunction. Results: Results fo the investigation demonstrated effectiveness of the intervention for all four participants. The improvements in /s/ accuracy appeared to coincide with improvements in oral functions, such as swallowing patterns and mouth breathing, and reduced compensatory behaviors, such as jaw sliding. Conclusion: This investigation provided evidence in support of the effectiveness of oromyofunctional therapy in the remediation of /s/ in children with persistent interdental lisps. Concurrent improvements in oral functions such as breathing, swallowing and correct resting tongue posture were observed.
