This study aims to evaluate the effect of mandibular advancement using the Twin Block appliance on the acoustic characteristics of speech in children with skeletal Class II malocclusion. Skeletal Class II malocclusion commonly caused by mandibular retrognathism may influence oral cavity configuration and potentially affect speech production. Functional appliances such as the Twin Block are widely used in growing patients to advance the mandible and improve jaw relationships. However limited evidence is available regarding their impact on speech acoustics.

This experimental before and after study will include children aged 10 to 14 years with skeletal and dental Class II malocclusion reporting to the Department of Orthodontics. Baseline records including clinical examination study models cephalometric radiographs photographs and speech recordings will be obtained before treatment T0. Participants will undergo mandibular advancement therapy using a Twin Block appliance. Follow up records will be obtained after completion of Twin Block therapy at 6 months T1 and again at 9 months from baseline T2.

Speech samples will be recorded in a quiet environment using a condenser microphone and analyzed using Praat software. Acoustic parameters including fundamental frequency F0 and formant frequencies F1 F2 and F3 for vowels a i and u will be measured. Cephalometric parameters and dental measurements will also be recorded to assess changes in craniofacial morphology and occlusion.

The study will compare acoustic speech characteristics before and after Twin Block therapy and evaluate the correlation between changes in speech parameters and craniofacial morphological changes following mandibular advancement treatment.