Orthognathic Speech Pathology: Phonetic Contrasts of Patients With Dental Discrepancies Pre- and Post-Treatment Analyses

The investigators are studying how speech is effected by jaw and tooth position in jaw surgery patients. Eighty percent of our jaw surgery patients have speech pathologies, compared to five percent of the general population, but speech pathologists do not understand why. The investigators hypothesize that open bites and underbites prevent most patients from being able to pronounce words normally and surgical correction will lead to improvement in speech. Patients will be audio recorded speaking and patients' tongue gestures ultrasound recorded before and after their jaw surgeries to observe what changes occur in their speech and tongue movements.

Purpose: The investigators are studying how phoneme distortion is effected by jaw disproportions in dentofacial disharmony (DFD) patients and whether speech improves after orthognathic surgery and orthodontic treatment. Spectral moment and tongue gestural analysis are being used to mechanistically determine how jaw position effects speech. The investigators hypothesize that skeletal open and underbites contribute to phoneme distortion and tongue gestural changes that improve following surgical correction of jaw position. All DFD patients are already seeking treatment from orthodontics and oral surgery. The study will observe how their speech changes before and after treatment. There is no randomization or intervention involved. Aim 1: Qualify the prevalence of auditory and visual speech distortions in the DFD population. Aim 2: Quantitatively evaluate the first spectral moment (kHz) of four articulating consonant sounds (/t/, /k/, /s/, and /?/ pronounced "sh"). Quantify and analyze the changes in speech distortions for orthognathic patients pre and post-operation. Aim 3: Evaluate tongue posture during speech with patients from Aim 2 pre and post-operation. Participants: Participants: Patients of the UNC dentofacial disharmony (DFD) clinic who have undergone orthognathic surgery for correction of jaw disharmonies. Procedures (methods): Patients will be recorded pronouncing a series of words highlighting a range of phonetic contrasts including --/s-sh/ and t-k/. words each presented on a screen using PowerPoint, 3 times each with carrier phrases). Recordings include an acoustic feed, a profile video of the jaws plus lips, and ultrasound imaging of the tongue relative to the palate and jaws. Research staff will score audio recordings according to their spectral moments and ultrasound recordings according to tongue movement and associate findings with degree of dental discrepancy. Prospective recordings will be collected at three timepoints: 1-3 months prior to jaw surgery, 3-8 months and 9-15 months post-operation for 60 overbite, 60 openbite and 60 underbite DFD patients. These time points were selected to co-occur with patients' surgical check-ups to ensure reliable data collection while minimizing confounding factors such as severe facial swelling and splint placement which occur immediately after surgery.