Orthognathic speech pathology: impacts of Class III malocclusion on speech

Abstract

Summary Introduction Patients with dentofacial disharmonies (DFDs) seek orthodontic care and orthognathic surgery to address issues with mastication, esthetics, and speech. Speech distortions are seen 18 times more frequently in Class III DFD patients than the general population, with unclear causality. We hypothesize there are significant differences in spectral properties of stop (/t/ or /k/), fricative (/s/ or /ʃ/), and affricate (/tʃ/) consonants and that severity of Class III disharmony correlates with the degree of speech abnormality. Methods To understand how jaw disharmonies influence speech, orthodontic records and audio recordings were collected from Class III surgical candidates and reference subjects (n = 102 Class III, 62 controls). A speech pathologist evaluated subjects and recordings were quantitatively analysed by Spectral Moment Analysis for frequency distortions. Results A majority of Class III subjects exhibit speech distortions. A significant increase in the centroid frequency (M1) and spectral spread (M2) was seen in several consonants of Class III subjects compared to controls. Using regression analysis, correlations between Class III skeletal severity (assessed by cephalometric measures) and spectral distortion were found for /t/ and /k/ phones. Conclusions Class III DFD patients have a higher prevalence of articulation errors and significant spectral distortions in consonants relative to controls. This is the first demonstration that severity of malocclusion is quantitatively correlated with the degree of speech distortion for consonants, suggesting causation. These findings offer insight into the complex relationship between craniofacial structures and speech distortions.

Three-Dimensional Analysis of Posterior Mandibular Displacement in Rats

“…The present study investigates in rats an important feature of human face, the mandibular shape, which is a potential determinant of self-esteem [ 24 , 65 ], it affects the individual’s social interaction [ 66 , 67 ] and professional success [ 68 ], and is important in the function of the orofacial complex [ 69 , 70 ]. Mandibular development is multifactorial and is regulated by genetic and environmental variables [ 21 , 71 ].…”

Impacts of Skeletal Anterior Open Bite Malocclusion on Speech

“…Cephalogram radiographs were traced to evaluate skeletal relationships (ANB, IMPA, Wits, FMA, SN-GoGn) as described, by a single examiner, blinded to patient identity, previously assigned DFD category, and the results of the speech evaluations. 11 Two weeks later, the same examiner retraced one-quarter of the cephalograms (n = 10, randomly chosen), for an intra-examiner concordance test to evaluate tracing reliability (Supplemental Table 3). Data were stratified by vertical status (overbite) and by anterior-posterior (AP) classification using overjet (OJ).…”

“…Speech analyses were adapted from Lathrop-Marshall et al 11 and Zajac et al 25 Subjects were qualitatively evaluated using a perceptual analysis for auditory and visual distortions by an experienced SLP in person, as described. 11 Subjects were seated in a sound-attenuated booth (Eckoustic Noise Control Products: Eckel Industries of Canada Limited) and fitted with a head-mounted microphone (AKG, model 520, Vienna, Austria). The microphone was connected to a single channel of the Computerized Speech Laboratory system (CSL Model 4500, Kay Pentax, Pentax Medical, NJ, USA).…”

“…10 Pathologic speech impacts communication and self-confidence, which impairs social interactions, career development, and quality of life. 8,[11][12][13] Production of consonants requires neuromuscular coordination of airflow against articulating structures including the tongue, teeth, and alveolus (Figure 1). This results in an acoustic signal that is perceived as a specific consonant.…”

“…This stems, in part, from the lack of quantitative speech evaluations in the DFD literature, which we address in this report by using spectral moment analysis (SMA). 11,[23][24][25] SMA is a method used to define characteristics of aperiodic noise in a speech signal using statistical descriptions. Here, we use SMA to quantitatively examine the relationship between vertical discrepancies and speech distortion in AOB patients.…”