Malocclusion and its relationship to speech sound production: Redefining the effect of malocclusal traits on sound production

• We compared occlusal features to speech samples in 115 subjects, 8 to 36 years old.
• Predictable malocclusal traits were associated with speech sound errors.
• The more handicapping the occlusion, the more likely the speech errors.
• Open bite was the feature most associated with sound distortions, especially /s/ and /t/.
• Lingual protrusion (lisp and tongue thrust) was the typical visual inaccuracy.

IntroductionThe purpose of this study was to identify variables of dental malocclusion with the greatest effect on sound production that can be easily identified during an orthodontic assessment.MethodsOne hundred fifteen patients (8.2-36 years of age) seeking orthodontic evaluation were assessed for speech sound production abnormalities. An orthodontic clinical examination assessed Angle classification, overjet, overbite, crowding, spacing, and crossbites. A standard speech sample was elicited from each subject.ResultsThe results indicated that 71 (62%) of the subjects made a production error, particularly with the /s/ and /t/ sounds. However, auditory distortions occurred in 12 subjects (20%), and 56 (80%) subjects had visual distortions of the sound. An open bite (>2 mm) was the key malocclusal factor underlying speech sound errors. There was statistical significance between the Orthodontic Treatment Priority Index and the sound errors of /s / and /t/ (mean score of 9.54 vs 6.29 for subjects without sound errors).ConclusionsPredictive malocclusal traits are associated with speech sound production errors. The more severe or handicapping the malocclusion, the more likely that a speech sound error will occur. Open bites of 2 mm are associated with sound production errors. Visual inaccuracy of the sound occurs with more frequency than auditory inaccuracy and is the most common articulation error noted with occlusal irregularities.