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Impact of a rapid palatal expander on speech articulation

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Introduction

Rapid palatal expanders (RPEs) have attachments cemented to the teeth and a screw that covers the palate. Because of their position and relative size, RPEs can affect speech. Our objective was to assess speech perturbation and adaptation related to RPE appliances over time.

Methods

RPEs were planned for the treatment of 22 patients in the orthodontic clinic at the University of Toronto in Canada. Speech recordings were made at 6 time points: before RPE placement, after placement, during expansion, during retention, after removal, and 4 weeks after removal. The speech recordings consisted of 35 sentences, from which 3 sentences were chosen for analysis. Speech acceptability was assessed perceptually by 10 listeners who rated each sentence on an equal-appearing interval scale. The vowel formants for /i/ and the fricative spectra for /s/ and /∫/ were measured with speech analysis software. Repeated-measures analysis of variance with post-hoc paired t tests was used for statistical analysis.

Results

When the appliance was placed, speech acceptability deteriorated. Over time, the ratings improved and returned to baseline when the appliance was removed. For the vowel /i/, the first formant increased, and the second formant decreased in frequency, indicating centralization of the vowel. The formants returned to the pretreatment levels during treatment. For the fricatives (/s/ and /∫/), low-to-high frequency ratios indicated that the fricatives were distorted when the appliance was placed. The ratios returned to baseline levels once the appliance was removed. The results for the spectral moments indicated that spectral mean decreased and skewness became more positive. Repeated-measures analysis of variance showed significant effects for time for all acoustic measures.

Conclusions

Speech was altered and distorted when the appliance was first placed. The patients’ speech gradually improved over time and returned to baseline once the appliance was removed. The results from the study will be useful for pretreatment counseling of patients and their families.

Section snippets

Material and methods

Ethics approval was granted by the Health Sciences Research Ethics Board at the University of Toronto in Canada. Based on a power calculation, it was determined that the minimum enrollment target was 15 participants. Twenty-two patients planned for treatment with an RPE in the Graduate Orthodontic Clinic at the University of Toronto were recruited for the study. Thirteen patients were female and 9 were male, with ages ranging from 9 to 19 years (mean, 14 years). The need for an RPE as part of a

Results

The listeners’ average ratings of the 3 sentences for each of the 6 times showed that, at TP2, the patients’ speech acceptability scores increased (speech acceptability deteriorated). Over time, the acceptability scores decreased (speech acceptability improved), only returning to TP1 levels at TP5. At TP6, the scores were decreased compared with the TP1 levels (speech acceptability improved). Figure 1 is a graphic representation of the results.

Repeated-measures ANOVA was performed to examine

Discussion

The listeners’ speech acceptability ratings demonstrated that RPEs had a negative effect on the patients’ speech acceptability. When the appliance was first cemented in the mouth, the patients’ speech acceptability deteriorated. The PESD patients fared worse than did the normal group. Over time, the patients adapted to the appliance. When the appliance was removed from the mouth, the patients’ speech acceptability returned to the TP1 scores. However, at TP6, the patients’ speech acceptability

Conclusions

Hyrax-type RPEs were shown to have a negative effect on speech. The adaptation to the RPE was initially incomplete, but patients adapted to the appliance over time. After the treatment, the patients’ speech acceptability ratings were better than before the treatment. Before a patient undergoes RPE treatment, the clinician should counsel the patient and parents about the nature and timeline of the effects of the appliance on speech.

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    The authors report no commercial, proprietary, or financial interest in the products or companies described in this article.

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    Copyright © 2011 American Association of Orthodontists. Published by Mosby, Inc. All rights reserved.