Comparative Evaluation of Change in Phonetics Before and After Treatment of Skeletal Class III Malocclusion in Growing and Adult Patients: A Prospective Longitudinal Study

Abstract

Background:

Skeletal Class III malocclusion can alter the relationship between the tongue, lips, teeth, and supporting oral structures, potentially affecting speech production. Although the skeletal effects of orthopedic and orthognathic treatment are well documented, evidence regarding treatment-related speech changes remains limited.

Objective:

To evaluate changes in speech sound production before and after treatment of skeletal Class III malocclusion and compare outcomes among growing patients treated with facemask therapy or bone-anchored maxillary protraction (BAMP), and adults treated with conventional orthognathic surgery or the surgery-first orthognathic approach (SFOA).

Materials and Methods:

A prospective longitudinal study was conducted in patients with skeletal Class III malocclusion. Participants were allocated into four treatment groups: facemask with bonded rapid maxillary expansion (RME), BAMP with bonded RME, conventional orthodontic–orthognathic treatment, and SFOA. Speech was assessed before treatment (T1) and after treatment completion (T2) using a standardized word list containing consonants commonly affected in Class III malocclusion. Recordings were evaluated for articulation errors.

Results:

All groups demonstrated improvement in speech sound production following treatment. The greatest reductions in articulation errors were observed for /s/ and /z/. Growing patients treated with BAMP showed greater improvement than those treated with facemask therapy. In adults, both surgical approaches reduced speech errors, with SFOA demonstrating greater improvement in selected speech parameters.

Conclusion:

Treatment of skeletal Class III malocclusion was associated with measurable improvement in speech sound production. Greater improvements were observed following BAMP in growing patients and SFOA in adults.