Effects of Hawley retainers on consonants and formant frequencies of vowels.

Objective: To assess (1) whether Hawley retainers cause speech disturbance and (2) the duration of speech adaptation to Hawley retainers with objective and subjective tests.

Materials And Methods: Twelve adolescents, aged 11.11 to 18.03 years, were included in this study. The assessment of speech sounds were done subjectively using an articulation test and objectively using acoustic analysis before and after Hawley retainer application.

Results: After wearing Hawley retainers, patients showed statistically significant speech disturbances on consonants [ş] and [z]. Regarding the vowels, statistically significant changes were recorded with [i], while F1 increased and F2 and F3 decreased.

Conclusions: The tongue changes its target position with the application of a foreign body within the mouth; however, in time it adapts to that new situation.