Page 135 - FINAL COMPENDIUM 2020-2021 27.2.2022

SPEECH EFFECT OF FIXED LABIAL ORTHODONTIC APPLIANCE IN PATIENT WITH CLASS III
INCISOR RELATIONSHIP

Law SW, Khairil Aznan MK, Badrulzaman AH
Introduction: Both pre-existing and orthodontic induced speech defect in individual with
malocclusion could cause a significant barrier in social and professional functioning.
Objective: To evaluate the long-term effect of fixed labial orthodontic appliance on
speech in individual with Class III incisor relationship. Materials and methods: The study
involved 19 test subjects with Class III incisor relationship and 19 control subjects with
Class I incisor relationship fulfilling the inclusion and exclusion criteria. It consisted of
two parts which were objective and subjective evaluation. For the objective evaluation,
speech recordings of four selected Bahasa Malaysia fricative consonants /f, v, s, z/ were
recorded and analysed with PRAAT software in control subjects as baseline as well as
test subjects at six different time-points which were before insertion of the fixed labial
orthodontic appliance (T0), within 24 hours after insertion of the appliance (T1), after 1
month (T2), after 3 months (T3), after 6 months (T4) and after 1 year (T5). Overjet was
measured at three different time-points which were T0, T4 and T5 in the test subjects.
Subjective evaluation was done by the test subjects answering a standardized
questionnaire at five different time-points which were T0, T2, T3, T4 and T5. Statistical
analysis was done using SPSS software version 23.0. Results: The test subjects took a
significant shorter voicing durations to utter all the five fricative consonants at T0 with
reference to the control subjects. At T1, the test subjects took a significant longer voicing
durations to utter all the sounds compared to T0. The voicing durations for each sound
were reduced to the level at T0 in the test subjects at T4. At T5, the voicing durations of
the test subject for each sound appeared to increase significantly compared to T0 and
became comparable to the voicing duration of the control subjects. Subjective
evaluation showed that the test subjects experienced a gradual and positive
improvement in the scoring of the standardized questionnaire during the study period.
Class III incisor relationship subjects had a significant pre-existing speech distortion with
reference to the control subjects with Class l incisor relationship. There was a significant
further deterioration in the speech quality of the Class III incisor relationship subjects
after insertion of the fixed labial orthodontic appliance and it took up to six months for
the speech distortion to resolve due to adaptation. Besides, it was found that the
correction of overjet in the Class III incisor relationship subjects led to a significant
improvement of the pre-existing speech distortion with reference to the subjects with
Class l incisor relationship.

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