Studying the impact of retention therapy types used in orthodontics on some consonants by phonetic analysis

In this study, the impact of various retainers upon speech, applied to the patients who had undergone a malocclusion treatment and reached the end of their orthodontic treatment in the Department of Orthodontics in Gaziantep University is discussed. Out of 33 patients on whom Hawley, Essix or Fixed retainer appliances were applied, audio tape recording was done without appliance pre-debonding (T0), within 24 hours after applying a retention appliance, post-debonding (T1), after one week (T2), one month (T3), and three months (T4). Along with scripting particular and proper texts to examine the change on the speech of the patients, the patients were asked perceptual questions on whether any changes were observed by themselves or their neighborhood. All the recordings were done in an insulated room and based on the consonants [ f ], [ t ], [ s ], [ ʃ ], [ ʧ ], [ k ] in relation to the location of labiodental, dental, alveolar, palatal, and velar zone, in the IPA chart. Following the segmentation process after recording, the intra-group changes of sounds at different time periods and intergroup differences concerning the appliance type were analyzed by examining the values of spectral moments such as cog, sd, skewness, and curtosis. In conclusion, it has been observed that phonetic changes of patients continued at the end of the first month; speech returned to normal in the third month of retention treatment. Considering the intergroup comparisons, speech was affected mostly by the essix appliance, the consonants were not affected as much in the patients using the fixed retainer appliance and better tolerance was noted.