Short term evaluation of interocclusal distance during speech after new removable prosthesis insertion

The aim of this study was to evaluate the interocclusal distance during the pronunciation of /m/ and /s/ sounds from Portuguese Language, in partially edentulous patients before and after new partial and total prosthesis installation. The subjects were divided into two groups: Experimental group, consisting of 9 patients entirely edentate in the upper maxillary arch and classified as Kennedy Class I in the lower arch; and Control group, consisting of 9 totally dentate patients. The subjects from the first group had their worn out dentures changed and the occlusal vertical dimension (OVD) corrected. A magnetic method of jaw tracking was used to measure the interocclusal distance (mm) during pronunciation of those phonemes. Comparison between groups, by t test, showed significant difference (p<0.05) for /m/ sound in all periods of time: before prosthesis installation - T0 (3.38±1.23), immediately - T1 (2.15±1.06), six hours - T2 (3.41±1.33), twenty-four hours - T3 (2.92±0.92), two days - T4 (4.80±1.93), one week - T5 (3.87±1.43), two weeks - T6 (3.03±0.96), one month - T7 (3.03±0.96), two months - T8 (4.47±1.45) and three months - T9 (4.33±2.56), except for six months - T10 after prosthesis installation. For /s/ sound phoneme the results were different (p<0.05) between the groups in T1 (2.89±1.33), T2 (3.37±1.22), T3 (3.19±1.06), T4 (3.86±1.21), T5 (3.83±1.32), T6 (3.27±1.10), T7 (3.37±0.99) and T10 (3.84±1.38) after oral rehabilitation. The paired-t test, for means comparison between before and after prosthesis insertion, indicated significant differences (p<0.05) for /m/ sound only in T1, and for /s/ sound in T1, T2, T3, T6, T7 and T10. It was concluded that new prosthesis insertion, correcting the OVD, changes the interocclusal distance, and for /m/ sound this distance could be recovered after six months of prosthesis wearing.