Association between the speaking space of /s/ sound and incisal overlaps in dentate and edentate subjects.

The purpose of this study is to determine the association of speaking space of /s/ sound with vertical and horizontal overlaps for two subject groups. Group I comprised 61 subjects with complete permanent dentition and Group II comprised 33 complete denture wearers. They had their mandibular movement determined by using an electromagnetic method. Speaking space of /s/ was obtained from each subject as they were instructed to say the word 'seis' three times. The mean interocclusal distance during /s/ production was considered the speaking space of /s/. Vertical and horizontal incisor overlaps were also measured. The mean value of speaking space of /s/ was 2.22 mm (± 1.38) for Group I and 2.61 mm (± 1.53) for Group II. In Group I, significant correlations were found between the speaking space of /s/ and vertical overlap (r=0.36, P<0.01), and between speaking space of /s/ and horizontal overlap (r=0.45, P<0.01). In Group II, no significant correlation was found between speaking space of /s/ and the overlaps. It was concluded that incisor overlap had a direct influence on the measure of speaking space of /s/ for dentate subjects, but this association was not present for complete denture wearers.