The anterior teeth of maxillary dentures play an important role in pronunciation as well as appearance of the subjects. It has been suggested that assessment of the quality of pronunciation of the /S/ sound during the arrangement of the anterior teeth in maxillary wax dentures would be useful for facilitating speech adjustments with new dentures. AbstractPurpose: The purpose of this study was to investigate the relationship between the intelligibility of the /S/ sound and the incisal overjet of the anterior teeth of in a maxillary denture.Methods: Five subjects who were fitted with maxillary dentures participated in this study. Using a speech recognition system for the evaluation of phonetic functions, the correct and incorrect ratios of the intelligibility of the sound of the monosyllable [Si] in five subjects were determined in relation to increases in the degree of incisal overjet of the anterior teeth in a maxillary denture by +0, +1, +2 and +4 mm relative to that of the dentures already in use. Results:In association with increase in the degree of incisal overjet in experimental dentures from +0 to +4 mm, while the appearance ratio of the correct [Si] sound decreased from 73.0±8.6% at +0 mm to 48.5±7.8 % at +4 mm, that of the incorrect [Si] sound increased from 17.4±4.7% at +0 mm to 36.0±10.6% at +4 mm. Conclusion:Increasing distance between the incisal edges of the maxillary and mandibular incisors make correct pronunciation of [Si] progressively more difficult.

It was indicated that the middle type of the major connector would be recommended from a viewpoint of phonetic function.

Within the limitations of the study, jaw-opening exercise prior to OA therapy reduced the risk of TMD pain associated with OA use. Therefore, jaw-opening exercise may contribute to the prevention of TMD pain.

Objective: To investigate the effects of the width and cross-sectional shape of the major connectors of maxillary dentures located in the middle area of the palate on the accuracy of phonetic output of consonants using an originally developed speech recognition system. Patients and Methods: Nine adults (4 males and 5 females, aged 24-26 years) with sound dentition were recruited. The following six sounds were considered: [∫i], [t∫i], [ɾi], [ni], [çi], and [ki]. The experimental connectors were fabricated to simulate bars (narrow, 8-mm width) and plates (wide, 20-mm width). Two types of cross-sectional shapes in the sagittal plane were specified: flat and plump edge. The appearance ratio of phonetic segment labels was calculated with the speech recognition system to indicate the accuracy of phonetic output. Statistical analysis was conducted using one-way ANOVA and Tukey's test. Results: The mean appearance ratio of correct labels (MARC) significantly decreased for [ni] with the plump edge (narrow connector) and for [ki] with both the flat and plump edge (wide connectors). For [çi], the MARCs tended to be lower with flat plates. There were no significant differences for the other consonants. Conclusion: The width and cross-sectional shape of the connectors had limited effects on the articulation of consonants at the palate.

Individuals using dental prosthetic appliances tend to mispronounce the /S/ sound, phonation of which depends on the shape of the palatal contour. Thus, prosthodontists need to create the palatal contour in complete dentures with care. Here, we report that by using a speech recognition system, the palatal contour can be easily adjusted in the waxed denture base. AbstractPurpose: This study used a speech recognition system to investigate the intelligibility of the /S/ sound, which is based on the palatal contour of complete dentures. Methods:Six subjects with an edentulous maxilla participated in the study. The experimental dentures were made of self-curing acrylic resin and four curvatures (0, 2, 4, 6 mm) of the palatal contour were evaluated. A speech recognition program automatically converted the phonetic signals into phonetic segment labels. Labels that correctly recognized the /S/ sound were defined, and the distribution of the correct labels was analyzed in relation to the palatal contour. Palatograms were also recorded to assess tongue movement. Results: Repeated-measures one-way analysis ofvariance revealed a significant effect of the curvature of the palatal contour on the appearance ratio of the correct [Si] labels (F=53.1, P<0.05). Tukey's multiple comparisons revealed a significant difference between 0 mm and 2 mm (P<0.001), 0 mm and 4 mm (P<0.001), 2 mm and 6 mm (P<0.001), and 4 mm and 6 mm (P<0.001). Based on the appearance ratios of the [çi] labels, the 0 mm curvature of the palatal contour was rated as yielding the highest intelligibility (P<0.01), and based on those of the [tSi] and [dJi] labels, the 6 mm curvature was rated as yielding the intelligibility (P<0.01 for both). When tongue movement was assessed from the palatograms, tongue contact was found to be similar to that in the typical palatogram for each recognized syllable. Conclusion:The curvature of the palatal contour affects the pronunciation of the /S/ sound, and the appropriate curvature of the palatal contour in complete dentures for correct pronunciation of this sound is 2 to 4 mm.