Analysis of the Relationship between the Incisal Overjet in a Maxillary Denture and Phonetic Function Using a Speech Recognition System

Abstract

Clinical significance 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. Abstract Purpose: 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 maxil-lary dentures participated in this study. Using a speech recognition system for the evaluation of pho-netic 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 .