We examined the influence on temporal aspects of three consonants, /k/, /c/ and /s/, of alterations in the oral environment produced by either palatal augmentation or by an increase in the vertical dimension of occlusion. Voice onset time (V.O.T.) for /k/ and /c/ was influenced more than aspiration time by the palatal augmentation. Consonant duration for /s/ was also influenced by palatal augmentation. Significant influence of an increase in vertical dimension on the timing was not recognized. Speech disorder caused by the malformation of palate seems to be more frequent than that caused by vertical dimension. Adaptation to prostheses would seem to be definitely concerned with orosensory feedback.
This study introduced a new method for three-dimensional (3D) examination of the bone structure around an implant and presented 3D bone-implant contact rates. A block of nondecalcified implant tissue was ground gradually at an interval of 80 micrograms for the collection of serial two-dimensional (2D) images. An image of the stained block surface was instantly recorded by a charge-couple device (CCD) camera and computer-aided system. A 3D model was reconstructed from 60-70 sheets of serial 2D images. The 3D bone structure around the implant was shown in perspective and displayed all sides of the implant. The bone-implant contact rate depended on the cutting position and direction in the specimen. The 3D model will be necessary and valuable for the biomechanical study of dynamic bone changes around implants.
Abstract:The purpose of this study was to investigate the influence of the alteration of palatal form on pronunciation. Three types of artificial palatal plates simulating the upper complete denture, which artificial posterior teeth position was more lingually than natural dentition, were made foreach dentulous subject. Difficulty of articulatory movements and sound qualities were assessed when the subjects pronounced/sa/,/si/,/ka/,/ki/,/ci/,/hi/, and/ri/with each plate. The distortional sounds judged by auditory psychological experiment were analysed by acoustic methods, and mandibular movements during pronunciation of them were measured. Results 1./ki/and/hi/were affected remarkably when the posterior position was more lingually, and /ri/,/ci/and/sa/were also affected. 2. The acoustic characteristics of distortional sounds were estimated by peak trajectories, supectrum envelopes, peak frequencies and sound waveforms of consonant parts, formant frequencies and formant trajectories of following vowels, and segmental durations.3. Mandibular movements did not influence directory on the acoustic characteristics of distortional sounds. It was thought that tongue and lips mainly influenced on those.
To assess speech disturbances caused by newly made prostheses, visual and acoustical methods, palatograms, sound spectrograms, etc., have been used. But the analysis and assessment requires somewhat professional knowledge and experience and much time, so such methods are not necessarily easier, and have the defect of being somewhat subjective. The purpose of this study is to develop a new speech test that is easy to use and more objective using the speech recognition unit. First, experimental palatal plates were made for a dentulous subject, and the utility of the speech recognition unit was estimated. The speech recognition unit and ordinary hearing were compared in utterance of ten Japanese monosyllables,
The purpose of this study was to investigate efficacies of acidic and neutral electrolyzed water as denture cleansers from the bacteriological aspect.Twenty-five upper full dentures of patients of an elderly care center were used in this study. Nine dentures were immersed in acidic electrolyzed water, eight in neutral electrolyzed water and eight in denture cleanser (Pika(R)) . Plaque samples were collected from fitting surface of the dentures by scrubbing before and after immersion, and the changes in the number of bacteria were observed.The results were as follows :1. Acidic and neutral electrolyzed water were effective as denture cleansers, and the rates of removal [log10 (bacteria number after immersion) /logic, (before immersion) ] tended to be constant. 2 . MRSA decreased by immersion in acidic electrolyzed water and in denture cleanser (MRSA was isolated from four dentures. Two were immersed in acidic electrolyzed water and two in denture cleanser).
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