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In this article, intrinsic problems lying in Prosthodontics research and educational field were pointed out and Prosthodontics as it ought to be as a nature science was discussed. Prospect of prosthetic dentistry/Prosthodontics as a clinical science was categorized the following four and discussed: 1) systematizing of conventional Prosthodontics, such as crown, bridge, partial and complete denture, 2) contribution to oral rehabilitation of mastication, swallowing, and speech for elderly and inpatient elderly, 3) innovation of prosthetic dentistry using more comfortable and aesthetic prosthesis, such as Implant and Adhesive Dentistry, and 4) translational research. Finally, essential prerequisites to achieve bright future of Prosthodontics were proposed.

目的: 客観的な咀嚼機能評価法を確立することは, 補綴処置の効果を評価するだけでなく, 診断や治療法の選択においても重要なことである. 今回, 着色ゼリーを用いた簡便な咀嚼機能評価法 (以下CG比色法) を考案し, 篩分法と比較しながら, その有効性について検討することを目的とした. また, 目視による比色判定の可能性を含め, 本評価法の進展性についても考察した.方法: 咀嚼機能に異常がない被験者13名に, 着色ゼリーを咀嚼させ, 口腔内残留色素の吸光度を測定した. 同時に, 節分法 (Manly法) による咀嚼機能評価も行い, 両者を比較検討することにより本評価法の有効性を評価した. また, 色素水溶液の色見本を参考に, 被験色素水溶液の吸光度を検者に推定させ, 目視による比色判定を試みた.結果: 咀嚼回数の増加とともに節分法の咀嚼値, CG比色法の吸光度も増加した. また, 筋分法は咀嚼回数が増えるに従い, 咀嚼値の増加率が減少するのに対し, CG比色法では吸光度の増加率は一定であった. また, 篩分法の咀嚼値はCG比色法の吸光度の対数に比例した. 目視による比色判定については, 色素水溶液の吸光度が0.5以下であれば, 実際の吸光度との間の誤差が比較的小さく, そのばらつきも小さかった.結論: CG比色法の吸光度と篩分法の咀嚼値とは対数関係にあり, 咀嚼回数が20回以下であれば, 本評価法は節分法と同等の有効性があることがわかった. また, 視感比色による咀嚼能率評価の可能性が得られた.

目的: インプラント上部構造には精度の高い適合性が要求されるため, さまざまな適合性の評価法が提唱されている. 著者らは, 上部構造連結部のスクリュー締め付け回転角/トルク計測装置を考案し, この装置を用いて, スクリュー固定式インプラント上部構造の適合性を作業模型上で評価した.方法: スクリュー固定術者可撤式上部構造を装着し, 術後良好に経過している患者14名, 計24上部構造 (単独植立3, 部分欠損20, フルブリッジ1) のスクリュー連結部について, 作業模型上で締め付け回転角/トルク値を計測し, 適合性を評価した. また, 締め付け順序の違い, ユニット数の違いによる影響について評価した.結果: すべてのスクリュー連結部の, 締め付け回転角/トルク値の平均は約2.6° (SD: 0.6°)/Ncmで, コントロールとしてアバットメントにスクリューのみを締め付けたものより有意に大きかった. 締め付け順序, ユニット数の違いによる締め付け回転角/トルク値の有意差は認められなかった.結論: スクリュー締め付け回転角/トルク値は, 上部構造の適合性評価に用いることが可能であると考えられた. 今回計測した上部構造の適合性は, acceptable fit内できわめて高かったことが示唆された.

目的: 歯科用磁性アタッチメントのキーパーと根面板とをレーザー溶接し, その吸引力と腐蝕性を従来の鋳接法と比較検討することである.方法: 市販の歯科用磁性アタッチメントのキーパーと歯科用金銀パラジウム合金を本実験に用いた. 鋳接法とレーザー溶接法を用いて試料を製作した. 自家製の測定装置を用いて, 磁石構造体とキーパーの吸引力を測定し, 製作方法により吸引力に差が生じるかを検討した. また, 0.9% NaCl溶液5mlに37℃ で21日間浸漬し腐食試験を行い, その表面性状を観察した.結果: 磁石構造体とキーパー間の吸引力については, 製作方法による差は生じなかった. キーパーの腐食試験では, 鋳接法により製作したすべての試料で錆を生じた. レーザー溶接法で製作した一部の試料では錆を生じたが, まったく錆を生じなかった試料もみられ, その試料の表面には腐食生成物は認められなかった.結論: 磁性アタッチメント用キーパーをレーザー溶接する方法が, 磁性アタッチメントの吸引力と腐食に及ぼす影響を鋳接法と比較検討した結果, 吸引力に対する影響は認められなかった. また, レーザー溶接したキーパーには腐食が全く生じなかったものが認められた. よって, ンーザー溶接によりキーパーと歯科用合金の境界を完全に溶接しシールドすれば, 腐食を生じる可能性が低くなり, キーパー付根面板の製作過程へのレーザー溶接の導入は有用であることが示唆された.

目的: チタンとハイドロキシアパタイト (以後, Ti, HAと略す) の異なる表面性状をもつインプラントについて伝導特性の相違を比較し, オッセオインテグレーションの評価を推定することを目的とした.方法: ウサギ脛骨に2種類の表面性状のインプラントを埋入した. 10週後に, インパルス打診試験を行い, インパルスハンマーと骨髄内に固定した小型圧力センサーにより, その振動特性と骨髄圧を測定し, インプラント材質間の差異を比較した. また, 組織学的にインプラント周囲骨の状態を検索し, 圧伝導特性との関係を検討した.結果: 観測されたインパルス継続時間では, HAで163±23μsec, Tiで165±20μsecと有意な差はなかった. 一方, 最大骨髄圧値は, HAで90.3±30.6mmHg, Tiで117.4±54.8mmHgと有意にTiのほうが大きく, また, 偏差もHAに比べTiのほうが大きかった. インパルス継続時間と最大骨髄圧値の間にはTiで負の相関関係が認められたが, HAでは相関が認められなかった. インプラント周囲骨の組織学的検索においては, インプラント間での差異は確認できなかった.結論: 骨髄圧値の測定から, TiとHAにおける圧伝導性の相違が認められた. 両者の周囲骨の組織像に差は認められず, インプラントの材質による影響が大きいことが示唆された. 評価法を構築していくうえで, 材質の特性の差異を考慮する必要性が示唆された.

目的: 高齢者の全身感染症の予防, 特に誤嚥性肺炎の予防が重要な課題の1つとなっており, われわれは, 義歯が微生物のリザーバーとなって誤嚥性肺炎などの感染症を引き起こしている危険性を指摘している. また, これらの感染症は, 薬剤耐性菌の出現により治療が困難となっている. そこで, デンチャープラークと咽頭より分離した微生物叢の関連性とカンジダの薬剤感受性について検討した.方法: 老人病院入院患者と大学病院外来患者の義歯装着者を対象に, 上顎義歯床口蓋部粘膜面および咽頭粘膜面における口腔レンサ球菌, ブドウ球菌, カンジダ, 緑膿菌, 大腸菌・大腸菌群, MRSAの検出率を評価し, さらにカンジダに関しては, 薬剤感受性試験を行った.結果: デンチャープラークから微生物が検出されると, 咽頭からも同種の微生物が検出される傾向にあった. 多くの微生物は, 大学病院外来患者より老人病院入院患者のほうが有意に高い検出率を示した. カンジダが検出されると, 同部位からブドウ球菌も検出されるケースが多かった. アムホテリシンBに対しては, 菌種に関係なく, 高感受性の傾向を示した. フルコナゾールに対しては, Gandida albicansが高感受性の傾向を示したが, Cglabrata, C. tropicalis, C. kruseiが低感受性の傾向を示し, 耐性株もあった.結論: デンチャープラークが, 咽頭の微生物叢に与える影響は大きいと考えられる.

Various types of occlusal scheme have been developed for a complete denture. Some investigators recommended lingualized occlusion as the scheme of occlusion for acomplete denture, but how to determine the buccal interocclusal distance in lingualized occlusion isunclear. The purpose of this study was to investigate the influence of the buccal interocclusal distance in lingualized occlusion on the pressure distribution under a complete denture. In this study, eight pressure transducers were placed in the basal surface of a mandibular denture. The pressure distribution under a complete denture and the required force were recorded when crushing three different foods: kamaboko, carrot, and peanuts.The results were as follows:1. The required force for crushing all test foods decreased as the buccal interocclusal distance increased.2. During the food crushing tests the positive pressure values were observed mainly on the working side and the positive pressure values decreased as the buccal interocclusal distance increased.3. The negative pressure values were observed on the non-working side, and the negative pressure values decreased as the buccal interocclusal distance increased.4. The required force for crushing test foods and the pressure applied to supporting tissues greatly decreased when crushing hard foods.

Dentures may act as a reservoir for bacteria which cause opportunistic infection such as aspiration pneumonia, and denture cleaning could prevent such an infection. Recently, the bacteriocidal effect of electrolyzed water (EW) on bacteria has been reported.In this study, the influence of EWs on the Candida albicans biofilm in vitro was investigated. C. albicans adhered avidly to type IV collagen. The biofilm was established on the cover slip coated with type IV collagen using Luria broth at 37°C for 5 days. The biofilms were treated with several kinds of EWs, and the efficacy of EWs was investigated.C. albicans well adhered to collagen-coated celldesk, produced glycocalyx-like substance and formed a biofilm after five-day incubation. Scanning electron microscopy revealed degradation of biofilm treated with EW. Vital CFU in the biofilm decreased time-dependently and logarithmically. Five treatments for one minute was more effective than one treatment for five minutes. The effect of EW synthesized by a home care device was equal to or higher than that synthesized by a medical device. These results suggested that EW, even if synthesized by the home care device, is a potent denture-cleanser.

This article describes image examinations concerned with implant treatment and soft tissue for restoring partially and completely edentulous patients.Image examination is necessary for implant treatment, preoperative evaluation of bone quality and shape, assessment of osseointegration and fitness between implant and abutment, postoperative assessment of bone remodeling, and marginal bone loss. Contrast X-ray media, pilot hole preparation, standard radiography, and digital image processing were used to evaluate the procedures. Especially, evaluation of bone quality was discussed.It is very important to evaluate soft tissue, for example, tongue, cheek, lips, and so on for restoring partially and completely edentulous patients. The evaluation is often forgotten during prosthetic treatment. Cephalography, ultrasonic measurement, and MRI were proposed for the evaluation, and the problems and overlook for the evaluation were discussed.

Many bacteria cover denture surfaces as denture plaque in the form of a biofilm, especially dentures of geriatric hospital inpatients. Dentures may act as a reservoir of microorganisms which cause opportunistic infection such as aspiration pneumonia. Oral health care, including denture plaque control could prevent such infection. Overviews of Candida spp. and Helicobacter pylori in denture plaque and the approach to denture plaque control for the prevention of systemic infection are presented in this report.

Anterior palatal form affects the speech and is one of the important factors for the fabrication of upper denture. Air pressure in the incisor region was measured to examine the influence of the anterior palatal form on speech in the previous report. In the present study, the palatogram and jaw position were measured during the utterance of Japanese/sa/, /si/, /ta/, and /ci/. Subjects used and the experimental denture were the same in the report.The results were as follows:1. Palatogram was influenced by alterations of anterior palatal form. The thicker the anterior palatal counter, the posterior construction for fricative or plosive in the palatogram positioned during the utterances of /sal, /si/ and /ci/. The influence of the anterior palatal form was not observed during the utterance of /ta/.2. The alterations of anterior palatal affected significantly the mandibular position. No general tendency was observed regardless of subjects.The tongue movements primarily compensated alterations of anterior palatal form. This experiment confirmed that adequate anterior palatal form, i.e., width and location of S-ridge and the location, is important for the /s/sound production.

The purpose of this study was to investigate the influence of anterior palatal form on air pressure during the production of /sa/, /si/, /ta/ and /ci/. The subjects used were 5 male 3 female edentulous patients, whech were native Japanese speakers. Each experimental maxillary denture was fabricated and four experimental thicknesses were defined as a function of alteration in the anterior palatal counter of complete denture. The tip of aluminum tube was placed in artificial incisor teeth and the other tip was connected to a differential micropressure transducer. Air pressure and the speech signal were recorded by a digital data recorder during speech production.The results were as follows:1. Air pressure signal in each sound was characterized by the number of peaks and the time relationship to speech signals.2. The anterior palatal form of complete denture had little influence on the time relationship between the peak of air pressure and speech signals.3. The peak value of air pressure ranged between 100 and 700 Pa in /sa/, 100 and 500 Pa in /si/, 50 and 600 Pa in /ta/, and 50 and 700 Pa in /ci/. The peak values of air pressure were different among the subjects. Four experimental anterior palatal forms significantly affected peak values of air pressure (ANOVA, p

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®). 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).

Dental treatment must meet the needs of the rapidly increasing elderly people in Japan. In addition, geriatric inpatients also increased with the increase of elderly people. Investigation was carried out to determine the oral condition and microflora in denture plaque of elderly patients in two geriatric hospitals and Tokushima Dental Hospital. The difference between healthy patients and geriatric inpatients was. discussed. The results of the preliminary survey were as follows:1. Inpatients in a geriatric hospital were more elderly, and the frequency of edentulous patients was fairly high. The prognosis of the denture was poor because of high frequencies of low residual ridge and oral diskinesia.2. Denture plaque of geriatric inpatients had the following characteristics compared to that of healthy elderly patients.1) Numbers of total bacteria, Streptococci, Candida, and Staphylococci in isolated denture plaque of the geriatric inpatients were larger than those of healthy patients.2) Linear relationships between numbers of total bacteria and Streptococci and between numbers of Candida and Staphylococci were found.3) The frequency of MRSA in the geriatric inpatients was higher than in the healthy patients.4) Numbers of total bacteria and Streptococci in denture plaque obtained in the inpatients with heart disease and cerebrovascular accident were much larger than those in the inpatients without these diseases.

In this study the mandibular distortion during mandibular movement was measured. The subjects were three females and one male. Two apatite implants were placed in a unilateral mandibular molar region at an interval of about 10 mm. The measuring apparatus consisted of a magnetic sensor attached to the medial implant and a magnet attached to the distal implant. The position of the distal implant relative to the medial implant during opening and protrusion of the mandible were measured six times every movement.At the maximum opening the position of the distal implant was deviated lingually in the range of 8 to 25 pm and at the maximum protrusion it was also deviated lingually in the range of 10 to 37 μm.These findings suggest that the stress concentration on the implant and surrounding bone is caused by mandibular distortion during mandibular movements if several superstructures of implants inserted in the mandibular molar region are connected firmly. In other words, it is important for the mandibular position at the impression and soldering operation procedure for the fabrication of the superstructure to decrease the stress.

The purpose of this study was to investigate the influence of the anterior palatal form on speech. The subjects used were 36 male and 14 female dentitions, which were native Japanese speakers. The palate of each subject was impressed and the study cast was made. Each palatal form was examined and classified. Parameters involve the palatal form ; WD-index, IM-angle, A-angle, PL 1, PL2, and PL 3 were measured. The acoustic characteristics during /s/ production of subjects were analyzed with a digital acoustic analysis system. The first and second peak frequencies and consonant duration of /s/, the first, second and third formant frequencies of following vowels were measured. The relation between the palatal form and the acoustic characteristic of /s/ sound was discussed.The following results were obtatined.1. Palatal form was classified into three types: Type 1 represents a rounded square arch with a gentle anterior palatal slope and the maximumpalatal depth was low. Type 2 represents a rounded square arch with a sharp slope and the maximum depth was great. Type 3 represents a narrow paraboloid or V-shaped arch with a sharp slope and the maximum depth was great.2. WD-index, IM-angle and PL 3 in male subjects were useful values to classify three palatal types, and WD-index, A-angle and PL 2 in female subjects.3. The palatal form had little influence on the acoustic characteristics of /s/ sound.

The purpose of this study was to investigate the influence of palatal form changing with the position of upper posterior artificial teeth on tongue movement for pronunciation of /s/sound. Subjects were seven males and speech material was /asa/. Two experimental palatal plates were made for each subject: a normal 1.5-mm-thick plate and the plate augmented by a 4-mm-thick lateral seal of palatal surface. Tongue-palatal contacts were measured by a dynamic palatography when wearing either of the two plates. The influence of the palatal form was estimated using the following parameters: the onset of the tongue-palate contact, maximum contact speed, the timing of the constriction for /s/, and palatogram pattern at the constriction and consonant duration for /s/.The speech behavior when wearing the augmented plate was divided into 4 groups comparing to normal plate:Group 1: Tongue-palate contact started earlier, maximum contact speed decreased and the timing of the constriction was constant.Group 2: The onset of tongue-palate contact and maximum contact speed were constant. Butthe timing of the constriction was delayed.Group 3: Tongue-palate contact started earlier, maximum contact speed decreased and thetiming of the constriction was delayed.Group 4: Temporal aspect of tongue-palate contact was constant. But the consonant durationwas shorter and abnormal palatogram pattern was observed.

The purpose of this study was to investigate the influence of the vertical dimension on pronunciation.Tongue pressures, mandibular movements and speech sounds were simultaneously recorded and analyzed for the following sounds:/asa/, /asi/, /ahi/, /aci/, /aki/, /ake/ and /ari/ when the vertical dimension was normal and increased by 4mm, 8mm and 12mm beyond the normal vertical dimension at the incisor.The results were as follows:1. The maximum tongue pressures tended to be smaller on for /asa/ than other sounds and be greater in more posterior palate in the normal vertical dimension.2. The maximum tongue pressures changed differently among subjects, sounds and measuring sites, but tended to decrease in anterior palate for any sounds and increase in posterior palate with increases in vertical dimensions.3. Tongue contacts usually started from posterior palate to anterior palate before the end of the preceding vowel, and tongue pressures usually came up to maximum between the end of the preceding vowel and the start of the following vowel. But the timings between sounds and tongue pressures were not evidently influenced with increasing vertical dimensions.4. It was found that changes in maximum tongue pressures with increasing vertical dimensions were related to those of simultaneous mandibular movements.

The purpose of this study was to investigate the influence of the vertical dimension of dentures on pronunciation.The results were as follows:1. The maximum tongue pressures tended to be greater in more posterior palate in the normal vertical dimension, just as in normal subjects.2. The maximum tongue pressures tended to decrease in anterior palate and increase in posterior palate with increases in vertical dimensions, just as in normal subjects. But, conversely, some of them had a tendency peculiar to complete denture wearers to increase in anterior palate for sounds /asa/, /asi/, etc.3. Tongue contacts usually started from posterior palate to anterior palate in the normal vertical dimension, just as in normal subjects. But the timings between sounds and tongue pressures weren't consistent with increases in vertical dimensions.4. The incisor position of mandible tended to be downward and back with a decrease in vertical dimension, and to be located differently with increases in vertical dimensions, just as in normal subjects.5. Changes in maximum tongue pressures with varying vertical dimensions were related to those of simultaneous mandibular movements, just as in normal subjects. In some cases, including/asa/ and /asi/, a correspondence peculiar to complete denture wearers was found.

PURPOSE Preliminarily to examine the efficacy of miconazole gel at inhibiting colonization of Candida species in overdenture wearers. METHODS The subjects were 26 overdenture wearers. Miconazole gel was used with the following directions: group A was prescribed miconazole gel 1.5 g 4 times daily for 1 week, group B was prescribed miconazole gel 0.5 g 4 times daily for 1 week. As a screening test, Candida species were examined in denture plaque, dental plaque, and pharyngeal mucosa. The number of Candida species, total bacteria, and oral streptococci were counted before and after application of miconazole gel to Candida-positive subjects. RESULTS Candida species were detected in 18 of 26 subjects and high incidence was found around the abutments under the denture base. All Candida species were sensitive to miconazole gel. Miconazole gel was applied to 13 subjects. The number of Candida was reduced after 1-week use of miconazole gel with few side effects during the application. CONCLUSION It is suggested that miconazole gel will be an effective and safe method for oral care and denture plaque control in overdenture wearers.

UNLABELLED A new digital image processing system to observe oral actions is proposed. The system provides analyses of motion pictures along with other physiological signals. The major components are a video tape recorder, a digital image processor, a percept scope, a CCD camera, an A/D converter and a personal computer. Five reference points were marked on the lip and eyeglasses of 9 adult subjects. Lip movements were recorded and analyzed using the system when uttering five vowels and [ka, sa, ta, ha, ra, ma, pa, ba[. RESULTS 1. Positions of the lip when uttering five vowels were clearly classified. 2. Active articulatory movements of the lip were not recognized when uttering consonants [k, s, t, h, r[. It seemed lip movements were dependent on tongue and mandibular movements. Downward and rearward movements of the upper lip, and upward and forward movements of the lower lip were observed when uttering consonants [m, p, b[.

In case of making complete dentures, we have to consider not only denture stability but also the restoration of aesthetics and function such as mastication and speech. However these are contradictory theoretically from the point of view of denture stability, and it is very difficult to satisfy both requirements in the case of a patient who has poor upper and lower alveolar ridges. We investigated the effect of artificial posterior teeth form and occlusal scheme on the distribution of pressure on supporting structures under complete dentures during mastication with upper and lower edentulous simulators. In this report, a guideline for the selection of occlusal scheme for complete dentures, based on our previous investigations, is described. The occlusal scheme remarkably affected the distribution of pressure under simulated complete dentures, as shown by comparing the distribution of pressure using two different occlusal schemes:fully balanced occlusion and lingualized occlusion. However other factors such as posterior teeth form and position affect the distribution of pressure as well, and are related to each other. Therefore, not only occlusal scheme but also posterior artificial teeth form has to be considered, and the form of posterior teeth should be carefully and comprehensively decided when making complete dentures.

In an edentulous patient after hemiglossectomy, acoustic characteristics of soundswere studied with and without complete dentures of different morphology. Forms of the denturepalatal plate were changed as follows: 1. normal palatal form 2. augmented form in the anteriorregion 3. augmented form as extensively as tongue, floor of the mouth and lower denture can bein contact with. Acoustic parameters characterised sounds were Formant, Voice onset time, Energy, Spike file and Spectral pattern. They were calculated with a minicomputer by usingliner prediction method and time domain method.Result1. Acoustic characteristics after the hemiglossectomy were as follows.(1) Formants characterised five vowels were similer one another as compared with normalsubjects and five vowels had a tendency to be centralization.(2) Lingua-alveolar plosive sound (/t/) was mistaken as bilabial sound (/p/).(3) Lingua-velar plosive sound (/k/) was mistaken as fricative sound (/h/).2. Improvement in sounds (especially, /i/ line and /∫/ sound) was observed with the augmentedcomplete denture as extensively as tongue, floor of the mouth and lower denture can bein contact with palate.

The purpose of this study was to investigate articulatory movements of tongue and mandible on pronouncing /S/ sound by analysing the timing of articulation and the pattern of tongue-palate contact. The lingual articulation, mandibular movements and speech sound of ten subjects were simultaneously recorded with an electropalatograph and a mandibular kinesiograph.Results1. The timing of lingual and mandibular articulation on pronouncing /S/ was generally constant regardless of sounds and was obtained on the average as follows:(1) The closing movement of mandible began about 110 msec before (V 1), the offset of preceding vowel and tongue-palate contact began about 40 msec before (V 1).(2) The mandible reached the closest speaking level about 10 msec after (V 1) and the tongue formed the maximum constriction about 20 msec after (V 1).(3) The opening movement of mandible began about 30 msec before (V 2), the onset of following vowel and releasing the maximum constriction began at the same time.2. As regards analysing the pattern of tongue-palate contact by numerical methods, there was individual variability in the pattern, but several characteristics among subjects were found as follows:(1) The variability of the pattern with the same subject and sound was small.(2) The perturbation of the pattern by the adjacent vowel was greater at the posterior portion of palate as compared with the anterior.(3) The influence by the preceding vowel at the forming time of the constriction and the influence by the following vowel at the releasing time was recoginized.(4) The pattern of tongue-palate contact for the muximum constriction was generally constant regardless of sounds except [ASK].

We proposed a new optical system to measure the movements of less accessible organs with soft tissue. The sensor unit is composed of a phototransistor and two LEDs. Two LEDs of light sources are driven by two phase signals with phase shift of 90 degrees. The distance between the sensor and the measuring object can be obtained as the function of the phase angle of reflex light signal detected by the phototransistor. The system can be easily constructed and provides simultaneous recordings of multiple points with the fast response in real time. The Relative precision is 0.5 mm and the resolution is 0.05 mm. Output characteristic of the system was less affected by the reflection factor of the object. We conducted to observe the tongue movements in speech production.