Language：Japanese   Publisher：岡山歯学会  

researchmap

Language：Japanese   Publisher：(一社)日本顎顔面補綴学会  

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: To examine how particle loss affects the evaluation of masticatory ability using the image analysis method. METHODS: The subjects were divided into two groups:Y-group (healthy young adults: 10 male, 10 female; mean age 27.6 ± 1.9 years), and D-group (denture wearing older adults: 13 male, 9 female; mean age, 75.1 ± 5.3 years). Raw carrots, peanuts, and a combined test food from 5 daily food materials (mixed foods) were selected as test foods. Images of the boluses were captured and processed after the subjects freely masticated the test foods until the point of swallowing or completed half strokes of total chewing cycles. The median particle size (X50) was calculated from the data for each particle. We compared X50 calculated from all particles obtained from the masticatory bolus (as X50N) with the X50 of only selectively larger particles (as X50R). RESULTS: Significant correlations were observed between X50N and X50R (p < 0.01) determined in almost all masticatory conditions. In particular, for particle sizes of 2 mm or more, the correlation coefficient between X50N and X50R was notably strong (r > 0.75). CONCLUSION: The method of analyzing only larger particles makes it possible to evaluate masticatory ability without losing the characteristics of the original particle size distribution of the entire bolus. This finding can be applied for the evaluation of masticatory ability, especially among older adults who have difficulty retrieving the total amount of test food due to decreased activities of daily living.

DOI： 10.2186/jpr.JPR_D_21_00069

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: This study aimed to investigate the effect of removable denture prostheses on the comminution progress in elderly people. METHODS: Twenty-two denture wearers of Eichner's classification B and C (75.1±5.3 years old) and 20 young fully dentate subjects (27.6±1.9 years old) participated in the masticatory examination, which used a combined test food from 5 daily food materials. Full masticatory cycles lasting until subjects needed to swallow and the half number of the cycles were adopted as masticatory conditions. Digital images of food particles under wet conditions were obtained for each bolus, and particles were analyzed by calculating the homogeneity and particle size indices. RESULTS: The characteristic properties of the food particles were observed using a homogeneity index in the elderly denture group for half masticatory strokes. Their homogeneity index was significantly higher than that of the young dentate group. By contrast, no significant difference was observed in the indices for particles immediately before swallowing between two groups. CONCLUSIONS: The comminuted particle size before swallowing in healthy denture wearers was not significantly different from that in the natural dentate group. The comminution of the first-half process in denture wearers was typical and could be one possible focus for meal property specifications in future studies.

DOI： 10.1016/j.jpor.2019.08.001

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

During mastication, some portion of the food bolus is gradually transported to the oropharynx before deglutition, which is known as stage II transport (STII). Although the importance of STII in mastication and deglutition has been widely acknowledged, food particle properties that are transported into the oropharynx by STII have not yet been fully specified. To reveal the food particle properties that are transported into the oropharynx by STII and to assess the usefulness of new food bolus sampling methods for the evaluation of masticatory efficiency. Twenty-two healthy volunteers participated in this study. Four different bolus sampling conditions were adopted: (a) the whole food particles were expectorated when the subject was aware of the first deglutition, (b) the last bolus to be swallowed at the end of unrestrained food intake was expectorated (aftermost bolus sample), (3) the whole food particles were expectorated when the subject felt ready to swallow after swallow-inhibited mastication (swallow-inhibited sample), (4) the particles were regurgitated from the oropharynx after the first STII (stage II-transported sample). Food particles were analysed using the homogeneity index and particle size index. There was no significant difference between food particles in the aftermost bolus sample and swallow-inhibited sample. The particles in the stage II-transported sample showed significantly more homogeneous and smaller sizes than other sampling conditions (P < .05). The food particles transferred to the oropharynx in the stage II-transported sample were smaller than those broken down by natural mastication.

DOI： 10.1111/joor.12879

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

BACKGROUND: Mastication has been regarded to play an important role in achieving quality daily life for the elderly. On the occlusal surface of posterior artificial teeth, parallel grooves of 1 mm depth and 1 mm width with an inter-groove distance of 2 mm have been found to significantly improve masticatory efficiency on a mechanical simulator. MATERIALS AND METHODS: In the present study, the effect of the grooved design on masticatory efficiency in edentulous subjects using a short-term crossover trial was evaluated. Six edentulous participants, 1 male and 5 females, were assigned into two groups. One received duplicated complete dentures with grooved molars first, and the other received duplicated complete dentures with conventional molars first. The design of the teeth was crossover after evaluating masticatory efficiency. Raw carrot, raw lettuce and mixed foodstuffs were used to evaluate masticatory efficiency. Subjects were instructed to masticate 20 strokes and arbitrary strokes until they felt like swallowing. RESULTS: The number of masticatory strokes taken was significantly smaller using the grooved design (p<.05). Masticatory efficiency analysis revealed that the grooved design achieved significantly higher masticatory efficiency at 20 masticatory strokes for raw carrot and mixed foodstuffs (p<.05). CONCLUSION: Results show that compared with conventional lingualized occlusion, the grooved design accomplishes higher masticatory efficiency in vivo. Considering the distinction of this design that it can be applied to any existing denture occlusion, the design might help improve the dietary life of the elderly.

DOI： 10.2174/1874210601812010255

PubMed

researchmap

Language：English   Publishing type：Research paper (scientific journal)  

PURPOSE: The low masticatory efficiency of denture prostheses impairs the ability of wearers to consume high-fiber foods. Hence, artificial teeth with high masticatory efficiency are required. This study aimed to establish an occlusal surface design for posterior artificial teeth in denture prostheses that is compatible with the existing artificial teeth arrangement and that has high masticatory efficiency for the comminution of raw vegetables. METHODS: A masticatory simulator for occluding complete dentures was used to evaluate the masticatory efficiency of four occlusal surface designs, i.e., with parallel grooves occluding at right angles to the opposing teeth, groove depths of 1 and 0.5mm, and inter-groove distances of 1, 2, and 3mm. Raw carrots, rice, raw lettuce, chicken breasts, and peanuts were used as test foods to evaluate food comminution. RESULTS: Grooved occlusal surface designs with a 1-mm groove depth and a 2- or 3-mm inter-groove distance demonstrated significantly greater masticatory efficiency than the conventional occlusal form (p<0.05). CONCLUSIONS: The superiority of grooved designs over the conventional design was particularly evident for lettuce and raw carrots in this study, both of which are considered difficult foods to chew with complete dentures.

DOI： 10.1016/j.jpor.2016.05.004

PubMed

researchmap

Language：Japanese   Publisher：(公社)日本補綴歯科学会  

researchmap

Language：Japanese   Publisher：(公社)日本補綴歯科学会  

researchmap

Language：Japanese   Publisher：(公社)日本補綴歯科学会  

researchmap

Language：Japanese   Publisher：(一社)日本口腔ケア学会  

researchmap

Language：Japanese   Publisher：日本顎口腔機能学会  

researchmap

Language：Japanese   Publisher：(一社)日本顎顔面補綴学会  

researchmap

Language：Japanese   Publisher：岡山歯学会  

researchmap

Language：Japanese   Publisher：(NPO)日本咀嚼学会  

researchmap

Language：Japanese   Publisher：岡山歯学会  

咀嚼中にStage II transportで咽頭に移送された食物粒子の粒度特性を明らかにし、日常的な咀嚼を反映させ得る実用的な咀嚼食塊の回収方法について検討した。当院に所属する職員ならびに歯学部の学生計12名(男性8名、女性4名、平均27.2±2.15歳)を対象とした。被験者に対し、咀嚼条件1「自由咀嚼を行わせ、その途中に嚥下運動が1回発生したと自覚した時に口腔内に存在している食材をすべてカップに吐出させて粒子を回収する」などの四つの条件下で咀嚼を行ってもらい、口腔内粒子の除去後、反芻様運動を行うよう指示することで中咽頭の粒子を口腔内に戻させ、その粒子を回収用吸引装置で回収した。その結果、咀嚼条件1の粒子が最も大きく、それ以外の条件下では肉眼的におおむね同様の大きさの粒子が観察される傾向にあった。中咽頭に移送されている粒子は小さく均等であり、咀嚼の完了した粒子が選別されて送り込まれていることが示唆された。

researchmap

Language：Japanese   Publisher：(公社)日本補綴歯科学会  

researchmap

Language：Japanese   Publisher：(公社)日本補綴歯科学会  

J-GLOBAL

researchmap

Language：Japanese   Publisher：(NPO)日本咀嚼学会  

researchmap

Language：Japanese   Publisher：医歯薬出版(株)  

researchmap

Language：English   Publisher：WILEY-BLACKWELL  

Elevation of the posterior part of the tongue is important for normal deglutition and speech. The purpose of this study was to develop a new surface electromyography (EMG) method to non-invasively and objectively evaluate activity in the muscles that control lifting movement in the posterior tongue. Neck surface EMG (N-EMG) was recorded using differential surface electrodes placed on the neck, 1 cm posterior to the posterior border of the mylohyoid muscle on a line orthogonal to the lower border of the mandible. Experiment 1: Three healthy volunteers (three men, mean age 37.7 years) participated in an evaluation of detection method of the posterior tongue lifting up movement. EMG recordings from the masseter, temporalis and submental muscles and N-EMG revealed that i) N-EMG was not affected by masseter muscle EMG and ii) N-EMG activity was not observed during simple jaw opening and tongue protrusion, revealing the functional difference between submental surface EMG and N-EMG. Experiment 2: Seven healthy volunteers (six men and one woman, mean age 27.9 years) participated in a quantitative evaluation of muscle activity. Tongue-lifting tasks were performed, exerting a prescribed force of 20, 50, 100 and 150 gf with visual feedback. For all subjects, a significant linear relationship was observed between the tongue-lifting force and N-EMG activity (P &lt; 0.01). These findings indicate that N-EMG can be used to quantify the force of posterior tongue lifting and could be useful to evaluate the effect of tongue rehabilitation in future studies.

DOI： 10.1111/joor.12389

Web of Science

researchmap

Language：Japanese   Publisher：岡山歯学会  

researchmap

Language：Japanese   Publisher：(公社)日本補綴歯科学会  

J-GLOBAL

researchmap

Language：Japanese   Publisher：(NPO)日本咀嚼学会  

researchmap

Language：Japanese   Publisher：日本顎口腔機能学会  

咀嚼に関する研究の中心となってきた歯科医学に多くの知識が存在するにもかかわらず、現在の高齢者の食に関する決定に対する歯科医師の関与はわずか3.1%にすぎず非常に少ないことが報告されている。摂食には多くの要因が関与するため例えば義歯装着等によって食形態を変更できるかどうかの総合的かつ客観的判断も現時点では困難とされており歯学領域でこれまで蓄積されてきた知識は活用されているとは言い難い。この観点から考えると、日常的に摂取している自然食品の咀嚼評価を、食レベル決定のための臨床判断基準として用いることには重要なニーズがあると考えられる。多種多様な日常食品を咀嚼・嚥下する実際の高齢者の食生活を考慮すれば、咀嚼能率の評価は単純化・普遍化から離れて、個々の患者の嗜好なども含めたオーダーメイド化された評価を目指すことが望まれる。本稿ではこれまでに報告された種々の食品の粒度解析関連の研究を紹介するとともに食レベル決定への関与の可能性という観点からまとめたものである。(著者抄録)

researchmap

Other Link： https://search.jamas.or.jp/index.php?module=Default&action=Link&pub_year=2014&ichushi_jid=J02994&link_issn=&doc_id=20150213300002&doc_link_id=%2Fex2gakuk%2F2014%2F002101%2F002%2F0008-0020%26dl%3D0&url=https%3A%2F%2Fwww.medicalonline.jp%2Fjamas.php%3FGoodsID%3D%2Fex2gakuk%2F2014%2F002101%2F002%2F0008-0020%26dl%3D0&type=MedicalOnline&icon=https%3A%2F%2Fjk04.jamas.or.jp%2Ficon%2F00004_2.gif