Antimicrobial Efficacy of a Portable UV-C-Based Coating Activation Device against Candida albicans Biofilm and SARS-CoV-2 as an Additional Feature: An In Vitro Study.


Mouth breathing reduces oral function in adolescence


Social frailty as a predictor of all-cause mortality and functional disability: a systematic review and meta-analysis


Association between working in small-scale cultivated land as a daily-life task and the physical and cognitive functions among elderly people in hilly and mountainous areas

中山間地域に居住する高齢者の生活行為としての畑作業と身体・認知機能との関連


Effect of Palatal Augmentation Prosthesis on Speech and Swallowing in Tongue Dysfunction:A Literature Review

Purpose: Palatal augmentation prosthesis (PAP) is used on patients with dysphagia and dysarthria. While several studies have evaluated the effects of PAP, evidence regarding the adaptation criteria, effects, and limitations of PAP are not well organized. This review aims to summarize its functions, limitations, and applications. Procedure: To investigate the adaptation criteria, effects, and limitations of PAP, we searched the English language literature published in PubMed from its inception through April 20, 2022. The leading search terms included ``palatal augmentation prosthesis.'' Main findings: The primary search used keywords that reflected 31 studies. Finally, nine cross-sectional studies and nine case reports were selected for full-text assessment after applying the inclusion criteria. Eleven studies described the efficacy of speech function: two for motility factors and nine for organic factors (with overlap). Thirteen studies described the effectiveness of swallowing function, four related to motility factors, and ten for organic factors (with overlap). Several studies have demonstrated that PAP effectively restores articulation and swallowing in patients with impaired tongue function after glossectomy for oropharyngeal cancer, sequelae of cranial nerve disease, or neuromuscular disease. However, few papers describe the scope of glossectomy and tongue movement restrictions, so it is impossible to describe the adaptation criteria, effects, and limitations. In this review, most case reports and cross-sectional studies did not provide information on the fabrication methods of PAP or the dentistsʼ experience. Thus, the effect of bias on palatal morphology in PAP patients remains unclear. Conclusions: The number of patients with dysarthria and dysphagia is increasing worldwide, similar to what is already occurring in Japan. Therefore, additional high-quality studies on the effects of PAP are required.


Can Measurement of Ultrasonic Echo Intensity Predict Physical Frailty in Older Adults?

Echo intensity (EI) of the tongue in ultrasonography is an easy and quantitative assessment of tongue function. Elucidating the relationship between EI and frailty, is expected to aid in the early detection of frailty and oral hypofunction in older adults. We assessed tongue function and frailty in older outpatients visiting a hospital. The subjects were 101 individuals aged 65 or older (35 men and 66 women, mean age 76.4 ± 7.0 years). Tongue pressure and EI were measured as assessments of tongue function and grip strength, and Kihon Checklist (KCL) scores were measured as assessments of frailty. In women, a significant correlation was not found between the mean EI and grip strength, whereas a significant correlation was noted between each score of the KCL and the mean EI; the scores increased as the mean EI increased. A significant positive correlation was found between tongue pressure and grip strength, but no significant correlation was observed between tongue pressure and the KCL scores. In men, no significant correlation was found between tongue assessments and frailty, except for a significant positive correlation between tongue pressure and grip strength. The results of this study suggest that EI of the tongue is positively associated with physical frailty in women and may be useful for early detection of physical frailty status.


Effective use of an extraoral vacuum in preventing the dispersal of particulate matter from metal dental materials.

When dentists adjust prostheses at the dental chairside, particulate matter (PM) from the dental material is dispersed. Little is known about the effective use of an extraoral vacuum (EOV) in preventing PM dispersal. This study aimed to evaluate the effective use of an EOV in preventing the dispersal of metal PM in dental offices. The following experimental conditions were planned: the distance from the EOV to the metallic materials (50, 100, 150, and 200 mm), the horizontal angle between the long axis of the micromotor handpiece and EOV (0°, 45°, and 90°), and the operating time of the EOV (during grinding, during grinding and 1 min thereafter, during grinding and the preceding 1 min, 1 min before and after grinding, and during grinding). Carborundum and silicone points were used for grinding and PM dispersal. Diameters (0.3, 0.5, 1.0, and 3.0 μm) were measured using a laser particle counter. Depending on the instrument used to grind, there were undetectable PMs of different diameters (Carborundum point: 0.3 and 0.5 μm, Silicone point: 0.3 μm). PMNs were reduced as the distance from the EOV to metal materials decreased. Operating the EOV before grinding along the long axis of the micromotor handpiece was effective in reducing the PMNs. PMNs dispersed when grinding metals were effectively reduced by positioning the EOV closer to the grinding surface (within 150 mm) along the long axis of the micromotor handpiece and operating the EOV before grinding.


Stress Reduction Effects during Block-Tapping Task of Jaw in Healthy Participants: Functional Near-Infrared Spectroscopy (fNIRS) Measurements of Prefrontal Cortex Activity

The purpose of this study was to explore the influence of simple jaw opening and closing task of chewing movements on the activities of the prefrontal cortex (PFC) from the viewpoint of stress reduction. We measured cerebral blood flow (CBF) in the PFC during a block-tapping task of the jaw in healthy participants. Eleven young healthy individuals with normal dentition (7 males and 4 females, mean age 28.0 ± 3.7 years) volunteered for this study. CBF was measured using a wearable, functional near-infrared spectroscopy device. Measurements were taken using the central incisors and first molars at interocclusal distances of 5 and 10 mm. The participants were asked to bite a hard/soft block. CBF in all conditions showed limited variability or decreasing trend compared to resting state before the task. The main effect was observed for interocclusal distance ( = 0.008), and there were no significant differences for measurement area of the PFC, tooth type, and material type. An interaction was found between tooth type and material type. In conclusion, these results suggest that simple and rhythmical chewing motion has an effect of reducing CBF in the PFC and resting the PFC, which is an especially notable aspect of periodontal sensory information in the molar.


青年期における姿勢と口腔機能との関連に関する実態調査

青年期における姿勢と口腔機能との関連に関する実態調査

The Journal of the Japanese Academy of Occulusion and Health


2-methacryloyloxyethyl phosphorylcholine polymer treatment prevents Candida albicans biofilm formation on acrylic resin

We aimed to evaluate the effectiveness of photoreactive 2-methacryloyloxyethyl phosphorylcholine (MPC) in inhibiting Candida albicans biofilm formation on polymethyl methacrylate (PMMA) and assess its mechanism and need for re-application by evaluating its interaction with salivary mucin and durability during temperature changes. PMMA discs were used as specimens. The MPC coating was applied using the spray and cure technique for the treatment groups, whereas no coating was applied to the control. The MPC treatment (MT) groups were further differentiated based on the number of thermal cycles involved (0, 1000, 2500, and 5000). The optical density was measured to assess mucin adsorption (MA). Contact angle (CA) was calculated to evaluate surface hydrophilicity. The presence of MPC components on the PMMA surface was assessed using X-ray photoelectron spectroscopy (XPS). C. albicans biofilms were evaluated qualitatively (scanning electron microscope images) and quantitatively (colony-forming units (CFUs)). Statistical analysis was conducted using two-way analysis of variance and Tukey's multiple comparison test. MA rate and CA increased significantly in the MT groups, which exhibited significantly fewer CFUs and thinner biofilms than those of the control group. Based on the XPS, MA, and CFU evaluations, the durability and efficacy of the MPC coating were considered stable up to 2500 thermal cycles. Additionally, a significant interaction was observed between mucin concentration and MPC efficacy. The photoreactive MPC coating, which was resistant to temperature changes for approximately 3 months, effectively prevented C. albicans biofilm formation by modifying surface hydrophilicity and increasing mucin adsorption.


Novel Magnetic Attachment System Manufactured Using High-Frequency Heat Treatment and Stamp Technique: Introduction and Basic Performance

Recently, a novel magnetic attachment with extremely low cost and high performance was developed. This article aims to introduce a novel magnetic attachment and to evaluate its basic eligibility for denture retention in clinical practice. The novel magnetic attachment system used in this study was the direct-bonding root-keeper-type Magteeth™ MT800 (MagneDesign, Nagoya, Japan). The retentive force without displacement (position 0) and after horizontal displacement to positions 0.5, 1, 1.5, 2, 2.5, and 3 mm were measured. The values relative to the retentive force without displacement were gradually decreased to 82.7 ± 16.3%, 68.8 ± 17.1%, 62.4 ± 15%, 47.2 ± 13.1%, 35.7 ± 9.9%, and 20.7 ± 6.5%, respectively. The retentive force and magnetic field strength did not change significantly after the load test (100 N load, 10,000 times). No new gap between the metal and resin was found in the root keeper- and magnet assembly-embedded blocks after the load test. Some scratches on magnetic assembly and root keeper surface, while no change in the resin texture after the load test were observed. Based on the findings of this preliminary study, this novel low-cost magnetic attachment exhibited favorable retention, strength, and durability for clinical use.


Does Prosthodontic Treatment Improve the Nutrition Status in the Elderly? Literature Review


Measurement of ultrasonic echo intensity predicts the mass and strength of the tongue muscles in the elderly


Relationship between oral susceptibility assessment and prefrontal cortex blood flow during occlusal force maintenance tasks

口腔内の感受性評価と咬合力維持タスク中における前頭前野の血流量との関連

The purpose of this study was to clarify the relationship between the periodontal tactile sensation and the activity of the prefrontal cortex. Eleven young, healthy Japanese participants (mean age 28.0±3.7 years) volunteered to participate in this study. We tested either the left side central incisors or the first molars. The periodontal tactile sensation of each tooth was evaluated using calibrated monofilaments (von Frey hairs). A magnitude estimation method was used as a psychophysical method, and the periodontal ligament tactile and periodontal tactile sensation values were determined by Stevens' power law. Prefrontal cortex activation was evaluated using a wearable functional near-infrared spectroscopy device that measured cerebral blood flow, and the experimental task involved maintaining occlusal force within an instructed range. The logarithmic values of the physical and sensory quantities of periodontal tactile sensation showed a linear relationship, and had a significantly high correlation coefficient. Regarding the periodontal tactile sensation values, no significant difference was found between the central incisors and first molars. In the molar teeth, negative correlations were found between the periodontal tactile sensation values and the cerebral blood flow in all measurement fields. Moreover, the mean occlusal force value of molars was below the instructed range, and showed significantly lower values compared to those of anterior teeth. Based on the above results, it was shown that Stevens' power law can be applied to periodontal tactile sensation, and the periodontal tactile sensation value in molars calculated from Stevens' power law is related to the cerebral blood flow in the prefrontal cortex and inhibition of occlusal force. The site-specific importance of the periodontal tactile sensation value was suggested during the task of maintaining occlusal force.

本研究では，歯根膜の触・圧覚への感覚刺激と前頭前野の活動の関連性を明らかにすることを目的とした．健常有歯顎を有する若年者11名を対象とし，対象歯は，上下顎左側中切歯および第一大臼歯とした．歯根膜触・圧覚の測定にはvon Freyの刺激毛を用いた．精神物理学的手法として，マグニチュード推定法を用い，Stevensのべき法則より歯根膜触・圧覚感受性値を算出した．前頭前野の血流量の測定には，ウェアラブル光トポグラフィーを用い，実験タスクとして，咬合力維持タスクを設定した．歯根膜触・圧覚の刺激物理量と感覚量の対数値はほぼ直線の関係を示し，有意に高い相関係数を示した．歯根膜触・圧覚感受性値に関しては，前歯と臼歯の間で有意な差は認められなかった．臼歯においてはすべての測定野で感受性値と血流の変化量との間に負の相関関係が認められた．また咬合力に関しては，臼歯のほうが前歯と比較し，有意に低い値を示した．以上の結果より，歯根膜触・圧覚において「Stevensのべき法則」が適用できることが示され，臼歯においてはその法則から導き出される感受性値が，前頭前野の血流量と咬合力の抑制に関連することが示され，咬合力維持というタスクにおける感受性値の部位特異的な重要性が示唆された．


Treatment outcomes of implant-assisted removable partial denture with distal extension based on the Kennedy classification and attachment type: a systematic review

Implant-assisted removable partial dentures (IARPDs) have recently become popular, but little information is available on the treatment outcomes based on the Kennedy classification and attachment types. The objective of this review was to evaluate the treatment outcomes of IARPD delivered for distal extension edentulous areas based on the differences in the Kennedy classification and attachment type. English-language clinical studies on IARPD published between January 1980 and February 2020 were collected from MEDLINE (via PubMed), the Cochrane Library (via the Cochrane Central Register of Controlled Trials), Scopus online database, and manual searching. Two reviewers selected the articles based on pre-determined inclusion and exclusion criteria, followed by data extraction and analysis. Eighty-one studies were selected after evaluating the titles and abstracts of 2410 papers. Nineteen studies were finally included after the perusal of the full text. Fourteen studies focused on Class I, 4 studies investigated both Class I and II, and only 1 study was conducted on Kennedy's class II. Eight types of attachments were reported. The ball attachment was the most frequently used attachment, which was employed in 8 of the included studies. The implant survival rate ranged from 91 to 100%. The reported marginal bone loss ranged from 0.3 mm to 2.30 mm. The patient satisfaction was higher with IARPD than with conventional RPDs or that before treatment. The results of prosthetic complications were heterogeneous and inconclusive. IARPD exhibited favorable clinical outcomes when used as a replacement for distal extension edentulous areas. The comparison between the clinical outcomes of Kennedy's class I and II was inconclusive owing to the lack of studies focusing on Kennedy Class II alone. The stud attachment was the most commonly used type in IARPDs. Overall, the different attachment systems did not influence the implant survival rate and patient satisfaction. Further high-quality studies are needed to investigate the attachment systems used in IARPD.

International Journal of Implant Dentistry


Did Kayoinoba Prevent the Decline of Mental and Physical Functions and Frailty for the Home-Based Elderly during the COVID-19 Pandemic?

The purpose of this study is to grasp the management situation of "" under the conditions of self-quarantine due to the COVID-19 pandemic. It is also to clarify the efficacy of "" using the Kihon Checklist (KCL) for the assessment of mental and physical functions in the elderly. The respondents were 136 elderly people aged 65 years and over who lived in A City, a standard rural area in Japan. The age, gender, living style, affluence for living, and the frequency of participation in "" were examined by using the KCL as a self-completed questionnaire. Finally, 101 respondents were included in the final analysis. There was no difference in the participation status before and after the spread of COVID-19. The frailty ratio tended to decrease from 23.8% to 19.8% between the two periods, but there was no difference in the frailty ratio. It is suggested that the participants in "" may have suppressed the deterioration of mental and physical conditions, excluding physical activity. This would prevent the frailty of the elderly, even during self-quarantine due to the spread of COVID-19.

International Journal of Environmental Research and Public Health


Objective Assessment of Poor Oral Hygiene Using the ATP Swab Test in the Elderly

高齢者におけるATP拭き取り検査による口腔衛生状態不良の客観的評価

 Purpose:The purpose of this study was to evaluate the assessment of poor oral hygiene using the ATP swab test.

 Method:A total of 102 consecutive elderly outpatients aged ≥65 years who visited for maintenance were enrolled between October 2019 and April 2020. The evaluation of poor oral hygiene included measurements of:Tongue Coating Index(TCI), number of bacteria by a rapid oral bacterial detection device(Bacterial Counter DU-AA01NP-H;Panasonic Health Care, Japan), and amount of ATP+AMP by the ATP swab test(Lumitester;Kikkoman, Japan). The specimens were a gargle solution rinsed with 10 mL of water for 5 seconds as soon as the patients came to the hospital or a cotton swab wiped on the tongue dorsum. The subjective assessment of hygiene of the oral mucosa and dentures was rated on a 5-point scale.

 Results:In the assessment of tongue dorsum hygiene, the number of bacteria and the amount of ATP+AMP were significantly correlated with TCI. There was also a significant correlation between the number of bacteria and the amount of ATP+AMP.

 Conclusion:The results of this study suggested that the ATP swab test might be used to objectively assess overall poor oral hygiene, including food residues.

 目的:ATP拭き取り検査キットを用いた口腔衛生状態不良の評価方法について，口腔機能低下症で示された評価法と比較し検討することを目的とした．

 方法:2019年10月から2020年4月までの間に徳島大学病院歯科にてメンテナンスを行っている高齢者102名に対し，残存歯数の測定および口腔衛生状態不良の検査を行った．口腔衛生状態不良の検査では，舌苔付着度(Tongue Coating Index，TCI)，細菌数測定装置による細菌数測定，およびATP拭き取り検査キットによるATP+AMP量の測定を行った．被検体は来院時すぐに10 mLの水で5秒間含嗽を行って吐き出した含嗽溶液と綿棒で舌背部を拭ったものとした．また，口腔内の衛生状態の包括評価として，5段階で口腔粘膜および義歯の主観的評価を行った．

 結果:舌背部の測定に関して，ATP拭き取り検査値とTCIにおけるSpearmanの順位相関係数は0.374(p<0.001)，TCIと細菌数における相関係数は0.429(p<0.001)，細菌数とATP拭き取り検査値における相関係数は0.388(p<0.001)であった．また，包括評価に関して，口腔粘膜の衛生状態とATP拭き取り検査(舌背部)，ATP拭き取り検査(含嗽溶液)，TCI，細菌数(含嗽溶液)との相関係数はそれぞれ-0.257(p＝0.009)，-0.274(p＝0.005)，-0.209(p＝0.035)，-0.321(p＝0.001)であった．義歯の衛生状態とATP拭き取り検査値(含嗽溶液)，TCIとの相関係数はそれぞれ-0.317(p＝0.001)，-0.232(p＝0.019)であった．

 結論:ATP拭き取り検査キットによる測定は，食物残渣などを含む総合的な口腔衛生状態不良を客観的に評価できる可能性が示唆された．


Reliability of screening methods to diagnose oral dryness and evaluate saliva secretion


Does periodontal tactile input uniquely increase cerebral blood flow in the prefrontal cortex?

We previously studied the effect of peripheral sensory information from sensory periodontal ligament receptors on prefrontal cortex (PFC) activity. In the dental field, an alternative dental implant without periodontal sensation can be applied for missing teeth. In this study, we examine whether periodontal tactile input could increase cerebral blood flow (CBF) in the PFC against elderly patients with dental implants lacking periodontal tactile (implant group), elderly individuals with natural teeth (elderly group), and young individuals with natural teeth (young group). The experimental task of maintaining occlusal force as closed-loop stimulation was performed. Compared with the young group, the elderly group showed significantly lower CBF. Contrastingly, compared with the young group, the implant group showed significantly lower CBF. There were no significant differences between the elderly and implant groups. Regarding the mean occlusal force value, compared with the young group and the elderly group, the implant group had a numerically, but not significantly, larger occlusal force exceeding the directed range. In conclusion, the periodontal tactile input does not uniquely increase PFC activity. However, increased CBF in the PFC due to the periodontal tactile input in the posterior region requires existing attention behavior function in the PFC.


Geometric assessment of imaging methods for complete denture form: Comparisons among cone-beam computed tomography, desktop dental scanning, and handheld optical scanning.


消滅可能性地域における後期高齢者の社会的フレイル傾向の実態と地域保健活動の可能性-美馬市木屋平の持続可能性に向けた通いの場の活用-

Journal of Shikoku Public Health Society


Assessment of potential clinical cascade between oral hypofunction and physical frailty: Covariance structure analysis in a cross-sectional study

No report has yet examined the impact of oral hypofunction on physical frailty in relation to intra-relationships of physical frailty assessment items. The purpose of this study was to verify the potential of a clinical cascade between oral hypofunction and physical frailty, and especially to support the hypothesis that the influence of oral hypofunction on physical frailty is greater than the intra-relationships among elements of physical frailty and that sex differences significantly affect these relationships. The participants were 272 older adults (101 men and 171 women; mean age 75.1 ± 7.5 years). Maximum occlusal force (MOF) and oral dryness (OD), as indicators of oral hypofunction, and grip strength (GS) and walking speed (WS), as indicators of physical frailty, were measured. Mutual relationship of four variables was verified using covariance structure analysis. In men, three paths from MOF to WS and GS and from WS to GS were confirmed, and those from MOF to WS and from WS to GS were found to be significant (P < .01). In women, three paths from MOF to WS and GS and from WS to GS were also confirmed, as with the men, and those from MOF to WS and from MOF to GS were found to be significant (P < .01). Model adaptability was shown to be good for both men and women. The results suggest our hypothesis was verified, and it is expected that the early detection of oral hypofunction, that is MOF, may be important for assessing physical frailty, especially in women.


高齢者における身体的能力の低下とその意識との関係:咬合力，握力，歩行速度

高齢者における身体的能力の低下とその意識との関係:咬合力，握力，歩行速度

The Journal of the Japanese Academy of Occulusion and Health


アルコール含有義歯安定剤であるホームリライナーが呼気中アルコール濃度へ与える影響の評価


Prefrontal cortex activity induced by periodontal afferent inputs downregulates occlusal force

The prefrontal cortex (PFC) plays an important role in several cognitive functions, such as planning, decision making, and social behavior. We previously reported that periodontal sensory input significantly increases PFC activity during the motor task of maintaining occlusal (biting) force. However, the relationships between periodontal sensation, PFC activity, and the performance of motor tasks have not been evaluated in detail. Therefore, using functional near-infrared spectroscopy, we investigated PFC activity by monitoring changes in cerebral blood flow (CBF) to specific areas of the PFC that corresponded to changes in occlusal force generated during four different biting tasks: (1) occlusion with the central incisor with an interocclusal distance of 5 mm (BI-5 mm); or (2) 10 mm (BI-10 mm); (3) occlusion with the first molars with an interocclusal distance of 5 mm (BM-5 mm), or (4) 10 mm (BM-10 mm). Occlusion of molars generated increased PFC regional CBF as the interocclusal distance decreased (BM-10 mm vs BM-5 mm). No significant differences in CBF during occlusion of incisors were found when comparing 5 mm and 10 mm intercostal distances (BI-5 mm vs BI-10 mm). The mean occlusal force generated by BM-5 mm occlusion was significantly lower than that generated by BM-10 mm occlusion. Taken together, our results suggest that the PFC decreases efferent signaling to motor units, to reduce occlusal force generated when periodontal sensation, which is greater when the interocclusal distance is reduced, is primarily responsible for maintaining occlusal force in the absence of sensations from the temporomandibular joint and muscle spindles.


Investigating eating behaviors and symptoms of oral frailty using questionnaires

A questionnaire survey was conducted to investigate eating behavior and the subjective symptoms of oral frailty, and to examine the relationship between them. A total of 744 subjects with ages over 65 years were included. The questionnaire comprised 18 question items indicating eating behavior and seven question items indicating oral frailty. All items were assessed according to 4 grades on a scale of 1 (not applicable) to 4 (applicable). The total score of oral frailty gradually increased with age. Regarding the scores for "eating recognition" and "eating habits", no changes were observed, however the scores for "eating action" demonstrated a decreasing tendency with age and the scores of 85 years age group was significantly lower than the 65-69, 70-74, and 75-79 years age groups. As a result of multiple regression analysis, among the significant independent variable, the scores of "I do not chew foods well" under the category of "eating action" showed the highest standard partial regression coefficients for dependent variable of symptoms of oral frailty. The significant association was found between the eating behavior and subjective symptoms of oral frailty, and this study suggests that the good chewing habit might be an important criterion for the prevention of oral frailty.


The aplication and usefulness of virtual reality aimd at encouraging an understanding of and reducing and eliminating prejudice dementia patients among local residents

地域住民の認知症に対する理解の促進と偏見の軽減・除去に関するバーチャルリアリティ技術の応用と有用性

To demonstrate the usefulness of a virtual reality device that authentically portrays the emotions of dementia patients and their families (VR Dementia Experience) for encouraging an understanding of and reducing and eliminating prejudice towards dementia patients among local residents. In Prefecture T, Town N, 85 residents of Neighborhood A were chosen as the intervention group, and 95 residents of Neighborhood B were chosen as the non-intervention group. The VR Dementia Experience was provided only to the residents of Neighborhood A. Residents of both neighborhoods completed a 35-item questionnaire regarding their degree of understanding and prejudice towards dementia patients before and after the intervention. Seventy-seven residents of Neighborhood A and 82 residents of Neighborhood B were analyzed. Their gender, age, and pre-intervention test baseline values were equivalent in the degree of understanding and prejudice. Significant increases were observed in 9 of 35 items for Neighborhood A residents (7 understanding-related, 2 prejudice-related) and 2 items for Neighborhood B residents (1 understanding-related, 1 prejudice-related). To ascertain the usefulness of the VR Dementia Experience, we compared the number of items with a significant increase: 9/35 (25.7%) in Neighborhood A and 2/35 (5.7%) in Neighborhood B. An effect (≥ 20%) was observed among the residents of Neighborhood A. Furthermore, after exposure to the VR Dementia Experience, the connection between understanding, prejudice, and dementia was strengthened among the residents of Neighborhood A compared to the residents of Neighborhood B. The VR Dementia Experience is a useful tool for encouraging an understanding of and reducing and eliminating prejudice towards dementia patients among local residents. However, to encourage the widespread usage of the technology, we should compare results with other public awareness campaigns as well as make improvements to the device and its VR content.


Effect of the temperature of water on ultrasonic denture cleaning

Denture plaque is a biofilm composed of various microorganisms aggregated with saliva. Various denture cleansers and cleaning apparatuses have been developed and studied. However, the optimum water temperature for denture cleaning is unknown. Therefore, the present study investigated the effects of water temperature during ultrasonic denture cleaning. In vitro, resin disks with artificial Candida albicans biofilm were pressed onto Candida GE media after ultrasonic cleaning with water at different temperatures for 5 min. The media were subsequently cultured at 37°C for 24 h. The colonies formed were observed and colony areas were quantified using ImageJ software (US National Institutes of Health, Bethesda, MD, USA). In situ, the bacterial count and degree of cleanliness on the tissue surface of maxillary dentures were measured before and after ultrasonic cleaning with water at different temperatures for 5 min. Changes in bacterial counts and cleanliness were calculated for each temperature. The ratio of the area occupied by bacterial colonies in vitro and reduction rates in situ after cleaning with warm water were markedly less than those observed after cleaning with cold water. Therefore, ultrasonic denture cleaning with warm water is more effective.


Comparison between two assessment tests for oral hygiene: adenosine triphosphate + adenosine monophosphate swab test and bacteria number counting by dielectrophoretic impedance measurement


歯磨剤に配合された顆粒成分のインプラント周囲溝への侵入性の調査

歯磨剤に配合された顆粒成分のインプラント周囲溝への侵入性の調査

Journal of Japanese Society of Oral Implantology

日本口腔インプラント学会誌


Geniohyoid muscle affects directly masticatory function: Evaluation using a decision tree analysis

To clarify the effect of geniohyoid (GH) muscle morphology and related function on masticatory ability using a decision-tree analysis. A total of 103 participants were enrolled. A cross-sectional area (CSA) of the GH muscle, neck circumference, body mass index, tongue pressure, jaw opening strength, and masticatory ability score were measured. The CSA of the GH muscle was selected as an independent variable for the first layer of the decision tree, with masticatory score as the dependent variable. These data suggest that the CSA of the GH muscle may have a large impact on the masticatory ability score when evaluating masticatory ability.

The International Journal of Prosthodontics


Duplicate complete dentures made by general digital devices: Evaluation of material properties and clinical trial

汎用デジタル機器を用いて製作した複製義歯:材料特性と臨床評価

Purpose: The purpose of this study was to investigate the validity of the process of duplicating complete dentures using general digital devices through the following tests: cytotoxicity test of materials used, adhesion test of materials to a silicone impression material and a self-curing resin, and questionnaires to operators on duplicate dentures in clinical situations.

Methods: The cell viability of mouse fibroblast-like cells in acrylonitrile- butadiene-styrene (ABS) and polylactic acid (PLA) were evaluated as a cytotoxicity test. The tensile strength between the silicone impression material/self-curing resin and ABS/PLA specimen was measured as adhesive strength using a universal testing machine. Six practitioners who used duplicate PLA complete dentures in 7 patients were asked to evaluate the duplicate denture using the original questionnaire.

Results: The cytotoxicity test showed that the cell viabilities in ABS and PLA were similar to that in acrylic resin at the cell culture times of 24, 48 and 72 hours. The adhesion test showed that the adhesive strength between the ABS/PLA and silicone impression material was significantly lower than that between the conventional self-curing resin and silicone impression material. Although the adhesive strength between the PLA and self-curing resin was low, there was no significant difference between the ABS and self-curing resin. The results of the questionnaire showed that the duplicate denture made of PLA would be of similar value compared to the conventional duplicate denture made of acrylic resin.

Conclusions: The present study suggests that the duplicate complete dentures made by our proposed digital process are clinically effective.

目的:われわれが提案した汎用デジタル機器を用いた複製義歯製作法の有用性を示すために，使用するアクリロニトリル-ブタジエン-スチレン(ABS)共重合樹脂，ポリ乳酸(PLA)樹脂の細胞毒性試験，シリコーン印象材および常温重合レジンとの接着試験，使用感に関する主観的評価を行った．

方法:細胞毒性試験では，ABS樹脂とPLA樹脂の浸漬液を用いてマウスの線維芽細胞様細胞の細胞生存率を測定した．接着試験では，専用の保持体にそれぞれの試験片を固定し，シリコーン印象材および常温重合レジンを圧接した後に，万能試験機を用いて引張試験を行った．使用感の評価には，専用の評価票を作成し，PLA製の複製義歯を使用する術者に回答させた．

結果:細胞毒性試験では，ABS樹脂，PLA樹脂ともに72時間までの細胞生存率の低下は認められなかった．接着試験では，トレー用レジンと比較して両試料ともにシリコーン印象材への接着強さは低かった．常温重合レジンとの接着強さでは，PLA樹脂は低かったが，ABS樹脂では従来のトレー用レジンと同等の接着強さであった．術者による複製義歯使用感の評価結果としては，従来のアクリルレジン製の義歯とほとんど変わらない評価が得られた．

結論:三次元プリンターで製作した複製義歯における材料的，臨床的評価から本術式の有効性が示唆された．


Development of an oral assessment sheet for evaluating older adults in nursing homes

A new general use oral assessment sheet (OAS), comprising three items each in three categories (i.e., oral hygiene, biting and chewing, and oral function), was developed to improve the oral health of older adults requiring nursing care. Seventy-nine care workers used the assessment sheet to evaluate oral conditions in 188 institutionalized older adults. Forty-five care workers and three dental professionals then assessed oral conditions in 45 institutionalized older adults using the test-retest method before and after dental professional guidance. Cronbach's alpha of the OAS was 0.72, and 0.65, 0.57, and 0.82 for the three subcategories of oral hygiene, biting and chewing, and oral function, respectively. After dental professional intervention, absolute and relative agreement coefficients increased to more than 0.6 and 0.89, respectively. Reliability and validity of the OAS were verified, and difficulties in oral assessment experienced by care workers were identified. [Res Gerontol Nurs. 2017; 10(5):234-239.].


各年齢階層におけるオーラルフレイルと身体的フレイルに関連する兆候:アンケートによる実態調査


Changes in food bolus texture during mastication

The purpose of this study was to survey the changes that occur in bolus texture from intake to swallowing during the mastication process for four types of food materials and to identify how texture is related to the number of chews. We recruited 15 young Japanese participants for this study. The subjects were asked to spit the food bolus just before swallowing when eating four different foods: cracker, boiled rice, hard gelatine gel, and soft gelatine gel. Three physical properties (hardness, adhesiveness, and cohesiveness) were measured in the bolus after being chewed for 25, 50, 75, 100, and 125% of the normal number of chews. Occlusal force and pressure as well as stimulated whole saliva volume were also measured. Extensive variation in the number of chews existed between subjects, but minimal intra-subject variation was observed. Hardness was observed to decrease, whereas cohesiveness and adhesiveness increased in a chew-dependent manner for the cracker, soft gelatine gel, and hard gelatine gel, but not boiled rice. Bolus texture appears to be largely related to the number of chews. Hardness also tended to be influenced by occlusion. The adhesiveness and hardness of the boiled rice were also greatly influenced by saliva volume and occlusal force, respectively. Hardness is an important rheological factor in food bolus texture and likely plays a significant role in determining the appropriate number of chews. Adhesiveness and cohesiveness appear to be secondary factors in this process. We propose a model of oral processing for application in determining the appropriate number of chews for an individual. Hardness appears to be an important rheological factor in food bolus texture, with adhesiveness and cohesiveness being secondary aspects. When food is hard or difficult to swallow, chewing behavior will likely be more influenced by the perception of bolus texture.


Duplication of complete dentures using general-purpose handheld optical scanner and 3-dimensional printer: Introduction and clinical considerations

To introduce a new clinical procedure for fabricating duplicates of complete dentures by bite pressure impression using digital technology, and to discuss its clinical significance. The denture is placed on a rotary table and the 3-dimensional form of the denture is digitized using a general-purpose handheld optical scanner. The duplicate denture is made of polylactic acid by a 3-dimensional printer using the 3-dimensional data. This procedure has the advantages of wasting less material, employing less human power, decreasing treatment time at the chair side, lowering the rates of contamination, and being readily fabricated at the time of the treatment visit.


Age-related changes in geniohyoid muscle morphology predict reduced swallowing function


Characterization of Swallowing Sound: Preliminary Investigation of Normal Subjects

The purpose of this study was to characterize the swallowing sound and identify the process of sound generation during swallowing in young healthy adults. Thirty-three healthy volunteers were enrolled and allocated into three experimental groups. In experiment 1, a microphone was attached to one of eight cervical sites in 20 subjects, participants swallowed 5 ml water, and the sound waveform was recorded. In experiment 2, 10 subjects swallowed either 0, 5, 10, or 15 ml water during audio recording. In addition, participants consumed the 5 ml bolus in two different cervical postures. In experiment 3, the sound waveform and videofluoroscopy were simultaneously recorded while the three participants consumed 5 ml iopamidol solution. The duration and peak intensity ratio of the waveform were analyzed in all experimental groups. The acoustic analysis of the waveforms and videofluoroscopy suggested that the swallowing sound could be divided into three periods, each associated with a stage of the swallowing movement: the oral phase comprising posterior tongue and hyoid bone movement; the pharyngeal phase comprising larynx movement, hyoid bone elevation, epiglottis closure, and passage of the bolus through the esophagus orifice; and the repositioning phase comprising the return of the hyoid bone and larynx to their resting positions, and reopening of the epiglottis. Acoustic analysis of swallowing sounds and videofluoroscopy suggests that the swallowing sound could be divided into three periods associated with each process of the swallowing movement: the oral phase comprising the posterior movement of the tongue and hyoid bone; the pharyngeal phase comprising the laryngeal movement, hyoid bone elevation, epiglottis closure, and the bolus passage to the esophagus orifice; and the repositioning phase comprising the repositioning of the hyoid bone and larynx, and reopening of the epiglottis.


An innovative masticatory efficiency test using odor intensity in the mouth as a target marker: a feasibility study

A large number of studies have reported the findings for masticatory efficiency tests; however, some objective masticatory efficiency tests have a drawback, in that subjects are required to spit out the test material. This study examined the possibility of a masticatory efficiency test that evaluates the intensity of odours released when chewing an odour compound-containing material. A total of 20 volunteers were used in this study. The odour intensity in the breath after chewing a gum was measured by portable odour sensor device. The odour intensity after chewing the gum was measured over four chewing durations and at four intervals between spitting out and measurement of the odour intensity. The volume of stimulated saliva was measured by calculating the difference in the weight of the gauze before and after chewing to examine the effect of saliva flow. With an increase in chewing duration, odour intensity reduced. The odour intensity was the highest immediately after chewing. There was a positive correlation between odour intensity and gummy jelly-related masticatory efficiency test value (G-METV), which was significant for 10-s chewing. The regression equation was calculated from three objective variables of odour intensity and G-METV as dependent variable. Pearson's correlation coefficient between G-METV and the odour intensity-related masticatory efficiency value (O-METV) was 0·68. The coefficient of variation of O-METV was significantly lower than that of G-METV. These results suggest that the masticatory performance can be estimated by measuring the odour intensity immediately after chewing food containing odour compounds for 10 s.


Periodontal tactile input activates the prefrontal cortex

The prefrontal cortex (PFC) plays a role in complex cognitive behavioural planning, decision-making, and social behaviours. However, the effects of sensory integration during motor tasks on PFC activation have not been studied to date. Therefore, we investigated the effect of peripheral sensory information and external information on PFC activation using functional near-infrared spectroscopy (fNIRS). Cerebral blood flow (CBF) was increased around bilateral Brodmann areas 46 and 10 during visual and auditory information integration during an occlusal force (biting) task. After local anesthesia, CBF values were significantly decreased, but occlusal force was similar. In conclusion, the effects of peripheral sensory information from the periodontal ligament and external information have minimal impacts on occlusal force maintenance but are important for PFC activation.


Magnet-retained two-mini-implant overdenture: Clinical and mechanical consideration.

Two-implant overdentures have become the accepted treatment for restoring mandibular edentulism. The dimensions of regular implants sometimes limit their use, such as in the case of narrow ridges. Mini-implants with reduced diameters (less than 3.0 mm) enable insertion into narrow ridges. A magnet-retained two-mini-implant overdenture system was developed and is described in this paper. Additionally, we describe a clinical mandibular procedure using the system and evaluate its biomechanical performance.


Hardness, cohesiveness, and adhesiveness of oral moisturizers and denture adhesives: selection criteria for denture wearers.

The mechanical properties of seven denture adhesives and eight oral moisturizers, all of which are commercially available, were evaluated using a texture pro le analysis. A new assessment chart is proposed for the selection criteria of denture adhesive and oral moisturizers using a radar chart with three axes: hardness, cohesiveness, and adhesiveness.


Part-digitizing system of impression and interocclusal record for complete denture fabrication

Few studies have reported the application of digital technology to removable dentures, particularly for the process of impression and interocclusal recording for complete denture fabrication. This article describes a part-digitizing system of impression and interocclusal records for complete denture fabrication. The denture foundation area in an edentulous mouth, including the border areas and residual ridge, is outlined by tracing the surfaces with a 3-D pen-type digitizer. Specialized trays for final impressions and interocclusal records were generated using computer-aided design and manufactured using the digital data. Final impression and interocclusal records were carried out using these specialized trays. The computer-aided method using preliminary digital impressions and specialized trays would be feasible for clinical use for complete denture fabrication.


Digital assessment of preliminary impression accuracy for edentulous jaws: Comparisons of 3-dimensional surfaces between study and working casts

The aim of this study was to compare 3-dimensional surfaces of study and working casts for edentulous jaws and to evaluate the accuracy of preliminary impressions with a view to the future application of digital dentistry for edentulous jaws. Forty edentulous volunteers were serially recruited. Nine dentists took preliminary and final impressions in a routine clinical work-up. The study and working casts were digitized using a dental 3-dimensional scanner. The two surface images were superimposed through a least-square algorithm using imaging software and compared qualitatively. Furthermore, the surface of each jaw was divided into 6 sections, and the difference between the 2 images was quantitatively evaluated. Overall inspection showed that the difference around residual ridges was small and that around borders were large. The mean differences in the upper and lower jaws were 0.26mm and 0.45mm, respectively. The maximum values of the differences showed that the upward change mainly occurred in the anterior residual ridge, and the downward change mainly in the posterior border seal, and the labial and buccal vestibules, whereas every border of final impression was shortened in the lower jaw. The accuracy in all areas except the border, which forms the foundation, was estimated to be less than 0.25mm. Using digital technology, we here showed the overall and sectional accuracy of the preliminary impression for edentulous jaws. In our clinic, preliminary impressions have been made using an alginate material while ensuring that the requisite impression area was covered.


審美歯治療のエンドポイントと評価方法

審美歯治療のエンドポイントと評価方法


Development of a digital impression procedure using photogrammetry for complete denture fabrication

We developed an innovative procedure for digitizing maxillary edentulous residual ridges with a photogrammetric system capable of estimating three-dimensional (3D) digital forms from multiple two-dimensional (2D) digital images. The aim of this study was to validate the effectiveness of the photogrammetric system. Impressions of the maxillary residual ridges of five edentulous patients were taken with four kinds of procedures: three conventional impression procedures and the photogrammetric system. Plaster models were fabricated from conventional impressions and digitized with a 3D scanner. Two 3D forms out of four forms were superimposed with 3D inspection software, and differences were evaluated using a least squares best fit algorithm. The in vitro experiment suggested that better imaging conditions were in the horizontal range of ± 15 degrees and at a vertical angle of 45 degrees. The mean difference between the photogrammetric image (Form A) and the image taken from conventional preliminarily impression (Form C) was 0.52 ± 0.22 mm. The mean difference between the image taken of final impression through a special tray (Form B) and Form C was 0.26 ± 0.06 mm. The mean difference between the image taken from conventional final impression (Form D) and Form C was 0.25 ± 0.07 mm. The difference between Forms A and C was significantly larger than the differences between Forms B and C and between Forms D and C. The results of this study suggest that obtaining digital impressions of edentulous residual ridges using a photogrammetric system is feasible and available for clinical use.

International Journal of Computerized Dentistry


MiR-494-3p induced by compressive force inhibits cell proliferation in MC3T3-E1 cells.

Mechanical stimuli regulate fundamental cell processes such as proliferation, differentiation, and morphogenesis. We attempted to identify microRNA (miRNA) whose expression is changed during compressive treatment in MC3T3-E1, a pre-osteoblastic cell line. Microarray analysis followed by reverse transcription-quantitative polymerase chain reaction revealed that compressive force at 294 Pa for 24 h in MC3T3-E1 cells increased levels of miR-494-3p, miR-146a-5p, miR-210-3p, and miR-1247-3p. Among these miRNAs, miR-494-3p was found to inhibit cell proliferation in MC3T3-E1 cells. Furthermore, cells subjected to compressive force showed slower cell growth compared with control cells. Levels of mRNA for fibroblast growth factor receptor 2 (FGFR2) and Rho-associated coiled-coil kinase 1 (ROCK1), which were predicted to be targets of miR-494-3p, were decreased by compressive force or overexpression of miR-494-3p mimics in MC3T3-E1 cells. Furthermore, binding sites of miR-494-3p within 3'-untranslated regions of Fgfr2 and Rock1 were determined using luciferase reporter assay. In conclusion, compressive force affected expressions of several miRNAs including miR-494-3p in MC3T3-E1 cells. Compressive force might inhibit cell proliferation in osteoblasts by up-regulating miR-494-3p followed by FGFR2 and ROCK1 gene repressions.

Journal of Bioscience and Bioengineering


インプラント上部構造における前装材破折と主機能部位との関連について

インプラント上部構造における前装材破折と主機能部位との関連について

Journal of Japanese Society of Oral Implantology

日本口腔インプラント学会誌


End points and assessments in esthetic dental treatment.

There are two key considerations for successful esthetic dental treatments. This article systematically describes the two key considerations: the end points of esthetic dental treatments and assessments of esthetic outcomes, which are also important for acquiring clinical skill in esthetic dental treatments. The end point and assessment of esthetic dental treatment were discussed through literature reviews and clinical practices. Before designing a treatment plan, the end point of dental treatment should be established. The section entitled "End point of esthetic dental treatment" discusses treatments for maxillary anterior teeth and the restoration of facial profile with prostheses. The process of assessing treatment outcomes entitled "Assessments of esthetic dental treatment" discusses objective and subjective evaluation methods. Practitioners should reach an agreement regarding desired end points with patients through medical interviews, and continuing improvements and developments of esthetic assessments are required to raise the therapeutic level of esthetic dental treatments.


Influence of food volume per mouthful on chewing and bolus properties

Behaviors relating to food intake, i.e., speed of chewing, number of chews, and bite size, are important for decreasing energy intake, which might reduce excess body weight and thus metabolic risk. This study aimed at investigating the influence of mouthful volume on the number of chews and food bolus properties in addition to clarifying appropriate eating behaviors related to mouthful volume. Fifteen young Japanese women volunteered to participate. The subjects were asked to spit the food bolus in a glass dish just before swallowing when eating 3 different foods: boiled rice, fish sausage, and peanuts. The 3 physical properties of solidity, adhesiveness, and cohesiveness were measured in the bolus, and the number of chews was noted. The number of chews significantly increased with increasing mouthful volume with all 3 foods; conversely, the number of chews per unit of food weight (g) decreased significantly with boiled rice and fish sausage. Trends were observed for solidity and cohesiveness, which varied with increasing mouthful volumes. Decreased mouthful volume resulted in a greater number of chews per weight of food and more appropriate bolus properties; therefore, a change in mouthful volume could be a useful behavior modification for regulation of energy intake.


Literature Review of Setting the Occlusal Plane for Edentulous Patients

無歯顎補綴における咬合平面設定に関する文献考察

The maxillomandibular registration is one of important processes to achieve patientsatisfaction with the function and esthetics for complete denture fabrication. Over the years, clinical decision of vertical and horizontal jaw relationship has been mainly discussed in the maxillomandibular registration. With regard to the occlusal plane setting, many clinicians have believed to decide the occlusal plane parallel to Camper's plane, however there is little information on the effect of occlusal plane setting on clinical meanings and outcome. The aim of this study is to analyze published literature focusing on the occlusal plane and the related oral function and esthetics, and to clarify clinical implications of occlusal plane setting. Two databases, "PubMed" and "Japana Centra Revuo Medicina" were searched to retrieve research papers focusing on the occlusal plane.Seventy four papers were selected from the database, and they were reviewed.Literature reviews suggests that many landmarks were described on the occlusal plane setting for edentulous patients; and Camper's plane has been most frequently referred, showed a good result in function, but not always good in esthetics. The influence of occlusal plane setting on clinical results: oral function, esthetics, denture stability, and patient satisfaction after denture delivery has to be examined.


Influence of female attachment installation load on movement and resultant forces in implant overdentures

This in vitro study investigated the effect of attachment installation conditions on the load transfer and denture movements of implant overdentures, and aims to clarify the differences among the three types of attachments, namely ball, Locator, and magnet attachments. Three types of attachments, namely ball, Locator, and magnetic attachments were used. An acrylic resin mandibular edentulous model with two implants placed in the bilateral canine regions and removable overdenture were prepared. The two implants and bilateral molar ridges were connected to three-axis load-cell transducers, and a universal testing machine was used to apply a 50 N vertical force to each site of the occlusal table in the first molar region. The denture movement was measured using a G(2) motion sensor. Three installation conditions, namely, the application of 0, 50, and 100 N loads were used to install each attachment on the denture base. The load transfer and denture movement were then evaluated. The resultant force decreased with increasing installation load for all attachments. In particular, the resultant force on implants on the loading side of the Locator attachment significantly decreased when the installation load was increased from 0 to 50 N, and that for magnetic attachment significantly decreased when the installation load was increased from 50 to 100 N. For the residual ridges on the loading side, the direction of the forces for all attachments changed to downward with increasing installation load. Furthermore, the yaw Euler angle increased with increasing installation load for the magnetic attachment. Subject to the limitations of this study, the use of any installation load greater than 0 N is recommended for the installation of ball and Locator attachments on a denture base. Regarding magnetic attachments, our results also recommend installation on a denture base using any installation load greater than 0 N, and suggest that the resultant force acting on the implant can be decreased by increasing the installation load; however, a large installation load of 100 N should be avoided when installing the attachment on the denture base to avoid increasing the denture movement.


Evaluation of Eating Behavior and Mouthful Volume: Validity of YN Eating Behavior Questionnaire

一口量に着目した食行動評価:YN食行動質問票の有効性

We created a simple questionnaire to promote better eating habits and behavioral modification for the prevention and improvement of metabolic syndrome, examined its reliability and validity, and finally, assessed its effectiveness. A questionnaire, comprising of eighteen items to promote behavioral modification, was prepared comprising of three factors, "dietary recognition" , "eating habits" and "eating action" and was developed based on data from 125 students at the Faculty of Dentistry, The University of Tokushima. Furthermore, to assess the effectiveness of this version of the questionnaire, we conducted a survey on 845 health-care providers in Tokushima Prefecture and Hyogo Prefecture. The results confirmed a relatively high internal consistency with a Cronbach's alpha coefficient of 0.735–0.762 for the three factors. The questionnaire scores in the "obese" group with a body mass index of 25 or higher were high for all three factors and a significant difference was noted between the "normal" and "thin" groups under the category of "dietary awareness" . Moreover, trends between men and women; and between age groups were ascertained, therefore suggesting that this questionnaire is effective in assessing eating behavior associated with obesity.


補綴装置および歯の延命のために(Part 6) 力のコントロール 力を受ける生体側の観点から


Do sensation differences exist between dental implants and natural teeth?: a meta-analysis.

The purpose of this systematic review was to survey evidence pertaining to the sensation differences between natural teeth and osseointegrated dental implants. Using the MEDLINE (online PubMed) database, Cochrane Library, and Scientific Citation index, we performed a systematic search of articles. We used the following search terms: "perception or sensation and dental implant." The systematic review of the extracted articles was performed to see the sensation differences between natural teeth and dental implants. A total of six studies on oral sensation, "tactile sensibility," and "thickness discrimination" were included in the meta-analysis. As to the "tactile sensibility", all studies indicated the threshold levels of the implants were about 4-20 times higher than that of natural teeth. The tactile sensibility of an implant was significantly higher than that of a natural tooth, with an standardized mean difference (SMD) of 8.3619 (95% CI, 6.3920-10.3317) and a P < 0.0001. As to the "thickness discrimination", all studies indicated the threshold levels of implants were about 1.2-2.3 times higher than that of natural teeth. The thickness discrimination was significantly higher than that of natural teeth with an SMD of 1.2368 (95% CI, 0.8699-1.6038) and a P < 0.0001. This meta-analysis suggested that both tactile sensibility and thickness discrimination thresholds of implants were significantly higher than those of natural teeth. This meta-analysis reconfirms that sensation differences between dental implants and natural teeth exist.


Blue-violet laser modification of titania treated titanium: antibacterial and osteo-inductive effects

Many studies on surface modifications of titanium have been performed in an attempt to accelerate osseointegration. Recently, anatase titanium dioxide has been found to act as a photocatalyst that expresses antibiotic properties and exhibits hydrophilicity after ultraviolet exposure. A blue-violet semiconductor laser (BV-LD) has been developed as near-ultraviolet light. The purpose of this study was to investigate the effects of exposure to this BV-LD on surface modifications of titanium with the goal of enhancing osteoconductive and antibacterial properties. The surfaces of pure commercial titanium were polished with #800 waterproof polishing papers and were treated with anatase titania solution. Specimens were exposed using BV-LD (λ = 405 nm) or an ultraviolet light-emitting diode (UV-LED, λ = 365 nm) at 6 mW/cm(2) for 3 h. The surface modification was evaluated physically and biologically using the following parameters or tests: surface roughness, surface temperature during exposure, X-ray diffraction (XRD) analysis, contact angle, methylene blue degradation tests, adherence of Porphyromonas gingivalis, osteoblast and fibroblast proliferation, and histological examination after implantation in rats. No significant changes were found in the surface roughness or XRD profiles after exposure. BV-LD exposure did not raise the surface temperature of titanium. The contact angle was significantly decreased, and methylene blue was significantly degraded. The number of attached P. gingivalis organisms was significantly reduced after BV-LD exposure compared to that in the no exposure group. New bone was observed around exposed specimens in the histological evaluation, and both the bone-to-specimen contact ratio and the new bone area increased significantly in exposed groups. This study suggested that exposure of titanium to BV-LD can enhance the osteoconductivity of the titanium surface and induce antibacterial properties, similar to the properties observed following exposure to UV-LED.


Should Occlusal Pressure be Applied in Fixing Magnet Assenmlies to Denture? An Evaluation using the Delphi Technique

The Journal of the Japanese Sociaty of Magnetic Applications in Dentistry


Long-term follow-up case reports on the use of magnetic attachment as intracoronal/extracoronal attachments


Stress Analysis of Magnet-Retained Mini-Implant Overdenture:InVitro Study

磁性アタッチメントを用いたミニインプラントオーバーデンチャーにおける力学的解析

The purpose of this study was to evaluate stress analysis of a magnet-retained mini-implant overdenture on an in vitro mandibular model. Mini implants less than 3.0 mm in diameter have been used as not only provisional use, but also permanent use to support overdentures.
Four mini implants (MagDen Fixture MFI4010RF, Shinwon Dental, Seoul, Korea) were placed in edentulous regions between bilateral canines in an acrylic resin mandibular model and the abutments (MagDen Keeper MFK4020, Shinwon Dental, Seoul, Korea) for magnet attachments were used. Seven strain gauges were attached on the resin surface around the right side of two mini implants. The surface of the model was covered with silicone impression material to simulate oral mucosa and an experimental complete denture was placed on the model. A vertical force of 50 N was applied to either one of the premolar, first molar and second molar of the experimental denture using a universal testing machine.
When four mini implants were supported, compressive strains were caused at the lingual side of the distal mini implant. The more posterior the loading point was, the lower the strain around the implant was generally. Although tensile strain was caused at the buccal side of the mesial mini implant, it decreased at the moment when compressive strain arose. When four implants were supported, the strain around the mini implants was distributed more evenly than those in the two implant-supported ones. The influence of implant positioning was examined by removing either two mesial or two distal attachments in the four mini implants. The maximum strain in two mesial implant-supported attachments was smaller than that in two distal implant-supported attachments.

Journal of Japanese Society of Oral Implantology

日本口腔インプラント学会誌


In Vitro Efficacy of Electrolyzed Dilute Sodium Hypochlorite Solution on Candidal Biofilm

In vitroカンジダバイオフィルムに対する電解次亜水の効果

The effectiveness of oral care interventions for preventing aspiration pneumonia and barriers to compromised elderly is universally-recognized in present medical practice. Quick and effective methods and materials are needed for oral health care. An electrolyzed dilute sodium hypochlorite solution was chosen as a sterilizing solution for oral health care and the sterilizing effect was evaluated using an in vitro candida biofilm. Three electrolyzed functional waters, namely strongly alkaline water, weakly acidic water, dilute sodium hypochlorite solution, two kinds of commercial mouth wash and distilled water were used as test solutions. Antibiofilm efficacy and residual chlorine concentration were evaluated before/after immersing candidal biofilm specimens in each solution. pH changes of the solutions and macroscopic observations of metal surface were evaluated before/after immersing three kinds of dental metals: steel bar, cobalt-chromium alloy and gold-silver-palladium alloy in the solutions to test the corrosion behavior. An electrolyzed dilute sodium hypochlorite solution showed high bactericidal capability of candida biofilm on cell desks and stable concentration of available chlorine, but high induction of metal corrosion.

口腔ケアは，要介護高齢者などの誤嚥性肺炎の予防など易感染性宿主に対する感染症予防において，医療現場で高く認知されている．効果的な口腔ケアをするにあたって適切な洗浄剤や清掃材料が求められる．本研究は，強力な殺菌効果が期待される電解次亜水に着目し，そのカンジダバイオフィルムに対する洗浄効果の評価法を用いて，その有効性と可能性について検討した． 試験液として，強アルカリ性電解水，弱酸性電解水，電解次亜水，2種類の市販の洗口液，滅菌蒸留水，計6種類を用いた．カンジダバイオフィルムを形成させた被着試料を用いて，各試験液の抗バイオフィルム効果およびバイオフィルム浸漬前後の有効塩素濃度の変化を検討した．歯科用金属に対する腐食性を検討するために，スチールバー，歯科用コバルトクロム合金，金銀パラジウム合金，計3種類の歯科用金属を用いて，試験液浸漬前後の pH の変化を測定した．また，試料表面の肉眼観察も行った． 電解次亜水は高いカンジダバイオフィルム殺菌・洗浄効果を認め，安定した有効塩素濃度が確保されたものの，金属腐食作用は強いことが示唆された．


Oral factors affecting titanium elution and corrosion: an in vitro study using simulated body fluid.

Ti, which is biocompatible and resistant to corrosion, is widely used for dental implants, particularly in patients allergic to other materials. However, numerous studies have reported on Ti allergy and the in vitro corrosion of Ti. This study investigated the conditions that promote the elution of Ti ions from Ti implants. Specimens of commercially pure Ti, pure nickel, a magnetic alloy, and a gold alloy were tested. Each specimen was immersed in a simulated body fluid (SBF) whose pH value was controlled (2.0, 3.0, 5.0, 7.4, and 9.0) using either hydrochloric or lactic acid. The parameters investigated were the following: duration of immersion, pH of the SBF, contact with a dissimilar metal, and mechanical stimulus. The amounts of Ti ions eluted were measured using a polarized Zeeman atomic absorption spectrophotometer. Eluted Ti ions were detected after 24 h (pH of 2.0 and 3.0) and after 48 h (pH of 9.0). However, even after 4 weeks, eluted Ti ions were not detected in SBF solutions with pH values of 5.0 and 7.4. Ti elution was affected by immersion time, pH, acid type, mechanical stimulus, and contact with a dissimilar metal. Elution of Ti ions in a Candida albicans culture medium was observed after 72 h. Elution of Ti ions in the SBF was influenced by its pH and by crevice corrosion. The results of this study elucidate the conditions that lead to the elution of Ti ions in humans, which results in implant corrosion and Ti allergy.


A Literature Review on the Perception of Implants : Comparison with Natural Teeth

インプラントの感覚能に関する文献的考察 天然歯との比較

日本口腔インプラント学会誌


磁性アッタチメントを用いたミニインプラントオーバーデンチャーの力学的解析

磁性アッタチメントを用いたミニインプラントオーバーデンチャーの力学的解析

日本口腔インプラント学会誌


Recording of individual identification information on dental prostheses using fluorescent material and ultraviolet light

The placement of individual identification on a prosthesis is very important for forensic dentistry and traceability. This article describes the unique naming/labeling of dentures with information for individual identification using a method in which information is invisible under natural light but visible under ultraviolet light-emitting diode/black light exposure. The use of laser beam machining with this method will enable the recording of a large amount of information.

The International Journal of Prosthodontics


固定方法からみたインプラント上部構造の臨床的・文献的考察

固定方法からみたインプラント上部構造の臨床的・文献的考察

As the connection mechanism between the superstructure and implant, the cement-retained type and screw-retained type are mainly used. The choice of a screw-retained versus a cement-retained superstructure is a complex and comprehensive decision involving many points of consideration. On the other hand, various retained methods that is complementary with each retained type have been proposed. In this article, various retained types which have been reported in the literatures and developed by us, were systematically assorted from the standpoints of retreivability, and the advantages were pointed out showing case photographs. This systematical information would help the selection of retained type of the superstructure.


Main occluding area in partially edentulous patients: changes before and after implant treatment

The 'main occluding area', the location where food crushing occurs during the first stroke of mastication, is reported to be an important concept; however, it is currently limited to findings in individuals with normal dentition. The purpose of this study was to assess the changes in the location, area and bite force of the main occluding area before and after implant treatments. We enrolled 50 partially edentulous and 22 normally dentate subjects. To identify the location of the main occluding area, each subject was instructed to freely bite once on a dental stopping using the partially edentulous side or the normally dentate area. The location, occluding contact area and bite force of the main occluding area before and after the implant treatments were analysed. The main occluding area was located at a reproducible location in the partially edentulous and normally dentate subjects. This location was principally the first molar region, and for the partially edentulous patients with missing teeth in the molar regions, it moved from the premolar region to the first molar region after treatment. The occluding contact area and bite force for the main occluding area increased (P < 0·05) after the implant treatment in the partially edentulous patients with missing teeth in the molar regions. These results suggest that the main occluding area can be restored to the first molar region after implant treatment and may be an important factor in the assessment of prosthodontic treatment.


The Survey on a General Youth's Eating Behavior

一般青年の食行動についての実態調査

Journal of Japanese Society for Mastication Science and Health Promotion


Biofilm formation of Candida albicans on implant overdenture materials and its removal.

The purposes of this study were to clarify the surface characteristics of various implant overdenture materials and the capabilities of Candida albicans adherence and biofilm formation on these surfaces, and to investigate the role of salivary mucin in biofilm formation. Seven commonly used implant and restorative materials were assessed. The surface roughness averages of all materials were limited to 0.07-0.10μm. Contact angles and salivary mucin absorption were measured. After 90-min initial adhesion and 2-day biofilm formation, the amounts of C. albicans were determined by counting colony-forming units and the morphological characteristics were observed by scanning electron microscopy (SEM). The effects of saliva coating and the influences of material surface property on initial adhesion, biofilm formation and its removability were analysed by univariate two-way analysis of variance and multiple linear regression analysis. Surface contact angle of materials, the index of hydrophobicity, was found to be correlated positively with initial adhesion and biofilm formation of C. albicans. A negative correlation between mucin absorption and removability of Candida biofilm indicates that mucin plays an important role in biofilm formation and its rigidity. SEM observation also revealed fewer Candida cells on saliva-coated Ti than on saliva-coated hydroxyapatite or acrylic resin. The materials with different hydrophobic property and compositions display diverse manners of salivary mucin absorption, initial adhesion and biofilm formation. The hydrophobic materials encourage enhanced initial adhesion, subsequently resulting in the active biofilm formation. Mucin has decisive effects on Candida immobilization and biofilm development on the materials. Surface hydrophilic property and composition of materials and salivary proteins, especially mucin, affect the process of Candida biofilm formation and influence the amount and rigidity of formed biofilm. The present data may be applied as a reference for selecting materials in implant overdenture treatment from a microbiological point of view.


Effects of physiotherapeutic exercise of the jaw on chewing movements in humans

下顎に対する理学療法が咀嚼動作に及ぼす影響

The Journal of Japanese Society of Stomatognathic Function


Alternative Decision Making Considerations in Prosthodontics


Carbon dioxide laser application enhances the effect of silane primer on the shear bone strength between porcelain and composite resin

The purpose of this study was to evaluate the effect of carbon dioxide laser irradiation on the performance of silane coupling agent as an adhesion promoter. The carbon dioxide laser used in this study was Opelaser 03S II, which irradiated the silane coupling agent applied on the adhesive surface of porcelain. Before and after thermal cycling, shear bond strength was measured using a universal testing machine. Without primer treatment, most of the specimens failed adhesively before reaching the end of the thermal cycling period. For the specimens irradiated with carbon dioxide laser after primer treatment, their shear bond strengths before and after thermal cycling were higher than those treated with primer only -with a significantly pronounced difference between these two groups especially after thermal cycling. Therefore, a combined surface treatment which involved silane application followed by laser treatment was feasible and efficacious for chairside porcelain repair.


social supoort for persons with cognitive dysfunction

高次脳機能障害者を支える法制度(社会的支援)

The Japanese Journal of Rehabilitation Medicine