Activities of the dorsolateral and medial prefrontal cortices during oral function training with cognitive training elements: a NIRS study.

BACKGROUND: Cognitive function plays a crucial role in human life, and its maintenance and improvement are essential in both young and older adults. Since cognitive decline can be associated with oral function decline, preventing the decline in both cognitive and oral functions is an urgent social issue. Several training methods to improve each function have been proposed. Previous studies have indicated that greater brain activity during training is associated with increased benefits for cognitive function. Although adding cognitive function elements to oral function training may promote the activation of brain activity during oral function training, the effects have not been validated. The main purpose of this study is to develop a novel training program that combines oral function training with cognitive training, which is expected to activate key brain regions involved in oral and cognitive functions, such as the left dorsolateral prefrontal cortex (DLPFC) and right medial prefrontal cortex (mPFC). METHODS: Four types of training programs combining oral and cognitive training: PaTaKaRa × calculation, lip exercise × N-back, tongue exercise × inhibition, and tongue exercise × memory, were developed. Each program had seven levels of difficulty [level 0 (no cognitive load) and level 6 (maximum difficulty)]. Twelve healthy young adults participated in the study and were instructed to perform all four programs. Brain activity in the left DLPFC and right mPFC were measured during each training session using two-channel near-infrared spectroscopy (NIRS). RESULTS: No significant brain activity was observed during training at level 0. Brain activity in the left DLPFC was significantly increased at levels 1 and 2 and in the left DLPFC and right mPFC at level 6 during PaTaKaRa × calculation training. Brain activity in the left DLPFC was significantly increased at level 6 during tongue exercise × inhibition training. Brain activity in the left DLPFC and right mPFC was significantly increased at level 6 during lip exercise × N-back training. CONCLUSION: Oral function training did not significantly increase brain activity; nevertheless, oral function with cognitive training stimulated brain activity in the prefrontal cortex. TRIAL REGISTRATION: UMIN-CTR. ID: UMIN000039678. date: 06/03/2020.

Difference in the Electromyographic Behavior of the Masticatory and Swallowing Muscles During Cued Versus Spontaneous Swallowing.

The risk of dysphagia and/or aspiration is determined using screening tests, such as the repeated saliva swallowing test and modified water swallowing test, which evaluate cued swallowing. However, humans masticate and swallow foods with various consistencies, forms, and amounts, without conscious awareness. Therefore, this study aimed to examine the difference in the behavior of masticatory and swallowing muscles during spontaneous versus cued swallowing through a series of mastication and swallowing processes by evaluating surface electromyogram (sEMG) signals. The effect of the consistency and amount of food on the behavior of these muscles was also investigated. The sEMG recordings of the masseter muscles and anterior belly of the digastric muscle for 12 subjects, and genioglossus muscle for 5 subjects were obtained. The genioglossus activity was recorded using custom-made ball electrodes. The test foods were cookies and tofu, in amounts of 2 g and 4 g. The normalized muscle activity (integrated EMG), duration of the muscle activity, initial activation timepoint of each muscle, and total duration of swallowing were compared among four conditions. The activity of each muscle was significantly higher during the swallowing of cookies than tofu, for 4 g vs 2 g, and for cued versus spontaneous swallowing. The duration of each muscle activity, initial activation timepoint, and total duration of swallowing were significantly longer for cookies versus tofu, for 4 g vs 2 g, and for spontaneous versus cued swallowing. These results suggest that the behavior of the masticatory and swallowing muscles is affected by cued swallowing and by the consistency and amount of food.

Inhibition of tooth demineralization caused by Streptococcus mutans biofilm via antimicrobial treatment using hydrogen peroxide photolysis.

OBJECTIVES: An antimicrobial technique utilizing hydroxyl radicals generated by the photolysis of 3% H2O2 has been developed recently. The present study aimed to evaluate the effect of H2O2 photolysis treatment on tooth demineralization caused by Streptococcus mutans biofilm. MATERIALS AND METHODS: To induce tooth demineralization, S. mutans biofilm was allowed to form on the maxillary first molars collected from Wistar rats via 24-h culturing. The samples were immersed in 3% H2O2 and irradiated with 365-nm LED (H2O2 photolysis treatment). Viable bacterial counts in the biofilm were evaluated immediately after treatment and after an additional 30-h culturing by colony counting. The acidogenicity of the biofilm, re-established 30 h after treatment, was assessed by measuring the pH. The effect of H2O2 photolysis treatment on tooth demineralization was assessed by measuring the depth of the radiolucent layer in micro-CT images. RESULTS: H2O2 photolysis significantly reduced viable bacterial counts in the biofilm to 3.7 log colony forming units (CFU)/sample, while the untreated group had 7.9 log CFU/sample. The pH of the biofilm re-established after treatment (6.6) was higher than that of the untreated group (5.3). In line with the pH measurement, the treatment group had a significantly lower depth of radiolucent layer in dentin than the untreated group. CONCLUSIONS: H2O2 photolysis treatment was effective not only in killing the biofilm-forming S. mutans but also in lowering the acidogenicity of the biofilm. Thus, this technique could inhibit tooth demineralization. CLINICAL RELEVANCE: H2O2 photolysis can be applicable as a new dental caries treatment.

Sensory neuromuscular electrical stimulation for dysphagia rehabilitation: A literature review.

BACKGROUND: Dysphagia is a common disorder following a cerebrovascular accident. It can cause detrimental effects on patient's quality of life and nutrition intake, especially in older adults. Neuromuscular electrical stimulation has been one of the management strategies for acceleration of the recovery. This review summarises the current evidence on sensory threshold stimulation of the procedure. METHOD: This review compiled data from the Internet database PubMed, Cochrane Library and Scopus using combination of MeSH thesaurus: 'Sensory threshold', 'electrical stimulation', 'neuromuscular stimulation', 'Deglutition', 'Dysphagia'. Eleven studies were intergraded into the review. RESULTS: Most of the studies show significant improvement to the outcomes of sensory neuromuscular electrical stimulation treatment. In many cases, the results of the treatment are comparable or superior to motor threshold stimulation and conventional therapy. However, the study design and parameters of the procedure varied greatly without conclusive standardised guidelines. CONCLUSION: The sensory neuromuscular electrical stimulation (SNMES) is a viable treatment option for treating oropharyngeal dysphagia. The most suggested application parameters are an intensity at sensory threshold, a frequency of 80 Hz, an impulse time of 700 µs, a combined total duration of 20 h of stimulation in a 2-week period, and placing the electrodes in the submental area of the neck. However, further research is necessary to construct a definitive guideline for clinicians.

Evaluation of the optimal hardness and thickness of music splints for wind instrument players.

STATEMENT OF PROBLEM: As players of single-reed wind instruments such as the clarinet and saxophone are likely to experience pain and trauma of the lower lip, a method to prevent these symptoms without disturbing the music quality and performance is required. PURPOSE: The purpose of this clinical study was to produce a custom music splint, an oral appliance for the players of single-reed wind instruments, by using sports mouthguard sheet materials and to determine its suppression effect on the pressure and pain of the lower lip and teeth and on fatigue and pain of the jaw. MATERIAL AND METHODS: The soft type and soft and hard 2-layer type of sheet materials for sports mouthguards were used to fabricate the music splints. Each type of material has 1-mm and 2-mm thicknesses; therefore, 4 kinds of music splint were produced. The participants, students who played wind instruments in university orchestras, were instructed to use each music splint when playing the instruments for 1 week (for at least 3 hours for each music splint) and to answer a questionnaire about the effect of each appliance. Eighteen participants answered the questionnaire. Based on the usual usage of oral appliances when playing instruments, the participants were classified into 2 groups; oral appliance typically used (group OA) (n=7) and oral appliance not used (group noOA) (n=11). To determine the effects of the 4 types of music splint, a multilevel linear regression analysis was applied to evaluate the nested structure of the data (α=.05). RESULTS: The use of the music splint significantly relieved pressure and pain on the lower lips. The soft type was more effective in group OA, and the thin type was more effective in group noOA. The thin- and soft-type music splints were associated with significantly better playing sensation and sound quality than other types of splint in both groups. CONCLUSIONS: The thin- and soft-type music splints can be effective and useful for suppressing oral symptoms when playing a single-reed wind instrument without disturbing the quality of the performance.

Effect of gingival height of a titanium base on the biomechanical behavior of 2-piece custom implant abutments: A 3-dimensional nonlinear finite element study.

STATEMENT OF PROBLEM: Titanium base (TiBase) abutments to restore an implant-supported single crown are available in different gingival heights, but information on the biomechanical effects of the gingival heights is lacking. PURPOSE: The purpose of this nonlinear finite element analysis study was to evaluate the effects of TiBase gingival heights on the biomechanical behavior of custom zirconia (CustomZir) abutments and TiBase, including von Mises stress and maximum and minimum principal stress. MATERIAL AND METHODS: TiBases with different gingival heights (0.5 mm, 1 mm, 1.5 mm, and 2 mm) with internal hexagon Morse taper connections were simulated in 3-dimensional models. The simulations (ANSYS Workbench 2020; ANSYS Inc) included the OsseoSpeed EV implant (Ø5.4 mm) (AstraTech; Dentsply Sirona), restoration, and surrounding bone in the mandibular first molar region. An occlusal force of 200 N was applied with a 2-mm horizontal offset toward the buccal side and a 30-degree inclination from the vertical axis. RESULTS: High-stress concentration was observed in the uppermost internal connection area on the buccal side and the antirotational part of the titanium abutment on the lingual side in all models. CustomZir abutments with a shorter gingival height exhibited larger concentrated areas of volume average stress von Mises stress and higher magnitude of maximum and minimum principal stress compared with a taller gingival height. CONCLUSIONS: A TiBase abutment with a taller gingival height reduced the fracture risk of a CustomZir abutment without increasing any mechanical risk.

A novel treatment based on powder jet deposition technique for dentin hypersensitivity: a randomized controlled trial.

BACKGROUND: This study aimed to evaluate the efficacy and safety of dentin hypersensitivity (DH) treatment using a newly developed device based on a powder jet deposition (PJD) technique that creates a hydroxyapatite (HAP) layer on the dentin surface, thereby alleviating the hypersensitivity. The effect of the PJD treatment was compared with that of conventional treatment using Teethmate Desensitizer (TMD; calcium-phosphate containing material with TTCP (Ca4(PO4)2O) and DCPA (CaHPO4)), which has been used clinically in Japan with well-confirmed effectiveness. MATERIALS AND METHODS: A randomized controlled trial was conducted including 35 patients who had symptoms of DH in two or more quadrants. Two test teeth were selected per patient (70 teeth in total) and randomly assigned to PJD or TMD treatment. The efficacy was evaluated using the improvement rate for air and scratch pain according to the scores obtained via visual analog scale 12 weeks after treatment. The safety assessment was performed focusing on gingival index (GI) and spontaneous pain. The t-test was used to analyze the non-inferiority of PJD treatment compared to TMD treatment. RESULTS: The improvement rate of air pain was 69.0% for PJD and 69.7% for TMD. The improvement rate of scratch pain was 80.8% for PJD and 81.7% for TMD. Non-inferiority with a margin of 10% was not observed for both air and scratch pain. No change was observed in GI from baseline and the improvement rate of spontaneous pain for PJD was higher than that for TMD. CONCLUSION: Non-inferiority of PJD to TMD treatment was not observed in this study; however, it was not statistically demonstrated, and the results were thus interpreted as inconclusive. PJD did improve the DH symptoms, as did TMD. PJD's therapeutic effect was most likely attributable to the deposition of a HAP layer on the tooth surface, which would alleviate hypersensitivity for at least 12 weeks without causing severe adverse events. TRIAL REGISTRATION: UMIN-CTR. ID: UMIN000025022. date: 02/12/2016.

Effect of customized abutment taper configuration on bone remodeling and peri-implant tissue around implant-supported single crown: A 3D nonlinear finite element study.

PURPOSE: The optimal configuration of a customized implant abutment plays a crucial role in promoting bone remodeling and maintaining the peri-implant gingival contour. However, the biomechanical effects of abutment configuration on bone remodeling and peri-implant tissue remain unclear. This study aimed to evaluate the influence of abutment taper configurations on bone remodeling and peri-implant tissue. MATERIALS AND METHODS: Five models with different abutment taper configurations (10°, 20°, 30°, 40°, and 50°) were analyzed using finite element analysis (FEA) to evaluate the biomechanical responses in peri-implant bone and the hydrostatic pressure in peri-implant tissue. RESULTS: The results demonstrated that the rate of increase in bone density was similar in all models. On the other hand, the hydrostatic pressure in peri-implant gingiva revealed significantly different results. Model 10° showed the highest maximum and volume-averaged hydrostatic pressures (69.31 and 4.5 mmHg), whereas Model 30° demonstrated the lowest values (57.83 and 3.88 mmHg) with the lowest excessive pressure area. The area of excessive hydrostatic pressure decreased in all models as the degree of abutment taper increased from 10° to 30°. In contrast, Models 40° and 50° exhibited greater hydrostatic pressure concentration at the cervical region. CONCLUSION: In conclusion, the abutment taper configuration had a slight effect on bone remodeling but exerted a significant effect on the peri-implant gingiva above the implant platform via hydrostatic pressure. Significant decreases in greatest and average hydrostatic pressures were observed in the peri-implant tissues of Model 30°. However, the results indicate that implant abutment tapering wider than 40° could result in a larger area of excessive hydrostatic pressure in peri-implant tissue, which could induce gingival recession.

Application of Diffusion Tensor Imaging Fiber Tractography for Human Masseter Muscle.

Diffusion tensor imaging (DTI) has been used to indicate the direction of nerve and muscle fibers by using the characteristics that water molecules preferentially diffuse along the fibrous structure. However, DTI fiber tractography for multipennate muscles, such as the masseter muscle, is challenging due to a lack of data regarding the imaging parameters. This study aimed to determine the optimal DTI parameters for masseter muscle fiber tractography. A 27-year-old healthy man voluntarily underwent DTI and T1-weighted magnetic resonance imaging of the right masseter muscle. Four imaging parameter settings were created by combining the following parameters that particularly affect the signal-to-noise ratio: b-value, number of excitations (NEX), and number of motion probing gradient (MPG) directions. DTI fiber tractography was performed using specific software for each parameter setting. The length and orientation of the muscle fibers in each layer were calculated. As a result, the masseter muscle fibers of each layer were identified on DTI. Although the detected fiber length was affected significantly by the imaging parameters, the fiber orientation was insignificantly affected. The appropriate combination of the b-value, NEX, and the number of MPG directions for masseter muscle fiber tractography could be determined based on previously reported anatomical data of the masseter muscle fibers. DTI may enable the non-invasive evaluation of masseter muscle fiber length and orientation. Elucidation of the details of masseter muscle fiber orientation is useful in evaluating stomatognathic biomechanics and muscle disorders.

Medical-Dental Collaboration and Interprofessional Training for Maxillofacial Diseases at Tohoku University Hospital.

The Tohoku University Hospital has been a clinical and research facility for all the related departments of Tohoku University. Medical-dental and interprofessional collaboration has resulted in special treatment teams, made up of members of departments such as the center for head and neck cancer, the center for dysphagia, and the cleft lip and palate center. Those treatment teams held conferences, case study meetings, reading sessions, and in-hospital seminars. The purpose of this study was to evaluate the outcomes of various medical-dental and the interprofessional collaboration at Tohoku University Hospital and training program to equip hospital dentists in higher medical institutions. The attainment targets are the acquisition of basic medical skills and knowledge under the guidance of supervising doctors. As a result, the hospital dentists could acquire their own specialized knowledge and skills certificated by each academic society. The smooth team treatment has been achieved, and the number of cases discussed by cancer boards and center for dysphagia has increased year by year due to the efficiency of their clinical pathways. On the dental care side as well, the wearing rates of maxillofacial prosthetic devices such as maxillofacial prostheses and palatal augmentation prostheses (PAP) have improved, which have contributed to improving patient's stomatognathic function. Tohoku University Hospital has been practicing collaboration between medical and dental professionals and it has produced mutual benefits. Our interprofessional training system based on the medical-dental collaboration could develop professionals who have acquired cross-disciplinary knowledge and skills from experienced doctors.

Morphological comparison of masseter muscle fibres in the mandibular rest and open positions using diffusion tensor imaging.

BACKGROUND: The masseter muscle has a complicated multipennate internal structure and exhibits functional differentiation when performing various stomatognathic functions. It is important to understand the internal structural changes of the muscle during functioning to elucidate characteristic muscle disorders such as local myalgia. Diffusion tensor imaging (DTI) may be useful for investigating the internal structural features of muscle. OBJECTIVES: To evaluate the features of masseter muscle fibres in human participants using DTI fibre tractography, and to elucidate the structural differences in the masseter muscle between the mandibular rest and open positions. METHODS: Five healthy men (age 31 ± 7 years) underwent DTI and T1-weighted MRI of the right masseter muscle in the mandibular rest and open positions. MR images were used as a reference for muscle layer segmentation (superficial, intermediate, and deep). DTI fibre tractography of the masseter muscle was performed and the orientation of the DTI fibres was analysed in each layer using coordinates based on the Frankfurt horizontal plane. RESULTS: The DTI fibre orientation of the deep layer significantly changed between the mandibular rest and open positions in the frontal plane (p < 0.05, Wilcoxon rank sum test). However, no significant change was found in the superficial and intermediate layers. CONCLUSION: DTI fibre tractography confirmed regional differences in the orientation change of the masseter muscle fibres between different mandibular positions. The results may support the existence of functional partitioning inside the masseter muscle and suggest that DTI may be useful for the evaluation of muscle fibres in multipennate muscles.

Resonance frequency analysis for evaluation of the connecting condition between fixed prostheses and their abutment teeth: An in vitro and finite element analysis study.

STATEMENT OF PROBLEM: Loss of retention is a clinical complication for fixed partial dentures (FPDs). However, a method sensitive enough to measure the early retention loss of FPDs is lacking. PURPOSE: The purpose of this in vitro and finite element analysis (FEA) study was to determine whether resonance frequency analysis (RFA) with a newly developed system can detect lack of FPD retention caused by cement loss. MATERIALS AND METHODS: Two evaluation methods were used: RFA of an in vitro model of a 3-unit FPD from the second premolar to the second molar and FEA by using a simplified model. The in vitro model was used to evaluate 4 connecting conditions: both crowns cemented, only the premolar crown cemented, only the molar crown cemented, and both crowns uncemented. Tapping stimulation (16 impulsive forces, 4 Hz) was directly applied to the buccal side of the second molar or the second premolar, and an attached 3D accelerometer sensor was used to record the resonance frequency (RF) of the tapped tooth. The amplitude, frequency, Q-value, and total area under the curve (AUC) of the RF values in the buccolingual direction were compared between connecting conditions. The FEA was done by using a simplified model of a 3-unit FPD with similar connecting conditions as the in vitro model study, and the RF amplitude and frequency of each tooth were calculated. Statistical evaluation included 1-way analysis of variance and the Tukey HSD test to compare the differences among each connecting condition under each parameter for measurement sites on the molar and the premolar, respectively (α=.05). RESULTS: For both the molar and premolar measurements in both the in vitro and FEA models, when the measurement site was on the uncemented tooth, the amplitude of RF-1 increased, the Q-value of RF-2 decreased, and the area under the curve increased (P<.05). CONCLUSIONS: The same 3 trends found between the measurement sites of the in vitro study and FEA indicated that RFA may be useful for detecting an FPD with loosening caused by cement loss, even partial cement loss.

Imaging of muscle activity-induced morphometric changes in fibril network of myofascia by two-photon microscopy.

Myofascia, deep fascia enveloping skeletal muscles, consists of abundant collagen and elastin fibres that play a key role in the transmission of muscular forces. However, understanding of biomechanical dynamics in myofascia remains very limited due to less quantitative and relevant approaches for in vivo examination. The purpose of this study was to evaluate the myofascial fibril structure by means of a quantitative approach using two-photon microscopy (TPM) imaging in combination with intravital staining of Evans blue dye (EBD), a far-red fluorescence dye, which potentially labels elastin. With focus on myofascia of the tibial anterior (TA) muscle, the fibril structure intravitally stained with EBD was observed at the depth level of collagen fibrous membrane above the muscle belly. The EBD-labelled fibril structure and orientation in myofascia indicated biomechanical responses to muscle activity and ageing. The orientation histograms of EBD-labelled fibrils were significantly modified depending upon the intensity of muscle activity and ageing. Moreover, the density of EBD-labelled fibrils in myofascia decreased with habitual exercise but increased with muscle immobilization or ageing. In particular, the diameter of EBD-labelled fibrils in aged mice was significantly higher. The orientation histograms of EBD-labelled fibrils after habitual exercise, muscle immobilization and ageing showed significant differences compared to control. Indeed, the histograms in bilateral TA myofascia of exercise mice made simple waveforms without multiple sharp peaks, whilst muscular immobilization or ageing significantly shifted a histogram with sustaining multiple sharp peaks. Therefore, the dynamics of fibre network with EBD fluorescence in response to the biomechanical environment possibly indicate functional tissue adaptation in myofascia. Furthermore, on the basis of the knowledge that neutrophil recruitment occurs locally in working muscles, we suggested the unique reconstruction mechanism involving neutrophilic elastase in the myofascial fibril structure. In addition to the elastolytic susceptibility of EBD-labelled fibrils, distinct immunoreactivities and activities of neutrophil elastase in the myofascia were observed after electric pulse stimulation-induced muscle contraction for 15 min. Our findings of EBD-labelled fibril dynamics in myofascia through quantitative approach using TPM imaging and intravital fluorescence labelling potentially brings new insights to examine muscle physiology and pathology.

Macrophage Polarization Related to Crystal Phases of Calcium Phosphate Biomaterials.

Calcium phosphate (CaP) materials influence macrophage polarization during bone healing. However, the effect of the crystal phase of CaP materials on the immune response of bone remains unclear. In this study, the effect of the crystal phases of CaP materials on the regulation of macrophage polarization was investigated. Human THP-1 cells and mouse RAW 264 cells were cultured with octacalcium phosphate (OCP) and its hydrolyzed form Ca-deficient hydroxyapatite to assess the expression of pro-inflammatory M1 and anti-inflammatory M2 macrophage-related genes. OCP inhibited the excessive inflammatory response and switched macrophages to the anti-inflammatory M2 phenotype, which promoted the expression of the interleukin 10 (IL10) gene. In contrast, HL stimulated an excessive inflammatory response by promoting the expression of pro-inflammatory M1 macrophage-related genes. To observe changes in the microenvironment induced by OCP and HL, inorganic phosphate (Pi) and calcium ion (Ca2+) concentrations and pH value in the medium were measured. The expression of the pro-inflammatory M1 macrophage-related genes (tumor necrosis factor alpha (TNFα) and interlukin 1beta (IL1ß)) was closely related to the increase in ion concentration caused by the increase in the CaP dose. Together, these results suggest that the microenvironment caused by the crystal phase of CaP materials may be involved in the immune-regulation capacity of CaP materials.

Morphological magnetic resonance imaging study of oral submucosal tissue and buccinator muscle dynamics in the posterior dentition: A clinical study.

STATEMENT OF PROBLEM: The relationship between the buccal mucosa-tongue side wall contact points and at what ratio the submucosal tissue (ST) and buccinator muscle (BUC) change during function are unclear. PURPOSE: The purpose of this clinical study was to clarify the space and dynamics of the ST and BUC in complete denture wearers by using magnetic resonance imaging and to investigate how denture base shape affects space sealing and the relationship between the ST and BUC. MATERIAL AND METHODS: Eight edentulous participants wearing maxillary and mandibular complete dentures were enrolled. Wax was added to the buccal border of the dentures, and axial and coronal magnetic resonance imaging scans were made during mandibular rest (MR) to observe the relationship of the buccal mucosa and tongue above the retromolar pads. In addition, on axial images, the thicknesses of the ST and BUC were measured at 3 sites: second molar center, second molar distal (SMD), and retromolar pad center (RPC). Coronal images were made during MR, partial mouth opening, and midmouth opening (MMo). At second molar center, SMD, and RPC, the thicknesses of the ST and BUC were measured at the maxillary buccinator attachment region (point A), the mandibular buccinator attachment region (point B), and the median point between A and B (point M). RESULTS: During MR, contact sealing of the buccal mucosa and tongue on the RPC was noted in 81% of participants. After expanding the denture base with wax, contact was lost in 86% of participants. The ST and BUC thicknesses on the RPC decreased significantly with the addition of wax. During MR, the ST became significantly thicker the further posteriorly it was located. The ST was significantly thicker at point M than at point A for all sections, regardless of mouth opening. The ST and BUC thicknesses in SMD and RPC were significantly thicker at point M than at point B during MR and MMo. The differences of the ST and BUC thicknesses depending on the opening amount were observed only at the point M. In the RPC, the thickness of the ST and BUC decreased significantly as the opening amount increased (ST thickness between MR and partial mouth opening, MR, and MMo: P=.007, P=.001, BUC: P=.018, P=.001, respectively) CONCLUSIONS: The thickness of the ST and BUC differed depending on the site. During mouth opening, these changes in thickness at each site are proportional to the differences in ST and BUC thickness.

Effectiveness and safety of a new dental plaque removal device utilizing micro mist spray for removing oral biofilm in vitro.

BACKGROUND: Removal of oral biofilm from the oral mucosa is essential for preventing risk of respiratory and gastrointestinal infection in elderly people. Currently, no device is available which can remove oral biofilm from oral mucosa effectively and safely. Therefore, the effectiveness and safety of the Micro Scale Mist UNIT (MSM-UNIT), a newly developed dental plaque removal device utilizing high speed sprays of fine water droplets, were evaluated for biofilm removal, including the rate and surface roughness for simulated tooth surface and mucous membrane. METHODS: Simulated tooth and oral mucosa coated with an artificial biofilm of Streptococcus mutans were used for evaluation of effectiveness, with uncoated substrates as the controls. The MSM-UNIT and a conventional air ablation device were operated under recommended instructions. The effectiveness was evaluated from the rate of removal of the biofilm, and the safety was evaluated from the damage observed by scanning electron microscope and surface roughness. RESULTS: The biofilm removal rate of the MSM-UNIT was significantly higher than that of AIRFLOW. Little damage was observed in the area treated by the MSM-UNIT. The surface roughness of the MSM-UNIT treated area on simulated tooth surface and oral mucosa showed no significant difference to the control area. In contrast, cracks and powder were observed in the area treated by AIRFLOW. In particular, the surface roughness of the AIRFLOW treated area for Toughsilon was significantly larger than that of the control. CONCLUSIONS: The MSM-UNIT could be used safely and effectively for removing biofilm not only on simulated tooth surfaces but also simulated mucous membrane. The MSM-UNIT has no harmful effect on teeth or oral mucosa, and may be used for comprehensive oral care for patients during nursing care and the perioperative period.

Usefulness of daily folic acid supplementation during methotrexate treatment of Japanese patients with rheumatoid arthritis.

OBJECTIVES: We investigated the effect of daily folic acid supplementation on methotrexate (MTX) toxicity and efficacy in Japanese patients with rheumatoid arthritis (RA). METHODS: We followed 19 patients treated with MTX who switched from taking weekly 5 mg folic acid supplementation (weekly regimen) to 1.25 mg daily (daily regimen). White blood cell (WBC) and platelet (PLT) counts, aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels, erythrocyte sedimentation rate (ESR), and C-reactive protein (CRP) levels were collected for 24 weeks following the change. RESULTS: We observed no significant changes in WBC or PLT counts. AST and ALT levels, which had exceeded the upper limits of their normal ranges at the beginning of the study, were improved significantly at weeks 4 and 8, no subsequent deterioration in liver function was found. Further, no significant changes in ESR and CRP levels were observed. CONCLUSION: Our data indicate that supplementing 1.25 mg of folic acid daily rather than 5 mg weekly reduces toxicity caused by MTX without affecting its efficacy.

Exercise-evoked intramuscular neutrophil-endothelial interactions support muscle performance and GLUT4 translocation: a mouse gnawing model study.

KEY POINTS: Fractalkine receptor antagonist inhibited neutrophil recruitment to masseter muscles and exacerbated fatigability during masticatory activity. Fractalkine-mediated neutrophil recruitment is required for both upregulation of myokines (CXCL1, interleukin-6) and enhanced GLUT4 translocation in response to masticatory activity. Fractalkine and intercellular adhesion molecule-1 expression in endothelial cells increased in response to masticatory activity. In vitro experiments demonstrated that contracting myotubes lack the ability to upregulate fractalkine but revealed that endothelial fractalkine upregulation is induced using a conditioned medium of contracting myotubes. ABSTRACT: Physical exercise stimulates neutrophil recruitment within working skeletal muscle, although its underlying mechanisms remain ill-defined. By employing a masticatory behaviour (gnawing) model, we demonstrate the importance of intramuscular paracrine and autocrine systems that are triggered by muscle contractile activity and reliant upon fractalkine/CX3CL1-mediated signals. These signals were revealed to be required for achieving proper GLUT4 translocation and glucose uptake to meet the glucose demands for fatigue alleviation. Specifically, fractalkine expression and neutrophil recruitment both increased in the masseter muscle tissues upon masticatory activity. Importantly, a fractalkine antagonist inhibited neutrophil accumulation and exacerbated fatigability during masticatory activity. We found that fractalkine-dependent neutrophil recruitment is required for both upregulation of myokines (i.e. CXCL1 and interleukin-6) and enhanced GLUT4 translocation in response to gnawing activity. Immunofluorescence analysis of masseter muscles demonstrated that fractalkine and intercellular adhesion molecule-1 expression are both upregulated in endothelial cells but not in myofibres. The in vitro exercise model further revealed that contractile activity failed to stimulate fractalkine upregulation in myotubes, implying that fractalkine is not a myokine (myofibre-derived factor). Nevertheless, endothelial fractalkine expression was markedly stimulated by a conditioned medium from the contracting myotubes. Moreover, intercellular adhesion molecule-1, a key adhesion molecule for neutrophils, was upregulated in endothelial cells by fractalkine. Taken together, our findings strongly suggest that endothelial fractalkine serves as a key factor for organizing a physiologically beneficial intramuscular microenvironment by recruiting neutrophils in response to relatively mild exercise (i.e. masticatory muscle activity).

Design and Progress of Oral Health Examinations in the Tohoku Medical Megabank Project.

In order to assess the long-term impact of the Great East Japan Earthquake on the oral health of disaster victims and to evaluate gene-environmental interactions in the development of major oral diseases and oral-systemic associations, the oral part of two large-scale genome cohort studies by the Tohoku Medical Megabank Organization (ToMMo), including the Community-based cohort (CommCohort) study and the Birth and Three-Generation cohort (BirThree) study, have been conducted. The study population comprised 32,185 subjects, including 16,886 participants in the CommCohort study and 15,299 participants in the BirThree cohort study, recruited from 2013 to 2017. The oral studies consist of a questionnaire regarding oral hygiene behavior, clinical examinations by dentists, and oral plaque and saliva sampling for microbiome analyses, which were carried out at seven community support centers in Miyagi prefecture. The median age of all participants was 55.0 years, and 66.1% of participants were women. Almost all participants reported that they brushed their teeth more than once a day. The median number of present teeth was 27.0, and the decayed, missing and filled tooth number was 16.0, with a significant difference according to age and sex. The median periodontal pocket and clinical attachment level was 2.48 mm and 4.00 mm, respectively. Periodontal parameters increased significantly according to age, except for the accumulation of dental calculus. The oral part of these extensive cross-sectional studies provides a unique and important platform for future studies on oral health and diseases that elicit through interactions with systemic diseases, lifestyles, life events and genetic backgrounds, and contributes to researches clarifying the long-term effects of disasters on oral health.

Effect of peri-implant bone resorption on mechanical stress in the implant body: In vivo measured load-based finite element analysis.

BACKGROUND: Research on resolving implant fracture is still gaining attention as it can be a serious treatment failure outcome. The implant fracture is likely to occur due to increased stress in implant body associated with peri-implant bone resorption. OBJECTIVE: This study aimed to investigate the relationship between degree of peri-implant bone resorption and stress distribution in implant body by using finite element analysis (FEA). METHODS: The magnitude and direction of loads on implants at the mandibular molar region were measured with 3D piezoelectric force transducers in a patient during maximal voluntary clenching, grinding and tapping to obtain input for the FEA as the loading condition. Simplified finite element bone models were generated to simulate the six patterns of peri-implant bone resorption progression which the bone levels from implant platform were set at 0, 1, 2, 3, 4 and 5 mm. Three types of implants with different diameters (3.5, 4.0 and 5.0 mm), corresponding abutments and screws were created. FEA using the in vivo measured load was conducted to investigate how peri-implant bone loss affects stress distribution in the implant body. RESULTS: Loading condition affected stress distribution in the implant body. As bone resorption increased, von Mises stress in the implant body became larger, which was marked in smaller diameter implants, and this change was amply demonstrated when the bone resorption increased from 0 to 2 mm. CONCLUSION: The FEA demonstrated that as peri-implant bone loss increased, the magnitude of stress in the implant increased, especially in small diameter implants.