To help elderly adults maintain good oral function, standardized oral motor training that considers missing posterior teeth needs to be established. This study aimed to investigate effect of bite position on masticatory muscle activity during tooth bite task using novel standardized bite device（BDs）. Twenty-five healthy male volunteers were classified by age into two groups: Young Adults（YA）group（n=12）and Pre-Elderly（PE）group（n=13）. Experimental design included three types of BDs（High-Force, Low-Force, and Dummy）, two age groups（YA and PE）, and two bite positions（premolar and molar）. For training, participants performed biting task 50-times on six types of bite training（three types of BDs×two bite positions）in random order. During training, electromyographic（EMG）activities were recorded from both masseter and temporalis muscles. Working / balancing side activity ratio（W/B ratio）of the masseter and temporalis muscles were calculated. The coefficient of variation（CV）from the relative ratio of the EMG RMS amplitude during each bite task in each channel was calculated. For all BDs, CV for EMG activities in both masseter and temporalis muscles were not significantly different by age or bite position. For High-Force and Low-Force BDs, W/B ratio of EMG activities in temporalis muscle were significantly higher than those in masseter muscle. Present study may suggest that our newly developed BD with built-in plate spring affected EMG activity in temporalis muscle on working side, but not in masseter or temporalis muscles on balancing side, regardless of age or bite position within the posterior teeth.

Injecting local anesthetics into the cervical sympathetic ganglion creates a stellate ganglion block. In this study, we examined changes in oral blood flow and vital signs after performing an SGB at the transverse process of the sixth cervical vertebra（i.e., C6SGB）. We enrolled 60 healthy adult male volunteers and performed C6SGB by injecting 6 mL of 1% mepivacaine hydrochloride. Subjects were divided into two groups: right-sided C6SGB（n = 30）and left-sided C6SGB（n = 30）. Buccal mucosa blood flow was measured on the treated and nontreated sides. Baseline measurements were taken 5 minutes before the injection, and subsequent readings were recorded at 5-minute intervals for 30 minutes post-injection. Heart rate（HR）and blood pressure（BP）were also measured at the same intervals. A physiological saline solution served as a control and was administered to the volunteers on a separate date for comparative measurements. Both the right-sided and left-sided C6SGB groups exhibited increased blood flow on the treated side for 30 minutes post-injection. The nontreated side also showed an increase but only for 10 minutes post-injection. Similarly, HR and BP increased for 30 minutes after the injection in both groups. C6SGB elevates facial blood flow on the treated side due to the local anesthetic’s effect on the cervical sympathetic trunk. The consequent uptick in blood flow on the non-treated side is thought to result from augmented venous circulation on both sides induced by C6SGB, along with a boost in arterial circulation specifically on the untreated side due to altered hemodynamics.

The purpose of the present study was to compare differences in age, sex, temporomandibular joint（TMJ）noise, presence of trismus and pain intensity in temporomandibular joint disorders（TMD）patients between in 2007 and in 2022. This study included 1,417 TMD patients who sought treatment for orofacial pain at the Orofacial and Head Pain Clinic in either 2007（n=762）or 2022（n=655）. For all TMD patients, age, sex, presence of TMJ noise, presence of trismus, the present pain intensity when the patient first visited the clinic and the worst pain intensity during past 6 months were recorded. The mean age of TMD patients was significantly higher in 2022 than in 2007. There was no significant difference in female-to-male ratio between in 2007 and in 2022. The proportion of patients with TMJ noise was significantly higher in 2007 than in 2022. There was no significant difference in trismus ratio between in 2007 and in 2022. The present pain intensity when the patient first visited the clinic was significantly higher in 2022 than in 2007. The worst pain intensity during past 6 months was significantly higher in 2022 than in 2007. The findings of the present study suggested that the pathology and complaint of TMD might be change with social situations.

Dental caries and periodontal diseases are oral infections caused by biofilm formation. The purpose of this study was to investigate the effects of novel ascorbic acid derivatives on oral biofilm formation by initial attachment bacteria. To reveal the effects of the novel ascorbic acid derivatives amino ascorbyl glucoside（aminoASG）, sodium ascorbyl glucoside（NaASG）, and amino ascorbic acid（aminoAS）, we performed biofilm formation and biofilm dispersion assays in 96-well plates using Actinomyces oris and Streptococcus gordonii. In the sucrose-dependent biofilm formation assay, 100 mg/mL aminoASG and 30–100 mg/mL NaASG inhibited biofilm formation of A. oris. Moreover, 50–100 mg/mL aminoASG and NaASG inhibited biofilm formation of S. gordonii. However, aminoAS did not inhibit biofilm formation by either A. oris or S. gordonii. In the biofilm dispersion assay, 1000 mg/mL aminoASG and NaASG were able to disperse the biofilm of A. oris. However, aminoAS did not disperse the biofilm produced by A. oris. Moreover, 300–1000 mg/mL of aminoASG dispersed the biofilms of S. gordonii, which NaASG and aminoAS were not able to disperse. This study revealed that the novel ascorbic acid derivatives, aminoASG and NaASG were effective in inhibiting biofilm formation and dispersing biofilms by the initial attachment bacteria.

Odontogenic ameloblast-associated protein（ODAM）is a secreted protein produced by junctional epithelium（JE）and mature ameloblasts and is involved in odontogenesis and attachment of JE to the tooth. We previously demonstrated that miR-200b and ODAM expressions were increased in inflamed gingiva collected during periodontal surgery using miRNA and DNA arrays. The purpose of this study was to investigate how mir-200b affects the expression of ODAM in inflamed junctional epithelium, therefore an inflammatory state was expressed by stimulating Ca9-22 human gingival epithelial cells with TNF-α or IL-1β. Ca9-22 cells were transfected with a miR-200b expression plasmid with or without treatment of TNF-α or IL-1β and analyzed the ODAM, IKKα, IKKβ and MKP-5 mRNA and protein levels by real-time PCR and Western blot. -480ODAM+3́-UTR luciferase（LUC）construct was transfected together with miR-200b expression plasmid in Ca9-22 cells, and measured LUC activities after stimulation by TNF-α or IL-1β. TNF-α and IL-1β-induced mRNA and protein levels of ODAM, IKKβ and MKP-5 were inhibited by overexpression of miR-200b. TNF-α o r IL-1β increased LUC activities of -480ODAM+3́-UTR were inhibited by miR-200b overexpression. TNF-α or IL-1β-induced -480ODAM3́-UTR LUC activities were inhibited by p38 MAPK, MEK1/2, IKKβ and NF-κB inhibitors. In conclusion, miR-200b appears to suppress TNF-α or IL-1β-induced ODAM expressions in gingival epithelial cells by targeting ODAM, IKKβ and MKP-5.

Although numerous studies on dental caries have been reported, they have been inconclusive and have not clarified the mechanism of caries progression in a unified manner. Fourier transform infrared spectroscopy（FTIR）is one of the most convenient and reliable methods for quantitative and qualitative molecular analysis. However, in the ordinary FTIR, the sample is crushed to a powder form, so the analysis results, including positional information such as site-specific variations of the analyte, are averaged out. Therefore, in this study, we analyzed the composition of human dentin using micro-Fourier transform infrared spectroscopy（micro-FTIR）, which enables measurement in small areas, in order to clarify whether there are differences among different areas, and to help elucidate the mechanism of caries progression. Polished specimens were prepared and used from human third molars without caries and with no evidence of treatment among the extracted teeth stored in our department. Compositional analysis was performed using micro-FTIR, measuring the mesial, occlusal, and distal surfaces of the dentin just below the enamel at four locations each. The results of this study showed that there was little difference in the dentin apatite ν 4 P-O, but two patterns were observed in ν3 P-O. Thus, two patterns of dentin crystallinity in the mesial, distal, and occlusal surfaces of the dentin just below the enamel were found to exist, and the location of these two patterns differed among individuals. Finally, in the C-O absorption band peaks, there was little difference in peak position among all samples, but there was a difference in intensity. Therefore, it can be inferred that although there was little difference in the peak value of the C-O absorption band in the dentin just below the enamel, differences in demineralization（solubility）can be recognized in each dentin region based on the difference in intensity. On top of that, the intensity of the absorption bands due to H₂O+amide Ⅱ differed from sample to sample. From the above, the composition of the dentin immediately below the enamel varied slightly from tooth to tooth, or from mesial, occlusal, and distal surfaces, suggesting that these differences may be related to the degree of crystallinity, solubility, and maturity and may influence the progression of caries.

Controlling salt intake is important for maintaining health. Salt intake is expected to be influenced by both the recognition threshold for salty taste and the salt concentration that makes food taste better（preference concentration）; however, there are large individual differences in both, and the determining factors are unknown. Saliva components are expected to affect the salty taste threshold and preference. In this study, we analyzed the relationship between ion concentrations in saliva, salty taste perception, and self-reported preference and intake frequency for salty foods. We determined the recognition threshold and preference concentration for salt taste in 50 adult volunteers using paper filter strips that impregnated with NaCl. Sodium and potassium concentrations in resting and stimulated saliva were measured. Additionally, we administered a questionnaire to examine the degree of preference and subjective intake frequency for six salty foods. Sodium and potassium concentrations in the resting saliva of the low recognition threshold group were lower（3.12±1.90 mM）and higher（18.75±4.23 mM）, respectively, than those of the high recognition threshold group（4.88±3.55 and 15.34±3.55 mM, respectively）. Sodium concentration was also lowe（r3.22±2.03 mM）in the low-preference concentration group than in the high group（4.92±3.77 mM）, whereas potassium concentration was unrelated. Sodium concentration in the resting saliva had a significant positive correlation with preference concentration（r = 0.412, p < 0.05）and degree of preference（r = 0.417, p < 0.01）. Cation concentrations in resting saliva probably affect the salt taste threshold and preference. High consumption of salty foods likely leads to an increase in the resting saliva sodium concentration, which in turn increases preference for salt and may induce a vicious circle.