Manual toothbrushes, self-toothbrushing, and replacement duration to remove dental plaque and improve gingival health: A scoping review from recent research.

OBJECTIVE: To investigate characteristics of manual toothbrushes, self-toothbrushing methods, and replacement duration of manual toothbrushes that effectively remove dental plaque, reduce gingivitis, and promote gingival health. STUDY DATA AND SOURCES: PubMed-MEDLINE, Scopus and Central Register Cochrane of Controlled trials (CENTRAL) were searched for randomized control trials (RCTs) from 01 January 2018 to 12 December 2023. Articles were subjected for including participants aged six years and older with a study duration of at least four weeks to investigate the efficacy of manual toothbrushes used self-toothbrushing. To investigate the appropriate time to replace manual toothbrushes, this study was focused on the physical properties of the bristles and changes in the microorganisms present in the bristles over time. STUDY SELECTION: Of 1520 retrieved articles, 26 studies were included after screening. The total number of manual toothbrushes was 40 and 5 kinds of self-toothbrushing techniques were selected in the review. 4 studies investigated the changes the physical properties bristles of manual toothbrushes. CONCLUSIONS: Among manual toothbrushes, the cross-angle and indicator bristles were found to significantly improve dental plaque index and gingival condition. Most toothbrushes with soft bristles had a trend of superior dental plaque removal and gingivitis improvement efficacy. Toothbrush with end-round shape bristles tip has tended to reduce the dental plaque and gingival index scores. Studies reported that brushing twice a day for at least two minutes using the Bass method had a positive effect on the dental plaque and gingival index. Further research is required to investigate the relationships between property physical bristle and clinical intraoral indices to clarify the replacement duration of manual toothbrushes. CLINICAL SIGNIFICANCE: The findings of this study could guide people's daily self-brushing habits, thereby aiding the prevention of periodontal disease. Moreover, our findings suggest the need for strategic clinical trial designs to verify the ideal timing to replace manual toothbrushes.

Effectiveness of e-learning to promote oral health education: A systematic review and meta-analysis.

BACKGROUND: In recent times during and after the COVID-19 pandemic, e-learning is increasingly being used to give oral health education. However, the efficacy of e-learning in improving and promoting the oral hygiene and oral health knowledge, attitude and practice is unclear. Therefore, this systematic review and meta-analysis aim to clarify the effectiveness of e-learning compared to other conventional education methods for providing oral health. METHODS: An electronic database search was performed on PubMed-Medline, Scopus, and CENTRAL (Central Register Cochrane of Controlled trials). Randomized controlled trials (RCTs), including cluster or group RCTs, were collected in this study. The risk of bias was assessed with the Cochrane Handbook for Systematic Reviews of Interventions. Five different meta-analyses were conducted for plaque index, gingival index, oral health knowledge, oral health attitude, and oral health practice using a random effects model. RESULTS: A total of 282 articles were found through the database search; 19 articles were included in the qualitative synthesis and 9 articles in the quantitative synthesis. The meta-analysis found that compared with conventional education, e-learning exhibited no positive effect. However, the use of e-learning was superior to conventional education methods for oral health practice for adults in subgroup analysis. CONCLUSIONS: This paper could not indicate the effectiveness of e-learning in comparison with conventional education for oral health in total. However, for adults, it may be effective to get the oral health practice compared to the conventional education. Our study limitation is that there are only few studies that have assessed the effectiveness of e-learning. Therefore, numerous further high-quality studies should be conducted regarding the efficacy of e-learning compared with conventional education methods for oral health promotion.

Development and evaluation of the "Toothbrushing Timer with Information on Toothbrushes" application: A prospective cohort pilot study.

OBJECTIVES: For people, it is challenging to be conscious of the appropriate toothbrushing time to maintain good oral health in daily life. The aim of this study was to preliminarily examine the utility of an application (app) that combines a toothbrushing timer and information on toothbrushes. MATERIALS AND METHODS: We developed the "Toothbrushing Timer with Information on Toothbrushes" app to help users ensure appropriate toothbrushing time and learn about the beneficial characteristics of toothbrushes. A total of 18 participants were registered for the study. At baseline (T0) and after 1 month (T1) of app usage, study participants answered a digital questionnaire that comprised three questions on oral health practice, self-efficacy in oral hygiene, and quality of life related to oral health (Oral Health Impact Profile-14 [OHIP-14]). RESULTS: Five participants were excluded from the analysis as they did not answer the digital questionnaire. Finally, 13 participants completed the survey with a follow-up of 1 month. The 13 participants were grouped into health professionals (n = 8) and non-health professionals (n = 5). The total scores for oral health practice and self-efficacy related to oral hygiene increased after a month of app usage in health professional and non-health professional groups. However, there were no significant differences between T0 and T1 in either group. The total score of OHIP-14 was lower at T1 than at T0 in both groups. Therefore, participants showed better oral health practice, self-efficacy in oral hygiene, and quality of life related to oral health at T1 compared with that at T0. CONCLUSIONS: Our app showed positive results for the users and is useful in maintaining and promoting oral health awareness and practice. However, our pilot study lacks sufficient power and did not yield significant differences. Therefore, high-quality clinical trials with larger sample sizes are warranted for further improvement and evaluation.

Associations between Oral Human Herpesvirus-6 and -7 and Periodontal Conditions in Older Adults.

BACKGROUND: The associations between oral human herpesvirus-6 (HHV-6) and HHV-7, periodontal conditions, and lifestyle-related diseases, such as hypertension, diabetes, and dyslipidemia, have not been fully investigated in older adults. METHODS: Seventy-four older patients who visited Hiroshima University Hospital were enrolled. Tongue swab samples were employed, and a real-time polymerase chain reaction was performed to detect HHV-6 and HHV-7 DNA. Dental plaque accumulation, probing pocket depth, and bleeding on probing (BOP) (i.e., a sign of periodontal inflammation) were examined. The periodontal inflamed surface area (PISA) value (i.e., an indicator of the severity of periodontitis) was also examined. RESULTS: Of the 74 participants, one participant (1.4%) was HHV-6 DNA-positive and 36 participants (48.6%) were HHV-7 DNA-positive. A significant association between HHV-7 DNA and probing depth was found (p = 0.04). The HHV-7 DNA-positive participants had a higher positive rate of a ≥6-mm periodontal pocket with BOP (25.0%) than the HHV-7 DNA-negative participants (7.9%). Additionally, the HHV-7 DNA-positive participants had a higher PISA value than the HHV-7 DNA-negative participants. However, there was no significant association between HHV-7 and the PISA value (p = 0.82). No significant association was found between HHV-7 and lifestyle-related diseases (p > 0.05). CONCLUSIONS: Oral HHV-7 infection is associated with a deep periodontal pocket.

Prevalence of oral Epstein-Barr virus and Porphyromonas gingivalis and their association with periodontal inflamed surface area: A cross-sectional study.

We previously reported that oral herpesviruses, such as Epstein-Barr virus (EBV), are associated with periodontitis. However, the relationship between oral EBV or dual oral EBV and Porphyromonas gingivalis infections and periodontal inflammation severity remains unclear. We conducted this study to determine the relationship between oral EBV and P gingivalis prevalence and the periodontal inflamed surface area (PISA) in middle-aged and older adults. We analyzed 205 patients (median age, 70 years) who visited Hiroshima University Hospital. Tongue swab samples were used to investigate the presence of EBV and P gingivalis DNA using real-time PCR. Probing pocket depth and bleeding on probing were measured at 6 sites per tooth. PISA scores were calculated based on the results of probing pocket depth and bleeding on probing. Propensity scores were calculated via logistic regression analysis of 8 clinical factors: age, sex, smoking status, remaining teeth, denture use, hypertension, diabetes, and hyperlipidemia. EBV DNA was present in 41 of the 205 participants (20.0%). Thirty-seven EBV-positive or -negative participants in 74 matched pairs after propensity-score matching were examined via univariate analysis. EBV-positive participants exhibited higher plaque control record scores and PISAs than did EBV-negative participants. EBV DNA was significantly associated with plaque control record scores and PISA (both P = .04). Of the 205 participants, 111 were positive for P gingivalis (54.1%). Nineteen participants (9.3%) were infected with both oral EBV and P gingivalis. Logistic regression analysis revealed that dual infection with EBV and P gingivalis was significantly associated with diabetes (odds ratio = 3.37, 95% confidence interval: 1.13-10.1; P = .03). Oral EBV prevalence is associated with oral hygiene and the spread of inflamed periodontal tissue. Diabetes may be a risk factor for dual infection with oral EBV and P gingivalis.

Analysis of the Deflection, Bristle Splaying, and Abrasion of a Single Tuft of a Polybutylene Terephthalate Toothbrush after Use: A Randomized Controlled Trial.

The aim of this study is to clarify the deflection, splaying, and abrasion of single tufts of polybutylene terephthalate (PBT) toothbrushes after use. A single-center randomized controlled trial is performed. The changes in deflection, bristle splaying, and abrasion are investigated for the middle single tuft of the top line (top-middle tuft) and the middle single tuft of the bottom line (bottom-middle tuft) of PBT toothbrushes with medium stiffness after 1 month, 2 months, and 3 months of use by 34 participants. A soft-material bending-resistance tester is used to assess the deflection of the single tufts. The deflection value of the top-middle tuft significantly increased after 1 month of use compared with the baseline. In contrast, the deflection of the bottom-middle tuft significantly increased after 3 months of use compared with the baseline and after 1 month and 2 months of use. Importantly, the change in deflection was distinctly different between the top- and bottom-middle tufts. The bristle splaying of both tufts significantly increased after use, but a significant change in bristle abrasion was not found. The bending stiffness of the top tuft of a PBT toothbrush may decrease more rapidly than that of the bottom tuft with use.

The Associations of Periodontopathic Bacteria and Oral Candida with Periodontal Inflamed Surface Area in Older Adults Receiving Supportive Periodontal Therapy.

The periodontal inflamed surface area (PISA) has been proposed for assessment of the total periodontal inflammatory status in people with periodontitis. This study was performed to investigate the associations of periodontopathic bacteria and candida with PISA in older people. We enrolled 100 patients aged ≥ 60 years who visited Hiroshima University Hospital. PISA and periodontal epithelial surface area (PESA) were calculated in each patient. Oral rinse samples were collected for DNA extraction. Periodontopathic bacteria and candida were detected by polymerase chain reaction. The mean values of PISA and PESA were significantly greater in T.forsythia-positive patients than in T.forsythia-negative patients. T.forsythia/C. albicans double-positive patients exhibited significantly greater PISA values than did non-double-positive patients. Additionally, PISA values were significantly greater in T. forsythia//T. denticola/C. albicans triple-positive patients than in T. forsythia//T. denticola/C. albicans non-triple-positive patients (p = 0.02). Propensity score-matching was performed between periodontopathic bacteria-positive and -negative patients using propensity scores generated from clinical factors. Importantly, T.forsythia/T. denticola double-positive patients exhibited significantly greater PISA values than non-double-positive patients among 72 propensity score-matched patients. Our preliminary results highlight the importance of the presence of T.forsythia and T. denticola for periodontal inflammation severity in older Japanese people.

Changes in Physical and Oral Function after a Long-Term Care Prevention Program in Community-Dwelling Japanese Older Adults: A 12-Month Follow-Up Study.

BACKGROUND: The aim of this prospective cohort study was to clarify changes in physical and oral function in older adults after completing a 3-month health program combining physical and oral exercise, oral health instruction, and nutritional guidance. METHODS: Subjects were 34 women aged at least 70 years (mean age 79.2 years) in Bungotakada City, Oita Prefecture, Japan. Physical and oral function was investigated on the first day (baseline), at the end of the program, and 6 and 12 months after completing the health program. Physical function was measured using handgrip strength test, timed up and go (TUG) test and one-leg standing time test. Oral diadochokinesis test and repetitive saliva swallowing test (RSST) were employed to assess oral function. RESULTS: TUG scores were significantly lower at 6 and 12 months than at baseline in participants aged ≥70 and <80 years. The repetition rate of the monosyllables /pa/, /ta/, and /ka/ was improved at the end of program in participants aged ≥70 and <80 years and increased to more than 6 times/second at 12 months. CONCLUSIONS: Our 3-month health program maintained improvements in oral and physical function in older women 1 year after completing the program.

Association of oral Epstein-Barr virus with periodontal health in Japanese adults.

Previous studies have demonstrated that oral Epstein-Barr virus (EBV) is associated with periodontitis. However, the relationship between periodontitis and oral EBV has not been fully elucidated by reducing the effects of confounding factors. The aim of the present study was to clarify the association between oral Epstein-Barr virus (EBV) and oral health status among middle-aged and older Japanese individuals. A total of 124 patients (46 males and 78 females; mean age, 69.2 years; age range, 35-90 years) who visited Hiroshima University Hospital between October 2018 and December 2019 were recruited into the present study. EBV DNA positivity was determined in 124 oral rinse samples using quantitative PCR. Periodontal disease-related bacteria were also detected by PCR analysis. EBV DNA was determined as positive in 16 of the 124 enrolled patients (12.9%). No significant difference was identified between EBV DNA and clinical factors (sex, age, remaining teeth, denture use, smoking or medical history). Of the 38 patients with periodontal pockets ≥6 mm, 10 were EBV DNA positive (26.3%). There was a significant association between EBV DNA positivity and probing depth (P=0.01). Additionally, a significant association was identified between bleeding on probing (BOP) and EBV DNA positivity (P=0.03). To investigate the relationship between EBV and periodontal health status, propensity score-matching was determined between participants without ≥4 mm periodontal pockets and BOP (participants with good periodontal health) and those with ≥4 mm periodontal pockets, BOP or both (participants with poor periodontal health). A total of 35 matched pairs were identified among the patients. Patients with poor periodontal health exhibited a higher EBV DNA positivity rate (25.7%) than those with good periodontal health (0.0%). Additionally, there was a significant association between EBV DNA positivity and periodontal health status (P=0.001). T. denticola-positive participants exhibited a higher EBV DNA positivity rate than negative participants (17.6 vs. 9.6%). However, there was no significant difference. The results indicated that oral EBV may be markedly associated with periodontitis in middle-aged and older Japanese individuals.

Relationship between the prevalence of oral human papillomavirus DNA and periodontal disease (Review).

Human papillomavirus (HPV) is a small DNA virus that infects the basal keratinocytes of squamous epithelium in the skin, and in the oral and genital mucosa. Smoking and sexual behavior have been recognized as significant risk factors for oral HPV infection. In the present review, the findings of recent studies of oral HPV infection in relation to periodontitis are discussed, as well as periodontopathic bacteria and periodontal herpes virus. Previous research suggests that HPV localizes to the inflammatory periodontal tissue. Inflammatory periodontal pockets may thus act as a reservoir for HPV. The interactions between HPV and periodontopathic bacteria remain unclear, but it is hypothesized that oral HPV infection may be related to a characteristic oral microbiome. Smoking is associated with HPV and periodontitis, as smoking induces destruction of periodontal tissue and suppresses the host defense, allowing HPV to infect periodontal tissue. Carcinogenic HPV and periodontitis may lead to the development of oral cavity cancer. However, oral HPV E6/E7 expression (transcriptionally active HPV) has not yet been fully investigated in patients with periodontitis. Collectively, the evidence suggests that oral HPV prevalence may be associated with periodontitis. The effect of clinical factors (age, sex, smoking, immunosuppressive condition and vaccination) on oral HPV DNA prevalence should be considered when clarifying the relationship between oral HPV and periodontitis. Additionally, the sampling method should be carefully chosen to directly detect HPV DNA in periodontal tissues.

Age-related changes in oral tactile and thermal sensation throughout adulthood.

Although the life expectancy of women is over 80 years in many countries, oral sensation has scarcely been compared between adults ≥ 80 years and younger age groups. The purpose of this study was to clarify age-related changes in oral sensation throughout adulthood. After exclusion of individuals with factors that might have confounded somatosensory performance, 123 female participants were divided into four age groups: 20-39 years, 40-59 years, 60-79 years, and 80-96 years. Perceptions of tactile and thermal sensations were examined at points on the anterior and posterior palate, anterior and posterior tongue, lower labial-attached gingiva, lower lip, and buccal mucosa; two-point discrimination was examined only on the tongue. The tactile and two-point discrimination thresholds for the anterior and posterior tongue were significantly higher in the 80-96-year-old group than in any other age group (p < 0.05). The tactile threshold for the buccal mucosa was significantly higher in the 80-96-year-old group than in the 60-79-year-old group (p < 0.05). The percentage of participants able to perceive a warm stimulus (50 °C) in the buccal mucosa was significantly lower in the 80-96-year-old group than in the 20-39-year-old group (p < 0.05). Only the topography of the warm sensation perception changed with age. This cross-sectional study suggests that oral tactile and thermal sensation for warm stimuli deteriorates with age in a site-specific manner, especially after the age of 80 years, but the same does not occur with cool stimuli.

Association of oral HPV16 infection with periodontal inflammation and the oral microbiome in older women.

The present preliminary study aimed to investigate the association between oral human papillomavirus type 16 (HPV16) DNA prevalence and periodontal inflammation in older women. The association between oral HPV16 infection and oral health status has not been fully elucidated in older Japanese women. The present study investigated older women aged ≥60 years who visited Hiroshima University Hospital. The present study excluded subjects with clinical factors affecting HPV infection, such as current smoking, oral cancer and pre-malignant lesions, and immunodeficiency. Finally, 46 female patients (mean age, 74.6 years) were analyzed. Quantitative PCR analysis was performed to detect HPV16 DNA in oral rinse samples. A total of 4 participants (8.7%) were HPV16 DNA positive. There was a significant association between the HPV16 DNA positivity rate and bleeding on probing (P=0.03). Additionally, Prevotella intermedia positive cases exhibited a significantly higher HPV16 DNA positivity rate than negative cases (33.3 vs 3.8%). Furthermore, analysis of 16S ribosomal RNA in bacterial flora was performed to examine microbiome diversity in participants with ≥6 mm periodontal pockets and bleeding on probing. Importantly, the average percentage of Porphyromonas was significantly higher in HPV16 DNA positive cases compared with in HPV16 DNA negative cases (5.57 vs. 1.44%). By contrast, the average percentage of Veillonella was significantly lower in HPV16 DNA positive cases than in HPV16 DNA negative cases (2.43 vs. 8.51%). Prevotella was also lower in HPV16 DNA positive cases than in HPV16 DNA negative cases (4.0 vs. 8.23%). These results indicated that people with both deep periodontal pocket inflammation and oral HPV16 infection may not have Prevotella- or Veillonella-dominant oral microbiomes, and their microbiomes may exhibit their own distinctive characteristics. In conclusion, the results suggested that oral HPV16 infection may be associated with periodontal inflammation in older Japanese women. Further research is required to clarify the detailed association between oral HPV infection and the oral microbiome.

Relationship between oral and physical function and length of participation in long-term care prevention programs in community-dwelling older Japanese women.

PURPOSE: The present study aimed to clarify the relationship between community-dwelling older women's participation period in community-based exercise programs and their oral and physical functioning. METHODS: From May to September 2019, we recruited 205 older women (mean age: 77.6 ± 5.5 years) who had joined weekly long-term care prevention programs such as community-based exercise programs that included oral and physical exercises, in Hiroshima Prefecture, Japan. Physical function was evaluated using a handgrip strength test, a Timed Up & Go test, a one-leg standing test, and a 30-s chair stand test. Tongue pressure, oral diadochokinesis, and Dysphagia Risk Assessment for the Community-dwelling Elderly were measured to evaluate oral functioning. After adjusting for clinical factors (i.e., age, BMI, hypertension, diabetes, stroke, heart disease, joint disease, osteoporosis, remaining teeth, denture use, oral wetness, history of dental examinations in the last year, use of interdental brush and/or dental floss), we compared the oral and physical function parameters of participants from varying program engagement periods using propensity score matching. RESULTS: A significant increase in mean handgrip strength was found in people who had been participating for ≥ 5 years compared with those who had been participating for < 5 years (p = 0.01). Furthermore, repetition of the monosyllable/ka/was significantly greater for people in the ≥ 5 years group compared with those in the < 5 years group (p = 0.03). CONCLUSION: Long-term participation in an exercise program is positively associated with handgrip strength and tongue motor function in independent older women.

TGF-ß1 induces amoeboid-to-mesenchymal transition of CD44high oral squamous cell carcinoma cells via miR-422a downregulation through ERK activation and Cofilin-1 phosphorylation.

BACKGROUND: The objective of this study was to clarify the molecular mechanism of amoeboid-to-mesenchymal transition (AMT) of CD44high oral squamous cell carcinoma (OSCC) cells. METHODS: Morphology and expression of mesenchymal genes were investigated in CD44high OSCC cells (CD44high OM-1 cells) cultured on laminin-coated soft silicone gel. Additionally, microarray analysis was performed to investigate microRNA (miRNA) expression inhibited by transforming growth factor-ß1 (TGF-ß1) in CD44high OM-1 cells. RESULTS: When CD44high OM-1 cells were cultured on 2.0-kPa laminin-coated silicone gel, the cells exhibited an amoeboid-like round morphology. Cofilin-1 expression was found in the nucleus and cytoplasm of amoeboid-like CD44high OM-1 cells. The invasive capacity was significantly reduced after Cofilin-1 knockdown. Additionally, Cofilin-1 knockdown cells had an irregularly extended shape. Phosphorylated Cofilin-1 was significantly upregulated by TGF-ß1. Additionally, TGF-ß1 enhanced N-cadherin and Snail mRNA expression and induced a spindle-shaped morphology. ERK1/2 phosphorylation was induced by TGF-ß1. Microarray analysis revealed that miR-422a exhibited the greatest downregulation (fold change: 0.22) in the presence of TGF-ß1. Importantly, TGF-ß1-inhibited miR-422a expression was recovered by the ERK inhibitor or ERK1/2 knockdown. Additionally, miR-422a inhibitor-transfected CD44high OM-1 cells exhibited high N-cadherin and Snail mRNA expression. Furthermore, Cofilin-1 knockdown and miR-422a inhibition induced a spindle cell morphology. CONCLUSION: Cofilin-1 is involved in the invasive ability of CD44high OSCC cells. TGF-ß1 contributes to AMT by downregulation of miR-422a via ERK activation and Cofilin-1 phosphorylation. Our findings suggest that miR-422a and Cofilin-1 play major roles in the maintenance of amoeboid-like CD44high cells.

Oral human cytomegalovirus prevalence and its relationships with periodontitis and Porphyromonas gingivalis in Japanese adults: a cross-sectional study.

OBJECTIVE: This study aimed to clarify the association between oral human cytomegalovirus (HCMV) and periodontitis in Japanese adults. METHODOLOGY: In total, 190 patients (75 men and 115 women; mean age, 70.2 years) who visited Hiroshima University Hospital between March 2018 and May 2020 were included. Oral rinse samples were taken to examine the presence of HCMV DNA using real-time polymerase chain reaction (PCR). P. gingivalis was detected by semi-quantitative PCR analysis. RESULTS: HCMV DNA was present in nine of 190 patients (4.7%). There were significant associations between HCMV presence and the presence of ≥4-mm-deep periodontal pockets with bleeding on probing (BOP) (P<0.01) and ≥6-mm-deep periodontal pockets with BOP (P=0.01). However, no significant relationship was observed between HCMV presence and periodontal epithelial surface area scores. Logistic regression analysis revealed that the presence of ≥4-mm-deep periodontal pockets with BOP was significantly associated with HCMV (odds ratio, 14.4; P=0.01). Propensity score matching was performed between patients presenting ≥4-mm-deep periodontal pockets with BOP (i.e., active periodontitis) and patients without ≥4-mm-deep periodontal pockets with BOP; 62 matched pairs were generated. Patients who had ≥4-mm-deep periodontal pockets with BOP showed a higher rate of HCMV presence (9.7%) than those who lacked ≥4-mm-deep periodontal pockets with BOP (0.0%). There was a significant relationship between HCMV presence and ≥4-mm-deep periodontal pockets with BOP (P=0.03). A significant relationship was found between HCMV/P. gingivalis DNA presence and ≥4-mm-deep periodontal pockets with BOP (P=0.03). CONCLUSIONS: Coinfection of oral HCMV and P. gingivalis was significantly associated with active periodontitis. Moreover, interactions between oral HCMV and P. gingivalis may be related to the severity of periodontal disease.

Changes in the Bristle Stiffness of Polybutylene Terephthalate Manual Toothbrushes over 3 Months: A Randomized Controlled Trial.

We previously reported that polybutylene terephthalate (PBT) toothbrushes become less effective for plaque removal after two months of use. However, it remains unknown how the bristle stiffness of PBT toothbrushes changes after several months of use. We performed a single-center randomized controlled trial to evaluate the bristle stiffness and bristle splaying of soft and medium manual toothbrushes among dental and medical students of Hiroshima University. Subjects were 80 participants who met the criteria. Participants were randomly assigned to the soft toothbrush group (n = 40) or the medium toothbrush group (n = 40). We collected toothbrushes immediately after first use (T0), after one month of use (T1), after two months of use (T2), and after three months of use (T3). Bristle stiffness was measured according to the International Organization for Standardization (ISO) 22254. The mean bristle stiffness (N/cm2) of soft and medium toothbrushes was significantly lower at T2 and T3 than at T0 (T2 vs. T0, soft; 3.63 vs. 3.89, P < 0.01 and medium; 4.33 vs. 4.52, P < 0.05, respectively, and T3 vs. T0, 3.62 vs. 3.89, p < 0.01 and 4.18 vs. 4.52, p < 0.001, respectively). Bristle stiffness was significantly reduced in soft and medium PBT toothbrushes after two months of use.

Association of physical performance with oral function in older women participating in community-based health exercise programs.

OBJECTIVES: This study aimed to clarify the relationship between physical performance and oral function in older women participating in community-based physical and oral exercise programs. MATERIAL AND METHODS: We included 163 older women (mean age: 77.4 ± 8.6 years) who participated in weekly health programs in Takehara City, Hiroshima Prefecture, Japan, from August to December 2018. Physical fitness was assessed using a handgrip strength test, a timed up and go test, a one-leg standing time with eyes open test, and a 30-s chair stand test (CS-30). Tongue pressure, oral diadochokinesis, and dysphagia risk assessment for the community-dwelling elderly were used to assess oral function. RESULTS: Participants were divided into women aged 65-74 years (younger group) and those aged ≥75 years (older group). There was no significant difference in oral function measures between the groups. A significant correlation was found between CS-30 and oral diadochokinesis for /pa/, /ta/, and /ka/ (Spearman's rank correlation; /pa/: r = .234, p = .009; /ta/: r = .299, p = .001; and /ka/: r = .283, p = .002) in the older group. Multivariable analysis revealed a significant positive relationship between CS-30 and /ta/ repetition in the older group (p = .016). CONCLUSIONS: Oral function (i.e., tongue motor function) may be associated with physical performance (i.e., lower leg muscle strength) in women aged ≥75 years. Further study is necessary to clarify sex differences in oral function deterioration.

Rational extended thermodynamics of dense polyatomic gases incorporating molecular rotation and vibration.

The paper aims to construct a rational extended thermodynamics (RET) theory of dense polyatomic gases by taking into account the experimental evidence that the relaxation time of molecular rotation and that of molecular vibration are quite different from each other. For simplicity, we focus on gases with only one dissipative process due to bulk viscosity. In fact, in some polyatomic gases, the effect of bulk viscosity is much larger than that of shear viscosity and heat conductivity. The present theory includes the previous RET theory of dense gases with six fields as a particular case, and it also includes the RET theory of rarefied polyatomic gases with seven fields in the rarefied-gas limit. The closure is carried out by using the universal principles, that is, Galilean invariance and objectivity, entropy principle, and thermodynamic stability (convexity of entropy), where the duality principle connecting rarefied gases to dense gases also plays an important role. A detailed discussion is devoted to the expression of the production terms in the system of balance equations. As typical examples, we study a gas with virial equations of state and a van der Waals gas. Lastly the dispersion relation of a linear wave is derived, and its comparison with experimental data is made. This article is part of the theme issue 'Fundamental aspects of nonequilibrium thermodynamics'.

High Rate of Oral Candida Detection in Dependent Japanese Older People.

The aim of this study was to clarify the association between oral Candida detection and the dependency status of older people. This study included 31 older people aged ≥70 years who had a certified need for long-term care or support and received care in a local day care center; it also included 27 independent older patients aged ≥70 years who visited Hiroshima University Hospital. Oral Candida was detected by a polymerase chain reaction using swab samples from the tongue surface. Oral moisture was significantly reduced in dependent older people, compared with independent older people (p = 0.003). There was a weak negative relationship between numbers of bacteria and levels of oral moisture (Spearman's rank correlation coefficient; R = -0.29, p = 0.01). Dependent older people exhibited a significantly higher rate of Candida albicans detection (35.5%) compared with independent older people (11.1%). Dependent older people also exhibited a higher rate of concurrent detection of both C. albicans and Candida glabrata (32.3%) compared with independent older people (11.1%), but this difference was not statistically significant. Thus, dependent older people may be more susceptible to oral C. albicans infection, compared with independent older people. Good oral hygiene is necessary to prevent oral Candida infection in dependent older people.

Bone Regeneration in a Canine Model of Artificial Jaw Cleft Using Bone Marrow-Derived Mesenchymal Stem Cells and Carbonate Hydroxyapatite Carrier.

OBJECTIVE: Cleft lip and palate (CLP) is a common anomaly of the orofacial region. Mesenchymal stem cell (MSC) transplantation has been a focus of regenerative medicine, and its application to the repair of bone defects in patients with CLP is highly anticipated. This study investigated the potential for using MSCs to regenerate bone in a jaw cleft as well as the survival of transplanted MSCs using a canine model of CLP. DESIGN: Mesenchymal stem cells collected from the bone marrow of beagle dogs were transplanted along with carbonate hydroxyapatite into jaw clefts in beagle dogs. Mesenchymal stem cells labeled with fluorescent silica nanoparticles were also transplanted, and a histological analysis was performed 3 months later to evaluate MSC survival. RESULTS: Carbonate hydroxyapatite regeneration into bone was enhanced by cotransplantation of MSCs. The survival rate of MSCs transplanted after 3 months was 5.7%. CONCLUSIONS: Transplanted MSCs promote bone regeneration, although their survival rate is low.