BACKGROUND:Lidocaine hydrochloride (LDCA) is one of the medications used to treat burning mouth syndrome (BMS). The purpose of this study is to investigate whether benzocaine (BEN) can also be used for the treatment and examination of BMS. This study used quantitative sensory testing to investigate the effects of two surface anesthetics on the sensory function of the tongue tip. METHODS:Thirty healthy women participated in this study. All participants completed a single-blind, randomized crossover study. Surface anesthetics- (2%LDCA, 20%BEN) and vaseline (control) were applied to the tongue tip. The experiment was conducted over three days, with each drug applied on a different day in a randomized order. The mechanical detection threshold (MDT), mechanical pain threshold (MPT), and numerical rating scale (NRS) were measured at the following points: before application of the drug (pre), immediately, at 5, 15, 30, and 60 minutes after application of the drug. RESULTS:MDT immediately (P < 0.01), at 5 (P < 0.01) and 15 (2%LDCA: P = 0.0112, 20%BEN: P = 0.0128) minutes after application of the drug were significantly higher than pre-values in both local anesthetic sessions. MPT immediately (P < 0.01), at 5 (P < 0.01), 15 (P < 0.01), and 30 (P = 0.0026) minutes after application of 2%LDCA was significantly higher than pre-values. MPT immediately (P < 0.01), at 5 (P < 0.01) and 15 (P = 0.0057) minutes after application of 20%BEN was significantly higher than pre-values. NRS scores did not differ significantly between measurement periods or between drugs. CONCLUSIONS:This study suggested that 2%LDCA and 20%BEN may have comparable anesthetic effects on the sensory function of the healthy tongue tip.

Objectives:To estimate the impact of explicit fluoride-related language in prefectural dental health ordinance on the dissemination of school-based fluoride mouth-rinse (S-FMR) programs. Methods:A longitudinal ecological design was employed to analyze prefectural-level panel data from Japan spanning 2007 to 2018. Ordinances enacted between 2010 and 2014 were categorized by the presence of explicit fluoride-related terms: 1) explicit mention of "fluoride mouth-rinse" (FMR group); 2) explicit mention of "fluoride application" (FA group); and 3) no fluoride-related policy language (NF group). The outcome was the proportion of children aged 4-15 years participating in S-FMR programs. Total prefectural income per year, prefectural mean age, and prefectural mean number of decayed, missing, or filled primary teeth (dmft) among 3-year-old children were included as covariates. The Callaway and Sant'Anna Difference-in-Differences (CSDID) method was applied to estimate the average treatment effects on the treated (ATT) for the FMR and FA groups under a conditional parallel trends assumption. Results:A total of 39 prefectures were analyzed. The pre-post increase in S-FMR participation was greater in the FMR group than in the FA or NF groups, with comparable differences (FMR: 12%; FA and NF: 5% each). In the CSDID analysis, both the FMR and FA groups showed a significant increase in S-FMR participation compared with the NF group, with a larger effect in the FMR group [FMR: 8% (95% CI: 2%-15%); FA: 5% (95% CI: 0%-9%)]. The event-study estimates indicated that the effects strengthened over time, particularly in the FMR group. Conclusions:Prefectural dental health ordinances explicitly refer to fluoride, particularly FMR, are associated with a greater dissemination of the proportion of children participating in S-FMR programs. These findings suggest that more specific and explicit policy language in dental health ordinances may enhance the dissemination of S-FMR programs.

AIM:Poor oral hygiene during pregnancy is associated with pre-term birth, low birth weight, and pregnancy-induced hypertension, suggesting its significant effects on both maternal and fetal health. However, global guidelines indicate that oral care during pregnancy remains an underdeveloped field, and no large-scale reports on dental studies conducted during pregnancy exist in Japan. Therefore, we assessed the key factors that contribute to maintaining oral health during pregnancy in a cohort of Japanese women. METHODS:We conducted dental examinations on 907 pregnant women in Matsudo City, Japan, and investigated the key factors for maintaining 379 women (41.7%) had untreated cavities. An increase in the frequency of toothbrushing was associated with a higher number of treated teeth (r=0.315, p < 0.001). However, periodontal disease-related factors such as gingival bleeding (71.2%) and the condition of periodontal pockets showed little correlation with brushing frequency(r=-0.139, p > 0.05 for untreated teeth and brushing frequency). CONCLUSIONS:While brushing teeth three times a day, including during pregnancy, is ideal, attention should also be directed to other aspects, such as brushing technique and thoroughness, which may require further consideration. This report serves as a foundation for obstetricians and dentists to recognize the importance of oral hygiene management during pregnancy and advocate for dental checkups during pregnancy, providing valuable opportunities to increase awareness regarding this issue.

Phenytoin (PHT)-induced gingival overgrowth is caused by the increased proliferation and reduced apoptosis of gingival fibroblasts in inflammatory gingiva. Licorice has long been used as a component of therapeutic preparations. It inhibits cell proliferation, induces cell apoptosis and has anti-inflammatory effects. 18-alpha-glycyrrhetinic acid (18 alpha-GA), the active compound in licorice, promotes apoptosis in various types of cells. The present study determined whether 18 alpha-GA affects apoptosis in gingival fibroblasts exposed to PHT. The present study aimed to establish a basis for the therapeutic application of 18 alpha-GA to treat the gingival overgrowth induced by PHT. Human gingival fibroblasts from healthy donors were cultured to semi-confluence and then stimulated in serum-free DMEM containing PHT with or without 18 alpha-GA for subsequent experiments. Apoptotic cells were detected by ELISA. Analysis of the distribution of cell cycle phases and the apoptotic cell population was performed by flow cytometry. The expression levels of mRNAs and proteins of apoptotic regulators were measured using reverse transcription-quantitative PCR and western blotting, respectively. Caspase (CASP) activities were assessed by an ELISA. Treatment with 18 alpha-GA markedly increased the number of apoptotic cells, reduced BCL2 mRNA expression, increased CASP2 and receptor (TNFRSF)-interacting serine-threonine kinase 1 (RIPK1) domain containing adaptor with death domain, Fas (TNFRSF6)-associated via death domain, RIPK1, tumor necrosis factor receptor superfamily; member 1A, TNF receptor-associated factor 2, CASP2, CASP3 and CASP9 mRNA expression, and also upregulated the protein expression levels and activities of caspase-2, caspase-3 and caspase-9. These results demonstrated that 18 alpha-GA induced apoptosis through the activation of the Fas and TNF pathways in the death receptor signaling pathway in gingival fibroblasts treated with PHT. 18 alpha-GA exhibited therapeutic potential for the treatment of PHT-induced gingival overgrowth.

Gingival overgrowth caused by cyclosporine A is due to increased fibroblast proliferation in gingival tissues. Cell cycle system balances proliferation and anti-proliferation of gingival fibroblasts and plays a role in the maintenance of its population in gingival tissues. When cells detect and respond to abnormalities (e.g. DNA damage), cell cycle progression is arrested in the G1 phase until the completion of damage restoration. In this study, we investigated the effects of cyclosporine A on G1 cell cycle arrest and on its regulators in gingival fibroblasts to clarify the mechanism of cyclosporine A-induced gingival overgrowth. Human gingival fibroblasts from healthy donors were cultured to semi-confluence and were then treated with or without 200 ng/mL (166 nM) cyclosporine A in D-MEM with 2% fetal bovine serum. Cell proliferation was assessed by counting total cell numbers. The distribution of cell cycle phases was assessed using flow cytometric analysis. The levels of mRNA and protein expression for cell cycle regulators were quantified using reverse transcription-quantitative PCR and western blot analysis, respectively. Treatment with cyclosporine A markedly increased cell proliferation, inhibited G1 cell cycle arrest, significantly increased CDC25A and CYCLIN E1 mRNA expression levels, significantly decreased P21, SMAD3 and SMAD4 mRNA expression levels, significantly upregulated the protein expression levels of CDC25A, CYCLIN E1, pCDK2 and pRB1 and significantly downregulated the protein expression levels of P21, SMAD3 and SMAD4. Treatment with cyclosporine A also increased MYC and ATM mRNA expression levels and decreased CDK2, ATR, P27, P53 and RB1 mRNA expression levels but not significantly. These results demonstrate that cyclosporine A causes gingival overgrowth due to the following mechanism in gingival fibroblasts: cyclosporine A increases levels of phospho-CDK2 and CYCLIN E1 by upregulating CDC25A and downregulating P21 with the downregulation of SMAD3 and SMAD4, which results in the inhibition of G1 cell cycle arrest.

Objectives: Cyclosporine A promotes gingival fibrosis by enhancing the proliferation of gingival fibroblasts, leading to gingival overgrowth. The population of gingival fibroblasts is regulated by cell cycle machinery, which balances cell growth and inhibition. Cells that detect DNA damage pause at the G1/S checkpoint to repair the damage instead of progressing to the S phase. Previous studies have linked drug-induced gingival overgrowth to the response of fibroblasts to lipopolysaccharide (LPS) and cyclosporine A. This research investigates the effects of cyclosporine A on the G1/S checkpoint and its mediators in LPS-treated gingival fibroblasts to clarify the mechanisms behind cyclosporine-A-induced gingival overgrowth. Methods: Semi-confluent human gingival fibroblasts were treated with LPS or cyclosporine A in DMEM. Cell proliferation was evaluated by counting the total number of cells. The distribution of the cell cycle phases was analyzed using flow cytometry. Additionally, the expression levels of mRNAs and proteins related to cell cycle regulators were quantified by reverse-transcription quantitative PCR and Western blotting, respectively. Results: Cyclosporine A treatment significantly enhanced cell proliferation and the G1-S cell cycle transition. It increased the mRNA levels of CDC25A and CYCLIN D while decreasing those of RB1, SMAD3, and SMAD4. Additionally, it upregulated the protein levels of CDC25A, CYCLIN D, CDK4, CDK6, and pRB and downregulated the protein levels of SMAD3 and SMAD4. Conclusions: Gingival overgrowth induced by cyclosporine A could be attributed to these alterations.

A decrease in oral function is a risk factor for aspiration pneumonia and suffocation, leading to a reduction in physical function and malnutrition at elderly people.. Therefore, there is a need to develop a simple method to improve oral function in older adults, including those requiring long-term care. This study aimed to elucidate the effects of chewing gum mastication training and habitation on the oral environment, eating habits of residents and users of the elderly facility. Subjects were randomly assigned to two groups, the intervention and control groups. The intervention group consisted of 28 subjects（80.0［74.0-87.0］years）who chewed gum for 2 minutes three times daily for 2 months and the control group consisted of 26 subjects（88.0［82.5-94.0］years. Oral examination, oral function, physical condition, dietary habits questionnaire, and caregiver’s Vitality Index（VI）were evaluated. As a result, intra-group comparisons before, during, and after the intervention showed significant differences in gum mastication ability（p = 0.004）, appetite related to diet（p = 0.026）, looking forward to eating（p = 0.011）, and VI（p = 0.047）in the gum mastication group. In addition, gum mastication ability（p = 0.018）and appetite（p = 0.003）marked significant differences in changes before and after the intervention for the two groups. Furthermore, logistic regression analysis also revealed the impact of the intervention by gum mastication. It was shown that the simple intervention of chewing gum mastication used here might lead to improved oral function, increased interest of the elderly in diet and food, and increased motivation.

Brushing with a toothbrush is effective for removing oral biofilms. However, toothbrushes can be a source of infectious diseases after use. Recently, the environmental impacts of plastics, such as marine pollution, have become an issue. This includes the disposal of plastic toothbrushes. Consequently, bamboo toothbrushes, with a low environmental impact, have become widely-used as alternatives. Although there are many reports on the hygiene of plastic toothbrushes after use, there are few reports on bamboo toothbrushes. Thus, we compared the hygiene of bamboo toothbrushes with those of plastic and biomass plastic toothbrushes after use and storage. Three types of toothbrushes were immersed in bacterial cultures and washed, and the number of bacteria on the toothbrushes after 12 and 24 h of storage was examined. The number of bacteria on the bamboo toothbrushes immediately after immersion was significantly higher than on the other two types, but this number was 95–99％ lower after 12–24 h of storage. No differences were observed for different bacterial species（Actinomyces oris and Streptococcus mutans）or different storage conditions（wet and dry）. However, pre-wetting before immersion significantly reduced the number of bacteria on the bamboo toothbrushes. These results indicate that the hygienic conditions of bamboo toothbrushes after 12–24 h of storage were comparable to those of plastic or biomass toothbrushes. Furthermore, pre-wetting the bamboo toothbrushes before use improved hygiene immediately after use. Bamboo toothbrushes are a better choice as they provide equivalent hygiene to that of plastic toothbrushes and also have a low environmental impact.

Background: Human beta-defensins (HBDs), epithelial-derived antimicrobial peptides, contribute to gingival health and periodontal disease. Particularly, the upregulation of HBD-3 expression in periodontal tissues is described to contribute to periodontal tissue regeneration. Specifically, the upregulation of HBD-3 expression in periodontal tissues is described to contribute to periodontal tissue regeneration. But there has been insufficient investigation of the inner epithelium in peri-implantitis, especially the HBD expression patterns as protection against oral infection. Objectives: The purpose of this study was to investigate the histopathological characteristics of the inner implant epithelium in peri-implantitis using histopathological and immunohistochemical methods and to compare it with the inner marginal epithelium in periodontitis. Materials and Methods: The biopsied cases consisted of 10 peri-implantitis, 11 periodontitis, and 10 controls. HE observation, measurement of the thickness of the inner epithelium, and immunohistochemical analysis for Ki-67 and HBD-3 were conducted. Results: Concerning the thickness of the inner epithelium, it was significantly higher in periodontitis (156.2 [138.0, 186.4] μm) than in peri-implantitis and control, 70.7 [67.5, 97.5] μm and 80.7 [76.6, 89.4] μm, respectively (p < 0.001). The Ki-67 positivity rates, both for inner epithelium and outer epithelium, were significantly higher in the following order: periodontitis, peri-implantitis, and control (p < 0.001). The inner epithelium is significantly elevated in the case of periodontitis (p < 0.001). For HBD-3, the intensity and region score (IRS) was significantly higher for inner epithelium than for outer epithelium (superficial layer) (p < 0.001) in all cases. The comparisons of IRS, significantly higher values were seen in inner epithelium of periodontitis than that of peri-implantitis (p < 0.001). Conclusion: Decreased production of HBD-3 in keratinocytes composing the inner implant epithelium may be one of the factors affecting tissue repair in peri-implantitis.

This study investigated properties of the fabricated poly-lactide-co-ε-caprolactone PLCL50)with poly-lactic acid(PLA)and poly-ε-caprolactone(PCL)in an equal ratio and the fibronectin(FN)and albumin(Alb), immobilized PLCL films, to apply them for barrier membranes for reconstructive bone augmentation. FN is a cell adhesion protein, and Alb is a cell adhesion-inhibiting protein. The contact angle of PLCL50-COOH, FN-PLCL50, and Alb-PLCL50 surfaces with double distilled water significantly decreased than the PLCL50 surface in the evaluation using film surface wettability analysis. The presence of fibronectin and albumin on PLCL50 films was demonstrated by X-ray photoelectron spectroscopy analysis(XPS). The number of cells attached to FN-PLCL50 films was more significant than those attached to the Alb-PLCL50 and PLCL50 films after 90 min and 3 days of culture. On the other hand, immobilizing albumin on the PLCL50 surface resulted in a significant decrease in attached cells after 90 min and 3 days. The quantification of mineralization of osteoblast MC3T3-E1 cells on FN-PLCL50 films was significantly higher than that of Alb-PLCL50 and PLCL50 films after 7, 14 and 21 days in the results of alizarin red staining and mineralization assay. The morphological differences in the attached MC3T3-E1 cells on FN-PLCL50, Alb-PLCL50 and PLCL50 were imaged by scanning electron microscopy . After 90 min, 3 and 7 days of culture, the attached MC3T3-E1 cells on the FNPLCL50 films were more spread than those on the Alb-PLCL50 and PLCL50 films. These results suggested that fibronectin and albumin effectively performed biological activities on PLCL50 films of osteoblast-like cells.

The use of high-volume intra-oral suction（HVIOS）is effective in reducing droplets and aerosols during dental treatment. However, there are few reports on the effects of different uses of HVIOS on droplets and aerosols. We examined the differences in the generation of droplets and aerosols with HVIOS. The teeth were scaled and ground. The number of droplets and aerosols associated with different uses of HVIOS was evaluated by settle plate sampling, aerosol particle measurement, and high-speed camera photography. The number of bacterial colonies in front of the dentist was significantly reduced when a HVIOS was placed at the left side of the mouth compared to when it was not used. In tooth grinding, on the dental care workers’ side, the group in which HVIOS was not used had the largest preoperative and postoperative differences for all particle sizes, followed by those placed at the left side of the mouth and placed at the labial side of the maxillary anterior teeth. Photographic images did not show white foglike spreads in front of the dentist and near the dentist’s side compared to other usages. We suggest that HVIOS is effective when it is placed at the left side of the mouth to reduce large particles in front of and near the dentist during tooth scaling and to prevent exposure to dental care workers during cutting of the maxillary anterior tooth.

To determine the status of outpatients at the Dental Hospital of Nihon University School of Dentistry at Matsudo, we surveyed new patients examined in the Department of Operative Dentistry between April 1, 2019 and March 31, 2020. The following six items were extracted from the patients’ electronic dental records: referral（yes/no）, sex, age, residence, chief complaint, and site of chief complaint. Patients were subsequently divided into groups according to referral status for comparison of the other items. To identify factors associated with referrals, we performed logistic regression analysis with referral as the dependent variable and sex, address, age, chief complaint, and site as independent variables; odds ratios and 95% confidence intervals were calculated for each variable. Odds ratios were high for age, site, chief complaint, and sex and yielded the following conclusions concerning these variables. Regarding age, most patients in the referral group were in their 40s and 50s, while most patients in the non-referral group were in their 60s and 70s. The majority of new patients were female, while the percentage of male patients was slightly higher in the referral group than in the non-referral group. The most common sites were the molars in both groups. The most common chief complaints in the referral group and the non-referral group were apical periodontitis and class 2 caries, respectively. These results suggested that compared with the non-referral group, patients in the referral group were younger, were diagnosed earlier, and visited our hospital with greater expectation of dental preservation through high-quality treatment.

PURPOSEA water fluoridation program launched in the United States in 1945 has become a worldwide application for caries prevention. Although such a program is important in Japan, water fluoridation in large communities has not been established. This study aimed to develop safe small-scale water fluoride equipment that can be easily used to carry out water fluoridation programs in areas with children in long-term care facilities, and in developing countries without water supply facilities.METHODSBatch-type NaF addition adjustment equipment was manufactured as small-scale water fluoride equipment. The fluoride concentration of the adjusted water with this equipment was measured using an ion meter and a fluoride composite electrode. All 51 water quality standards set by the Ministry of Health, Labour, and Welfare of Japan were tested.RESULTSThe fluoride ion concentration of the adjusted water was 0.7 mg/L and it was constant and stable. The adjusted water conformed to the water quality standard values of the Japanese Water Supply Law.CONCLUSIONWater produced with small-scale water fluoridation equipment had a fluoride concentration of 0.7 mg/L, which is the recommended concentration for caries prevention. The fluoride concentration was stable.

Chieko Taguchi, Fuyuki Sato, Chen Wang, Shigeru Nakamura, Kosuke Oikawa, Ujjal Kumar Bhawal, Hiroyuki Okada, and Kazumune Arikawa. Oral Biol Res 2022;46:141-9. https://doi.org/10.21851/obr.46.04.202212.141

The incidence of phenytoininduced gingival overgrowth is the highest among drugs that induce gingival overgrowth.Histological analysis has demonstrated that phenytoininduced gingival overgrowth is characterized by increased fibroblast proliferation and collagen formation in the gingiva.Cell cycle regulation, which induces cellular proliferation and division or apoptosis, is important to maintain fibroblast homeostasis in tissues.We previously demonstrated that gingival overgrowth is caused by the effect of phenytoin treatment to inhibit G 1 cell cycle arrest in gingival fibroblasts.In this study, we investigated the role of phenytoin in the apoptosis of human gingival fibroblasts to clarify the mechanism of phenytoininduced gingival overgrowth.Human gingival fibroblasts were cultured in DMEM and were treated with or without 0.25 µM phenytoin for 21 days.The following assays were then performed: 1) determination of the percentage of viable and dead cells by trypan blue staining, 2) determination of the relative amounts of apoptotic cells by absorptiometry, 3) nuclear staining using Hoechst 33258 for histological observation of apoptotic cells, and 4) RT -PCR analysis of mRNA expression levels of cyclin D and cyclin E. The results show that treatment with phenytoin decreased the number of apoptotic cells compared with the control.Phenytoin also increased the percentage of viable cells and decreased the percentage of dead cells compared with the control, and increased the cyclin D mRNA expression level compared to the control.We conclude that phenytoininduced gingival overgrowth results from the combined effects of those mechanisms to inhibit apoptosis in gingival fibroblasts.

However, these membranes do not exhibit any biological function, such as bone adaptability or cell affinity.5) reported that immobilized fibronectin on a PLA surface facilitated cell attachment and proliferation upon NaOH surface hydrolysis and condensation reactions using watersoluble carbodiimide according to their Cai et al. (