Abstract Aim The outbreak of the new Coronavirus Disease 2019 (COVID‐19) has spread and caused a public healthcare crisis. The habit of toothbrushing is the critical and fundamental measure for controlling the oral health. There has been no report on whether tooth brushing habit is associated with a risk of severity of COVID‐19 infection. We examined the association between toothbrushing habits and the severity of COVID‐19 infections. Methods The cross‐sectional data were used from the Japan COVID‐19 and Society Internet Survey (JACSIS), a large‐scale Internet survey conducted in 2022 (n = 32 000). If the severity of COVID‐19 infection worsens, hospital treatment or the respiratory ventilator treatment may be required. We examined whether daily toothbrushing is a factor on the suppression of the exacerbation of COVID‐19 infection. Results From all participants, 4756 people were diagnosed with SARS‐CoV‐2 infection. Multivariable logistic regression analysis showed that toothbrushing habit was a significant factor related to the severity of COVID‐19 infection. Conclusion Daily toothbrushing is a very important factor for preventing the exacerbation of COVID‐19 infection.

Swallowing is induced by a central pattern generator in the nucleus tractus solitarius (NTS). We aimed to create a medullary slice preparation to elucidate the neural architecture of the central pattern generator of swallowing (Sw-CPG) and record its neural activities. Experiments were conducted on 2-day-old Sprague-Dawley rats (n = 46). The brainstem-spinal cord was transected at the pontomedullary and cervicothoracic junctions; the medulla was sliced transversely at thicknesses of 600, 700, or 800 μm. The rostral end of the slice was 100 μm rostral to the vagus nerve. We recorded hypoglossal nerve activity and electrically stimulated the vagus nerve or microinjected bicuculline methiodide (BIC) into the NTS. The 800-μm slices generated both rhythmic respiratory activity and electrically elicited neural activity. The 700-μm slices generated only respiratory activity, while the 600-μm slices did not generate any neural activity. BIC microinjection into the NTS in 800-μm slices resulted in the typical activity that closely resembled the swallowing activity reported in other experiments. This swallowing-like activity consistently lengthened the respiratory interval. Despite complete inhibition of respiratory activity, weak swallowing-like activity was observed under bath application of a non-NMDA receptor antagonist. Contrastingly, bath application of NMDA receptor antagonists resulted in a complete loss of swallowing-like activity and no change in respiratory activity. These results suggest that the 800-μm medullary slice preparation contains both afferent and efferent neural circuits and pattern generators of swallowing activity. Additionally, NMDA receptors may be necessary for generating swallowing activity. This medullary slice preparation can therefore elucidate Sw-CPG neural networks.

BACKGROUND: Most cancers are lifestyle-related and are thus preventable. Lifestyle habits can be improved by individual efforts; for example, because oral health is suggested to play a preventive role in cancer risk, toothbrushing is considered a critical and fundamental measure for controlling oral health. This study aimed to investigate the association between toothbrushing and cancer risk. METHODS: Cross-sectional data from the Japan COVID-19 and Society Internet Survey, a large-scale (n = 32,000) online survey conducted in 2022, were used. From September 12 to October 19, 2022, questionnaires were distributed to candidates selected by simple random sampling from a Japanese Internet research company's panelists to represent the Japanese population. The association between toothbrushing and cancer risk according to cancer prevalence was then analyzed. RESULTS: Among all 32,000 participants, 2,495 (7.8%) who had any cancer previously were analyzed. Multivariable logistic regression analysis revealed a significant association between toothbrushing habit and cancer risk. CONCLUSION: The findings of this study suggest that daily toothbrushing is essential for maintaining oral health and preventing cancer.

Abstract Aim Oral cGVHD is one of the phenotypes of organ involvement of cGVHD and is a complex, frequent, and highly impactful complication of allogeneic hematopoietic cell transplantation (HSCT). Few studies have compared the incidences and risk factors of oral cGVHD, and they have not been discussed. We performed to evaluate the risk factors for oral cGVHD after allogeneic HSCT in a single center. Methods A retrospective study of clinical hematological data of all consecutive patients who underwent HSCT for malignant hematologic disease and then developed oral chronic graft versus host disease (cGVHD) in a single center from 2012 to the present was performed to evaluate the risk factors for oral cGVHD. Allogeneic HSCT was performed for 179 patients. Assessment of individual risk factors (age, sex, primary diagnosis, stem cell source, human leukocyte antigen [HLA] matching, regimen, donor age, and status after remission induction therapy) was completed to identify the effects of covariates of the independent variables. Results Seventy‐two (40.2%) patients were considered to have oral cGVHD within 36 months after HSCT. Statistical analysis showed that age, sex, stem cell source, HLA matching, regimen, donor age, and status after remission induction therapy were not significant factors related to oral cGVHD, whereas the primary disease was significant. Conclusion The primary disease was a significant risk factor for oral cGVHD. The oral cGVHD was more common in myeloid neoplasms (MNs) patients than in lymphoid neoplasms (LNs) patients.

OBJECTIVES: To investigate the usefulness of harmonized 18F-FDG-PET/CT parameters for predicting the postoperative recurrence and prognosis of oral tongue squamous cell carcinoma (OTSCC). METHODS: We retrospectively analyzed the cases of 107 OTSCC patients who underwent surgical resection at four institutions in Japan in 2010-2016 and evaluated the harmonized PET parameters of the maximum standardized uptake value (SUVmax), metabolic tumor volume (MTV), and total lesion glycolysis (TLG) for the primary tumor as the pSUVmax, pMTV, and pTLG. For lymph node metastasis, we used harmonized PET parameters of nodal-SUVmax, nodal-total MTV (tMTV), and nodal-total TLG (tTLG). The associations between the harmonized PET parameters and the patients' relapse-free survival (RFS) and overall survival (OS) were evaluated by the Kaplan-Meier method and Cox proportional hazard regression analysis for model 1 (preoperative stage) and model 2 (preoperative   +  postoperative stages). RESULTS: The harmonized SUVmax values were significantly lower than those before harmonization (p=0.012). The pSUVmax was revealed as a significant preoperative risk factor for RFS and OS. Nodal-SUVmax, nodal-tMTV, and nodal-tTLG were significant preoperative risk factors for OS. The combination of pSUVmax + nodal-SUVmax significantly stratified the patients into a low-risk group (pSUVmax <3.97 + nodal-SUVmax <2.85 or ≥2.85) and a high-risk group (pSUVmax ≥3.97 + nodal-SUVmax <2.85 or pSUVmax ≥3.97 + nodal-SUVmax ≥2.85) for recurrence and prognosis (RFS: p=0.001; OS: p<0.001). CONCLUSIONS: The harmonized pSUVmax is a significant prognostic factor for the survival of OTSCC patients. The combination of pSUVmax and nodal-SUVmax identified OTSCC patients at high risk for recurrence and poor prognosis at the preoperative stage.

PURPOSE: During the Coronavirus Disease 2019 (COVID-19) pandemic, there has been concern about nosocomial infections acquired through dental practice, where machines - such as air turbines - that generate aerosols are used, and where there are many opportunities to come into contact with saliva and blood. Because there is no report to date on whether dental treatment is associated with a risk of SARS-CoV-2 infection in Japan, the aim of the present cross-sectional study was to examine the risk of SARS-CoV-2 infection associated with dental treatment. MATERIALS AND METHODS: Cross-sectional data were gathered from the Japan COVID-19 and Society Internet Survey (JACSIS), a large-scale internet survey conducted in 2021 (n=28,175). From September 27, 2021, to October 30, 2021, the questionnaires were distributed to candidates selected from the panelists of a Japanese Internet research company to represent the Japanese population regarding age, sex, and residential prefecture using a simple random sampling procedure. The risk of SARS-CoV-2 infection related to dental treatment was examined and analysed. RESULTS: Multivariable logistic regression analysis showed that younger age, male sex and living alone were statistically significant factors positively associated with SARS-CoV-2 infection, whereas the presence or absence of dental treatment was not statistically significantly correlated with SARS-CoV-2 infection. CONCLUSION: The present epidemiological study showed that dental treatment is not a positive risk factor for SARS-CoV-2 infection in Japan.

Aims Since it is known that oral problems affect various medical diseases, the effects of restrictions on visits for dental treatment on exacerbations of various systemic medical diseases were examined.Method and materials The data were used from the Japan COVID-19 and Society Internet Survey, a large-scale internet survey conducted in 2021 (n = 28,175). The questionnaires were distributed to 33,081 candidates who were selected to represent the Japanese population regarding age, sex and residential prefecture using a simple random sampling procedure. Patients currently undergoing treatment for diabetes mellitus, hypertension, asthma, cardiocerebrovascular disease, hyperlipidemia, atopic dermatitis, and mental illness, such as depression, were extracted from the total participants. Then, whether discontinuation of dental treatment affected the exacerbation of their systemic disease was examined.Results Overall, 50-60% of patients with each systemic disease had continued to receive dental treatment, and 4-8% of them had discontinued dental treatment. On univariate and multivariate analyses, discontinuation of dental treatment is a risk factor in the exacerbation of diabetes mellitus, hypertensive conditions, asthma, cardiocerebrovascular disease and hyperlipidemia.Conclusion The present epidemiological study showed the relationship between oral health and systemic health, which can provide meaningful insights regarding future medical-dental collaboration in Japan.

OBJECTIVE: To examine skeletal morphology and dental arch relationships at 8 years of age following early 2-stage palatoplasty, which consists of soft palate plasty at 1 year of age and hard palate closure at 1.5 years of age, and to compare the results with those of conventional pushback palatoplasty. DESIGN: Retrospective. SETTING: Single institutional study. PATIENTS: Eighty-six patients with nonsyndromic complete unilateral cleft lip and palate (UCLP) were selected. INTERVENTION: The subjects were divided into 2 groups according to the palatoplasty protocols, as follows: 45 patients, who underwent early 2-stage palatoplasty (ETS group), and 41 patients, who underwent 1-stage pushback palatoplasty (PB group). MAIN OUTCOME MEASURES: Skeletal morphology was assessed using lateral cephalometric analysis, and dental arch relationships were examined using the GOSLON yardstick. RESULTS: Cephalometric analysis revealed that the anterior-posterior length of the maxilla, measured by PTM-A and PTM-ANS, both projected to the nasal floor (NF) plane, was longer in the ETS group than in the PB group (PTM-A/NF, p = .04; PTM-ANS/NF, p = .03, unpaired t-test), although no significant difference was observed in SNA (p = .09, unpaired t-test). Upper posterior facial height was shorter in the ETS group than in the PB group (p = .02, unpaired t). Assessments with the GOSLON yardstick showed that the ETS group presented better dental arch relationships than the PB group (p = 0.04, Mann-Whitney's U-test). CONCLUSIONS: The present results suggested that the ETS protocol reduced the negative effects of palatal surgery on facial development and dental arch relationships in patients with complete UCLP at 8 years of age.

Orexins are multifunctional hypothalamic neuropeptides that participate in the stimulation of feeding behavior and energy expenditure. However, little is known about their neuromodulatory effects in lower brainstem effector regions, including in the trigeminal neuronal system. The aim of this study was to examine the effects of orexin-A (Ox-A) on the membrane properties of mesencephalic trigeminal (Mes V) neurons that are critically involved in the generation and control of rhythmical oral motor activities. Whole-cell patch clamp recordings were obtained from Mes V neurons in coronal brain slices prepared from Sprague-Dawley rats (postnatal day 12-17). Bath application of Ox-A (100 nM) shortened the duration of the after-hyperpolarization following the action potential, while the interspike frequency of firings during repetitive discharge increased, together with a shift in the frequency-current relationship toward the left. In addition, Ox-A amplified the resonance at the depolarized membrane potential, accompanied with an increase in both Q-value and resonant frequency. A further voltage-clamp experiment demonstrated that Ox-A increased the peak current density of the persistent sodium current (INaP) and shifted its activation curve to the hyperpolarization direction. These results suggested that Ox-A may increase Mes V neuronal excitability by enhancing INaP, possibly sharing a common mechanism with another orexigenic hypothalamic neuropeptide, neuropeptide Y.

OBJECTIVES: The aim of the present study was to evaluate the functional and esthetic results of marginal mandibulectomy for mandibular cancer using a lateral approach with a simple, straightforward mouth corner incision. STUDY DESIGN: Six mandibular cancer patients (2 men, 4 women; age range: 65-80 years; mean age, 73.1 years; all stage I) were treated using this approach. With this approach, the surgical field was widely exposed, and mandibulectomy was performed with sufficient surgical margins. Intraoperative frozen specimens of remaining tissues showed no malignancy in all cases. In all 6 patients, follow-up imaging assessments were obtained, with no local recurrence after 12 to 78 months. RESULTS AND CONCLUSIONS: An overall functional, physical, and esthetic assessment of oral behavior and oral appearance was made of all patients by the FACT-H&N questionnaire, which showed that functional lip behavior and esthetic lip appearance were not much affected by the present surgical approach, and good quality of life was maintained. Thus, the lateral approach with the mouth corner incision is an effective and useful alternative for the molar part of mandibulectomy.

Osteo-odontokeratoprosthesis (OOKP) is a technique invented by Strampelli in 1963, in which the patient's own tooth root is used to support an optical cylinder. It uses an autologous tooth-bone-periodontal complex to mount an optical cylinder, which is stabilised by overlying autologous buccal mucosa. OOKP involves two, staged procedures done by ophthalmologists and oral surgeons, and the main contribution from the oral surgeon is during the first stage. To date we have done nine first-stage, and completed eight second-stage, OOKP operations in Japan with a mean follow-up of eight years and 11 months by modifying the original method of the oral surgery. All OOKP procedures were unilateral, and canines were selected as the donor teeth. Patients developed ocular blindness as a result of Stevens-Johnson syndrome, ocular cicatricial pemphigoid, and chemical and thermal burns to the cornea and ocular surface. All eight patients who completed the second stage have been stable, and there have been no major perioperative or postoperative oral complications. The patients' visual acuities were stable with no serious complications. Here we report the technical details of the oral contribution to OOKP.

[Abstract]Six patients with iatrogenic and noniatrogenic foreign bodies in the maxillary sinus are presented. Four patients had iatrogenic foreign bodies, including a dental implant, a maxillary wisdom tooth, a maxillary wisdom tooth root and a dental root canal filler. The other two patients with non-iatrogenic foreign bodies fractured an interdental brush while cleaning their teeth and it entered the maxillary sinus. For surgical extraction of foreign bodies, the intra-oral and trans-nasal approaches were performed in 5 patients and 1 patient, respectively. A total of 130 Japanese patients with foreign bodies in the maxillary sinus from 1981 to 2015 were reviewed. The rate of iatrogenic and non-iatrogenic cases were 97.7%, and 2.3% respectively. With regard to dental foreign bodies, all of the reported patients had a tooth root in the maxillary sinus, and our patients with displacement of an entire tooth(including the crown and root)in the maxillary sinus was rare. It is necessary for dentists to perform detailed preoperative evaluation and careful extraction of maxillary wisdom teeth. There were 3 patients with broken interdental brush in the maxillary sinus. The common point of those 3 patients and our 2 patients was that relatively new interdental brushes were used, and been inserted into the periodontal pocket, which is an incorrect cleaning method. It is important for dentists and dental hygienists to provide instructions on the appropriate method of cleaning the teeth with interdental brush in order to prevent fracture and entry of the broken brush into the maxillary sinus.

In the present study, we compared the incidence and severity of oral mucositis among patients undergoing allogeneic hematopoietic stem cell transplantation after fludarabine-based regimens with busulfan 12.8 mg/kg (FB12.8), with busulfan less than or equal to 9.6 mg/kg (FB9.6), and with melphalan 140 mg/m2 (FM). The incidence of oral mucositis after FB12.8 was the highest among these 3 groups. After FM, all of the patients had developed oral mucositis by day 7. The mean disease duration of oral mucositis after FB12.8 was 13.5 days, whereas the mean disease duration after FM was 24.9 days, and was significantly prolonged as compared to that after FB12.8 (p=0.0009). The incidence of severe oral mucositis (grade 3) after FM was significantly higher than that after FB12.8 (p=0.03). As stated above, although the incidence of oral mucositis after FB12.8 was higher than that after FM, oral mucositis after FB12.8 showed improvement relatively quickly without deterioration. In contrast, the higher incidence of severe oral mucositis and the delay in resolution of mucositis after FM were remarkable.

We analyzed the effects of neuropeptides produced in the hypothalamic area on the pattern of feeding behavior using adult Wistar rats. Intraventricular injection of α-MSH, antiorexigenic agent, prolonged the latency to eat, decreased cumulative food intake and the duration of feeding bouts. In contrast, AgRP, orexigenic agent produced in arcuate nucleus, stimulated the drinking behavior in all cases examined, but showed only modest effects on the feeding behavior. We also examined the direct effects of neuropeptides on the membrane properties of mesencephalic trigeminal neurons using whole cell patch-clamp recording technique. Both orexin and NPY demonstrated inward current and stimulated membrane excitabilities by acceleration of spike repolarization and increase of spike frequency in repetitive discharges. These effects were suppressed in the presence of H89 or cherelythrine, suggesting the involvement of PKA, PKC dependent signaling pathway.

This study demonstrated that centrally injected orexin (Ox) or neuropeptide Y (NPY), potent stimulants of ingestive behavior, augmented fool intake and facilitated feeding behavior occurring with characteristic changes of EMG activities of masticatory muscles. Whole cell recordings from both trigeminal motoneurons and mesencephalic trigeminal neurons involved in the emergence of masticatory muscle activities revealed excitatory effects of Ox on these neurons by depolarizing membrane potential and increasing action potential frequency in repetitive firing activities. These results suggest that an elevation of intracerebral Ox may has a facilitative role in feeding behavior by regulating excitabilities of trigeminal motor outputs.

Applying brainstem transection techniques to the neonatal rat brainstem in vitro, we found that the activity of the motoneuron population recorded from the motor branch of the trigeminal nerve exhibited LTP-IE. We thus demonstrated the usefulness of this type of preparation for the study of rudimentary oral-motor activity and observed changes in TMN excitability. In addition, on testing with the whole-cell patch-clamp method, TMNs exhibited a significant increase in excitability with a leftward shift in F-I curves generated with depolarizing current injections. These findings indicate that TMNs exhibit LTP of intrinsic excitability. Blocking the calcium influx prevented LTP-IE. These results indicate that TMNs shows LTP-IE, and calcium influx is necessary for induction of LTP-IE.

我々は、今回の研究により、三叉神経運動ニューロンが、単一神経細胞内において神経可塑性を持ち、その興奮性を変化させる機能も持つことを明確にした。 実験は、生後2-4日目のSD系ラットを用い、ハロセン吸入麻酔下にて麻酔後、脳幹を摘出し、脳幹スライスを作成した後、三叉神経運動核中の三叉神経運動ニューロンを顕微鏡下にて同定し、同神経細胞より、神経活動を記録した。記録はAPV、CNQX、Bicuculline、Strychnineといった興奮性および抑制性神経伝達物質の拮抗薬をチャンバー内投与し、神経伝達を抑制した状態で行った。パッチクランプ法および細胞外神経記録法にて、Inductionを与えられた三叉神経運動ニューロンが有為に発火頻度を増やし、その興奮性を増強させることを発見した。昨年の単一ニューロンの神経活動変化に加え、運動ニューロン群での興奮性の変化を観察したことは、神経間を通した三叉神経感覚系からの刺激により、三叉神経運動ニューロンの活動性が高まり、顎運動の生理学的活動性が高まっていることを示唆させるものである。この可塑性が長期継続し、LTP(Long Term Potentiation)を持つことは、三叉神経系の発達や順応に関わっていると考えられる。

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