Tokyo Dental College

Organ morphogenesis is essential for not only integrated organ functions in the body but also the determination of adult-tissue stem cells and their niche. Only hair follicle organs can cyclically regenerate in the variable bulbous germinative region as a form of programmed organ regeneration in adults. Here, we identified a cell population, hair follicle organ-intrinsic mesenchymal cells, with PDGFRα+/Sca1+/CD34high+ mesenchymal cells, from the boundary zone of the epithelial stem cell niche by using the organ germ method, which plays essential roles in entering and promoting the downgrowth phase of the hair cycle. The bioengineered hair follicle germ reconstituted from bulge region-derived epithelial stem cells, dermal papillae and mesenchymal cells has full functions, including downgrowth, full-size hair follicle regeneration and the hair cycle, both in in vitro artificial skin and after intracutaneous skin transplantation. This study provides significant contributions to the basic and medical science of adult organ-inductive potential stem cells and their niches in organ morphogenesis and the adult hair cycle.

The hyoid lesser horn (LH) forms a transient joint with the greater horn in human fetuses. The chondroglossus muscle attaches to the LH; however, its morphology remains unclear. We hypothesized that the muscles involved in LH accelerate joint formation. We examined 34 human fetuses with crown-rump length of 39-230mm. The LH joint was bilaterally absent in eight fetuses; the largest specimen "without" joints was 110mm crown-rump length, whereas the smallest specimen "with" joints was 55mm. The chondroglossus was identified as oblique muscle fibers attached to the LH medial aspect (23/34). The chondroglossus, Adjacent to the transverse lingual muscle (TLM), the chondroglossus ran supero-antero-medially to join the genioglossus. The TLM (21/34) and middle pharyngeal constrictor (pars chondropharyngica; 21/34) originated from the LH. The latter ran posteriorly from the LH medial to the hypoglossal nerve, whereas the middle constrictor arose largely from the greater horn. Notably, without LH attachment, the anterior margin of the mylohyoideus muscle (MPCM) was connected to the TLM using thick fascia wrapped around the LH. Therefore, LH disrupts the muscular ring surrounding the oropharynx. The variation in joint formation timing (9-16 weeks gestational age) suggests that the chondroglossus, TLM, and MPCM development do not require joint movement. Alternatively, an elongated greater horn may provide joint-like space.

Dental hygienists are professionals responsible for maintaining oral health and assisting in dental treatments. During their training programs, they acquire essential skills and knowledge, including precise intraoral instrument manipulation, such as scaling. Although technical textbooks are available, skills that rely on finger and hand sensations-such as instrument manipulation-are difficult to describe objectively, making instruction heavily dependent on the instructor's expertise. Previous studies have attempted to address this issue by developing measurement systems with inertial measurement units (IMUs) attached to scalers. However, while these systems record scaler dynamics qualitatively, they lack a visual feedback function, rendering them inadequate as self-learning tools for students. In this study, we installed two types of sensors on the scaler and the back of the hand and developed a monitor application that provides real-time visual feedback, allowing students to intuitively understand their operation. Furthermore, we added a function to measure the pressure between the supporting tooth and the fourth finger (fixation pressure) and display it on the monitor along with the scaler and wrist movements.

Socioeconomic inequalities in disability-free life span have been widening. We evaluated the mediating role of multiple modifiable risk factors, including tooth loss, on socioeconomic inequalities in disability onset and mortality among Japanese older adults. This prospective cohort study utilised data from the Japan Gerontological Evaluation Study, targeting adults aged ≥65 years. The 2013 baseline questionnaire survey participants were followed until 2022 (n = 48,474; median follow-up 9.0 years). Time-varying mediators were also assessed in questionnaire surveys in 2016 and 2019. Discrete-time survival analysis estimated the association of socioeconomic status (SES) -a standardised principal component score incorporating household income, wealth, and years of education-with disability or mortality onset. The Karlson-Holm-Breen method decomposed total effects into pathways through 11 mediators, including tooth loss and major risk factors for disability and mortality. During the follow-up, 29.1% became disabled or died. Compared to the highest SES group, the lowest SES quartile group exhibited hazard ratios (95% confidence intervals [CI]) of 1.26 (1.19, 1.34) for disability or mortality. Tooth loss exhibited the second largest indirect effect (proportion mediated [95% CI], 12.4% [8.0, 17.2]), following moderate depression (16.0% [11.7, 21.5]). Tooth loss exhibited the strongest association with SES, attributing to the large indirect effect. The findings suggest that tackling inequalities in tooth loss may be an effective way to reduce socioeconomic inequalities in a disability-free life span.

Objectives: This study aimed to comprehensively evaluate and compare the therapeutic effects of Right Angle Maxillary Protraction Appliance (RAMPA) therapy on nasal airway volume in pediatric patients, specifically differentiated by their baseline radiological paranasal sinus status. The objective was to quantify airway volume changes (absolute and percentage) in clear and opacified sinus groups, investigate the influence of age, sex, and treatment duration on these changes, and elucidate potential differences in the underlying mechanisms of airway expansion between groups. Study Design: A retrospective comparative cohort study design was employed. This study includes a “clear sinus group” of 26 patients (mean age: 6.6 years) with radiologically clear sinuses at baseline and an “opacified sinus group” of 20 patients (mean age: 6.8 years) diagnosed with rhinosinusitis and exhibiting significant sinus opacification on baseline CBCT scans. Upper airway volumetric measurements were performed using CBCT scans acquired pre- (T1) and post-treatment (T2), with data analyzed using Invivo 5 software. Results: RAMPA therapy significantly increased upper airway volume in both cohorts. The clear sinus group showed an approximate 18% mean increase (4886.9 mm3 absolute), while the opacified sinus group demonstrated a remarkably greater 61% mean increase (11,192.8 mm3 absolute). This difference was statistically significant. In the clear sinus group, airway volume gain positively correlated with treatment duration (p = 0.0303). Conversely, no significant correlation was found in the opacified sinus group (p = 0.288), suggesting rapid obstruction relief as a dominant mechanism. Sex did not significantly influence outcomes, and age was not a strong independent predictor of volume change magnitude. Conclusions: RAMPA therapy effectively increases upper airway volume in pediatric patients, with a substantially greater effect in those with baseline sinus opacification due to rapid obstruction resolution complementing skeletal changes. The mechanism of action differs by sinus status, with clear sinus patients showing gradual, duration-dependent skeletal adaptation and opacified sinus patients exhibiting immediate, duration-independent gains primarily from sinus clearance. These findings provide crucial insights for tailored clinical decision-making.

Background: Impaired mucus drainage from the paranasal sinuses is often associated with nasal obstruction and reduced airway function in growing patients. Orthopedic maxillary protraction and expansion techniques can enhance airway dynamics, but their underlying fluid–structure mechanisms remain insufficiently understood. Objective: To validate that the Right Angle Maxillary Protraction Appliance (RAMPA), combined with a semi-rapid maxillary expansion (sRME) intraoral device gHu-1, improves mucus drainage by enhancing nasal airflow through nasal cavity expansion. Methods: The effects of RAMPA therapy were analyzed using computational fluid dynamics (CFD) for single-phase (air) and two-phase (air–mucus) flows within the nasal cavity, employing the unsteady RANS turbulence model. Finite element method (FEM) results from prior studies were synthesized to assess changes in the center and radius of maxillary rotation induced by RAMPA-assisted sRME. A male patient (aged 8 years 7 months to 11 years 7 months) treated with extraoral RAMPA and the intraoral appliance (gHu-1) underwent pre- and post-treatment cone-beam computed tomography (CBCT) and ear, nose, and throat (ENT) evaluation. Results: FEM analysis revealed an increased radius and elevated center of maxillary rotation, producing expansion that was more parallel to the palatal plane. CFD simulations showed that nasal cavity expansion increased airflow velocity and pressure drop, enhancing the suction effect that promotes mucus clearance from the frontal sinus. Clinically, nasal passages widened, paranasal opacities resolved, and occlusal and intermolar widths improved. Conclusions: RAMPA combined with sRME improves nasal airflow and maxillary skeletal expansion, facilitating paranasal mucus clearance and offering a promising adjunctive approach for enhancing upper airway function in growing patients.

Traditional non-surgical periodontal therapy (NSPT) is based on debriding supra-gingival and sub-gingival calculus and providing advice regarding oral health care techniques. Chlorhexidine is used as a mouthwash to prevent plaque and bacterial accumulation. Honey is used to treat periodontitis, inflammation of the gingiva, plaque development, and odor management. A quasiexperimental study was conducted in the Department of Dental Pharmacology, Department of Periodontology, and the Outpatient Department of Dentistry of Bangladesh Medical University (BMU), Dhaka, Bangladesh, between January and December of 2024, to evaluate the efficacy of honey comparing to chlorhexidine mouthwash in non-surgical periodontal therapy. A total of 66 participants were enrolled in this study based on inclusion and exclusion criteria. Among them, 33 participants were in the intervention group (treated with honey), while the rest 33 participants were in the control group (treated with chlorhexidine mouthwash). Oral health status, periodontal condition, and other study-related information were collected through a data collection sheet. Probing pocket depth (PPD) was measured at baseline, 3 months, and 6 months to compare outcomes in both groups to compare the efficacy of honey and chlorhexidine. Participants of the control group had a mean age of 39.7±13.2 years, while the participants of the intervention group had a mean age of 40.5±11.7 years. A male predominance was observed in both groups with 19(57.6%) and 20(60.6%) male patients respectively. Regarding PPD, at baseline examination, there was no difference between two groups (3.35±0.67 vs. 3.14±0.56; p=0.19). However, after 3 months (3.07±0.91 vs. 2.65±0.68; p=0.04) and after 6 months (3.03±1.13 vs. 2.43±0.91; p=0.02), statisticaly significant differences were observed. Overall, honey worked better than chlorhexidine to reduce probing pocket depth. Moreover, adverse drug reactions were observed more in the control group (39.4%) than that of the intervention arm (9.1%) (p=0.004). Honey’s natural antimicrobial and anti-inflammatory properties contributed to significant reductions in probing pocket depth (PPD) and showed less adverse effects compared to chlorhexidine mouthwash. Mugda Med Coll J. 2025; 8(2): 145-149

A bidirectional relationship exists between sleep-disordered breathing (SDB) and stroke. Post-stroke patients have worse oral health status. Post-stroke patients with worse SDB would also have worse oral health status. Post-stroke patients in convalescent rehabilitation wards were enrolled in this study. An overnight sleep test using WatchPAT to measure the apnea-hypopnea index (AHI) was conducted. Each oral health assessment tool (OHAT) score between three groups divided by SDB severity was compared, and binary logistic regression analysis was used to assess the association between the total OHAT score and AHI. Also, a receiver operating characteristic curve analysis was performed using the total OHAT score for severe or non-severe SDB. Among the 196 participants enrolled, 140 participants (78 men and 62 women; mean age, 73.3 ± 12.4 years) underwent a sleep test, with 91 completing it. Significant differences were found between non- or mild SDB and severe SDB groups, as well as between moderate SDB and severe SDB groups in terms of natural teeth and total OHAT score. Binary logistic regression analysis revealed a significant association between AHI and total score of OHAT after adjusting for confounding factors. The cut-off value of the total OHAT score for severe or non-severe SDB was seven, with sensitivity and specificity of 0.524 and 0.735, respectively. This study revealed that oral health status is associated with SDB severity, highlighting the need for dental professionals in convalescent rehabilitation wards to be involved with SDB.

A standard approach to the diagnosis of dry eye disease across eye care practitioners is critical to reassuring the patient, providing consistency between practitioners and informing governments as to the true prevalence and resulting healthcare needs. The Tear Film & Ocular Surface Society (TFOS) Dry Eye Workshop (DEWS) III has reviewed the evidence-base since their previous reports published in 2017 and revised the definition to "Dry eye is a multifactorial, symptomatic disease characterized by a loss of homeostasis of the tear film and/or ocular surface, in which tear film instability and hyperosmolarity, ocular surface inflammation and damage, and neurosensory abnormalities are etiological factors." Key features from the definition include that dry eye disease is multifactorial, is a disease and not a syndrome and is always symptomatic. Differential diagnosis and ocular examination guidance is given along with the risk factors that should be discussed with the patient. The recommended screening questionnaire is the OSDI-6 with a cut-off score ≥4. A positive result together with a non-invasive breakup time <10s or alternatively tear film hyperosmolarity (≥308mOsm/L in either eye or an interocular difference >8mOsm/L) or alternatively >5 corneal fluorescein and/or >9 conjunctival lissamine green punctate spots and/or lid margin lissamine green staining of ≥2mm length & ≥25 % width, gives a diagnosis of dry eye. Subclassification was separated into tear film deficiencies (lipid, aqueous and mucin/glycocalyx), eyelid anomalies (blink/lid closure and lid margin) and ocular surface abnormalities (anatomical misalignment, neural dysfunction, ocular surface cell damage/disruption and primary inflammation/oxidative stress) components, with appropriate clinical tests and cut-offs provided to identify these etiological drivers in an individual, to inform appropriate management and therapy.