Tokyo Dental College (東京歯科大学, Tōkyō Shika Daigaku) is a private university in the city of Chiyoda-ku, Tokyo, Japan. The predecessor of the school was founded in 1890, and it was chartered as a university in 1946.It is the only institution specializing exclusively in the teaching of dentistry in all of Japan.The College's course spans over six years in which students study ten months per year. Freshmen students' courses include: Chemistry and Physics, Anatomy and Histology (General and Dental) and Physiology. However, junior students focus on Pathology (General and Dental), Bacteriology , Metallurgy, Prosthetic Dentistry and other things. Seniors on the other hand study, Oral Surgery, Orthodontia, Operative Dentistry, Crown and bridge-work, Laboratory work and Infirmary practice.
The purpose of this study was to investigate the impacts of diabetes and smoking on the risk of tooth loss in adults and the elderly. Dental receipts and specific health checkup data were used to assess increase in tooth extraction among people with a high blood glucose level or a smoking habit. The data were obtained from a database maintained by DeSC Healthcare Corporation, which supports the integrity of data held by health insurers. Dental receipts and specific health checkup data from 2018 to 2021 were used to obtain information on fasting blood glucose levels, smoking habits, and tooth extraction in 12,219 individuals aged 45-69 years. The results showed that the proportion of tooth extractions between 2018 and 2021 (32.3%) was higher in those with hyperglycemia. The proportion of tooth extractions in smokers (34.0%) was also significantly higher than that in non-smokers (21.6%). These results suggest that measures must be taken to promote dental and oral health care in those with hyperglycemia and in those with a smoking habit.
Skeletal stem/progenitor cells (SSPCs) play a fundamental role in maintaining skeletal homeostasis throughout life. Leptin receptor (Lepr)-positive cells were initially identified as SSPCs in the long bone marrow and later in the craniofacial skeleton, where they localize within the periodontal ligament (PDL), particularly among fibroblastic cells (PDLCs). However, their hierarchical organization, maintenance of stemness, and relationships with other SSPC populations remain poorly understood. Through lineage tracing and single-cell RNA sequencing facilitated by Runx2-GFP expression, we identified a Lepr+ subpopulation characterized by Thy1 expression but lacking Runx2, which is hierarchically positioned at the apex of the Lepr+ PDLC lineage and gives rise to downstream osteogenic progeny. However, their SSPC capacity to contribute to osteocytes and cementocytes is quantitatively limited and declines with age, and this contribution may exhibit sexual dimorphism. At the singlecell transcriptome level, Lepr+ PDLCs shared an expression profile with long bone-derived Lepr+ SSPCs; however, the expression of Kit ligand (Kitl) was uniquely restricted to Lepr+ cells within the PDLCs. In contrast, they were not enriched for other PDLC-associated SSPC markers, such as Axin2, Gli1, and Acta2. Although Lepr+ PDLCs contributed to bone regeneration by differentiating into osteocytes after tooth extraction, their contribution was limited. Moreover, genetic ablation of Lepr+ PDLCs did not reduce the regenerated bone volume, suggesting compensatory contributions from other SSPC populations. Collectively, these findings reveal a previously unrecognized hierarchical and functional organization of Lepr+ PDLCs and demonstrate that their contribution to skeletal homeostasis progressively declines with age, with potential compensation by other SSPC populations.
Bone is a multifunctional organ that provides structural support and hosts the bone marrow, a key site for hematopoiesis and systemic homeostasis. These dual features have long attracted the attention of both bone biologists and hematologists. Each field has pursued the identification of stem-like cells responsible for hard tissue formation and the regulatory microenvironment/niche that supports hematopoietic stem cells (HSCs), which give rise to all blood cell lineages. Converging advances in bone and hematopoietic biology have led to the identification of skeletal stem/progenitor cells (SSPCs), a multifunctional population that gives rise to osteolineage cells and serves as a principal component of the HSC niche. This landmark discovery was largely enabled by Cre/loxP-based genetic mouse models. Among them, the leptin receptor (LepR)-Cre system has become one of the most widely used tools in skeletal stem cell research worldwide. In this review, we summarize the historical background and recent advances in SSPC research, specifically LepR+ SSPCs, highlighting their function and lineage plasticity during development, adolescence, aging, and fracture healing. Advanced genetic labeling-based studies and single-cell transcriptomics unveiled the fate, dynamics and indispensible roles of LepR⁺ SSPCs under both homeostatic and pathological conditions.
Opioid analgesia and adverse outcomes vary across individuals. We show that runt-related transcription factor 1 (Runx1) modulates the microglial transcriptome and is a genetic determinant of opioid antinociceptive responses and withdrawal. In mice, Runx1 deletion in microglia produces distinct ultrastructural and transcriptomic signatures, reducing morphine potency despite no prior opioid exposure. These mice also require greater post-operative morphine and display exacerbated morphine-induced hyperalgesia and withdrawal. Single-cell RNA sequencing (scRNA-seq) and chromatin immunoprecipitation sequencing (ChIP-seq) analyses reveal a unique microglial state, with Runx1 regulating inflammatory signaling and key microglial functions. In humans, association analyses link RUNX1 variants to inter-individual differences in perioperative opioid requirement and withdrawal severity. Identifying RUNX1 susceptibility genotypes may be important for understanding individual variability in opioid responses, with potential relevance for future personalized approaches.
The radiopacity of adhesives is important for radiographic diagnosis and micro-computed tomography (micro-CT) evaluation of adhesive restorations. However, most universal adhesives lack sufficient radiopacity. This study examined the radiopacity and intracavity distribution of four universal adhesives-Scotchbond Universal Adhesive (SBU), Scotchbond Universal Plus Adhesive (SBP), Clearfil Universal Bond Quick ER (UBQ), and G-Premio Bond (GPB)-using a cylindrical cavity model. Cavities were prepared in bovine enamel-dentin blocks and scanned using micro-CT at 5.0 μm/voxel after cavity preparation, adhesive application, and resin composite filling (n = 3). The adhesive layer region was geometrically defined from sequential datasets and analyzed using actual 16-bit grayscale values. Grayscale values, adhesive layer thickness, and composite-filling-induced volume changes were evaluated by three-dimensional difference analysis. SBP showed a grayscale value equivalent to that of dentin, whereas SBU, UBQ, and GPB were statistically indistinguishable from air. Adhesive thickness increased from the lateral walls to the cavity floor, and reduced-density regions were observed in UBQ and GPB. Therefore, SBP was the only tested universal adhesive with dentin-equivalent radiopacity, enabling reliable micro-CT evaluation and reducing the risk of radiographic misdiagnosis. The proposed grayscale-based approach may support future non-destructive investigations of dental adhesive behavior.
