Semaphorins (Sema) are known to play an important role in bone remodeling by mediating the interactions between bone cells and immune cells. In this study, we investigated the differences in peri-implant bone resorption and the expression of Sema 3A and 4D around titanium (Ti) and zirconia (Zr) implants using a Göttingen minipig model of peri-implantitis. Bilateral mandibular first premolars were extracted in two minipigs, and after a 12-week healing period, three Ti and three Zr implants were placed. Peri-implant inflammation was experimentally induced by ligature placement, and peri-implant tissues were collected after an additional 12 weeks. The animals were divided into a control (Ctrl) group and a peri-implantitis (PI) group. Vertical and horizontal bone resorption was evaluated using cone-beam computed tomography with three-dimensional reconstruction, and Semaphorin expression in the surrounding alveolar bone was analyzed by quantitative real-time PCR (qRT-PCR). Significantly greater vertical bone resorption was observed around Ti implants (1.91 ± 0.32 mm in the Ctrl group and 4.55 ± 1.89 mm in the PI group) compared with Zr implants (1.32 ± 0.01 mm and 2.48 ± 0.36 mm, respectively). Similarly, horizontal bone resorption around Ti implants (1.10 ± 0.14 mm in the Ctrl group and 3.22 ± 0.45 mm in the PI group) was greater than that around Zr implants (0.76 ± 0.32 mm and 1.22 ± 0.15 mm, respectively). The bone resorption rate was also higher around Ti implants (16.4 ± 1.24% in the Ctrl group and 40.7 ± 8.66% in the PI group) than around Zr implants (9.0 ± 2.97% and 23.4 ± 3.08%, respectively). Sema 3A expression was higher in peri-implant bone around Zr implants (2.29 ± 0.26 ng/μL in the Ctrl group and 1.75 ± 0.09 ng/μL in the PI group) than around Ti implants (1.00 ± 0.12 ng/μL and 0.05 ± 0.08 ng/μL, respectively), whereas Sema 4D expression was more prominent around Ti implants (1.00 ± 0.12 ng/μL in the Ctrl group and 1.23 ± 0.06 ng/μL in the PI group) than around Zr implants (0.08 ± 0.19 ng/μL and 0.60 ± 0.18 ng/μL, respectively). In addition, Sema 4D expression exceeded that of Sema 3A regardless of inflammatory status. These findings indicate that differences in implant material may be associated with distinct Sema expression patterns, which could influence peri-implant bone remodeling, particularly through the involvement of Sema 4D in bone resorption around Ti implants.

Type 2 diabetes mellitus (T2DM) is associated with an increased risk of skeletal fragility that cannot be fully explained by changes in bone mineral density (BMD). Altered bone remodeling has been implicated in impaired bone quality in diabetes; however, the effects of sodium-glucose cotransporter 2 (SGLT2) inhibitors on bone metabolism remain unclear. In this study, the effects of ipragliflozin (IPRA) on bone metabolism were investigated in T2DM mice using bone histomorphometric analysis. Male db/db mice were treated with IPRA (1.0 or 10.0 mg/kg) for 9 weeks. BMD of the femur and tibia was measured, and trabecular bone microarchitecture and remodeling parameters were evaluated in the proximal tibial metaphysis. Compared with non-diabetic control mice, db/db mice exhibited significantly reduced BMD of the femur and tibia. IPRA administration did not result in significant changes in BMD at either dose. In contrast, bone histomorphometric analysis revealed marked deterioration of trabecular bone microarchitecture in db/db mice, accompanied by increased bone resorption and decreased bone formation. IPRA administration was associated with favorable changes in trabecular bone microarchitecture-related parameters, including increases in bone volume per tissue volume and trabecular thickness and a decrease in trabecular separation, particularly at the higher dose. In addition, osteoclast-related parameters were reduced and bone formation-related parameters were increased in db/db mice treated with IPRA at the higher dose, indicating partial attenuation of diabetes-associated alterations in bone remodeling. These findings suggest that IPRA modulates dysregulated bone remodeling and affects trabecular bone microarchitecture at the tissue level in T2DM, without inducing detectable changes in BMD.

C-type natriuretic peptide (CNP) serves as a key regulator of endochondral ossification. CNP promotes midfacial growth along the sagittal plane, and guanylate cyclase B (GC-B) (CNP receptor) is important for craniofacial skeletal development. However, the mechanism of the CNP/GC-B system underlying the regulation of endochondral ossification of the craniofacial region remains unclear. To clarify the contribution of chondrocyte-derived CNPto craniofacial region, we used cartilage-specific CNP knockout (KO) mice. The impact of CNP deficiency on craniofacial development was assessed through a two-tiered analysis. The mice underwent a morphological assessment at 12 weeks of age, followed by a histological assessment at 2 weeks of age. Cartilage-specific CNP KO mice showed reduced growth of the midfacial skeleton along the sagittal direction, as well as stenosis of both the foramen magnum (FM) and spinal canal. Histological analysis revealed a significant reduction in the thickness of the spheno-occipital synchondrosis (SOS), a critical site for craniomaxillofacial skeletal formation. The cell size and number within the hypertrophic zone of the SOS appeared to be decreased. These results suggest impaired endochondral ossification. This research elucidated the mechanisms of the CNP/GC-B system underlying craniofacial growth by evaluating the impact of CNP produced by chondrocytes themselves, providing further insights in the field.

The objective of this study was to quantitatively evaluate the impact of surface treatment on the surrounding bone when subjected to horizontal orthopedic force on the anchor screw with surface treatment by performing structural analysis of the surrounding bone. Hydrophilicity was imparted as the surface treatment to the anchor screw. Samples were collected 3, 5, 7, 14, and 28 days later for bone morphometry and histological evaluation. As a result of applying orthopedic force, the surrounding bone of the surface-treated anchor screw maintained a bone contact rate similar to that under normal load. In the untreated group, bones detached from the screw, showing a significantly lower bone contact rate compared to normal load conditions. The surface-treated group, even under orthopedic force conditions, exhibited a bone contact similar to that under normal load. The long diameter /short diameter of bone lacunae showed significantly lower values in the region subjected to compressive stress. These results suggested that anchor screws without surface treatment can withstand normal horizontal loads but may not endure orthopedic force, leading to early bone detachment and surrounding bone absorption. By achieving good primary stability, surface-treated anchor screws, demonstrated the potential to withstand immediate horizontal orthopedic force.

Tooth eruption occurs as the tooth germ forms roots and migrates vertically toward the oral mucosa. This process is facilitated by alveolar bone formation surrounding the tooth germ and by periodontal ligament and gingival fiber traction. Despite these phenomena being well described in relation to tooth eruption, the role of periodontal tissues in the furcation area of multirooted teeth during vertical eruption remains unclear. The present study compared the developmental processes of periodontal tissues in the furcation and cervical regions and investigated the growth characteristics of furcation during the eruptive phase. Paraffin sections of the maxillary second molars of rats aged 18, 20, 32, and 56 days were prepared for histological observations. Sections were stained with hematoxylin and eosin and subjected to immunohistochemical staining with anti-Osterix, anti-proliferating cell nuclear antigen (PCNA), and anti-periostin antibodies, as well as histoenzymatic staining for tartrate-resistant acid phosphatase (TRAP), to examine osteoblasts, proliferative activity, periodontal fibers, and osteoclasts. Numerous highly active osteoblasts, identified as Osterix-immunopositive cells, were observed in the furcation area until day 20, followed by rapid formation of the interradicular septum by day 32. PCNA-immunopositive cells exhibited a distribution similar to that observed for osteoblasts. Osteoclasts, identified by TRAP positivity, appeared after establishment of the interradicular septum. Periostin-immunopositive periodontal fibers were observed during the formation of the interradicular septum. No temporal changes were observed in cellular activity, osteoblasts, osteoclasts, or the maturation of periodontal fibers in the cervical region, and alveolar bone formation capacity was maintained at a constant level. These findings suggest that the rapid formation of the interradicular septum promotes the maturation of the periodontal ligament, thereby supporting the vertical eruption of multirooted teeth.

We aimed to clarify the prognostic significance of SRY-box transcription factor 2 (SOX2) expression in oral squamous cell carcinoma (OSCC) and to evaluate its relationship with tumor proliferative activity assessed by Ki-67. We included 42 patients with OSCC who underwent surgical resection. Immunohistochemical staining for SOX2 and Ki-67 was performed using formalin-fixed, paraffin-embedded specimens; subsequently, labeling indices were evaluated. We analyzed the relationships between immunohistochemical expression patterns and clinicopathological factors; further, we assessed overall survival (OS) and disease-free survival (DFS) using Kaplan–Meier analysis and Cox proportional hazards models. In the univariate analysis, SOX2 expression alone showed a non-significant trend toward poorer OS; however, it was not an independent prognostic factor in multivariate analysis. Ki-67 expression was not significantly associated with OS; however, high Ki-67 expression emerged as the only independent prognostic factor for DFS. Notably, patients with a combined SOX2-low/Ki-67-high immunophenotype showed significantly worse OS than those with other immunophenotypes; moreover, this combination remained an independent prognostic factor for OS together with clinical stage. Taken together, our findings indicate that combined immunohistochemical evaluation of SOX2 and Ki-67 can identify a biologically aggressive subgroup of OSCC. Therefore, integration of differentiation- and proliferation-related markers may improve prognostic stratification beyond conventional clinicopathological assessment in OSCC.

Mechanical stress (MS) loading induces alveolar bone remodeling by osteogenesis and osteoclastogenesis on the tension and compression sides, respectively during orthodontic tooth movement (OTM). Reduced blood flow alters low-oxygen conditions on the compression side of the MS loading force. Osteocytes constitute over 90% of bone cells and express receptor activator of NF-κB ligand (RANKL) and osteoprotegerin (OPG), crucial for osteoclast differentiation, as well as sclerostin, which inhibits osteoblast differentiation, leading to reciprocal regulation in bone remodeling. However, many aspects of the relationship between mechanosensors expression in osteocytes and alveolar bone remodeling under hypoxia require clarification. Furthermore, osteogenesis-related molecule expression during OTM has focused on periodontal ligament cells, and their role in osteocytes remains unclear. We investigated mechanosensors expression in MLO-Y4 mouse osteocytes under hypoxia or CoCl₂ treatment as pseudohypoxic condition and changes in the expression of osteogenesis-related molecules using the CCK-8 assay, quantitative reverse transcription polymerase chain reaction, enzyme-linked immunosorbent assay, and western blot. Compared with normoxia, hypoxia or CoCl₂ treatment had little effect on the proliferation rate of MLO-Y4 cells. Hypoxia induced hypoxia-related molecule expression, including hypoxia-inducible factor 1α (HIF1α), decreased the RANKL/OPG ratio due to OPG upregulation, and downregulated sclerostin via phosphorylation of Akt and cyclic AMP response element-binding protein. In contrast, compression upregulated RANKL, increasing the RANKL/OPG ratio. MLO-Y4 cells expressed Piezo1 and activated Piezo1 upregulated HIF-1α expression. Our findings suggest that hypoxia enhances osteogenesis by downregulating the RANKL/OPG ratio and sclerostin expression, whereas compression enhances osteoclastogenesis by upregulating RANKL.

Root canal irrigation is an important procedure in root canal treatment. Nano-bubbles have attracted considerable attention across various fields because of their cleaning and disinfecting properties, and Hyperdense-Nanobubble Ozone Water (Hd-NBOW) was recently developed. Hd-NBOW improves sterilization efficacy, and the presence of nano-bubbles may also enhance the cleaning effect. This study assessed the efficacy of Hd-NBOW as a root canal irrigant. Various root canal irrigants were used to irrigate the root canal of a smear layer model for 1 minute, after which the number of opening dentinal tubules was quantified. Next, various root canal irrigants were applied to a biofilm model for one minute, after which the metabolic activity of the biofilm was measured. Additionally, various root canal irrigants were applied to an infected root canal model for 1 minute, bacteria were cultured before and after irrigation, and the numbers of colony forming units (CFU) were determined. The same procedure was repeated 2 days later, and the treatment was performed a total of 3 times. The number of opening dentinal tubules in the smear layer model irrigated with Hd-NBOW was comparable to that in the model irrigated with 3% ethylenediaminetetraacetic acid solution. The biofilm model demonstrated a reduction in metabolic activity with Hd-NBOW irrigation, comparable to that with sodium hypochlorite solution. A reduction in CFU levels was observed immediately after cleaning with Hd-NBOW. Two days later, the CFU count still showed a decline. Hd-NBOW can be used for root canal irrigation because it has both smear layer removal and bactericidal effects on infected root canals.