To assess the current status of patients with dental metal allergies in Japan. This study analyzed dental metal allergy in 1225 patients (1:3 male to female ratio; average age 53.0 ±16.5 years), including 300 who were scheduled to undergo dental implant surgery, between 2006 and 2016. For diagnosis of metal allergy, patch tests using metal allergens were performed. Additionally, when necessary, metal element analysis of dental alloys was performed in the mouths of some patients using an X-ray fluorescence analyzer for those who exhibited positive reactions. Among 925 patients (i.e., excluding those scheduled to undergo dental implant surgery [n=300]), nearly one-half (44.0%) exhibited a positive response to any metal element in the patch test. The positivity rates were as follows: nickel (22.5%); palladium (14.8%); and zinc (11.5%). Almost one-half (42.3%) of the patients had diseases associated with metal allergy. Among patients who exhibited a positive reaction to any metal element in the patch test, more than two-thirds (67.9%) had dental alloys containing the positive metal element(s). One-half (55.6%) of the patients who underwent treatment to remove the metal experienced improvement in symptoms. In patients who underwent patch testing as an implant preoperative examination, several (2.7%) exhibited a positive reaction to titanium. Dental metals, including nickel, palladium and zinc, which are indispensable to dental treatment in Japan, had high positivity rates in patch testing, and one-half of the patients improved following removal of the metal. Additionally, there were several patients with allergy to titanium.

A tricalcium-silicate-nanoparticle-containing cement (Biodentine) was developed to overcome the disadvantages of existing mineral trioxide aggregate (MTA) dental materials. This study aimed at evaluating the effects of Biodentine on the osteogenic differentiation of human periodontal ligament fibroblasts (HPLFs) in vitro and the healing of furcal perforations created experimentally in rat molars in vivo, in comparison to MTA. The in vitro studies performed the following assays: pH measurement using a pH meter, the release of calcium ions using a calcium assay kit, cell attachment and morphology using SEM, cell proliferation using a coulter counter, marker expression using quantitative reverse transcription polymerase chain reaction (qRT-PCR) and cell mineralized deposit formation using Alizarin Red S (ARS) staining. In the in vivo studies, MTA and Biodentine were used to fill the rat molar perforations. Rat molars were processed at 7, 14 and 28 days for analysis of inflammatory processes using hematoxylin and eosin (HE) staining, immunohistochemical staining of Runx2 and tartrate-resistant acid phosphate (TRAP) staining. The results demonstrate that the nanoparticle size distribution of Biodentine is critical for osteogenic potential at an earlier stage compared to MTA. Further studies are required to elucidate the mechanism of action of Biodentine in osteogenic differentiation.

The adhesion of zirconia and soft tissue is very important for the success of zirconia implants. The aim of this study was to characterize the effects of excimer laser treatment of zirconia on the adhesion of L929 fibroblasts. In this study, polished zirconia disks treated with an excimer laser were the experimental group and untreated zirconia disks were the control group. Surface roughness and contact angles of zirconia disks were measured. mRNA expression levels of integrin β1 and collagen type I α1 in L929 fibroblasts cultured on zirconia disks were measured using qRT-PCR. Cell morphology was evaluated using 3D laser microscopy and the expression of vinculin was characterized using confocal microscopy. There was no significant difference in the surface roughness of zirconia disks, but contact angles were significantly lower. mRNA expression of integrin β1 was significantly higher at 3, 6 and 24 h and of collagen type I α1 was significantly higher at 6 and 24 h. L929 fibroblasts tended to form elongated microspikes and vinculin colocalization in those microspikes. Furthermore, vinculin was strongly expressed in filopodia of L929 fibroblasts at 24 h. These results suggest that excimer laser treatment improves adhesion between zirconia disks and L929 fibroblasts.

Studies have indicated moderate to high choline transporter-like protein 1 (CTL1) expression in colon, pancreatic, breast, lung, and glioma cancers. However, studies on CTL1 in oral squamous cell carcinoma (OSCC), a highly invasive cancer, remain limited. We aimed to investigate the expression and localization of CTL1 in OSCC and its association with cell proliferation. Using in vitro experiments, we evaluated CTL1 expression and localization in the OSCC cell lines HSC-3 and HSC-4 by immunocytochemistry and western blotting. A cell proliferation assay was performed using hemicolinium-3, a choline uptake inhibitor. Using in vivo and ex vivo experiments, we assessed CTL1 expression in rat and human tongue cancer tissues by immunohistochemical and immunofluorescent staining. Here, we show that CTL1 is strongly expressed intracellularly and localized in organelles of HSC-3 and HSC-4 cells. CTL1 significantly accumulated around the nucleus in Ki67-positive cells with proliferative potential, suggesting increased production and transport of CTL1. Conversely, the number of cells in the HC-3 treated group in both HSC-3 and HSC-4 cells decreased. These results suggest that intracellular production of CTL1 is further increased in Ki67-positive cells, and choline uptake may lead to cell proliferation. In vivo and ex vivo experiments revealed high CTL1 expression in tongue cancer, with stronger expression in well-differentiated tumors than that in poorly-differentiated ones. Our study demonstrates that CTL1 is associated with OSCC proliferation and tumor differentiation. These findings suggest that CTL1 may function as a potential marker for tumor differentiation and progression of OSCC.

Background/Objectives: The optimal healing process following root canal treatment involves biological apical sealing through new cementum formation. Bone morphogenetic protein 7 (BMP-7) has recently gained attention as a potential regulator of cementoblast differentiation and periodontal regeneration. However, its effects on periodontal ligament fibroblasts (PDLFs) and the underlying mechanisms remain incompletely understood. This study aimed to investigate whether BMP-7 induces cementoblast-like differentiation of PDLFs both in vivo and in vitro via the BMP-SMAD signaling pathway. Methods: In a rat pulpectomy model, root canals were treated with or without BMP-7 and examined histologically and immunohistochemically for F-spondin (Spon1) expression. In vitro, human PDLFs were stimulated with BMP-7, and analyses of mineralization, cementoblast marker expression, alkaline phosphatase activity, and SMAD-1/5/9 phosphorylation were conducted. Results: Immunohistochemical analysis revealed that Spon1-positive regions increased around the apical area following BMP-7 treatment, suggesting the induction of cementoblast-like differentiation. In vitro, BMP-7 enhanced the expression of cementoblast-associated genes and mineral deposition while activating SMAD-1/5/9 signaling. Phosphorylation was suppressed by the BMP receptor inhibitor LDN-193189, indicating canonical BMP-SMAD pathway involvement. Conclusions: Although the specific concentration range of maximal activity remains to be determined, the findings collectively suggest that BMP-7 can promote cementoblast-like differentiation of PDLFs and may contribute to apical healing through cementum-related mechanisms. These results provide mechanistic and biological insights that support the potential of BMP-7 as a modulator for biologically favorable periapical tissue regeneration following root canal therapy.

The attachment of the oral epithelium to the abutment surface is crucial for the long-term success of dental implants. This study aimed to evaluate the attachment of human epithelial cells to anodized titanium surfaces. Anodized titanium discs were used as the experimental group, while machined titanium discs served as the control. Surface roughness and wettability were first measured for each group. Next, human epithelial cells were seeded onto each disc at a density of 4.0 × 10⁴ cells/cm² and evaluated 3, 6, and 24 h later for cell proliferation, as well as mRNA expression and protein levels of laminin and integrin β₄. Surface roughness was comparable between the two groups; however, wettability was significantly higher in the experimental group. Cell proliferation increased over time in both groups and showed no significant difference. Notably, the expression levels of both laminin and integrin β₄ were significantly higher in the experimental group at 24 h. Furthermore, protein localization of laminin and integrin β₄ was observed along the cell margins on the anodized surface. These findings suggest that anodization enhances epithelial cell attachment by promoting the expression and peripheral organization of key adhesion molecules.