Pharmacological studies revealed that thiolutin (THL) prevented or treated NLRP3-associated inflammatory diseases. The activation of the NLRP3 inflammasome plays a crucial role in the pathogenesis of periodontitis. However, no study has demonstrated the therapeutic potential of THL in periodontitis. Human gingival fibroblasts (HGFs) were incubated with 1 μg/mL of lipopolysaccharide (LPS) and 5 mM of adenosine triphosphate (ATP), activating the NLRP3-mediated inflammatory response and intervened with THL at doses of 10 nM. Subsequently, cell viability, lactate dehydrogenase release, cell apoptosis, the contents of proinflammatory and oxidative stress factors, including superoxide dismutase (SOD), glutathione (GSH), malondialdehyde (MDA), reactive oxygen species (ROS), interleukin (IL)-6, tumor necrosis factor (TNF)-α, IL-1β, and IL-18, and the expression levels of NOD-like receptor protein 3 (NLRP3)-related proteins were detected by CCK-8, propidium iodide fluorescence staining, enzyme-linked immunosorbent assay, quantitative reverse transcription-polymerase chain reaction, and western blotting, respectively. THL countered the inhibitory effects on cell viability and promoted the effects on cell apoptosis, production of IL-6, TNF-α, IL-1β, and IL-18, and NLRP3-related proteins induced by LPS/ATP stimulation. Furthermore, the SOD, GSH, ROS, and MDA levels were not affected by THL intervention, suggesting that the recovery of LPS/ATP-induced HGF injury by THL depends on inflammatory response but not oxidative stress. The present study demonstrated that THL repressed the release of inflammatory factors mediated by NLRP3 inflammasome activation in LPS/ATP-induced HGFs rather than oxidative stress levels to ameliorate inflammatory injury and pyroptosis and exerted protective effects on HGFs.

The aim of this study was to evaluate the effects of microneedling (MN) combined with an injectable hyaluronic acid (HA) gel on soft tissue regeneration in a rat gingival recession model. In this split-mouth study, seven Sprague-Dawley rats with artificially created gingival recession areas were randomized for treatment with MN+HA or HA. HA was injected in the gingival recession area of the right maxillary molar and MN+HA was performed in the gingival recession area of the left maxillary molar of rats, both 3 times, 7 days apart. At 2 weeks after the last treatment, each rat was euthanized and the surgical areas, including the maxillary first molar and periodontal tissue, were excised and evaluated by stereomicroscopy, histochemistry and enzyme-linked immunosorbent assay. Physical parameters representing periodontal soft tissue regeneration, including the vertical distance from the lowest point of the gingival margin to the crown margin along the long axis of the tooth, the gingival height and the gingival thickness, were significantly improved in the MN+HA group compared with the HA group. The MN+HA group showed a significant increase in the expression of Type 1 collagen compared with the HA group. Thus, this study demonstrates for the first time that the application of MN combined with a HA gel, a nonsurgical therapy, in a rat animal model of gingival recession improves the degree of gingival recession, increases gingival thickness and promotes periodontal soft tissue regeneration. Secondly, the effect of MN combined with the HA gel injection to promote periodontal soft tissue regeneration was significantly better than the HA gel injection alone, which suggests that the participation of MN effectively promotes periodontal soft tissue regeneration.

This study aimed to compare the implant stability of an implant-porous titanium complex with that of an implant-porous hydroxyapatite complex. Implant-porous titanium and implant-porous hydroxyapatite complexes were placed in the tibia of four New Zealand white rabbits. After 4 weeks, the implant stability quotients (ISQs) were measured. Histological observations and histomorphometric measurements were performed. There was no significant difference in the ISQ values and bone implant contact ratios between both groups. In contrast, the newly formed bone area ratios were significantly lower in the implant-porous titanium than in the implant-porous hydroxyapatite. Histologically, osteoconduction was observed in both groups in the upper cortical bone region; however, lesser new bone was formed in the lower bone marrow region in the implant-porous titanium than in the implant-porous hydroxyapatite. In conclusion, implant-porous titanium and implant-porous hydroxyapatite complexes have favourable implant stability. However, osteoconduction was insufficient with the implant-porous titanium complex compared with the implant-porous hydroxyapatite complex. This may be improved by making titanium bioactive through surface treatment or other means.

Autophagy and senescence play important roles in cellular homeostasis. However, it remains unknown whether autophagy positively or negatively affects cellular senescence. We cultured human keratinocytes (HaCaT) with or without etoposide (ETO) treatment to examine whether autophagy mediates induction of DNA damage response (DDR)-related cellular senescence. DDR-related cellular senescence was observed in 5.0-μM ETO-treated cells through increased expression of γH2AX, p53 binding protein1 (53BP1), and senescence-associated β-galactosidase (SA-β-Gal), whereas no senescent changes were observed in 1.0-μM ETO-treated cells. Senescent cells also showed increased expression of activated ataxia-telangiectasia mutated (ATM) signaling pathway-related factor, such as pATM, pp53, and p21. The 5.0-μM ETO-treated senescent cells showed downregulated expression of LC3 and Beclin-1, but expression of Rubicon, which is a negative regulator of autophagy, was upregulated even though no senescent-induced cells (1.0-μM treated cells) revealed increased expression of LC3 and Beclin-1. The 1.0-μM ETO-treated cells pretreated with N-acetylcysteine (NAC) showed increased expression of senescent markers and p21 as well as Rubicon. This study revealed that Rubicon-regulated autophagy mediates ETO-induced DDR-related cellular senescence through the activation of the ATM/p53/p21 signaling pathway. Impaired autophagy due to Rubicon overexpression accelerates induction of DDR-related cellular senescence.

Recent years have seen attempts to perform access cavity preparation in a minimally invasive manner from the standpoint of preserving the tooth substance. However, age-related changes in pulp cavity morphology are unavoidable and may sometimes hinder the operator. Few studies appear to have addressed these changes in detail. The aim of this study was to identify age-related differences in the side walls of the pulp chamber for access cavity preparation using ultra-high-resolution micro-computed tomography (micro-CT). Specimens were human extracted maxillary first molars showing no caries, attrition, or abrasion, classified by age at extraction into adult (age 21-40 years, n=20), middle-aged (age 41-60 years, n=20), and senior (age ≥61 years, n=22) teeth. Specimens were scanned by micro-CT, with the resulting data used to create 3-dimensional (3D) reconstructions for examination of pulp cavity morphology. We also measured dentin thickness using reference lines and measurement lines, and compared the differences between age groups. The observations and measurements of dentin thickness made using these 3D reconstructions showed that in senior teeth, narrowing of the pulp cavity between the mesial and distal side walls was evident from the midline to the pulp chamber floor compared with adult teeth. Narrowing of the pulp cavity was also evident from immediately below the midline of the distobuccal wall to the pulp chamber floor. The dentin thickness of each side wall was measured, and the results showed that senior teeth were significantly thicker than adult teeth in the mesial, distal and distopalatal side walls. These results suggest that when preparing access cavity in senior patients, it is necessary to remove the distobuccal side wall in addition to the mesial and distal side walls for identification of canal orifice in maxillary first molar.

In organs, multiple functionally differentiated cells and stem cells are organized to express specific functions through a series of complex interactions. The Wnt signaling pathway is deeply involved in these processes throughout life. The dependence of Wnt signaling on spatiotemporal specificity and the changes in vivo interactions caused by the balance and distribution of Wnt ligands and antagonists. Regeneration is thought to involve reconstitution of the growth mechanism, and thus control of stem cells and tissue regeneration has been attempted by mimicking canonical Wnt signals. Wnt10a has been reported to be involved in tooth development and regeneration. These findings indicate the importance of understanding and reproducing involvement of Wnt10a in dental pulp regeneration for development of regenerative dental treatment. Accordingly, we examined the spatiotemporal specificity of Wnt signals involved in dental pulp regeneration by morphologically examining changes in Wnt signals over time in regenerated dental pulp using ectopic tooth root implantation. Expression levels of Wnt10a and DKK1 in regenerated dental pulp suggest that Wnt expression does not increase continuously with time as regeneration increases, which reflects the spatiotemporal specificity of Wnt. In addition, the Dkk1 expression kinetics had a phase shift relative to those of Wnt10a: Dkk1 expression was low when that of Wnt10a was high, and Wnt10a expression decreased when Dkk1 expression increased. These results suggest that canonical Wnt signals have an elaborate control mechanism in regenerated pulp, as suggested in previous reports. Moreover, Wnt reflects the percentage of regenerated pulp. Therefore Wnt is a potential biomarker of pulp regeneration.