The present study aimed to analyze novel mechanisms underlying Nrf2-mediated anti-apoptosis in periodontal ligament stem cells (PDLSCs) in the periodontitis oxidative microenvironment. We created an oxidative stress model with H₂O₂-treated PDLSCs. We used real-time PCR, Western blotting, TUNEL staining, fluorogenic assay and transfer genetics to confirm the degree of oxidative stress and apoptosis as well as the function of nuclear factor-erythroid 2-related factor 2 (Nrf2). We demonstrated that with upregulated levels of reactive oxygen species (ROS) and malondialdehyde (MDA), the effect of oxidative stress was obvious under H₂O₂ treatment. Oxidative molecules were altered after the H₂O₂ exposure, whereby the signaling of Nrf2 was activated with an increase in its downstream effectors, heme oxygenase-1 (HO-1), NAD(P)H:quinone oxidoreductase 1 (NQO1) and γ-glutamyl cysteine synthetase (γ-GCS). Additionally, the apoptosis levels gradually increased with oxidative stress by the upregulation of caspase-9, caspase-3, Bax and c-Fos levels in addition to the downregulation of Bcl-2. However, there was no alterations in levels of caspase-8. The enhanced antioxidant effect could not mitigate the occurrence of apoptosis. Furthermore, Nrf2 overexpression effectively improved the anti-oxidative levels and increased cell proliferation. At the same time, overexpression effectively restrained TUNEL staining and decreased the molecular levels of caspase-9, caspase-3, Bax and c-Fos, but not that of caspase-8. In contrast, silencing the expression of Nrf2 levels had the opposite effect. Collectively, Nrf2 alleviates PDLSCs via its effects on regulating oxidative stress and anti-intrinsic apoptosis by the activation of oxidative enzymes.

Background: The purpose of this study was to obtain measurements of the anatomical structures of the mandibular buccal shelf (MBS) using cone-beam computed tomography (CBCT) for the safe insertion of orthodontic mini-implants. Methods: The sample consisted of the CBCT records of 100 subjects. The scans were imported into a reconstruction program. Measurements were taken in the coronal plane for three different roots: the mandibular first molar distal root (6D), second molar mesial root (7 M), and second molar distal root (7D). The inferior alveolar nerve canal (IANC) was used as a reference to determine the safe insertion depth. The roots of the mandibular molars were used as a reference to determine the maximum safe insertion angle. Analysis of variance with post hoc analysis and Kruskal-Wallis H test with post hoc analysis were used for data analysis. Results: For the 6Ds, the average bone depth was 20.33 ± 3.6 mm, the average depth above the IANC plane was 9.55 ± 2.97 mm, and the average maximum safe insertion angle was 47.47 ± 18.94°. For the 7Ms, the average bone depth was 22.06 ± 2.85 mm, the average depth above the IANC plane was 10.71 ± 2.67 mm, and the average maximum safe insertion angle was 43.14 ± 15.26°. For the 7Ds, the average bone depth was 23.75 ± 2.86 mm, the average depth above the IANC plane was 12.12 ± 2.61 mm, and the average maximum safe insertion angle was 28.39 ± 10.96°. From anterior to posterior, the buccal bone depth and depth above the IANC gradually increased (P < 0.01), there was no significant difference in the maximum safe insertion angle between the 6Ds and 7Ms (P = 1.000), but the significant difference was observed between 6Ds and 7Ds, 7Ms and 7Ds (P < 0.000). Conclusions: The optimal implantation site for mini-implant in the MBS is at the buccal site corresponding to the second molar. A maximum insertion length of ≤ 12 mm and a maximum insertion angle which respects the long axial of the tooth root of ≤ 28° are recommended for the safe insertion of mini-implants in the MBS.

Introduction: Changes in oral neutrophil number and function may occur in patients after orthodontic treatment, affecting the oral immune microenvironment. However, the specific mechanisms are unclear. In this study, we describe the changes in the levels of neutrophil extracellular traps (NET) markers and inflammatory factors in the gingival crevicular fluid (GCF) and saliva of patients after orthodontic treatment and further explore the correlation between them.Methods: 68 patients underwent fixed orthodontic treatment in the Department of Orthodontics from January 2021 to June 2023 were selected. GCF and saliva samples were collected from the patients 1 day before orthodontic treatment and 2 h, 24 h, and 1 week after orthodontic treatment to evaluate changes in NET marker and inflammatory factors. The differences in and associations between NET markers and inflammatory cytokine levels in the GCF and saliva of patients were evaluated.Results: After fixed orthodontic treatment, the neutrophil elastase (NE), myeloperoxidase (MPO), citrullinated histone 3 (CitH3), and MPO-DNA in the GCF and saliva of the patients increased gradually, the interleukin (IL)-1β and IL-8 in the GCF increased gradually, and there were significant differences among the different time points (P<0.05). There was a positive correlation between the NE, MPO, CitH3, MPO-DNA, IL-1β and IL-8 in the GCF of patients at 2 hours and 24 hours after orthodontic treatment (P<0.05). There was a significant positive correlation between the GCF and saliva levels of NE, MPO, CitH3, MPO-DNA, IL-1β and IL-8 (P0.05).Conclusion: This study significantly reveals that NET marker levels in the GCF and saliva rapidly change following the initial orthodontic arch wire stress. The inflammation in periodontal tissues induced by orthodontic stress has the potential to trigger oral inflammation via the GCF. These findings are crucial for understanding the oral immune microenvironment changes during orthodontic treatment, providing a theoretical basis for preventing and treating orthodontic - related periodontal complications, thus having important implications for improving orthodontic treatment outcomes.