Through loss-and gain-of-function experiments in knockout and transgenic mice, Forkhead box O (FOXO) family transcription factors have been demonstrated to play essential roles in many biological processes, including cellular proliferation, apoptosis and differentiation. Osteogenic differentiation from mesenchymal stem cells (MSCs)into osteoblasts is a well-organized process that is carefully guided and characterized by various factors, such as runt-related transcription factor 2 (Runx2), β-catenin, osteocalcin (OCN), alkaline phosphatase (ALP) and activating transcription factor 4

Periodontitis is a widespread oral disease that results in the loss of alveolar bone. Low-intensity pulsed ultrasound (LIPUS), which is a new therapeutic option, promotes alveolar bone regeneration in periodontal bone injury models. This study investigated the protective effect of LIPUS on oxidative stress in periodontitis and the mechanism underlying this process. Methods: An experimental periodontitis model was induced by administering a ligature . Immunohistochemistry was performed to detect the expression levels of oxidative stress, osteogenic, and osteoclastogenic markers in vivo . Cell viability and osteogenic differentiation were analyzed using the Cell Counting Kit-8, alkaline phosphatase, and Alizarin Red staining assays. A reactive oxygen species assay kit, lipid peroxidation MDA assay kit, and western blotting were used to determine oxidative stress status in vitro . To verify the role of nuclear factor erythroid 2-related factor 2 (Nrf2), an oxidative regulator, during LIPUS treatment, the siRNA technique and Nrf2 -/- mice were used. The PI3K/Akt inhibitor LY294002 was utilized to identify the effects of the PI3K-Akt/Nrf2 signaling pathway. Results: Alveolar bone resorption, which was experimentally induced by periodontitis in vivo , was alleviated by LIPUS via activation of Nrf2. Oxidative stress, induced via H 2 O 2 treatment in vitro , inhibited cell viability and suppressed osteogenic differentiation. These effects were also alleviated by LIPUS treatment via Nrf2 activation. Nrf2 silencing blocked the antioxidant effect of LIPUS by diminishing heme oxygenase-1 expression. Nrf2 -/- mice were susceptible to ligature-induced periodontitis, and the protective effect of LIPUS on alveolar bone dysfunction was weaker in these mice. Activation of Nrf2 by LIPUS was accompanied by activation of the PI3K/Akt pathway. The oxidative defense function of LIPUS was inhibited by exposure to LY294002 in vitro . Conclusions: These results demonstrated that LIPUS regulates alveolar bone homeostasis in periodontitis by attenuating oxidative stress via the regulation of PI3K-Akt/Nrf2 signaling. Thus, Nrf2 plays a pivotal role in the protective effect exerted by LIPUS against ligature-induced experimental periodontitis.

It was more reliable to study the associated factors on TMD with the exclusion of the possible confounding factors, and only unilateral chewing preference and psychological stress had a significant association with TMD. In addition, the salivary cortisol levels might assist to assess psychological stress in epidemiological research.

Human periodontal ligament stem cells (hPDLSCs) sheets play an important role in periodontal tissue engineering. Low‐intensity pulsed ultrasound (LIPUS) has been reported as an effective stimulus to regulate cell biological behavior. The present study aims to explore the potential of LIPUS to promote the formation and function of hPDLSC sheets (hPDLSCSs). Hematoxylin–eosin (H&E) staining, western blot, real‐time PCR, alkaline phosphatase (ALP), and alizarin red staining were used to evaluate the formation and osteogenic effect of LIPUS on hPDLSCSs in vitro. Hydroxyapatite with or without hPDLSCSs was transplanted in the subcutaneous pockets on the back of nude mice and histological analysis was performed. H&E staining showed increased synthesis of extracellular matrix (ECM) and real‐time PCR detected a significant increase in ECM‐related genes after LIPUS treatment. In addition, LIPUS could promote the expression of osteogenic differentiation‐related genes and proteins. ALP and alizarin red staining also found LIPUS enhanced the osteogenesis of hPDLSCSs. After transplantation in vivo, more dense collagen fibers similar to periodontal ligament were regenerated. Collectively, these results indicate that LIPUS not only promotes the formation and osteogenic differentiation of hPDLSCSs but also is a potential treatment strategy for periodontal tissue engineering.