Osteocytes, which develop from osteoblasts, are recognized as the main cells embedded in mature bone tissue. The traditional notion is that osteocytes exclusively play a structural role, however, with the development of related research in recent years, the role of osteocytes in bone metabolism has been explored. Periodontitis is a chronic inflammatory disease initiated by plaque biofilm, and is the main cause of adult tooth loss. Clinically, periodontitis primarily manifests as attachment loss, bleeding on probing and other symptoms. Alveolar bone resorption is the most characteristic pathological change. Current research demonstrated that osteocytes sense mechanical stress, participate in bone remodeling, regulate mineral balance, and participate in endocrine function. Thus, these cells play an important role in bone homeostasis and systemic metabolic balance. Osteocytes are actively involved in the development of periodontitis through the high expression of receptor activator of nuclear factor kappa B ligand (RANKL), secretion of sclerostin, and effect on apoptosis, senescence and autophagy. In the future, the detection of bone cell metabolism-related products will have certain application prospects for the clinical evaluation of periodontitis prevention and treatment. Therefore, this paper reviewed the role of osteocytes in bone homeostasis and the relationship between osteocytes and periodontitis, to provide new ideas for the prevention and treatment of periodontitis.

As a highly conserved signal pathway in evolution, the WNT signaling pathway plays an essential role in periodontium growth, development and injury repair. The Axin-associated protein Axin2 is a direct effector molecule of the WNT signaling pathway and labels WNT-responsive cells well. Studies have shown that Axin2-positive (Axin2⁺) cells in the periodontium have the potential for self-renewal, replication and multidirectional differentiation. This article reviews the temporal and spatial distribution of Axin2⁺ cells in periodontal tissue development and the role and regulatory mechanism of Axin2⁺ cells in periodontal tissue development, regeneration and tissue remodeling to provide new ideas for periodontal tissue regeneration. The literature review showed that Axin2⁺ cells were the main cell source of periodontium development, and Axin2⁺ cells played essential roles in tooth extraction socket healing, implant osseointegration, periodontal tissue remodeling and junctional epithelium regeneration. The function of Axin2⁺ cells was positively regulated by the canonical WNT signaling pathway. However, the regulatory mechanisms of other signaling pathways on Axin2⁺ cells remain to be elucidated.

Hydrogen-rich water (HRW) shows excellent antibacterial, anti-inflammatory, antioxidant, and wound-healing properties and plays a positive role in the treatment of various diseases, such as brain injury, kidney injury, and periodontitis. Current studies found that HRW can inhibit periodontopathogenic biofilm formation, inhibit oral connective tissue and bone tissue destruction, and show anti-inflammatory and antioxidant properties in periodontitis. Additionally, HRW can alleviate periodontal tissue damage by inhibiting oxidative stress and up-regulating the expression of antioxidant enzymes, such as glutathione peroxidase and superoxide dismutase. HRW exerts anti-inflammatory effects by regulating the nuclear factor erythroid 2-related factor 2 and mitogen-activated protein kinase pathways, which are closely associated with inflammation. Additionally, HRW inhibits the expression of inflammatory cytokines, such as interleukins, inhibits the growth and proliferation of bacterial plaque biofilms, and down-regulates glycosyltransferases and glucan-binding proteins to prevent bacterial adhesion and subsequent development of periodontitis. Furthermore, HRW has a positive effect on the expression of various cell growth factors, α-smooth muscle actin, and type Ⅰ collagen, which promotes wound healing. Current clinical studies have demonstrated the biological safety of HRW (to a certain extent) and reported no adverse reactions. However, most studies on HRW in oral diseases are preclinical in vivo and in vitro studies. Therefore, further clinical studies are required to validate the therapeutic significance and optimal therapeutic regimen of HRW in human periodontitis. This article aims to review the therapeutic role and the underlying mechanisms of HRW in periodontitis.