In China, the prevalence of diabetes is increasing each year. Diabetic periodontitis, as a major complication of diabetes, retains a strong bidirectional correlation with diabetes. Periodontitis increases the risk of diabetes, and hyperglycemia aggravates periodontal inflammation. In recent years, efficient treatments for diabetic periodontitis have been increasingly emphasized, and the prevention and control of diabetic periodontitis remain difficult. It is very challenging to find the best way to recognize risk factors and increase the diagnosis rate. Deeply understanding the local and systematic biological features of diabetic periodontitis could lead to the development of clinical preventive and therapeutic strategies. This article reviews the clinical and biological characteristics of diabetic periodontitis and its treatment progress from a systemic and local perspective, with the aim of extending the work on the prevention and treatment strategies for diabetic periodontitis.

Gingival pigmentation is a nonplaque gum disease. Patients are often afraid to communicate with others because of gum color problems, which affect the social and mental health of patients. The commonly used treatment methods for gingival pigmentation include scalpel excision, gingival grinding, laser therapy, cryosurgery and electrosurgery. In this paper, the progress of gingival pigmentation treatment was reviewed in terms of bleeding, pain, tissue healing and recoloring. The results showed that the clinical effect of laser treatment was better. Among them, the semiconductor laser had more advantages in reducing bleeding, pain and the restaining rate, while the Er:Cr:YSSG/Er:YAG laser performed better for promoting tissue healing. Clinicians can choose the best kind of laser to use according to the actual situation. For patients with thin gingival biotypes, floating gingival transplantation or substitute materials can be selected to restore the gingival morphology. With the in-depth study of melanin regulation mechanisms, various drugs, such as ascorbic acid, natural peptides, synthetic peptides and derivatives, may be the main research direction for the treatment of gingival pigmentation in the future.

Periodontitis is a chronic inflammatory disease that affects the tooth-supporting tissues, and it constitutes a major global public health concern. Methylation modifications, including DNA methylation, histone methylation, and RNA m⁶A modification, represent reversible processes coordinately regulated by methyltransferases, demethylases, and binding proteins. In periodontitis, aberrant methylation modifications suppress Toll-like receptor 2 expression, leading to oral microbial dysbiosis. These modifications further disrupt normal immune regulatory functions through C-C motif chemokine ligands, Fc-γ receptor-mediated phagocytosis, and NF-κB signaling pathways, resulting in localized immune-inflammatory imbalance in periodontal tissues. In addition, various methylation modifications regulate the expression of Runt-related transcription factor 2 (RUNX2), osteoblast-specific transcription factor Osterix (OSX), and receptor activator of nuclear factor-κB ligand (RANKL), thereby interfering with osteoclast and osteoblast differentiation, disrupting bone homeostasis, and ultimately driving alveolar bone resorption. Methylation-related biomarkers demonstrate promising potential for periodontitis screening and prognostic evaluation. While numerous abnormally methylated sites have been identified in periodontitis, the precise signaling pathways and comprehensive epigenetic regulatory networks remain to be fully elucidated. This review systematically summarizes the functional roles of DNA methylation modifications in the pathogenesis of periodontitis and explores their potential value in etiological studies, diagnostic biomarker discovery, and targeted therapeutic interventions, with the aim of providing novel perspectives for periodontitis prevention and treatment strategies.

T helper cells (Th cells) play an important role in periodontitis. During the progression of periodontitis, the levels of pro-inflammatory cytokines such as INF-γ and IL-17, which are produced by Th1 and Th17 cells, are elevated, while the levels of anti-inflammatory cytokines such as IL-4 and TGF-β, which are secreted by Th2 cells and regulatory T cells (Tregs), are diminished. Interventions using mesenchymal stem cells (MSCs) or their exosomes can alter the dynamics of helper T cell populations and their associated cytokine profiles, thereby mitigating the bone loss associated with periodontitis or even promoting bone regeneration. Mesenchymal stem cell-derived exosomes (MSC-exos) have been shown to directly modulate Th cell activity through the proteins and microRNAs they transport. Recent studies indicate that MSC-exos carry immune-suppressive protein molecules: PD-L1 and IDO contribute to regulating the balance between Th17 and Tregs; TGF-β inhibits the proliferation of T lymphocytes while facilitating differentiation into Tregs by sustaining forkhead box protein O3 (FOXP3) and Smad expression; and CD73 catalyzes the conversion of monophosphate adenosine into adenosine, which interacts with A2A receptors on Th1 cells to induce apoptosis in Th1 cells. In addition, microRNAs exhibit immunoregulatory functions: periodontal ligament stem cell-derived exosomes contain miRNA-155-5p, which targets sirtuin-1 to suppress Th17 cell differentiation. Furthermore, evidence in rat models of periodontitis suggests that these exosomes may also carry miR-205-5p targeting XBP1 to restore the balance between Th17 and Tregs. Dental pulp stem cell-derived exosomes reestablish this balance via the miR-1246/Nfat5 axis. Bone marrow mesenchymal stem cell-derived exosomes harbor miR-1246, which targets ACE2 to promote differentiation towards Tregs. Moreover, MSC-exos can indirectly enhance the differentiation of Tregs through interactions with other immune entities, such as antigen-presenting cells or macrophages. This article reviews the changes and roles of helper T cells in periodontitis, as well as the regulatory role of exosomes on helper T cells, hoping to provide new ideas for immunotherapy in the treatment of periodontitis.

Inflammatory bowel disease (IBD) is a group of chronic, non-specific inflammatory diseases of the gastrointestinal tract including primarily Crohn’s disease and ulcerative colitis, which are affected by multiple factors. Periodontitis is a type of disease characterized by plaque biofilm as the initiating factor and chronic destruction of alveolar bone via resorption. An increasing number of studies have reported a correlation between periodontitis and IBD, but the relationship between the two remains unclear. In this study, we explore the internal relationships between the two diseases from three dimensions, including epidemiological, biological, and associated treatment evidence. Based on epidemiological evidence, periodontitis was found to be associated with an increased risk of IBD, which also affects periodontal health, although the bidirectional correlation needs to be further studied by expanding the number of data sources. From the biological evidence, both clinical studies and animal experiments show that IBD and periodontitis are interconnected. Based on evidence from association therapy, drugs that are beneficial for the treatment of IBD are also effective in the prevention and treatment of periodontitis. In addition, drugs that are good for improving periodontitis can also significantly alleviate IBD. The interaction mechanism between IBD and periodontitis includes the microbial pathway and the immunization route. The microbial pathway refers to the increase in the probability of intestinal tract ectopic colonization by oral bacteria transmitted through the mouth-gut axis or blood, resulting from the increase in the proportion of opportunistic pathogens in the oral cavity of patients with periodontitis and the influence of IBD on the secretion of gastric juice and the balance of intestinal flora. These microorganisms further aggravate IBD inflammation by releasing virulence factors, destroying the intestinal mucosal barrier, and triggering inflammatory responses. In periodontitis, adaptive immunity is activated in the mouth, leading to the production of a large number of immune cells, including Th17 containing the intestinal homing marker α4β7 integrin on their surface. Increased ligand expression of α4β7 integrin in the intestinal mucosa of patients with IBD accelerates oral Th17 cell transfer to the intestine, thereby worsening intestinal inflammation. In parallel, the abnormal expression of cytokines, such as TNF-α, IL-1β, IL-10, IL-6, IL-21, soluble CD40 ligand (sCD40L), IL23, and INF-γ, in the oral cavity of patients with IBD was observed, suggesting that IBD may affect periodontitis through immunity. These cytokines represent targets for the treatment of both diseases and provide a research direction for their prevention and treatment in the future.