Objective To investigate mutations in a family lineage with congenital absence of lower incisors, identify mutation sites and explore the effects of mutations on protein structure and function to provide new insights into the mechanisms underlying the development of congenital absence of lower incisors. Methods Whole-exome sequencing and Sanger sequencing were used to screen the possible causative genes in this family lineage. The validated genes were analyzed for functional prediction and amino acid conservation at the mutation sites. The three-dimensional structure of the protein was predicted by AlphaFold and PyMOL. Candidate gene expression was analyzed using mouse genome informatics and the spatiotemporal transcriptome atlas. Single-cell RNA sequencing data were used to analyze downstream pathways potentially regulated by the LENG9 gene. Results A family pedigree with congenital absence of lower incisors was identified during clinical practice. A phenotype of congenitally missing lower incisors was present in the proband and the proband’s younger brother. The proband had distal molar relationship and distal canine relationship on both sides, mild crowding of upper anterior teeth, scattered spaces in the mandible, and deep overbite as well as deep overjet, whereas the proband’s parents did not have a missing tooth phenotype. Through whole-exome sequencing, a mutation(c.392C>T: p.Arg131His) was identified in exon 1 of the LENG9 gene, and the arginine at position 131 was highly conserved among various species. Bioinformatics analyses showed that LENG9 was expressed in the jaws and teeth. GO and KEGG pathway annotation analyses indicated that LENG9 may play a role in the pathogenesis of congenital tooth agenesis by regulating oxidative phosphorylation-related pathways. Conclusion In this study, we report a family lineage with congenital absence of lower incisors and a de novo mutation in LENG9 (c. 392C>T: p. Arg131His), and the findings suggest that the mutation LENG9 may be the causative gene responsible for the congenital absence of lower incisors in this family lineage with congenital tooth agenesis.

Objective To reveal the role of family with sequence similarity member 20-b (Fam20b) in the development of craniofacial organs originating from the first branchial arch mesenchyme. Methods Pax2-Cre;Fam20b^f/f mice were generated and analyzed for postnatal skeletal morphology by whole-mount Alcian blue-Alizarin red staining, for histological features by Masson’s trichrome staining, for cell proliferation/apoptosis in the first branchial arch using Ki67/TUNEL assays, and for frontal bone mineralization by Von-Kossa staining, for glycosaminoglycan chains (GAGs) distribution by Alcian blue staining. Results At embryonic day 10.5 (E10.5), extensive apoptosis in proximal mandibular mesenchyme of Pax2-Cre;Fam20b^f/f mice led to a Pierre Robin sequence-like phenotype (micrognathia, glossoptosis and cleft palate) with microcephaly, delayed anterior fontanelle closure and condylar hypoplasia. Furthermore, Pax2-Cre;Fam20b^f/f mice exhibited the impaired vertical growth and hypomineralization of the frontal bone, as well as the reduced GAGs deposition, premature chondrocyte differentiation and enhanced subperichondral ossification in condyle. Conclusion Conditional knockout of Fam20b in the first branchial mesenchyme induced excessive apoptosis in proximal mandibular mesenchyme which resulted in micrognathia. Additionally, impaired ossification and mineralization of the frontal bone, combined with reduced GAGs deposition and premature maturation in condylar cartilage, suggests the suppressed intramembranous ossification and the enhanced subperichondral ossification by the deficient GAG chain synthesis.

Objective To study the role of circRNA_3498 targeted inhibition of autophagy in the destruction of periodontal tissue in mice with type 2 diabetes mellitus (T2DM). Methods The peripheral blood mononuclear cells from patients with T2DM and healthy volunteers were extracted for transcriptome sequencing and bioinformatics analysis of the differential expression of circRNA. The T2DM mouse model was constructed and the changes of autophagy related protein LC3B, interleukin(IL)-1β and IL-18 in the periodontal tissue structure of mice with T2DM were observed by immunohistochemical staining. Bone marrow-derived macrophages (BMDMs) were isolated from mice. The expression of circRNA_3498 in macrophages was interfered using lentivirus and siRNA. Western blot and ELISA were performed to detect the levels of LC3B, IL-1β, IL-18, as well as macrophage markers CD86 and CD206. Results Compared with the healthy people, circRNA_3498 was highly expressed in PBMCs of patients with T2DM (P<0.05). The expression level of LC3B was reduced in periodontal tissue of mice with T2DM, while IL-1β and IL-18 showed high expression (P<0.05). Lentivirus interference in BMDMs stimulated the expression of circRNA_3498, resulting in a significant decrease in the expression levels of LC3-Ⅱ/LC3-Ⅰ (P<0.05), a reduction in CD206 positive expression (P<0.05), an increase in CD86 positive expression (P<0.05), and an increase in the levels of IL-1β (P<0.01) and IL-18 (P<0.05). After siRNA-circRNA_3498 intervention to inhibit the expression of circRNA_3498, the results were reversed. Conclusion circRNA_3498 promotes inflammation of periodontal tissue by targeting inhibition of autophagy related proteins in mice with T2DM.

Objective To investigate the effect of low-level laser therapy (LLLT) on orthodontic tooth movement (OTM) in rats and its underlying mechanism. Methods An OTM rat model, which was combined with LLLT, was established. The mesial movement distance of the maxillary first molars was compared between the force-applied with LLLT group (F⁺L⁺ group) and the force-applied only group (F⁺L^- group) using micro-CT analysis. A cellular stress model was constructed using THP-1 cells subjected to compressive force and laser irradiation. mRNA sequencing was performed to identify differentially expressed genes (DEGs) between force-applied with laser irradiation THP-1 cells and force-applied only cells, followed by functional enrichment analysis. The expression changes of pathway-related genes and markers were further validated by quantitative real-time PCR (qRT-PCR) and Western blot. Results The mesial movement distance of the maxillary first molars was significantly greater in the F⁺L⁺ group compared to the F⁺L^- group (P<0.05). DEG analysis revealed significant enrichment in the mitophagy pathway in the F⁺L⁺ THP-1 cells versus the F⁺L^- cells. qRT-PCR and Western blot confirmed that the expression levels of the mitophagy-related genes OPTN and SQSTM1, whose products are key adaptors in the process, were decreased in the F⁺L⁺ cells. Concurrently, the key mitophagy initiators PINK1 and Parkin were also downregulated. Conclusion LLLT effectively accelerates OTM in rats. This acceleratory effect may be mediated through the inhibition of the mitophagy pathway.

Objective To investigate the risk factors associated with the need for surgical intervention in patients with oral and maxillofacial space infection(OMSI). Methods A total of 18 OMSI patients who underwent surgical intervention in our hospital were selected as the experimental group, and 24 OMSI patients who improved with only antibiotic treatment during the same period were selected as the control group. Statistical analysis was performed on patients’ baseline demographic characteristics, initial serological markers(including complete blood count, CRP, and composite indices such as NLR and PLR), clinical symptoms, and systemic disease history to retrospectively identify risk factors for surgical intervention in patients with orofacial space infections. Results In the univariate analysis, there were no significant differences(P>0.05)in baseline demographic characteristics(age and gender), clinical symptoms(whether respiration and swallowing were affected, and whether trismus was present), and history of systemic diseases(diabetes mellitus and cardiovascular disease) between the two groups.However, significant differences were observed in the percentage of neutrophils, absolute number of lymphocytes, absolute number of monocytes, and NLR between the groups(P<0.05). In the multivariate binary Logistic regression model, the percentage of neutrophils, absolute number of monocytes, and NLR were retained as risk factors for surgical intervention outcomes. The area under the ROC curve(AUC) was 0.86(95% confidence interval: 0.75-0.97). The Hosmer-Lemeshow test showed a P-value of 0.604(P>0.05), indicating a good fit of the model. Conclusion Abnormal levels of neutrophil percentage, absolute number of monocytes, and high NLR in the initial serological indicators of patients with oral and maxillofacial space infections are risk factors for the need for surgical intervention later on.

Objective To investigate the effects of the high-pull headgear-activator combined with a tongue crib appliance on the skeleton, teeth, lateral profile soft tissue, and hyoid bone in growing patients with skeletal Class Ⅱ high-angle malocclusion. Methods A randomized controlled study design was adopted. Seventy-six patients with skeletal Class Ⅱ high-angle malocclusion were randomly assigned to either the experimental group (n=38) or the control group (n=38). The experimental group received sequential treatment with the high-pull headgear-activator combined with a tongue crib, while the control group received treatment with the high-pull headgear-activator alone. Standard lateral cephalograms were obtained for all patients before and after treatment. Cephalometric analysis was performed using Dolphin software to compare the differences in treatment outcomes between the two groups. Results Compared to the control group, the experimental group showed significant reductions in the hard tissue measurements including L1-NB distance, L1-NB angle, lower incisor inclination (L1-MP), mandibular plane angle (FMA), and Y-axis angle (P<0.05). This indicated that the combined appliance was more effective in retracting the lower incisors and inducing counterclockwise rotation of the mandible. Regarding the lateral profile, mentum convexity (B-NPo) and mentolabial sulcus depth (Bs-LLPos) increased (P<0.05), while the soft tissue mentum retroversion angle (Bs-Pos-C) decreased (P<0.05), suggesting that the combined appliance better promoted mandibular development and significantly improved chin morphology. For hyoid bone position, the horizontal distance from the hyoid bone body to the orbitale (H-Or), the vertical distance from the hyoid bone body to the Frankfort horizontal plane (H-FH), and the vertical distance from the hyoid bone body to the palatal plane (H-PP) all decreased (P<0.05), while the distance from the hyoid bone body to the most anteroinferior point of the third cervical vertebra (H-C3) increased (P<0.05), indicating an anterior-superior displacement of the hyoid bone. Conclusion The high-pull headgear-activator combined with a tongue crib appliance can more effectively retract lower incisors, promote mandibular development, improve chin morphology, and guide the hyoid bone to move anteriorly and superiorly. It may represent an efficient comprehensive treatment approach for growing patients with skeletal Class Ⅱ high-angle malocclusion.

Objective To summarize the clinical significance of arthroscopy in the diagnosis and treatment of temporomandibular joint synovial chondromatosis(TMJ SC). Methods Seventeen cases with TMJ SC who were surgically treated by arthroscopy from September 2020 to September 2024 in The Peking University Stomatological Hospital were retrospectively analyzed. Data including preoperative examination, maximum incisal opening(MIO), and visual analog pain score(VAS) were analyzed and summarized. Results All the 17 TMJ SC cases were treated by arthroscopy, consistent with the postoperative pathological diagnosis. Postoperative review by MRI showed that joint cavity lesions disappeared. No recurrence was observed during postoperative follow-up, and clinical symptoms were improved to varying degrees. Conclusion For TMJ SC, arthroscopic surgery has advantages such as minimal trauma and wide indications, which can effectively alleviate clinical symptoms, improve temporomandibular function, and reduce the occurrence of postoperative complications.

Palatogingival groove (PGG) is a developmental anatomical defect located on the lingual root surface, frequently observed in maxillary lateral incisors. The periodontal attachment in this region is delicate, which makes it vulnerable to plaque accumulation and increases the risk of periodontal inflammation, leading to combined periodontal-endodontic lesions. This article reports a case of a combined periodontal-endodontic lesion in a left maxillary lateral incisor caused by PGG. The tooth was successfully preserved through microscopic root canal therapy combined with intentional replantation. Additionally, a literature review was performed to highlight the key diagnostic features and treatment strategies for PGG.

Stomatology is a highly practical subject, and the training of practical skills is an indispensable part of the training program for stomatology undergraduates. The traditional dental laboratory teaching has shortcomings such as insufficient practice opportunities and limited display content, but the virtual simulation experiment teaching changes the traditional teaching mode and provides an unprecedented opportunity for dental laboratory teaching reform. This paper reviews the development of dental virtual simulation system and its application in dental education, and discusses the advantages and current challenges of dental virtual simulation teaching, aiming at promoting the informatization and modernization reform of dental laboratory teaching, improving the quality of dental laboratory teaching and the clinical skills of dental students.

MXene nanomaterials, as emerging two-dimensional materials with exceptional physicochemical characteristics, have garnered significant attention in biomedical research owing to their excellent electrical, thermal, and mechanical properties as well as their biological activities, including antioxidant, anti-inflammatory, osteogenic, and antimicrobial properties. Emerging evidence highlights MXene’s groundbreaking immunomodulatory potential by scavenging reactive oxygen species (ROS), modulating the immune microenvironment, and targeting immune cell functions (e. g., macrophage polarization, dendritic cell activation, T cell differentiation, and neutrophil function). The immunomodulatory properties of MXene have demonstrated promising applications in various biomedical fields such as cancer therapy, bone defect repair, wound healing, antiviral infection, stem cell transplantation, and neural interface construction. In this paper, the immunomodulatory mechanism of MXene nanomaterials and their applications in biomedical fields are systematically reviewed. Furthermore, future research directions are proposed emphasizing the molecular mechanism of MXene’s interaction with immune cells and optimization of its biomedical properties.

The skeletal Class Ⅱ malocclusion is characterized by the maxillary protrusion and/or mandibular retraction. In recent years, the mandibular plane control of the skeletal Class Ⅱ malocclusion has gradually become a hot topic. For example, patients with mandibular retraction expected to improve the lateral appearance by the mandibular counterclockwise rotation; patients receiving molar distalization were concerned that the lateral appearance might be affected due to the potential mandibular clockwise rotation. The results in different articles were controversial. This review explored the effect of posterior tooth intrusion, posterior tooth extrusion, Class Ⅱ elastics, molar distalization and mandibular advancement on the mandibular plane angle to provide reference for clinicians.

Endo-periodontal lesion (EPL) involves both periodontal and pulpal tissues, often leading to a difficult-to-determine prognosis for the affected tooth and posing significant challenges to clinical practice. The 2018 World Workshop on Periodontal and Peri-implant Diseases and Conditions proposed a new classification standard for EPL. This article starts from the new EPL classification, centers on root damage, full-mouth periodontal condition, and lesion extent, and systematically reviews multiple prognostic factors for EPL-affected teeth by integrating aspects such as anatomical abnormalities (palatogingival grooves, complex root canal systems), systemic factors (diabetes, smoking), dentition condition, and sociopsychological factors. By summarizing recent research, it aims to provide scientific evidence and practical guidance for clinicians in making diagnostic and therapeutic decisions regarding EPL-affected teeth.

This paper focuses on the transformation of pulp regeneration technology from being limited to young permanent teeth to being extended to mature permanent teeth, and elaborates on the research progress and challenges of pulp regeneration in mature permanent teeth. In terms of research progress, through the analysis of clinical randomized controlled trials, systematic reviews and Meta-analyses, etc., it has been confirmed that the pulp regeneration technology for mature permanent teeth is feasible and has a high success rate. However, pulp regeneration in mature permanent teeth faces numerous challenges, such as infection control, sources of stem cells and scaffolds, sources of growth factors, and the aging microenvironment. Pulp regeneration holds great potential and challenges in the treatment of mature permanent teeth. Although the prospects are promising, a series of problems need to be overcome, and a sound and standardized treatment system needs to be established before pulp regeneration can be promoted as an effective treatment for diseases such as pulp necrosis of mature permanent teeth.