Osteosarcoma (OS) is the most common non-hematopoietic primary malignant bone tumour, accounting for around 19% of malignant bone tumours. It often occurs in the metaphyses of long bones, such as the distal femur and proximal tibia). OS of the jaw is rare, accounting for only about 6% of all OS cases, and the incidence of cervical lymph node metastasis is extremely low, with only a few case reports and small retrospective studies documented in the literature, and OS of the maxilla with contralateral lymph nodes metastasis is even rarer, with no relevant reports to date. In this paper, the present authors report a rare case of contralateral cervical lymph node metastasis of maxillary OS after surgery with no documented ipsilateral involvement and analyse the clinical manifestations, imaging manifestations and treatment of this case in the light of relevant literature. Based on this special rare case, its value and inspiration for the clinical diagnosis and treatment of OS of the jaw are explored.
 
Keywords: cervical lymph node metastasis, contralateral metastasis, osteosarcoma of the jaw

Bone, a dynamic and complex tissue, possesses limited regenerative potential, which poses formidable challenges in orthopaedic surgery and clinical dentistry. In particular, for large bone defects beyond critical size, compromised physiological conditions due to comorbidities (i.e. osteoporosis and type 2 diabetes) or severe trauma, its intrinsic healing capacity often falls short, necessitating advanced therapeutic interventions. For decades, research on bone regeneration has predominantly focused on biomaterial design, growth factor delivery and cell-based therapies. More recently, a paradigm shift has occurred, recognising the critical role of the bioelectric microenvironment in orchestrating bone homeostasis and repair. At the forefront of this exciting field, the pioneering work of Professor Xuliang Deng and colleagues at Peking University School of Stomatology has systematically elucidated the intricate interplay between electrical signalling cues and bone regeneration, paving the way for novel electroactive biomaterial strategies. These are summarised by the accompanying review article,1 which is published in this issue of the Chinese Journal of Dental Research.

Objective: To characterise the subset dynamics of innate lymphoid cells (ILCs) in human and murine periodontitis to elucidate their roles in disease progression.
Methods: Human gingival samples were harvested from periodontitis patients and healthy controls. A murine ligature-induced periodontitis model was established. Gingival ILC subsets (ILC1s, ILC2s, ILC3s) were analysed by flow cytometry.
Results: Human periodontitis exhibited elevated total ILCs (from 1.34% to 2.06%) and a pronounced increase in ILC3s (from 0.92% to 29.70%). In mice, 3 days post-ligation, there was a marked decrease in total ILCs (from 10.80% to 0.85%), primarily due to the depletion of ILC2s (from 81.55% to 60.08%), whereas ILC1s (from 1.41% to 15.07%) and ILC3s (from 0.75% to 2.87%) expanded. These changes became even more pronounced 7 days after ligation.
Conclusion: Species-specific ILC dynamics underscore distinct immunopathogenic mechanisms: human periodontitis is characterised by the predominance of ILC3s, whereas, in murine disease, there is an association with the loss of ILC2s and an expansion of pro-inflammatory ILC1s/ILC3s. These observations place ILC3s as central mediators in chronic human diseases and emphasise the necessity for therapeutic strategies tailored to target specific ILC subsets.
 
Keywords: innate immunity, innate lymphoid cells, murine ligature-induced periodontitis, periodontitis

Objective: To compare the sequential healing of maxillary sinuses grafted with two different xenogeneic bone substitutes processed at either a low (300°C) or high (1200ºC) temperature.
Methods: A sinus augmentation procedure was performed bilaterally in 20 rabbits and two different xenogeneic bone grafts were randomly used to fill the elevated spaces. Healing was studied after 2 and 10 weeks, in 10 rabbits during each period.
Results: After 2 weeks of healing, very small amounts of new bone were observed in both groups, and were mainly confined to close to the sinus bone walls and osteotomy edges. After 10 weeks of healing, new bone was found in all regions, with higher percentages in those close to the bone walls and to the osteotomy. In this period of healing, the proportion of new bone in the 300°C group was 20.0% ± 4.3%, and in the 1200ºC group it was 17.2% ± 4.3% (P = 0.162). In the 1200ºC group, translucent, dark fog-like shadows in regions of the grafts were hiding portions of new bone (interpenetrating bone network).
Conclusion: Both biomaterials provided conditions that allowed bone growth within the elevated space, confirming that both biomaterials are suitable to be used as a graft for sinus floor augmentation.
 
Key words: animal study, bone healing, histology, sinus floor augmentation, sinus membrane
 

Objective: To investigate the differences between temporomandibular articular fossa bone surface and the envelope surface of the mandibular condyle movement.
Methods: Thirty-four healthy adults underwent skull base and mandible scans using CBCT and performed mandibular border movement using the mandibular movement recording system. Landmarks of the fossa and tubercle were indicated and distance and angle parameters were measured on the 3D models reconstructed from the CBCT. The condyle movement envelope surfaces were formed according to models reconstructed from CBCT and the mandibular movement trajectory using computer simulation. The highest and lowest points of the envelope surface were indicated to create parameters. The data were analysed using a paired t test in SPSS (version 24.0, IBM, Armonk, NY, USA).
Results: The mandibular fossa bone surface was statistically different to the envelope surface for the height of the first peak of the envelope surface (3.280 ± 1.319 mm) and depth of the mandibular fossa (6.338 ± 2.389 mm) (the ratio was 51.75%), the height of the second peak of the envelope surface (1.463 ± 0.745 mm) and the height of the tubercle (2.000 ± 0.968 mm) (the ratio was 73.15%), and the downwards angle of the envelope surface (25.933 ± 7.539 degrees) and the posterior slope angle of the articular tubercle (35.059 ± 5.224 degrees) (the ratio was 73.97%).
Conclusion: The downwards angle of the envelope surface was statistically significantly smaller than the posterior slope angle of the articular tubercle, suggesting that the condyle movement is flatter than the mandibular fossa bone surface.
 
Key words: artificial fossa component, condyle movement, envelope surface, mandibular fossa bone surface, temporomandibular joint
 

Renal cell carcinoma (RCC) is often diagnosed in advanced stages and a third of patients have distant metastasis at diagnosis. Metastasis may be the first evidence of clear cell RCC in many cases. RCC most often metastasises to the lung, liver, bone, brain and thyroid; however, metastatic disease to the oral cavity, especially the mandible, is rare. The purpose of this study is to report a case of clear cell RCC metastatic to the mandible and review the literature. The mandible lesion underwent radical excision in this case. Notably, no metastatic lesions were detected in the lungs and liver in this patient until 15 months after the mandibulectomy. The patient lived for around 2.5 years after the diagnosis of RCC.
 
Key words: mandible, mandibular metastasis, renal cell carcinoma (RCC)

The dentine sialophosphoprotein (DSPP) gene is the only identified causative gene for dentinogenesis imperfecta type 2 (DGI-II), dentinogenesis imperfecta type 3 (DGI-III) and dentine dysplasia type 2 (DD-II). These three disorders may have similar molecular mechanisms involved in bridging the DSPP mutations and the resulting abnormal dentine mineralisation. The DSPP encoding proteins DSP (dentine sialoprotein) and DPP (dentine phosphoprotein) are positive regulators of dentine formation and perform a function during dentinogenesis. The present review focused on the recent findings and viewpoints regarding the relationship between DSPP and dentinogenesis as well as mineralisation from multiple perspectives, involving studies relating to spatial structure and tissue localisation of DSPP, DSP and DPP, the biochemical characteristics and biological function of these molecules, and the causative role of the proteins in phenotypes of the knockout mouse model and in hereditary dentine defects.
 
Key words: dentine mineralisation, dentine sialophosphoprotein, hereditary dentine defects, mutation