Because of the poor prognosis and of oral mucosal melanoma, and patients' short survival, large, randomised, clinical studies are difficult. We have investigated its demographic characteristics and analysed the effect of treatment, resection margins, and metastases on survival. We recorded age, sex, site of primary tumour, and types of treatment, survival, and metastases in 74 patients treated at the Department of Oral and Maxillofacial Surgery, Seoul National University Dental Hospital. Survival was analysed based on bony invasion, depth of invasion, and resection margins, and we found that it varied depending on the primary site (p=0.002), and declined with liver (p=0.001) or brain (p=0.033) metastases. The two-year survival according to the primary site was as follows: palate 85% (n=32), anterior maxillary gingiva 53% (n=13), mandible 58% (n=13), and posterior maxillary gingival 74% (n=10) and buccal mucosa 50% (n=4). The two-year survival was 34% (n=8) in patients with liver metastases and 23% (n=7) in patients with brain metastases. In cases of bony invasion (p=0.005), depth of invasion (p=0.042), unclear resection margin (p=0.023), or higher T stages (p=0.009), the survival declined considerably. Neck dissection did not affect survival (p=0.343). Survival of the patients given chemotherapy was significantly lower (p=0.013) and the two-year survival was 54.0%. The patients given radiotherapy showed no significant difference in survival compared with those not given radiotherapy (p=0.107). In conclusion, primary site, bony invasion, resection margins, depth of invasion and systemic metastases were critical to predict prognosis and selection of treatment of oral mucosal melanoma.

The periodontal complex consisting of alveolar bone, cementum, and periodontal ligaments (PDL) supports human teeth through the systematic orchestration of mineralized tissues and fibrous tissues. Importantly, cementum, the outermost mineralized layer of dental roots, plays an essential role by bridging the inner ligaments from the dental root to the alveolar bone. When the periodontal complex is damaged, the regeneration of each component of the periodontal complex is necessary; however, it is still challenging to achieve complete functional regeneration. In this study, we tried to control the regeneration of cementum and PDL by using a human PDL stem cell (hPDLSC) sheet engineering technology with the pretreatment of recombinant human BMP-2 (rhBMP-2). Isolated hPDLSCs obtained from extracted human teeth were pretreated with rhBMP-2 for in vitro osteogenic differentiation and grafted on the micro/macro-porous biphasic calcium phosphate (MBCP) blocks, which represent dental roots. The MBCPs with hPDLSC sheets were implanted in the subcutaneous layer of immune-compromised mice, and rhBMP-2 pretreated hPDLSC sheets showed higher mineralization and collagen ligament deposition than the no-pretreatment group. Therefore, the rhBMP-2-hPDLSC sheet technique could be an effective strategy for the synchronized regeneration of two different tissues: mineralized tissue and fibrous tissues in periodontal complexes.

Joo-Young Park, DDS, PhD Associate Editor of JKAOMS. JKAOMS 2023;49:105-6. https://doi.org/10.5125/jkaoms.2023.49.3.105

Understanding the homeostatic mechanism of invariant natural killer T (iNKT) cells is a critical issue in iNKT cell biology. Because interleukin (IL)-15 is required for the thymic generation of iNKT cells, IL-15 has also been considered necessary for the homeostasis of peripheral iNKT cells. Here, we delineated the in vivo cytokine requirement for iNKT cells, and we came to the surprising conclusion that IL-7, not IL-15, is the homeostatic cytokine for iNKT cells. Employing a series of experimental mouse models where the availability of IL-7 or IL-15 was manipulated in peripheral tissues, either by genetic tools or by adult thymectomy and cytokine pump installation, we demonstrate that the abundance of IL-7, and not IL-15, limits the size of the peripheral iNKT cell pool. These results redefine the cytokine requirement for iNKT cells and indicate competition for IL-7 between iNKT and conventional αβ T cells.