CXCL13 and periodontitis: The scRNA‐seq study by Qian et al. reported that Major Histocompatibility Complex class II cell surface receptor HLA‐DR+ endothelial cells, CXCL13+ fibroblasts, and NLR Family Pyrin Domain Containing 3 (NLRP3) + macrophages were involved in the development of periodontitis.113