“…However, given that the GCF originates from a complex repertoire of cells within the periodontal tissues, such as gingival epithelial cells, fibroblasts, and other immune cells (Khalaf, Lonn, & Bengtsson, ), it is not possible to pinpoint the origin of the apoptotic signals or to assign them to a specific cell type. In addition, periodontopathogens can induce apoptosis by affecting caspase‐3 in gingival epithelial cells (Fujita et al, ) and fibroblasts (Alamri et al, ), by influencing p53 in human osteoblasts (Zhang et al, ) and fibroblasts (Alikhani et al, ), and by regulating TRAIL in gingival cells (Lucas et al, ) and osteoblasts (Mori et al, ). Thus, the source of the apoptotic cells releasing caspase‐3, p53, and TRAIL into the GCF cannot be fully delineated because of the rich cellular content of the periodontal tissues and sulcus.…”