IL1A and chronic periodontitis: Interleukin-1 (IL-1) plays a leading role in mediating the destruction of periodontal tissues, and evidence from previous studies supports its important role in patients with periodontitis: IL-1 levels in gingival crevicular fluid are significantly higher in patients with chronic periodontitis than in periodontally healthy individuals, and particularly high levels have been observed in older patients compared with younger ones.