CD68 and Peri-Implantitis: According to peri-implantitis severity classification [19], slight (n = 6), moderate (n = 6), and advanced (n = 6) cases revealed CD68 expression mean values of 13% (95% CI 7–19), 15.8% (95% CI 10.9–20.8), and 12.8% (95% CI 11–14.8), respectively.