Figure. Mean change (± standard error) in subgingival bacterial load (n = 16/treatment group and time-point) from baseline (BL), and 2, 4, 8, and 12 wks later in each treatment group [Nc = negative control (no treatment), Rp = subgingival debridement via root planing, Rpsingle = root planing + single application of a mixture of beneficial bacteria, Rpmulti = root planing + multiple applications of a mixture of beneficial bacteria]. * represents a treatment strategy that is significantly different from Nc (p < 0.05). Arrows represent significant differences among treatment strategies (p < 0.05). (a) Total number of anaerobic species. (b) Total number of black-pigmented bacteria. (c) Total number of aerobic species. (d) Total number of P. intermedia species. (e) Total number of P. gulae species. (f) Total number of C. rectus species.