In this 2x2x2 factorial design study, 229 moderate to advanced chronic periodontitis patients stratified according to current smoking status were recruited in USA and Sweden. Patients were randomly assigned to 8 groups, all of which were treated by SRP plus none, one, two or three adjunctive treatments. Thus, patients were assigned to groups that did or did not receive Surg, LAb, SAb or LAb+SAb (All) providing 8 treatment combinations (Surg + All, Surg + SAb, Surg + LAb, Surg alone, SRP + All, SRP + SAb, SRP + LAb, SRP alone). Clinical, microbiological and immunological measurements were taken for 2 years (at baseline, 3, 6, 12, 18 and 24 months). To focus on changes diseased sites, analysis was restricted to sites with baseline pocket depth greater than 5 mm. (also, these were the only sites treated by LAb). In this report, main effects and interactions were evaluated for PD reduction and AL gain two years post therapy for 187 of patients. Mean values were computed for each treatment group and averages after 2 years were compared to baseline by ANOVA. Factorial ANCOVA was used to examine significance of differences between Surg or not, SAb or not and LAb or not for PD reduction and AL gain using baseline attachment level or pocket depth as covariates and including current smoking as a factor.