The Shapiro Wilk test was used to investigate whether or not the data were normally distributed. Continuous variables with unequal variances were compared by means of Welch and Tamhane's T2 post-hoc test for BMI, PD, CAL and the levels of 8-OHdG. The comparison of the age, GI, PI and BOP was analyzed using the Kruskal-Wallis non-parametric test followed by post hoc group comparisons with the Bonferroni-adjusted Mann-Whitney U test. Paired Student's t-test or Wilcoxon rank-sum test was used to compare the measurements at two points (baseline and after SRP). The Spearman's rank correlation test was also used to detect the relationship between biochemical and clinical findings.