Statistical analysis
PD
Sample size was calculated based on the primary outcome parameter (mean PD) from a study utilizing 300 mg of n-3 PUFAs during non-surgical periodontal treatment [The statistical unit was the patient, and all sites with PD ≥ 4 mm at baseline were considered for the statistical analyses. The primary outcome variables were mean PD and PD change (Δ) at 3 and 6 months. Secondary variables were mean CAL, REC, BOP, FMPI and their changes (Δ), number of sites with PD ≥ 4 mm and BOP, the percent of closed pockets (PD ≤ 4 mm without BOP) at 3 and 6 months in relation to baseline, and number of key periopathogens and serum lipid concentrations at 6 months in relation to baseline.All continuous variables were expressed as the mean ± SD. Statistical comparison of differences within the groups at three time points were determined by the one-way ANOVA test. Scheffe’s test was used for multiple comparisons as a post hoc test when statistical significances were identified in the ANOVA test. The differences between test and control groups were analyzed with the t-test. The Kolmogorov–Smirnov test and the Fisher’s test were used for verification of normal distribution and analysis of variances. The differences in the changes (Δ) from baseline to 3/6 months between the groups were analyzed using Mann–Whitney U test. All tests were conducted at the significance level of α ≤ 0.05.