Fig. 4

Pairwise comparison of major peaks in serum and saliva samples of the four groups. A-G Major peaks of Ramen spectra in serum samples; The selected peaks in serum samples revealed no notable difference among the 4 groups; H-P Major peaks of Ramen spectra in saliva samples; The mean Raman intensities of the major peaks at 747 cm⁻¹ (hemoglobin), 1120 cm⁻¹ (lipid), 1300 cm⁻¹ (Fatty acids), 1328 cm⁻¹ (adenine) and 1574 cm.⁻¹ (protein) were higher in the PC-Perio group than those in the H-Perio group (P < 0.05). Inter-group difference of continuous variables was determined by Bonferroni-corrected ANOVA or Kruskal–Wallis test as appropriate. *P < 0.05; **P < 0.001