Methods:FORTY EIGHT systemically healthy patients with CP are included in this study. They were divided into two groups: 1) SRP + 0.75% Boric acid gel (BA group); 2) SRP + Placebo gel (Placebo group). At baseline, 3 month, and 6 months after treatment, clinical measurements, including plaque index (PI), modified sulcus bleeding index (mSBI), probing depth (PD), clinical attachment level (CAL) and radiographic parameters intrabony defect depth (IBD), percentage change in radiographic defect depth reduction (DDR%) were assessed.