Objective: To evaluate and compare the clinical effects between locally delivered Andrographis paniculata gel (AP gel) and 10% doxycycline gelas an adjunct to scaling and root planing (SRP) in the treatment of chronic periodontitis subjects, who were involving on supportive periodontal therapy (SPT).

Materials and methods: Twenty nine systemically healthy subjects with chronic periodontitis, who were involving on supportive periodontal therapy, were recruited in this split mouth, single–blinded, randomized controlled clinical trial (RCT), 6 months study. The subjects had to have three non–adjacent single root teeth with probing depth (PD) ≥ 5 mm and bleeding on probing (BOP), they had not recieved periodontal therapy within 6 months before study. The disease sites were randomly treated with; SRP plus AP gel, SRP plus 10% doxycycline gel, or SRP alone. Probing depth (PD), relative attachment level (RAL), gingival index (GI), plaque index (PI) and BOP were recorded at baseline, 3 and 6 months after treatments.

Results: Clinical changes were significantly improved in all treatment groups (p<0.05). When compared the clinical outcomes among the treatments, found that the treated sites with SRP plus AP gel or SRP plus 10% doxycycline gel were similar. These two treatment modalities can increased more number of treated sites with RAL gain >2 mm and reduced GI better than SRP alone.

Conclusion: The local application of AP gel or 10% doxycycline gel as an adjunct to SRP showed better improvement of clinical parameters. These benefit may be reduce the need of periodontal surgery in some patients or reduce the frequency of periodontal maintenance visit.