Materials and methods. Twenty-four subjects with localized or generalized moderate-to-severe chronic periodontitis underwent scaling and root planing. One tooth in each quadrant with a probing depth of >4 mm was chosen for combined gel and SRP, with contralateral tooth as control (SRP treated site). Clinical assessment was carried out at baseline and 1 and 3 months later microbial assessment was performed by real-time PCR. Periodontal probing depth (PPD) was considered as primary outcome.

Results. Twenty patients completed the study. Baseline PPDs were 4.90±0.78 and 5.05±0.79 in the SRP and gel groups, respectively (P>0.05), which decreased to 3.67±0.59 and 3.7±0.83 one month after treatment and 3.25±0.65 and 3.38±0.79 three months after treatment. Although values decreased significantly in both groups after one and three months (P=0.001 in the SRP and P=0.001 in the gel group), the inter-group difference was not significant neither at one-month (P=0.47) nor at three-month (P=0.77) intervals. The only clinical parameters exhibiting statistically significant inter-group differences was BOP in both one-month (P=0.004) and three-month (P=0.0001) intervals. All the other clinical measurements showed significant decreases after one and three months in both sites but without inter-group differences. 

Conclusion. Subgingival application of xanthan chlorhexidine gel combined with scaling and root planing reduced bleeding of periodontal pockets. Clinical trials to evaluate effectiveness of this gel in aggressive and severe periodontitis modified by systemic factors are suggested.