Effectiveness of liquorice gel as an adjunct to non-surgical periodontal therapy in chronic periodontitis: a randomized controlled, clinical and microbiological trial

Dental plaque bacteria are the primary cause of periodontitis, leading to inflammation of periodontal supporting tissues. For non-surgical therapy, scaling and root planing (SRP) is still the best option. Liquorice, a herbal agent rich in bioactive metabolites such as glabridin, glycyrrhizin, licoricidin, licochalcone A, and licorisoflavan A, has shown potential benefits in oral health. However, limited in vivo evidence exists regarding its efficacy in periodontitis. Therefore, this study aimed to evaluate the effectiveness of liquorice gel as an adjunct to SRP in patients with periodontitis. A randomized controlled clinical trial (RCT) was conducted involving 32 adults with moderate pockets and chronic periodontitis, who were randomly allocated to the two groups. Group A (test group, SRP + Liquorice gel), and Group B (control group, SRP). All patients underwent a comprehensive scaling and root planing procedure, received oral hygiene instructions, and were recalled after 21 days (baseline). Patients with persistent pockets were included in the study. Clinical parameters like probing pocket depth (PPD), clinical attachment level (CAL), sulcus bleeding index (SBI), and plaque index (PI), along with microbiological indicators, were assessed at baseline, 1 month, and 3 months. Statistical analysis was performed using Friedman’s test followed by the Mann–Whitney U test for intergroup comparison. Both groups demonstrated significant clinical and microbiological improvements from baseline to 1 month and 3 months ( p < 0.001). The test group receiving liquorice gel adjunctive to scaling and root planing demonstrated greater reductions in plaque index (PI) and sulcus bleeding index (SBI), along with comparatively greater suppression of Aggregatibacter actinomycetemcomitans and Porphyromonas gingivalis. Clinical attachment level (CAL) improvements were comparable between groups. Both groups also demonstrated significant reductions in probing pocket depth (PPD) over the study period; however, intergroup differences in PPD were not statistically significant at the evaluated follow up intervals. Adjunctive liquorice gel was associated with additional improvements in selected clinical and microbiological outcomes, particularly plaque accumulation, gingival bleeding, and selected periodontal pathogens, compared with SRP alone over the three-month follow-up period. Trial registration The study was prospectively registered with the Clinical Trial Registry of India (CTRI/2023/12/060526; registered on 19 December 2023).