Background: Chronic periodontitis is one of the most common causes of tooth loss and is rather common in the population. Treating chronic periodontitis remains a challenge for dental practitioners. The purpose of this study was to assess the clinical effects of sub-gingival application of 0.2% hyaluronic acid gel after root planing in the treatment of chronic periodontitis.

Materials and Methods: In this split mouth study, 733 periodontal pockets of 28 patients with moderate to severe chronic periodontitis were chosen for investigation. They were divided into 2 groups: control group and experimental group. The experimental group received sub-gingival administration of 1 ml of 0.2% hyaluronic acid gel into each pocket immediately after root planing and then after 1 week, 2 weeks and 3 weeks. Clinical parameters were assessed at baseline and 6 weeks after root planing. Subgingival plaque was assessed at baseline and 6 weeks after root planing. Quantitative real-time PCR for Porphyromonas gingivalis (Pg), Treponema denticola (Td), Fusobacterium nucleatum (Fn) Tannerella forsythia (Tf) were performed at the same time.

Chronic periodontitis is one of the most common causes of tooth loss and is rather common in the population. Treating chronic periodontitis remains a challenge for dental practitioners. There are new applications of materials to promote the healing process and increase the effectiveness of treatment of CP such as antimicrobial and healing support agents which were used at scaling and root planing (SRP) phase with the desire to improve the effectiveness of treatment and reduce the frequency of surgical phase, in order to reduce treatment cost for patients. One of those materials is hyaluronic acid (HA).

HA is a polysaccharide with many important roles: maintaining stability, adjusting the viscosity of biological fluids, homeostasis, adjusting osmotic pressure, supporting structures ... The wide application of HA in medicine is due to its capability of binding multiple water molecules, bimproving tissue hydration and preventing mechanical damage, bacteriostatic, anti-inflamatory, osteoinductive.

This study was the first to be conducted in Vietnam to evaluate the effect of HA on the response of periodontal tissue in chronic periodontitis and its bactericidal efficiency. The bacteria we study were Porphyromonas gingivalis (Pg), Treponema denticola (Td), Fusobacterium nucleatum (Fn) Tannerella forsythia (Tf), which were important species in periodontitis development. The research results can supplement scientific evidence about the effects of this compound and clarify the usefulness of HA in clinical chronic periodontitis treatment.

We performed a randomized, controlled clinical trial with split-mouth design. Study procedure consisted of information collecting, clinical measurements and, data analysis. The study was conducted in full accordance with the World Medical Association Declaration of Helsinki 2000 and was registered at ClinicalTrials.gov No. 312/ĐHYD-HĐĐĐ.

Participants from 18 years old with a minimum number of 20 teeth who came for periodontitis treatment, were recruited at the Department of Periodontology, Faculty of Odonto-Stomalogy, the University of Medicine and Pharmacy at Ho Chi Minh City (FOS-UMPH). We selected patients with at least 3 teeth in the contralateral quadrants diagnosed with moderate or severe chronic periodontitis according to AAP (2015): gingival bleeding at examination, ≥5mm periodontal pocket depth, bone resorption on X-ray film ≥16% or >3mm root length.

Patients who were allergic to ingredients, being pregnant/lactating, smoking, alcoholic; who had undergone periodontal therapy in the last 6 months, received antibiotic therapy, anti-inflammatory agents, statins, drug induced gingival enlargement (such as phenytoin, cyclosporin, nifedipine) in the last 3 months were excluded. We also excluded patients with systemic diseases such as cardiovascular disease, hypertension, diabetes mellitus, or orthodontic treatment and patients who refused to participate in the study and/or follow-up visits.

According to Rajan (2014), to obtain the difference of probing pocket depth (PPD) of 2 groups (control and HA), we got and were the average PPD and 1.38 and were standard deviation of two groups, respectively. With α = 0.05 and β = 0.2, we calculated N = 25. 28 subjects were enrolled to prevent sample loss.

Masking of control and HA treatment were applied to patients, the periodontist and outcome assessing investigators for all clinical and laboratory parameters. Only an independent investigator who applied HA knew the name of the drug due to the nature of the study. Another investigator who performed the statistical assignment phase was to all patient information and to the following analysis and evaluation of the data.

In this split mouth study, 733 periodontal pockets of 28 patients with moderate to severe chronic periodontitis were chosen for investigation. They were divided into 2 groups: control group and experimental group. The experimental group received sub-gingival administration of 1 ml of 0.2% hyaluronic acid gel into each pocket immediately after root planing and then after 1 week, 2 weeks and 3 weeks. Clinical parameters were assessed at baseline and 6 weeks after root planing. Subgingival plaque was assessed at baseline and 6 weeks after root planing. Quantitative real-time PCR for Porphyromonas gingivalis (Pg), Treponema denticola (Td), Fusobacterium nucleatum (Fn) Tannerella forsythia (Tf) were performed at the same time. Wilcoxon sign-rank test and Mann-Whitney test were used for comparison of means.

Inclusion Criteria:

• Patients with at least 3 teeth in the contralateral quadrants diagnosed with moderate or severe chronic periodontitis according to AAP (2015): gingival bleeding at examination, ≥5mm periodontal pocket depth, bone resorption on X-ray film ≥16% or >3mm root length.

Exclusion Criteria:

• Patients who were allergic to ingredients, being pregnant/lactating, smoking, alcoholic; who had undergone periodontal therapy in the last 6 months, received antibiotic therapy, anti-inflammatory agents, statins, drug induced gingival enlargement (such as phenytoin, cyclosporin, nifedipine) in the last 3 months