assess the clinical and laboratory effects of the local and sub gingival application of a 0.8% hyaluronic acid gel (GENGIGEL®) as an adjunct to scaling and root planning (SRP) in chronic moderate to severe periodontitis patients as indicated by expression of Human Beta Definsin-2 (HBD2) in gingival crevicular fluid (GCF).

Patients who fulfilled the selection criteria will be included in the study. One quadrant will be treated with HA gel (test) and the other without to serve as control. Clinical examination will be done in a dental chair under standard conditions of light, using mouth mirror and graduated Williams Periodontal Probe.

All patients will receive full mouth scaling and root planing with hand instruments and ultrasonic scalers at baseline. Thereafter, in the test quadrant, 1 ml of 0.8% hyaluronic acid gel will be administered subgingivally in all selected test sites at baseline and 1 week later. The following clinical parameters will be recorded at baseline, after 6 weeks and 12 weeks post treatment. Oral hygiene instructions will be given to all patients. The clinical measurements and treatment will be performed by a single examiner.For every patient and control subject, GCF samples will be collected at baseline, 6 weeks and 12 weeks post treatment. The samples will be pooled from two periodontal sites with clinical attachment level of 3 mm or more (in the two different quadrants). The sampling area will be isolated with cotton rolls and carefully will be cleaned supragingivally with sterile cotton pellets. A sterile absorbent paper point will be inserted into the gingival crevice or pocket until resistance will be felt. The paper point will be held in place for 30 s and then will be transferred to a vial containing 100 μL of distilled water and vigorously will be mixed. The paper points will be removed, and the samples will be centrifuged and will be washed twice with distilled water. The resultant pellets will be resuspended in 0.4 mL of distilled water. The samples will be coded and stored at -70 °C until use for ELISA test for identification of Human beta Defensin-2.

Inclusion Criteria:

• Patients should be systemically healthy with moderate to severe chronic periodontitis of more than 4 mm probing depth in at least two sites in different quadrants.
• Patient should exhibit no known allergies
• Participants should have the ability to attend the hospital regular intervals.

Exclusion Criteria:

• pregnancy
• nursing
• hypertension
• patient with chronic diseases such as diabetes mellitus or rheumatoid arthritis. -Participants should not be under antibiotics and\or had receive any periodontal therapy for the last 6 months.
• Participants should not taking drugs that could affect the state of the gingival tissues.
• Participants must not be undergoing orthodontic therapy, caries free
• Participants must not be using any other supplemental plaque control measures like mouthwashes.
• Participants should not have the habit of taking alcohol, smoking or chewing tobacco and do not suffer from any systemic disease.

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