the aim of this clinical trial is to compare the efficacy of hyaluronic acid (HA) used as an adjunctive to scaling and root planing (SRP) and red injectable platelet rich-fibrin (i-PRF) in the non-surgical treatment of stage III periodontitis. The main question it aims to answer is: is there a difference between HA and red i-prf when used as an adjunct to SRP in terms of efficacy?

Participants who are eligible will be assigned to one of the treatment groups:

• Group 1= receives HA+ SRP
• Group 2= receives red i-prf + SRP
• Group 3= receives only SRP

Researchers will compare Groups 1,2 and 3 to see if there's a difference in the periodontal parameters measured.

Complete medical and dental histories as well as informed consent will be collected from eligible participants, and periodontal charting will be done for them.

The selected patients will be allocated into three groups (each containing 25) with the help of a computerized randomizer (Randomizer.org):

• Group one (G1): 25 patients will be treated with hyaluronic acid gel as an adjunct to scaling and root planing by applying one ml of 0.8% HA to the base of the pocket (subgingivally) and 0.2 ml of 0.2% HA topically (applied by the patient).
• Group two (G2): 25 patients will be treated with red i-PRF as an adjunct to scaling and root planing.
• Group three (G3): 25 patients will be treated with scaling and root planing only.

The clinical examiner will not be informed of the treatment groups' distribution.

Before the baseline examination, a full mouth supragingival scaling and root planing will be performed under local anesthesia in one or two sessions (over a 24-hour period). Patients will be informed on self-performed plaque control measures, including using the modified Bass brushing technique using a soft toothbrush and regular toothpaste twice a day and interdental cleaning using interdental brushes once a day. Patients will receive the same toothbrushes, toothpaste, and interdental brushes.

The clinical parameters will be recorded at the baseline (1st visit) before the treatment and will be repeated in the fourth week (2nd visit), eighth week (3rd visit), and twelfth week (fourth visit). During this period, reinforcement of plaque control will be given to maintain good oral hygiene.

Data from previous studies will be used to calculate the sample size (Zijnge et al., 2010) regarding the PD change measurement. It is found that the difference in PD (δ) is around 0.3mm, whereas the standard deviation in groups (σ) is around 0.2mm. Our aim is to achieve a statistical power of > 90% as well as a 0.05 significance level. Thus, 18 participants per group will be needed. However, as some dropouts may be expected, a minimum of 25 patients per group will be recruited.

Statistical analysis will be done using SAS 9.4 Software (SAS Institute Inc., Cary, NC, USA). Means and standard deviations (SD) will be calculated for all continuous variables (periodontal parameters: CAL, PD, BOP, GI, PI) at the baseline, fourth week, eighth week, and twelfth week. Repeated linear mixed-effects models (PROC MIXED in SAS) will be used to examine the changes in all periodontal parameters over the four-time points within each group and between groups. An unstructured covariance matrix will be used, residual plots will be visually reviewed to check model fit, and extreme outliers will be eliminated using the restricted likelihood distance. A Tukey-Kramer correction will be applied to all pairwise comparisons. One-way ANOVA is to be used to examine group differences in PD reduction and CAL. A p-value of 0.05 will be considered statistically significant.

Inclusion Criteria:

• clinical periodontal loss and radiographic bone loss of stage III/grades A and B with no history of systemic disease.
• at least four periodontal sites with a pocket depth of six mm or greater
• radiographic evidence of bone loss extending to the middle third of the root
• clinical attachment loss of five mm or more

Exclusion Criteria:

• uncontrolled systemic conditions (uncontrolled diabetes or uncontrolled hypertension)
• bleeding disorders, or on anticoagulant therapy
• alcohol users
• pregnant or lactating females
• heavy smokers (more than ten cigarettes per day)
• chemo or radio therapy
• antibiotic/anti-inflammatory drugs over the last three months before treatment.