This study design will be a prospective, Split mouth, randomized controlled trial in which the effectiveness of subgingival irrigation with probiotic solution on periodontal healing outcome in patients with moderate-to-severe periodontitis as compared to chlorhexidine gluconate at baseline, 4 weeks and 12 weeks from baseline.

Subjects satisfying the inclusion and exclusion criteria will be selected for the study. In this split mouth study design all the clinical parameters will be recorded at baseline. Once the scaling and root planing of the selected subject is done then the contralateral quadrants will be randomly assigned to 2 groups i.e. control group and test group.

Group I : SRP + Chlorhexidine gluconate 0.12% (ICPA Health Products Ltd.)

Group II : SRP + Probiotic solution (Freshly prepared using Darolac sachets by Aristo Pharmaceuticals Pvt. Ltd.)

Single time Subgingival irrigation will be performed at baseline by using oral irrigation device (WaterPik).

SAMPLE SIZE : 28 Sample size was determined using the estimates of mean and standard deviation values from literature [Jain R, Chaturvedi R, Pandit N, Grover V, Lyle DM, Jain A. Evaluation of the efficacy of subgingival irrigation in patients with moderate-to-severe chronic periodontitis otherwise indicated for periodontal flap surgeries. J Indian Soc Periodontol. 2020 Jul-Aug;24(4):348-353.] 

[Pandya DJ, Manohar B, Mathur LK, Shankarapillai R. Comparative evaluation of two subgingival irrigating solutions in the management of periodontal disease: A clinicomicrobial study. J Indian Soc Periodontol. 2016 Nov-Dec;20(6):597-602.] using the formula , Z_1-α/2 is the z variate of alpha error i.e. a constant with value 1.96 

Z_1-β i.e. a constant with value 0.84 (Reference for the formula: Chow S, Shao J, Wang H. 2008. Sample Size Calculations in Clinical Research. 2nd Ed. Chapman & Hall/CRC Biostatistics Series. page 89. Reference for the values: https://www.jcpcarchives.org/full/sample-size-for-experimental-studies-53.php) Approximate estimates: 80% power, Type I error to be 5%, Type II error to be 20%, True difference of atleast 0.7 units between the groups, Pooled standard deviation of 0.941 , Substituting the values, n   =   2 (2.8)²  [0.941]² /(0.7)²n = 28.3 Approximately 28 subjects / patients per group should complete the study at the endpoint follow up. For follow-up studies, to avoid loss by loss to follow up / attrition, kindly consider recruiting 5-25% more subjects so that even after attrition, we would be able to achieve the required minimum sample size. Also taking into consideration the attrition to be 10% , n= N / (1-0.10) ,n =   28.32  / (1-0.10) =   31.47 Approximately 32 subjects / patients per group need to be recruited in the present study.