Periodontitis is considered an inflammatory disease that results in the disruption of oral hemeostasis and is associated with the presence of dental plaque influenced by genetic and environmental factors. It is well-establised that smokers have an increased severity of periodontal disease,a higher prevalance of tooth loss and total edentulism.

Antimicrobial peptides (AMPs) are soluble molecules participating in the innate immunity of mucosal surfaces against pathogens. Dysregulated expression of AMPs has been considered a possible causal mechanistic link in the microbial dysbiosis associated with periodontal disease and some risk factors, including tobacco smoking, diabetes mellitus, and obesity.Antimicrobial peptides as a part of innate immunity are important molecules that provide a balance between disease and health. Moreover, they are considered to be an important intermediate step in initiating an initial immune response against the microbial side of the gingival epithelium and in the transition to acquired immunity. Cathelicidins, in particular - which play an important role in regulating the immunological response of oral tissues, are a group of peptides released from neutrophil granules and they are present only in humans in the form of LL-37.

Inclusion Criteria:

1. Presence of a minimum of 15 natural teeth.
2. At least four non-adjacent teeth sites in each jaw having CAL ≥ 5 mm and PD > 5 mm in one or more sites.
3. Bleeding on probing (BOP) ≥ 30%.
4. Tooth loss due to periodontitis ≤ 4 teeth.
5. For smoker's patients; study will include patients who regularly smoked at least 10 cigarettes/day for a minimum of 5 years.
6. For non-smokers patients; study will include patients who had never smoked.

Exclusion Criteria:

1. Individuals with a history of systemic diseases or immunological disorders.
2. Individuals using hormone replacement therapy.
3. Pregnant and lactating women.
4. Individuals that received periodontal treatment within the last 6 months.
5. Individuals with a history of systemic antibiotics and anti-inflammatory drugs within the last 3 months.

Group 1: Smokers with stage III,IV periodontitis Group 2: Non-smokers with stage III,IV periodontitis Group 3: Healthy patients