The aim of this study is to evaluate whether the use of a chlorhexidine based oral antiseptic will improve clinical results of non-surgical periodontal therapy (NSPT) in smokers with periodontitis.

A randomized controlled clinical trial will be carried out on 60 subjects with periodontitis- 30 smokers and 30 non-smokers. All subjects will be clinically examined. The following periodontal indices will be measured: Full mouth plaque score (FMPS), Full mouth bleeding score (FMBS), Pocket probing depth (PPD), Clinical attachment level (CAL), Gingival recession (GR) and Tooth mobility (TM). All subjects will have NSPT carried out. Half of the subjects in each group will use a 0.12% chlorhexidine based mouth rinse twice a day during 15 days. Clinical examination will be repeated 8 weeks after NSPT and compared.

A total of 60 subject will be recruited among patients seeking periodontal treatment at the Department. All subjects will have periodontitis diagnosed according to the criteria outlined in the 2017 Classification of Periodontal and Peri-implant Diseases and Conditions. The subjects will be divided into two groups based on smoking status. The first group of 30 subjects will consist of cigarettes smokers and the second group of 30 non- smokers. All the subjects in the first group smoke for a minimum of 3 years and at least 10 cigarettes a day. Patients smoking e-cigarettes, tobacco heating systems, cigarettes without filter and occasional smokers will be excluded from the study. Moreover, minors, pregnant woman, patients with systemic diseases affecting periodontal tissues, immunodeficient patients, patients who used antibiotics in the previous six months, patients with orthodontic appliances or retainers and patients who previously had periodontal therapy or were in supportive therapy will be excluded from the study. A randomization plan based on sex (male; female), age (</> 50 years), nicotine exposure (smoker; non-smoker) and intervention (with/ without CHX) will be made using an online randomization software. All subjects will undergo a clinical examination before and 8 weeks after non-surgical periodontal therapy. Clinical examination will include all teeth except third molars and will be carried out using a millimeter graduated PCP-15 UNC periodontal probe (Hu-Friedy, Chicago, USA). The following periodontal indices will be measured: Full mouth plaque score (FMPS), Full mouth bleeding score (FMBS), Pocket probing depth (PPD), Clinical attachment level (CAL), Gingival recession (GR) and Tooth mobility (TM).

All subjects will have non-surgical periodontal therapy carried out according to the principles of Guided biofilm therapy (GBT) (EMS Dental, Geneve, Switzerland) using AIRFLOW Prophylaxis Master ultrasonic instruments (EMS Dental, Geneve, Switzerland) and Gracey curettes (Hu- Friedy, Chicago, USA). Moreover, half of the subjects in each group, 15 smokers and 15 non-smokers, will use a 0.12% chlorhexidine-digluconate based mouthwash (Curasept ADS 212, Curasept SpA, Saronno, Italy) twice a day for one minute during a period of 15 days. Subsequently, four subgroups of 15 subjects will be formed- non-smokers (NS), non-smokers who used CHX (NS-CHX), smokers (S) and smokers who used CHX (S-CHX).

Inclusion Criteria:

• patients with periodontitis smokers and non smokers.

Exclusion Criteria:

• minors, pregnant woman, patients with systemic diseases affecting periodontal tissues, immunodeficient patients, patients who used antibiotics in the previous six months, patients with orthodontic appliances or retainers and patients who previously had periodontal therapy or were in supportive therapy
• Patients smoking e-cigarettes, tobacco heating systems, cigarettes without filter and occasional smokers

only data not affecting participants personal data will be shared upon reasonable request