Background/Aim: There are no studies that have compared the gingival crevicular fluid (GCF) levels of IL-1β in non-smokers (NS) and electronic nicotine delivery system (ENDS)-users before and after scaling and root planing (SRP) in patients with gingivitis. The aim of the present study is to compare the effect of scaling and root planing on the expression of IL-1β in the GCF among ENDS-users and NS clinically.

Methods: Self-reported current ENDS users and NS would be included. A questionnaire would be used to collect demographic data. All patients would undergo SRP. Clinical measures, periodontal parameters [probing depth (PD), plaque index (PI), and bleeding on probing (BOP)], and GCF IL-1β would be measured at baseline. At 1-week (T1) and 3 weeks (T2) of follow-up, periodontal parameters and GCF IL-1β levels would be re-assessed.

2.1. Ethical approval Ethical approval was obtained from the Ethics Committee of Health Sciences Center at Kuwait University. All volunteering individuals were requested to read and sign a consent form written in simple English and Arabic.

2.2. Study Area/Setting The present longitudinal study was conducted between November 2021 and September 2022 at the Kuwait University Dental Center (KUDC). The study participants were regular patients attending the KUDC and the sampling design was convenience sampling.

2.3. Selection Criteria The inclusion criteria: ENDS-users, non-smokers, age (18-25), gender (men), periodontal health status (gingivitis), having minimum number of 20 teeth, and medically healthy. The exclusion criteria: Patients who did scaling and root planing in the past 3 months, T-cigs smokers, and dual smokers.

2.4. Data Collection Methods, Instrument Used, Measurements A standardized questionnaire including a consent form was used to gather information regarding gender, age (in years), nationality, marital status, highest level of education, oral hygiene status, last dental visit, last time that scaling and root planing was done, smoking status, type of smoked product, duration of ENDS usage (in years), frequency of ENDS usage per day, number of ENDS puffs taken per session, family smoking history, exposure to secondhand smoke, general health status, and attitude towards smoking.

2.5. Blinding

2.6. Study Participants Twenty current ENDS-users and eighteen NS were recruited to participate in this study. All participants were requested to refrain from eating and using any oral hygiene method for at least 3 hours prior to their visit.

2.7. Sample Collection For screening of subjects for their use of tobacco products, saliva was collected and tested for the content of nicotine using chairside test kits (NicAlert, Confirm Bioscience, CA, USA). Unstimulated saliva (UWS) was collected before clinical assessment using non-invasive techniques. Prior to salivary and GCF samples collection, each participant's vital signs were measured and recorded. The participants were asked to rinse their mouth with water before a baseline salivary sample is collected to measure cotinine levels. Each participant was asked to collect saliva passively in their mouth and expectorate in a tube every one minute until three millimeters of saliva is collected. The tubes were then stored at -80°C. After that, GCF samples were collected using filter paper strips. GCF will be sampled from four sites at fully erupted, caries-free permanent molars (mesiobuccal and distobuccal of each molar) with gingival index (GI) score of 2 or 3 for gingivitis group. Scaling and root planing was provided for each participant and saliva and GCF samples were obtained in the same manner explained previously after one week and three weeks.

2.8. Power Analysis Power analysis was determined using a computer software (nQuery Advisor 6.0, Statistical Solutions, Saugas, MA., USA) with an alpha and effect size of 0.05 and 0.3, respectively. Sample size estimation was based on the presumption that a mean difference of 1 mm in clinical AL and PD should be detected at a significance-level of 0.05 and a desired study power of at least 80%. It was estimated that a sample size of at least 20 patients/group would achieve 95% study power with a 0.05 two-sided significance-level.

2.9. Analysis of Cotinine and IL-1β in GCF Saliva levels of cotinine was measured to determine the electronic cigarettes status using a high sensitivity, quantitative enzyme immunoassay (ELISA) kit. Then, IL-1β GCF levels was analyzed using commercially available ELISA kit. The difference in the levels of the biomarker before and after the intervention will provide an insight of the soft tissue response to the treatment. This will show the deleterious effect of electronic nicotine delivery systems on the soft tissue response to therapy.

2.10. Clinical Examination In all patients, Löe & Silness gingival index (GI)(Löe and Silness 1963) and Silness & Löe plaque index (PI)(Silness and Löe 1964) were recorded.

2.11. Statistical Analysis Statistical analyses was done using SPSS software (SPSS Version 26, Chicago, IL., USA).

Inclusion Criteria:

• The inclusion criteria: ENDS-users, cigarette smokers, non-smokers, age (18-60), gender (men), periodontal health status (gingivitis/periodontitis), having minimum number of 20 teeth, and medically healthy.

Exclusion Criteria:

• The exclusion criteria: Patients who did scaling and root planing in the past 3 months.

The investigators, care providers and outcome assessors would be blinded to the smoking status of the participants