Table 1.
Eligibility criteria
| Inclusion criteria | |
| Aged over 18 years old | |
| Smoker of burnt tobacco (≥10 factory-made cigarettes/day or 7 g [0.25 oz]) loose tobacco/day or 14 hand-rolled cigarettes/day) | |
| Not currently using an e-cigarette, or not having used one for more than 2 days in the last 30 days | |
| Willing and able to come to the DCRF for the required study visits | |
| Having a minimum of 16 natural teeth (excluding third molars) | |
| Being diagnosed with periodontitis, having interproximal pocket probing depths (PPDs) of ≥ 5 mm at ≥ 8 sites | |
| Exclusion criteria | |
| Having used an e-cigarette for more than 2 days in the last 30 days | |
| Infectious or systemic diseases (myocardial infarction, cerebrovascular accident; phaeochromocytoma; uncontrolled hyperthyroidism; liver or kidney problems; chronic obstructive pulmonary disease) that may be unduly affected by participation in this study | |
| Haemodynamically unstable patients hospitalised with severe arrhythmias | |
| Patients taking the medication adenosine (due to drug interaction risk) | |
| Lack of capacity to be able to consent to the research project and/or inability to follow study instructions | |
| Participation in a dental research study within the previous 20 days | |
| Pregnant by medical history, or nursing | |
| Received any non-surgical periodontal therapy other than a routine scale and polish in the last 6 months | |
| Currently undergoing or requiring extensive dental, orthodontic or implant treatment, or treatment for peri-implantitis | |
| Clinical characteristics requiring further discussion with potential participants | |
| Asthma (severity needed to be assessed, patient made aware that nicotine replacement therapy (NRT) is better than smoking but best to use NRT as a short-term stop smoking treatment) | |
| Long-term throat disease (severity needs to be assessed, NRT use may exacerbate symptoms) | |
| Stomach ulcer, duodenal ulcer, irritation or inflammation of the stomach or throat (NRT may exacerbate symptoms) | |
| Diabetes mellitus (advised to monitor their blood glucose more closely when initiating treatment, advised to discuss this with their doctor or diabetic nurse specialist) | |
| Those taking theophylline, clozapine and ropinirole medications (metabolised by CYP 1A2 and with a narrow therapeutic window, can be affected by stopping smoking, advised to see their doctor to discuss changing the dose prior to starting the quit attempt). |