Periodontitis patients, 40 cigarette smokers and 40 non-smokers (defined by cotinine measures in serum), were recruited to this double arm prospective cohort study. Data were collected 3 months following non-surgical and surgical periodontal treatment, and following 12 months with supportive periodontal therapy. Data collected were clinical attachment level, probing depth, bleeding on probing,oral bacteria, serum, blood (PAXgeneBlood), and gingival crevicular fluid.

The overall aim of this work was to study clinical outcomes of active and supportive periodontal therapy in smokers and non-smokers with chronic periodontitis at patient, tooth, and site level. Moreover, to compare the periopathogenic microflora and inflammatory markers in gingival crevicular fluid and in blood in smokers and non-smokers following therapy.

Eighty patients, 40 smokers and 40 non-smokers, with moderate to severe chronic periodontitis were included in this prospective cohort study and treated non-surgically and surgically, and then followed-up in a supportive periodontal therapy program for 12 months. Smoking status was validated measuring serum cotinine levels at pre-treatment and 12 months following supportive periodontal therapy.

Clinical measurements included full mouth recordings of clinical attachment level, probing depth, bleeding on probing, and plaque index at pre-treatment and following active and supportive periodontal therapy. At the same timepoints, subgingival plaque samples of 20 subgingival periopathogenic bacterial species were analysed using checkerboard DNA-DNA hybridization. Blood samples (PAXgeneBlood), serum, gingval crevicular fluid were also collected at the three timepoints.

Inclusion Criteria:

• healthy subjects
• age 35-75 years
• diagnosed with chronic periodontitis
• at least four non-adjacent teeth with proximal sites with a PD ≥6 mm and clinical attachment loss ≥5 mm with BoP and no radiographic signs of apical pathology.
• either smokers (>10 cigarettes per day for at least 5 years) or non-smokers (never smoked or not within the last 5 years).

Exclusion Criteria:

• subjects who presented with any current medical condition or used medications known to affect periodontal healing
• incorrectly reported smoking status
• use of antibiotics within 6 months of the study
• received subgingival scaling within 6 months of the study