Does smoking exposure alter the effect of non-surgical periodontal therapy?

This prospective longitudinal observational study aimed to explore the impact of varying levels of smoking exposure on periodontal healing over a 12-month period following non-surgical periodontal therapy.

The study included 80 individuals in the age range of 20-70 years, who were both, smokers at baseline, and also diagnosed with periodontitis. Initially, all participants were enrolled in a smoking cessation program and were provided with non-surgical periodontal therapy (NSPT). Subsequently, all patients were recalled after every 3 months for supportive periodontal care and data collection. Socio-demographic features and periodontal health parameters were recorded, which included clinical attachment level (CAL), periodontal pocket depth (PPD), bleeding on probing, etc. For smoking, data about frequency, duration and salivary carbon monoxide and cotinine levels were recorded.

Descriptive statistics was used to depict and compare periodontal health and smoking parameters at different time intervals. In addition, exploratory factor analysis method was employed to identify distinct patterns of smoking behavior over a 1-year study period. Accordingly, patients were classified into three categories. Lastly, in order to assess the impact of NSPT among patients in different smoking categories, mixed-effects regression modeling was used.

The distribution of smokers was light smokers/quitters (46 individuals), moderate smokers (17 individuals) and heavy smokers (17 individuals). With NSPT an improvement in the mean CAL, PPD, and number of sites with PPD ≥4/5/6/7 mm was observed in all light, moderate and heavy smokers. Mean CAL (±SD) changed from 3.2 ± 1.5 to 2.5 ± 1.3, 3.5 ± 1.6 to 2.6 ± 1.3, and 4.2 ± 1.5 to 3.6 ± 1.3 and mean PPD changed from 2.5 ± 0.8 to 1.9 ± 0.4, 2.6 ± 1.0 to 2.0 ± 0.7, and 2.7 ± 0.8 to 2.1 ± 0.5 in light, moderate and heavy smokers respectively. Similar changes were observed in other periodontal and smoking parameters, e.g., salivary cotinine levels changed from baseline to 1 year, from 276.0 ± 155.7 to 213.8 ± 160.6, 564.8 ± 77.8 to 518.6 ± 197.6, and 764.0 ± 205.9 to 728.9 ± 116.7 in different smoking categories. Lastly, regression coefficients (RCs) were evaluated using regression modeling. RCs (and confidence intervals) for light and moderate smokers were CAL = -0.7 (-0.9 to -0.6), PPD -0.6 (-0.7 to -0.5) and CAL -0.4 (-0.1 to 0.3), PPD -0.4 (-0.8 to -0.1) respectively. In heavy smokers, a positive value of the regression coefficient for CAL was observed, indicating a trend of "increase in CAL value" (RC = 0.5, -0.1 to 1.2).

The study concluded that in smokers, NSPT done along with SPC yielded positive results. However, these results were influenced by the level of smoking exposure in a dose-response manner.