Comparing the Effect of Scaling and Polishing on Nine Oral Health and Dental Aesthetic Measures between Current and Never Smokers from the SMILE Study Cohort

Objectives: To evaluate the short-term effects of professional scaling and polishing on nine oral health and dental aesthetic outcomes in current smokers and never smokers. Methods: A total of 371 participants from the SMILE Study Cohort (305 smokers and 66 never smokers) were assessed at baseline (V0) and 14 days after scaling and polishing (V1). Outcomes included Modified Gingival Index (MGI), quantitative light-induced fluorescence parameters (ΔR30, reflecting the percentage of tooth surface covered by mature plaque, and ΔR120, reflecting the percentage covered by thicker deposits including calculus), MacPherson-modified Lobene Stain Index (MLSI) for buccal and lingual surfaces, Whitening Index for Dentistry (WID), Simple Oral Hygiene score (SOH), oral health-related quality of life (OHQoL), and general health perception (EQ-VAS). Linear mixed model analysis was used for between-group comparisons of V0-V1 changes. Results: At baseline, smokers exhibited significantly worse values across all objective indices. Following intervention, significant improvements were observed in MGI, ΔR30, ΔR120, MLSI, and SOH in both groups (p<0.0001). MGI improved by a median of -0.5 units in smokers (IQR: -0.8/-0.2) and -0.08 units in never smokers (IQR: -0.3/-0.02); the magnitude of improvement was significantly greater in smokers (p<0.0001). Similarly, greater reductions in ΔR120 (p=0.010), buccal MLSI (p<0.0001), and lingual MLSI (p<0.0001) were observed in smokers compared to never smokers. WID showed no significant changes in either group. OHQoL improved slightly without between-group differences; EQ-VAS did not change significantly. Conclusions: Professional scaling and polishing produced consistent short-term improvements in objective oral health indicators in both smokers and never smokers, with greater gains among smokers reflecting their higher baseline burden. Clinical Significance: Regular professional mechanical plaque removal is clinically beneficial for smokers, producing measurable short-term improvements in gingival and aesthetic parameters even in the presence of ongoing tobacco exposure, although smoking cessation remains essential for long-term oral health.