Oral Microbiota, Dental Caries and Periodontal Status in Smokeless Tobacco Chewers in Karnataka, India: A Case-control Study

Purpose: The aim of the present study was to compare dental caries and periodontal disease status associated with oral microflora among smokeless tobacco chewers and non-chewers. Materials and Methods: Forty-two smokeless tobacco chewers and 42 non-chewers (age 20 to 60 years) were assessed for dental caries and periodontal disease status using the Decayed Missing Filled Surface (DMFS) Index, Community Periodontal Index (CPI) and Loss of Attachment (LA) Index. Stimulated saliva and subgingival plaque samples were collected from each subject for performing a culture-based analysis of 20 types of oral microorganisms. Qualitative and semi-quantitative culture-based analysis using MacConkey agar, and aerobic and anaerobic blood agar was carried out to determine the total cultivable microflora. Mutans-Sanguis agar, Pfizer selective Enterococcus agar and Rogosa SL agar were used for the culture of microorganisms associated with dental caries. Mann-Whitney U test and Student t test were employed to compare colony-forming units (CFUs) and caries experience between smokeless tobacco chewers and nonchewers. Z proportionality test was used to compare the periodontal disease status. Results: Caries experience among chewers (26 of 42), that is those subjects who were affected by caries, was significantly less at 61.9% (mean DMFS = 3.5) compared to non-chewers (38 of 42, 90.5%) (mean DMFS = 5.5) (P 0.05). Deep pockets measuring > 5.5 mm on a CPI probe were found among 26.2% of chewers and 19.1% of nonchewers, with no statistically significant differences (P > 0.05). Counts of Lactobacillus species were significantly lower among chewers (median CFU = 0.788 x 105) than among non-chewers (median CFU = 1.52 x 105) (P 0.05). Prevotella and Porphyromonas species had a median CFU of 0.04 x 105 in chewers and 0.15 x 105 in non-chewers, whereas Fusobacterium species had a median CFU of 0.02 x 105 in chewers and 0.1 x 105 in non-chewers (P 0.05). Conclusions: A higher percentage of caries among non-chewers can be explained by greater numbers of Lactobacillus species in this population. Chewers experienced a slightly higher incidence of periodontal disease than non-chewers, but the difference was not significant. These clinical observations suggest a lower ability of Gram-negative bacteria to mediate more periodontal disease in this population. Keywords: dental caries, periodontal disease, smokeless tobacco