ABSTRACT
Background: Streptococcus mutans (S. mutans) is associated with the onset of caries. Since root exposure in patients affected by periodontitis leads to higher caries rates, progressively more severe forms of periodontal disease might associate with elevated counts of S. mutans. Aim: To determine whether increasingly destructive forms of periodontal disease are associated with higher counts of S. mutans in untreated patients. Methods: 206 subjects aged 20-75 were classified into three groups according to the severity of periodontal disease: 1) gingivitis, 2) chronic slight periodontitis and 3) chronic moderate or chronic severe periodontitis. S. mutans counts (cfu/mL) were obtained by direct counting on selective agar plates from saliva samples. A cumulative proportional logistic regression model was adjusted for S. mutans counts. Results: The model failed to show differences by gender, but periodontal diagnosis had a significant effect on S. mutans counts depending on age. While in the group with moderate and severe periodontitis the probability of having high counts of S. mutans significantly increased with age, the probability remained unchanged in individuals with chronic slight periodontitis or gingivitis. Conclusion: High S. mutans levels appear directly co-associated with increased severity of periodontal disease at older ages in untreated patients.