Methods: The standard strains of s.mutans (ATCC25175) and sanguis(ATCC10550) were cultured on blood agar and incubated for 48h in different environments: atmospheric air, microaerophillic, carbon dioxide, cigar and three type of cigarette smoke (Winston ,ultralight Winston and kent). Then digital photographs of the colonies were taken and the diameter of the colonies was measured. Data were analyzed using post hoc and general linear model statistical tests.
Results: Both cigar and cigarette smoke significantly increased the growth of s.mutans and s.snguis. in almost all environments except cigar smoke, the growth of mutans was more than sanguis. The diameter of mutans colonies in dioxide ,microaerophilic, cigar and cigarette smoke (Winston,ultra light wniston and kent) showed in order: 82%, 65%, 69%, 106%, 92% increase and the diameter of sanguis showed in order: 45%, 53%, 137%, 89%, 40%, 55% increase.
Conclusions: These findings indicate that cigarette smoke increases the mutans/sanguis ratio but cigar smoke decreases this ratio.
Keywords: Bacterial, Microbiology, Tobacco and streptococcus mutans