Biofilms of black tooth stains: PCR analysis reveals presence of Streptococcus mutans.

This study investigated the presence of the black-pigmented bacteria Prevotella nigrescens and Prevotella intermedia, the non-black-pigmented bacteria Actinomyces spp and particularly the cariogenic pathogen Streptococcus mutans in the dental biofilms of patients with or without black extrinsic tooth stains, using the multiplex polymerase chain reaction (PCR) technique. Analysis of the dental biofilms of patients with (n=26) or without (n=26) black tooth stains was performed using duplex PCR for the 16S ribosomal RNA gene (P. nigrescens, P. intermedia, Actinomyces spp) and glucosyltransferase-I gene for S. mutans. P. nigrescens and S. mutans were the most frequent bacteria detected in both groups. The least frequently detected were P. intermedia and Actinomyces spp. The similar bacterial composition of dental biofilms of black tooth stains and healthy tooth surfaces indicates that black tooth stains are not free of cariogenic bacteria.