Incipient caries lesions on cementum by mono- and co-culture oral bacteria

Objectives There is increasing prevalence of root caries. We hypothesized different biofilms will cause varying demineralization in cementum. This study investigated the extent of demineralization of cementum by oral biofilm formed from three major cariogenic microorganisms: Streptococcus mutans, Lactobacillus acidophilus, and Actinomyces israelii. Sound cementum tooth blocks were incubated with mono-, bi-, and tri-species combinations of the bacteria under investigation. Materials and methods The matrix (amide I) and phosphate content of the lesions was analyzed by Fourier-transform infrared spectroscopy (FTIR), and calcium and phosphorus levels were analyzed by scanning electron microscopy and energy-dispersive spectroscopy (SEM-EDX). Results The log[amide I:HPO42− absorbance] values showed that A. israelii mono-culture caused significantly more demineralization than the other bacterial cultures. log[Ca:P] showed that all carious lesions were confined to the cementum. Conclusions Oral biofilm arising from bacterial species A. israelii alone was the most cariogenic of those tested and produced the most demineralization in incipient carious lesions in cementum.