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PORTLAND, Ore., USA: In a recently published study, U.S. researchers have found that certain strains of bacteria associated with dental caries were dominant in children even one year after treatment for microbial plaque and tooth decay.
The study, conducted about one year ago at the Oregon Health and Science University's School of Dentistry, involved seven children aged 3 to 5 who had been diagnosed with severe early childhood caries and had undergone full-mouth dental rehabilitation therapy, including application of chlorhexidine gluconate, followed by amalgam, composite and crown restorations, at the school's pediatric dental clinic. Plaque samples were taken from each participant prior to the therapy, two to four weeks after rehabilitation, and at the recall visit six months later.
The researchers found 37 strains of Streptococcus mutans and two strains of Streptococcus sobrinus, among others, present during the entire study. Both are closely linked to the development of dental caries. Although dental rehabilitation therapy reduced the diversity of oral streptococci from several genotypic strains to one or two dominant strains by six months post-therapy in most patients, the researchers were able to identify six new strains of the S. mutans group that had emerged one year post-dental rehabilitation. Potentially, these were the result of re-infection from the primary caregiver or other external sources, they suggested.
Moreover, some of the minor strains were found to be resistant to xylitol, exhibiting increased cariogenic potential. Xylitol is a sugar alcohol capable of reducing plaque formation and suppressing bacterial growth of cariogenic bacteria that is used in dental products such as chewing gum. Thus, the researchers hope that the study will provide insight into the use of xylitol treatment for caries preventive maintenance therapy in children with severe early childhood caries and lead to potential applications in personalized dentistry practice, said Dr. Curtis Machida, principal investigator and professor of integrative biosciences and pediatric dentistry.
The study was published online in the December issue of the Journal of Oral Microbiology.
