Prevalence of Aggregatibacter actinomycetemcomitans and Fusobacterium nucleatum among Clinical Orthodontic and Non-Orthodontic Saliva Samples

Objectives: The oral flora is a complex ecosystem characterized by numerous bacterial species and changes to the levels of these bacteria in health, disease, and dental treatments such as orthodontics. Although some studies have documented changes in periodontal pathogen burden during orthodontic treatment using saliva, most have focused on traditional cariogenic bacteria and some periodontal pathogens, such as Porphyromonas gingivalis or Fusobacterium nucleatum– far fewer have focused on Aggregatibacter actinomycetemcomitans – commonly associated with aggressive periodontitis. Therefore, the main objective of this study was to evaluate the prevalence of this organism among orthodontic and non-orthodontic patients from a public dental school clinic.

Experimental Methods: Using an approved protocol, samples were taken from orthodontic (n=39) and non-orthodontic (n=45) patients. DNA was extracted and screened for Aggregatibacter actinomycetemcomitans. Males and females were equally represented, although a majority of patients participating in this study were Hispanics and ethnic minorities.

Results: PCR analysis of the DNA isolated from these patient samples revealed that more than half (54%) of the orthodontic samples harboured significant levels of Aggregatibacter actinomycetemcomitans, compared with only one-quarter (25%) of samples from non-orthodontic patients. In addition, screening for Fusobacterium nucleatum revealed a slightly increased prevalence among orthodontic patients (27%) compared with non-orthodontic patients (19%).

Conclusions: These results are significant as Aggregatibacter actinomycetemcomitans has been traditionally observed as facilitating heterotypic communities of overtly pathogenic organisms, compared with other gram-negative oral microbes. These heterotypic biofilm communities exhibit greatly increased capacities to resist antimicrobial drugs and other host immune factors and the capacity to facilitate heterotypic associations within the biofilm may be restricted to a few key species. This project successfully demonstrated evidence that non-invasive salivary screening of orthodontic patients may be sufficient to assess and detect changes to this periodontal pathogen – thereby increasing the potential quality and efficiency of orthodontic dental treatment among this patient population.