Root Canal System Research Paper

Microbes of the infected root canal system
Historically, the most wide-spread method for detecting and characterizing bacteria has been by culturing. Culturing bacteria allows the analysis of their morphology, virulence, gram-staining pattern, the quantization of viable microorganisms, as well as the testing of their susceptibility to antibiotics. Consequently, this method may not allow normally viable bacteria to cultivate as the selected culturing media may not have the nutritional and physiologic requirements that are needed for the sampled bacterial species to replicate(1). It is thought that only one percent of bacteria can be cultured(2). Additionally, culturing also has low sensitivity, is dependant on the sample transporting method, …show more content…
Secondary endodontic infections are when there is re-infection of the root canal system after endodontic treatment. These newly introduced microbes were not part of the previous infection and may have entered the root canal system through recurrent caries, exposed dentinal tubules or open marginal restorations. Unlike biofilms of primary endodontic infections which are polymicrobial, the bacteria causing persistent and secondary endodontic infections are usually composed of one or few species. It is thought that facultative bacteria are more resistant than obligate anaerobes and that gram-positive bacteria are more resistant than gram-negative bacteria(7). These microbes are usually gram positive and regularly include Enterococcus faecalis, Propionibacterium spp, Lactobacillus spp, Streptococcus spp, and Actinomyces spp (4). Other microbes include Candida albicans, and gram negative bacteria, such as F. nucleatum, Prevotella intermedia, and Campylobacter rectus (8). These persistent bacteria are very hardy, as they are able to remain viable without nutrients while being encased in root canal filling materials, and are able to survive the disinfecting irrigants during endodontic treatment. E. faecalis is a facultative anaerobic gram-positive coccus. E. faecalis has been shown to be a major pathogen in persistent endodontic infections of root-filled teeth. E. faecalis has been reported to be present in up to 67% of secondary infections cases while only being present in 18% of primary endodontic cases(9). E. faecalis can remain viable in environments with a high pH, low nutrients, and high and low temperatures. It is small and able to migrate deep into dentinal tubules where it can avoid disinfecting irrigants and can survive the high pH produced by irrigants and intracanal medicaments by use of a proton pump. The