To investigate the microbiological flora recovered during root canal re-treatment from teeth with single root canals in a Scottish sub-population with failed orthograde root canal treatment (RCT). Furthermore, the effect of photoactivated disinfection upon microbial content of root canals during RCT was additionally determined.
Methods:
A double blind randomised controlled trial was undertaken upon 47 consenting adults exhibiting failed RCT and requiring orthograde re-RCT. Patients were divided into an active photoactivated disinfection (PAD) group and placebo control cohort. RCT procedures were standardised across all treated cases with the use of conventional canal preparation techniques (rotary ProTaper Universal, DENTSPLY) and antimicrobial irrigants (sodium hypochlorite 2.5% and chlorhexidine gluconate 0.2%). However, experimental cohort received the additional step of PAD whilst control group received an inert non-antimicrobial placebo dye. Root canal contents were sampled at four differing stages during the RCT procedure by sterile hand files. Microbial survival during each step was analysed using conventional culture techniques and selective media was used to grow Enterococcus faecalis.
Results:
Conventional microbiological analysis revealed a predominantly Gram +ve pattern of microbes recovered from root canals of failed cases. Enterococcus faecalis was isolated from 22% of canals at the start of treatment. Upon completion of canal cleansing and shaping, Enterococcus faecalis was still present within 4% of root canals. Streptococcus species was the most common isolate, being cultured from 28% of canals with failed RCT. The use of PAD had limited capability of reducing microbiological counts within re-root canal treatment cases over and above conventional disinfection.
Conclusions:
Enterococcus faecalis was recovered in fewer canals in failed root canal treatment cases within a Scottish sub-population compared to other geographical cohort studies. The use of photoactivated disinfection in root canal treatment appears to have limited benefit over and above current disinfection regimens.