Disinfection Efficacy of Current Regenerative Endodontic Protocols in Simulated Necrotic Immature Permanent Teeth

• This study showed that inadequate disinfection could lead to activation of the immune system.
• This activation could be a potential cause for lower survival levels of the stem cells of the apical papilla.
• Adequate debridement of the root canal was achieved using triple antibiotic paste (TAP) and double antibiotic paste at 10 mg/mL.
• 10 mg/mL TAP proved to be most effective.

IntroductionThe lack of mechanical debridement and reduced concentrations suggested for chemical debridement to maintain stem cell viability call into question the disinfection efficacy of current regenerative protocols. Current protocols vary in the concentration and type of antibiotic medicaments used. The aim of this study was to determine if simulated immature teeth infected with Enterococcus faecalis can be completely disinfected by following current standardized regenerative protocols and to evaluate the probable effects of residual bacteria on stem cell toxicity.MethodsSixty-eight caries-free maxillary incisors were used. S1 sampling protocols were validated in both negative and positive control groups via culture, scanning electron microscopy, and confocal laser scanning microscopy. All teeth, except the negative controls, were inoculated with E. faecalis. The teeth were divided into the following groups: group 1, triple antibiotic paste (ciprofloxacin:metronidazole:minocycline) at concentrations of 10, 1, and 0.1 mg/mL; group 2, double antibiotic paste (ciprofloxacin:metronidazole) at concentrations of 10, 1, and 0.1 mg/mL; group 3: Ultracal XS calcium hydroxide (Ultradent, St Louis, MO); and controls, negative and positive controls. Current regenerative protocols recommended by the American Association of Endodontists were followed. S2 sampling was performed after 4 weeks and tested for bacterial presence via culturing, scanning electron microscopy, and confocal laser scanning microscopic analysis.ResultsThe data showed that calcium hydroxide and the current recommended antibiotic concentrations are not capable of completely eliminating bacteria from simulated necrotic immature permanent teeth.ConclusionsOverall, this study focuses on the need to re-evaluate the balance between stem cell toxicity and bacterial elimination in order to determine the appropriate concentrations and medicaments for successful regenerative endodontic procedures.