Endodontic inter-appointment flare-ups: An example of chaos?

Pain and/or swelling after instrumentation of a root canal constitute a significant complication during endodontic treatment. Despite a large number of articles discussing the causative factors behind endodontic flare-ups, the exact mechanism is still not understood. The seemingly irrational behavior of endodontic inter-appointment flare-ups may be due to sensitive dependence on initial conditions. A model based on Lorenz'' chaos theory is presented as a possible explanation for the sudden emergence and unpredictability of flare-ups. Evaluation of the Hypothesis: All studies agree on some common traits regarding inter-appointment flare-ups: Careful instrumentation can still cause flare-up; the host inflammatory response behaves as a complex nonlinear network; and also the poly-etiologic nature of this phenomenon all illustrate the sensitive dependence on initial conditions of the system. Integrating more variables (e.g., different species of bacteria) into this already complex system will make it increasingly chaotic reflecting its unpredictable behavior.