Flare-ups in endodontics: I. Etiological factors.

An ongoing and frequently vexing problem in endodontics is the development of pain and swelling (“flare-up”) during or after endodontic therapy. In some instances, flare-ups may occur following an access opening without root canal instrumentation. The attendant clinical symptomatology may be of such magnitude as to alarm both the therapist and the patient. In this and a subsequent article, the possible etiological factors will be explored and some therapeutic suggestions will be made. Although the reasons for such exacerbations are not always clear, a number of hypotheses, some of which may be interrelated, will be offered and discussed. Among these are: (a) alteration of the local adaptation syndrome; (b) changes in periapical tissue pressure; (c) microbial factors; (d) effects of chemical mediators; (e) changes in cyclic nucleotides; (f) immunological phenomena; and (g) various psychological factors.