Histopathological profile of surgically removed persistent periapical radiolucent lesions of endodontic origin R. M. Love & N. Firth Department of Oral Diagnostic and Surgical Sciences, University of Otago, Dunedin, New Zealand Abstract Love RM, Firth N. Histopathological profile of surgically removed persistent periapical radiolucent lesions of endodontic origin. International Endodontic Journal, 42, 198–202, 2009. Aim To determine the types of periapical lesions associated with root filled teeth with persistent periapi- cal pathosis that required surgical treatment based on specific inclusion and exclusion criteria. Methodology Periapical lesions from a consecutive clinical sample of 100 patients were examined histo- pathologically to determine a definitive diagnosis. Results Females were more represented (n = 56), the average age was 46.5 years and there were no age differences between gender or lesion type. A diagnosis of periapical granuloma was the most common finding with a similar number present in females (n = 40) and males (n = 37). A cyst was present in 18% of the cases with a majority of females (n = 12) represented in the sample. Evidence of foreign material, with an appear- ance consistent with endodontic sealer materials, was seen in 25 periapical granulomas, two cysts and one scar. Two periapical scars were seen, one had a history of apicectomy and amalgam root-end filling while the other was associated with extruded root filling material. Conclusions By using defined clinical inclusion and exclusion criteria a predictable clinical diagnosis of a persistent periapical lesion due to endodontic origin can be reliably made. Periapical granulomas and cysts were the most common periapical lesions of endodontic origin associated with persistent periapical pathosis with the overall incidence of periapical cysts similar to previous studies. The presence of endodontic material in a high proportion of periapical lesions suggests a cause-effect association with the inference that clini- cians should employ canal preparation techniques that limit apical extrusion of material. Keywords: endodontic material, periapical cyst, periapical granuloma, persistent periapical pathology. Received 8 June 2008; accepted 9 October 2008 Introduction Infection of the root canal system is central to the development of inflammatory periapical pathosis (Ka- kehashi et al. 1965, Mo¨ller et al. 1981) where micro- bial invaders and/or their products invoke a complex, primarily protective, inflammatory response in the periradicular tissues (Stashenko et al. 1998). However, these host defense systems cannot enter the root canal in teeth with necrotic pulps and eliminate the invading microbes, as a consequence the inflammatory response results in the formation of various types of periapical lesions. There are a number of classifications for periapical lesions of endodontic origin based on aetiology, symp- toms or histopathological features, for example The World Health Organization Classification leans toward a clinical classification (World Health Organization 1995) while Nair (1997) describes a histopathological classification. Although all classifications have their use a clinician is primarily concerned with the histo- pathological diagnosis of biopsied tissue to confirm the clinical diagnosis or to provide a definitive diagnosis and further information on various factors such as an Correspondence: R. M. Love, Department of Oral Diagnostic and Surgical Sciences, University of Otago, PO Box 647, Dunedin, New Zealand (e-mail: robert.love@dent.otago.ac.nz). doi:10.1111/j.1365-2591.2008.01500.x International Endodontic Journal, 42, 198–202, 2009 ª 2009 International Endodontic Journal 198