REVIEW Association between diabetes and the prevalence of radiolucent periapical lesions in root-filled teeth: systematic review and meta-analysis Juan J. Segura-Egea 1,2 & Jenifer Martín-González 1 & Daniel Cabanillas-Balsera 1 & Ashraf F. Fouad 3 & Eugenio Velasco-Ortega 4 & José López-López 5 Received: 7 December 2015 /Accepted: 16 March 2016 /Published online: 8 April 2016 # Springer-Verlag Berlin Heidelberg 2016 Abstract Introduction The question of whether diabetes mellitus can influence the outcome of root canal treatment (RCT) remains unclear. The aim of this systematic review and meta-analysis was to analyze scientific available evidence on the association between diabetes and the presence of radiolucent periapical lesions (RPLs) in root-filled teeth (RFT). Methods The review question was as follows: in adult patients who had endodontically treated teeth, does the absence or presence of diabetes result in an increase in the prevalence of RPL associated to RFT? A systematic MEDLINE/ PubMed, Wiley Online Database, Web of Science, and Scopus search was conducted using the following MeSH and keywords: Diabetes Mellitus OR Diabetes OR Diabetic OR Hyperglycemia, AND Endodontics, Periapical Periodontitis, Periapical Diseases, Apical Periodontitis, Periradicular Lesion, Periapical Radiolucency, Radiolucent Periapical Lesion, Root Canal Treatment, Root Canal Preparation, Root Canal Therapy, Root Filled Teeth, Endodontically Treated Teeth. Seven studies reporting data on the prevalence of RPL associated to RFT both in diabetic and control subjects were included. Results After the study selection, seven epidemiological stud- ies fulfilled the inclusion criteria, representing data from 1593 root canal treatments, 1011 in non-diabetic control subjects, and 582 in diabetic patients. The calculated pooled odds ratio (OR = 1.42; 95 % CL = 1.11–1.80; p = 0.0058) indicates that diabetic patients have higher prevalence of RFT with RPLs than controls. Conclusion Available scientific evidence indicates that diabe- tes is significantly associated to higher prevalence of periapical radiolucencies in endodontically treated teeth, be- ing an important putative pre-operative prognostic factor in RCT. Clinical relevance Taking into account that diabetes is the third most prevalent chronic medical condition among dental patients, endodontic providers should be aware of the relation- ship between the outcome of endodontic treatment and diabetes. Keywords Diabetes mellitus . Meta-analysis . Periapical inflammation . Persistent apical periodontitis . Root canal treatment outcome . Root-filled teeth Introduction Apical periodontitis (AP) is an inflammatory process around the apex of a tooth root, following the bacterial infection of the pulp space of the tooth [1]. The bone lesion associated with apical periodontitis is characterized radiographically by the presence of radiolucent periapical lesion (RPL), i.e., a radio- lucent image surrounding the root apex of the affected tooth [2]. AP is an extraordinarily prevalent problem [3]. In the USA, radiographic signs of periapical disease are evident in * Juan J. Segura-Egea segurajj@us.es 1 Endodontic Section, Department of Stomatology, School of Dentistry, University of Sevilla, Seville, Spain 2 Facultad de Odontología, Universidad de Sevilla, C/ Avicena s/n, 41009 Seville, Spain 3 Department of Endodontics, University of North Carolina, Chapel Hill, USA 4 Comprehensive Dentistry, Department of Stomatology, School of Dentistry, University of Sevilla, Seville, Spain 5 Oral Medicine, Department of Odontostomatology, School of Dentistry, University of Barcelona, Barcelona, Spain Clin Oral Invest (2016) 20:1133–1141 DOI 10.1007/s00784-016-1805-4