April 2003 ■ Journal of Dental Education 459 Transfer of Advances in Science into Dental Education Diabetes Mellitus as a Modulating Factor of Endodontic Infections Ashraf F. Fouad, D.D.S., M.S. Abstract: Diabetes mellitus is a chronic disease with serious health consequences. The association between diabetes and peri- odontal disease is well documented. However, the progression and healing of endodontic infections in diabetic patients has not been adequately studied. In this review, diabetes mellitus is explored as a potential modulating factor of endodontic pathosis. Recent data on the relationship between the clinical presentation of pulpal and periradicular disease, as well as the outcome of endodontic treatment in diabetic and nondiabetic patients, are presented. Diabetics who present for endodontic treatment, particularly those with periradicular pathosis, may have increased perioperative symptoms. Cases with preoperative periradicular lesions are less likely to be determined successful two years or longer postoperatively if the patient reports a history of diabetes. Studies examining the pathogenesis of periradicular lesions in mouse models with uncontrolled type 1 diabetes suggest that the lesion size may be increased and the animals have increased serious sequelae. Preliminary findings suggest that some bacterial species may be more prevalent in necrotic pulp of diabetic than nondiabetic patients. More studies are needed to further explore the microbiology of endodontic infections and to determine effective treatment strategies in both diabetic and nondiabetic patients. Dr. Fouad is Associate Professor, Department of Endodontology, School of Dental Medicine, University of Connecticut Health Center. Direct correspondence and requests for reprints to him at Department of Endodontology, School of Dental Medicine, University of Connecticut Health Center, 263 Farmington Ave., Farmington, CT 06030-1715; 860-679-2726 phone; 860-679- 2208 fax; fouad@nso.uchc.edu. Key words: endodontic infections, periradicular lesions, diabetes mellitus, outcomes analysis, NOD mice D iabetes mellitus is a chronic disease with serious long-term debilitating complications and no known cure. The relationship between oral health and diabetes has been extensively stud- ied, particularly with respect to periodontal disease and, to a lesser extent, dental caries. Endodontic in- fections are very prevalent and are caused by micro- bial factors that are very similar to those that cause periodontal disease. However, the literature on the pathogenesis, progression, and healing of endodon- tic pathosis in diabetic patients is remarkably scarce. In this review, the epidemiology and pathogenesis of periradicular infections will be briefly described. The literature addressing the natural history of endodon- tic infections and endodontic treatment outcome in diabetics will be discussed. Finally, recent data on the microbiology and host response in periradicular infections of diabetic and nondiabetic hosts will be presented. Epidemiology and Pathogenesis of Periradicular Lesions Periradicular (PR) lesions result from irritation of the PR tissues by polymicrobial irritants from root canals, in teeth with necrotic pulps. The prevalence of PR lesions in the general population of the United States has not been established. However, estimates based on prevalence in other countries and prevalence among dental clinic populations in this country show that the percentage of individuals with PR lesions in at least one tooth is 41-47 percent. 1-5 This prevalence tends to increase to 60-72 percent in older patients. 6,7 In dental patient populations, the percentage of teeth with PR lesions has been estimated to range