The Outcome of Endodontic Treatment: A Retrospective Study of 2000 Cases Performed by a Specialist Noboru Imura, MS, DDS, Ericka T. Pinheiro, PhD, MS, DDS, Brenda P.F.A. Gomes, PhD, MS, DDS, Alexandre A. Zaia, PhD, MS, DDS, Caio C.R. Ferraz, PhD, MS, DDS, and Francisco J. Souza-Filho, PhD, MS, DDS Abstract The purpose of this study was to evaluate the treatment outcome of initial endodontic treatment and nonsurgical retreatment performed by an endodontic specialist in his private office. A total of 2,000 teeth were examined clinically and radiographically and the results were ana- lyzed statistically by Pearson or Fisher’s Exact test and multivariate logistic regression. The multivariate analysis evaluated joint associations among various factors, using logistic regression models. The dependent variable for this analysis was the dichotomous outcome: healed versus disease. The overall endodontic success rate was 91.45%, and the healed rate was significantly higher for initial endodontic treatments than for nonsurgical retreatments; teeth without lesion than for those with lesions; teeth treated without complications than for those with com- plications; recall period of 18-24 months than for other periods, and teeth with final coronal restoration than for those without. Of the 1376 teeth treated in the initial endodontic treatment sample, the success rate was 94.0%. Multivariate analysis identified the presence of procedural complications (file breakage, perforation and flare-up), as well as the absence of the restorations at follow-ups as the significant predictors of outcome, show- ing lower rates of success. Of the 624 teeth in the non- surgical retreatment sample, 85.9% were successful. Step- wise logistic regression analysis revealed that preoperative radiolucency was a strong statistically significant factor to determine lower rates of success than in its absence. Two additional variables (age and tooth type) were found to have a significant influence on the outcome of the retreat- ment sample. A higher healed rate was observed for the 50-59 years age groups than others, while multirooted (molars) teeth revealed a significantly lower percentage of success than pre-molars and anterior teeth. (J Endod 2007; 33:1278 –1282) Key Words Initial endodontic treatment, multivariate analysis, non- surgical retreatment, outcome of endodontic treatment, retrospective study N umerous retrospective studies (1-9) have been performed evaluating the success and failure of initial (first-time) endodontic treatment and nonsurgical retreatment based on clinical examination and radiographic appearance. However, reporting out- comes of endodontic treatment have shown considerable differences in the data com- position, clinical procedures, and methodology (10). Therefore, data obtained from significantly large patient samples regarding end- odontic treatment outcomes are important, especially in relation to case selection and treatment planning. Such information enables the clinician to make more predictable decisions regarding the long-term prognosis of endodontic treatment, allowing the patient to retain their natural dentition in function. Another approach to assess the outcome of endodontic therapy is the analysis of multiple treatment variables, providing the clinician more tools for clinical decision making and assessment of teeth prognosis. Multivariate methods have been developed to analyze the simultaneous influence of several variables on one dependent variable and allow judgment and discussion of the relative importance of each variable (9). Despite the numerous retrospective studies (1-9), long-term evaluations for sev- eral years of teeth endodontically treated by specialists are rare. Usually, teeth treated by specialists seem to be more technically difficult. Certainly, many factors are considered when referring a patient for specialist care. These include technical difficulty, patient management, and tooth position, among others. The aim of this study was to analyze the outcome of endodontic treatment performed by a specialist in his private office, using logistic regression analysis. Materials and Methods A total of 2000 teeth performed by a specialist (NI) in his private office during a 30-year-period (March 1971-March 2000) were followed up with reference to the dental records. Among all patients who had returned for recall, 2000 teeth were ran- domly selected for this survey. This study material included a variety of clinical condi- tions. Original Endodontic Therapy Procedure For each tooth, the following preoperative information was recorded: demo- graphic data, tooth location, number of root canals, previous endodontic treatment, clinical signs and symptoms, response to percussion, vitality tests, and periapical status. Based on these findings, the preoperative condition was classified as one of the follow- ing: vital (healthy or irreversibly inflamed pulpitis), nonvital, endodontically treated, with or without periapical lesion, and symptomatic or asymptomatic. For each tooth, the following intraoperative information was recorded: type of irrigation used, number of treatment sessions; interappointment dressing (if used); occurrence of procedural complications such as perforation, breakage of files, and flare-up; length of canal filling (at apical level, 1 mm short or more and beyond); and temporary restoration placed. Only small modifications were made to clean and shape the canals. After conventional straight-line access preparation was obtained, a modified step-down instrumentation technique was used as the routine procedure in which the coronal two thirds of the canal were enlarged with Gates-Glidden burs. The working length was established at 1 mm from the radiographic apex. The apical third was then prepared by using stainless steel files with step-back increments of 0.5 mm until a final file size #30 or larger could be placed at the working length. Irrigation was copious and frequent using 0.5% or 2.5% sodium hypochlorite. In nonsurgical retreatment cases, full-coverage coronal restorations were either accessed through or cut in half and discarded. Posts when present were vibrated ultrasonically or removed by using burs. From the Piracicaba Dental School, State University of Campinas, UNICAMP, Piracicaba, Sao Paulo, Brazil. Address requests for reprints to Dr Francisco José de Souza- Filho, Área de Endodontia, Faculdade de Odontologia de Piraci- caba-UNICAMP, Avenida Limeira 901, Piracicaba, Sao Paulo, Brazil. E-mail address: franciscosouzafilho@yahoo.com.br 0099-2399/$0 - see front matter Copyright © 2007 by the American Association of Endodontists. doi:10.1016/j.joen.2007.07.018 Clinical Research 12 78 Imura et al. JOE — Volume 33, Number 11, November 2007