Endodontic retreatment had the highest risk association for VRF after 1-8 years of follow up. Indirect and individual restorations were not significantly associated with VRF.

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To assess the previous periapical status and the quality of root canal filling as predictors of the outcome in initial nonsurgical endodontic procedures. A retrospective cohort study was designed in which the presence of a previous periapical lesion was determined radiographically. The quality of the root filling was evaluated in terms of homogeneity, taper, and apical extension. The response variable was dichotomized to success and failure. Bivariate analyzes and a mixed generalized linear model interpreted the association between the explanatory variables and the outcome of the initial non-surgical endodontic procedures. A total of 349 roots were evaluated, and a failure rate of 13.18% was established. Poor filling quality was determined in 8.3% of the roots. As a main result, the presence of a preoperative periapical lesion did not determine a significant risk to the failure of the initial treatment. Unlike, a poor quality of the obturation determined association with an unfavorable outcome like this: (1) homogeneity (OR 2.32; p = 0.0181); (2) taper (OR 5.8; p = 0.0); and, (3) extension (OR 3.41; p = 0.0). Therefore, a significant association between inadequate quality of the root filling and failure of the primary non-surgical endodontic procedures was found. Short length of filling was highly associated with failure. The presence of previous periapical lesion was not found to be a significant predictor for treatment outcomes.

To estimate the degree of concordance and consistency in the radiographic and tomographic evaluation of the periapical area. A study of diagnostic tests was designed. Three blind evaluators analyzed radiographic images, which were selected at two different points in time. An oral radiologist and an endodontist determined the second observation moment. The degree of similarity and variability, concordance and consistency for each radiograph was set at 95% confidence. A Kappa coefficient (κ), for radiographic findings and a correlation coefficient of Lin (CCC) for tomographic measurements was established. 12 radiographies and 19 tomographs were evaluated. The intraobserver consistency determined a k= 1 (Almost Perfect) and a CCC from 0.42 to 0.95 (Poor to Substantial) for both observation times. For radiographies, the interobserver concordance did not show changes between the first and second observation. Values include a k= 0.56-0.80 (Moderate to Good) and a CCC with greater degree of agreement, after training, as follows: axial view: CCC 0.86, 95% of Confidence Interval (CI) 0.69-0.94, coronal view: CCC 0.90 95%CI 0.75-0.96, and sagittal view: CCC 0.96, 95%CI 0.90-0.98. The statistical tests estimated the consistency and concordance to observe radiographically and tomographically the periapical tissue in endodontics.

Background This nested case-control study can be viewed as an efficient way to sample subjects from a large cohort study case-control study aimed to analyze the effect of different clinical factors on the appearance of vertical root fractures in endodontically-treated teeth (ETT) over time. Material and Methods By matching 90 cases and 270 controls nested in a cohort of 450 patients. Incident “cases” included those ETT in which a confirmed VRF. The “controls” were ETT with clinical and radiographic evidence of normality. When an “incident case” was detected, three random “controls” according to the evaluation time registered in years were selected. Time interval corresponded to the exposure time from the end of the endodontic treatment until the tooth was included in the study. Demographic and clinical parameters included: age, gender, type, and location of the tooth, type of endodontic treatment, number of appointments necessary to complete the endodontic treatment, use of intra-canal medication, the apical extension of the filling, type of coronal restoration, the role of the tooth in the rehabilitation treatment, presence of intra-radicular posts, and presence of an adjacent implant, were analyzed over time. Statistical analysis: univariate descriptive analysis, Pearson’s χ2 test, and a logistic regression model adjusted for the most significant variables with a 95% confidence interval. Results The prevalence of vertical root fractures was 16.42%. The multivariate analysis confirmed that re-treatment (OR:12.19; OR:4.28; P <0.05) lasting five to ten years and intra-canal medication (OR:6.16; P =0.004) for more than eleven years significantly more associated with the risk of vertical root fracture. For teeth with intra-canal post or direct coronal restorations, the risk of vertical root fracture was three times lower. Conclusions Endodontic re-treatment and the use of intracanal medication such as calcium hydroxide should be considered primary and secondary risk factors, respectively, according to the appearance of VRF over time. Key words: Apical surgery, endodontic re-treatment, endodontically-treated teeth, risk factors, vertical root fracture.