Clinical outcomes of teeth treated endodontically through pre-existing crowns

Abstract

Aim: To determine the incidence and treatment outcome usingclinical and radiographic assessment as well as evaluate possibleprognostic factors affecting treatment outcome when root canaltreatment was provided through existing crowns. Methodology: The study population comprised of patients who had primary root canal treatment performed through pre-existingcrowns from January 2011 to November 2014 at the NationalDental Centre, Singapore. Teeth diagnosed with irreversible pulpi-tis or pulp necrosis, with or without apical periodontitis wereincluded in the sample. After excluding teeth with incompletedata, or had extraction or re-treatment performed, as well asincluding only one tooth per patient, 197 patients were eligiblefor the study. One hundred and seventy-one patients (68.5%recall rate) were examined clinically and radiographically for con-dition of the crown and periapical status. Periapical healing statuswas determined by two examiners who reviewed and comparedimmediate post-obturation and follow-up radiographs side by side.Treatment outcome was dichotomized into ‘favourable’ (healed/healing in progress, absence of clinical signs and symptoms) or‘unfavourable’ (uncertain/post-treatment disease, and/or clinicalsigns and symptoms). The Chi square test was performed to findsignificant associations (p<0.05) between several covariablesand the periapical healing status of the root filled teeth. Univari-ate and multivariate logistic regression analyses were performedon prognostic factors that were significant. Results: The incidence of such treatment modality was low, at3.1% in 47 months. Favourable radiographic outcome for thesample of 171 teeth was 76.6% and 80.5% for per-tooth and per-root evaluation respectively. Including 16 teeth with treatmentfailure (re-treated or extracted) as having an unfavourable out-come, favourable outcome based on clinical and radiographicassessment was 61.5% for per-tooth evaluation based on a sampleof 187 teeth. Multivariate logistic regression analysis revealedthat maxillary teeth had a lower chance (OR=0.46; 95% CI:0.21–1.00;p<0.05) of a favourable outcome as compared tomandibular teeth. Teeth with adequate length of root filling weremost likely to exhibit favourable periapical healing outcome(OR=3.2; 95% CI: 1.50–6.84;p<0.001).Conclusions: Within the limitations of this study, favourableradiographic treatment outcome for this treatment modality wassimilar to other outcome studies. Root canal treatment through prosthesis with intact margins and maintaining them as finalrestorations is a viable treatment option.