Survival study on teeth after successful endodontic surgical retreatment: influence of crown height, root length, crown-to-root ratio and tooth type

Abstract

Aim: To assess the influence of the crown height, root length, crown-to-root ratio, and tooth type on the survival of teeth subjected to surgical endodontic retreatment and classified as periapically healed. Methodology: A single operator performed endodontic microsurgery interventions between 2008 and 2018 on teeth with refractory apical periodontitis. The present analysis selected the teeth classified as “complete periapical healing” according to the scale suggested by Molven. The postoperative periapical radiographs and those taken at the last recall visit were analysed by two independent calibrated examiners, who measured crown height and root length in a blind manner. The crown-to-root ratio was calculated as the ratio of the two variables. The level of inter- and intra-operator agreement was tested with Bland–Altman plots with 95% limits of agreement. An independent statistician conducted a survival analysis using Kaplan–Meier plots and a log-rank test (α = 0.05) to assess the significance of the differences among the subgroups defined by the following criteria: (a) crown height median; (b) root length median; (c) crown-to-root ratio 1; (d) crown-to-root ratio median; (e) single-rooted teeth vs. multi-rooted teeth. Results: At the end of the analysis, 42 patients were evaluated, each one contributing to the study with a single tooth. The mean follow-up period was 4.2 ± 2.4 years. Survival estimates were significantly improved for the teeth with roots longer than 8 mm, in comparison with that with shorter roots (p mediana; lunghezza radicolaremediana; rapporto corona-radice1; rapporto corona-radicemediana; denti monoradicolati vs. pluriradicolati. Risultati: Al termine dell’analisi il campione era costituito da 42 pazienti, seguiti per 4,2±2,4 anni, ciascuno dei quali ha contribuito allo studio con un dente. Le stime di sopravvivenza sono risultate significativamente migliori per i denti con radici più lunghe di 8 mm nel confronto con quelle di lunghezza inferiore (p < 0.05). Non sono emerse ulteriori differenze statisticamente significative dal confronto tra gli altri sottogruppi considerati. Conclusioni: Nelle condizioni del presente studio retrospettivo, elementi dentari con radici residue lunghe a seguito di chirurgia apicale hanno mostrato migliori probabilità di sopravvivenza, paragonati a elementi con radici più corte di 8 mm. Le altre variabili testate non hanno influenzato la sopravvivenza dei denti sottoposti a resezione apicale. Keywords: Crown-to-root ratio, Late failure, Retrospective study, Survival analysis, Surgical endodontic retreatment, Parole chiave: Analisi di sopravvivenza, Fallimento tardivo, Rapporto corona-radice, Ritrattamento endodontico chirurgico, Studio retrospettivo