Secondary Root Canal Treatment with Reciproc Blue and K-File: Radiographic and ESEM-EDX Analysis of Dentin and Root Canal Filling Remnants

Carlo Prati; Fausto Zamparini; Andrea Spinelli; Gian Andrea Pelliccioni; Chiara Pirani; Maria Giovanna Gandolfi

doi:10.3390/jcm9061902

Secondary Root Canal Treatment with Reciproc Blue and K-File: Radiographic and ESEM-EDX Analysis of Dentin and Root Canal Filling Remnants

J Clin Med. 2020 Jun 18;9(6):1902. doi: 10.3390/jcm9061902.

Authors

Carlo Prati¹, Fausto Zamparini^{1

2}, Andrea Spinelli¹, Gian Andrea Pelliccioni¹, Chiara Pirani¹, Maria Giovanna Gandolfi²

Affiliations

¹ Endodontic Clinical Section, School of Dentistry, Department of Biomedical and Neuromotor Sciences (DIBINEM), Alma Mater Studiorum University of Bologna, 40125 Bologna, Italy.
² Laboratory of Green Biomaterials and Oral Pathology, School of Dentistry, Department of Biomedical and Neuromotor Sciences, University of Bologna, 40125 Bologna, Italy.

Abstract

Secondary root canal treatment requires the complete removal of filling materials with different chemical-physical properties. A newly developed single-use NiTi instrument (Reciproc Blue, RB) may be more effective in root canal retreatment. The aim of the present study was to evaluate morphology and composition of remnants after retreatment with RB compared to traditional K-File technique, in canals obturated with Thermafil/AH Plus. Twenty-four single-rooted human teeth were shaped with NiTi obturated with AH-Plus/Thermafil and retreated using RB NiTi instruments or manual K-Files. Radiographs were taken to evaluate endodontic space and radiopacity of residual filling-material before/after procedures. After retreatment, samples were longitudinally split and observed by environmental scanning electron microscopy connected to energy dispersive X-Ray spectroscopy (ESEM-EDX) to analyze the debris/remnant position, microchemistry, and dentinal surface morphology. Time for retreatments was recorded and compared using one-way ANOVA (p-value = 0.05). Radiopaque filling residuals were found in both groups. RB system resulted statistically faster than manual K-File in retreatment procedure (p < 0.001). Root canal space radiographic appearance obtained after retreatment with RB was wider than K-File (p < 0.05). ESEM-EDX revealed 4 different morphological dentin area. Area-1: debris-free with typical Ca, P, and N composition of dentin and detected in 70% of the surface. Area-2: presence of deproteinized smear layer free from N and debris in 15% of the surface. Area-3: a thick packed smear layer N-free and with fine debris consisting of trace elements from sealer in 10% of the surface. Area-4: packed with debris and trace elements. No difference was observed between both instruments regarding root canal space appearance and ESEM-EDX analysis. Both systems were able to remove filling material but created a dentine morphology composed of packed debris and filling materials embedded into the smear layer. Dentin surface composition resulted in collagen depleted by irrigation procedures. The reciprocating system required less time to complete retreatment.

Keywords: ESEM-EDX; K-file; NiTi instruments; Reciproc Blue; periapical X-Ray; retreatment.