A titration model for evaluating calcium hydroxide removal techniques

Objective Calcium hydroxide (Ca(OH)2) has been used in endodontics as an intracanal medicament due to its antimicrobial effects and its ability to inactivate bacterial endotoxin. The inability to totally remove this intracanal medicament from the root canal system, however, may interfere with the setting of eugenol-based sealers or inhibit bonding of resin to dentin, thus presenting clinical challenges with endodontic treatment. This study used a chemical titration method to measure residual Ca(OH)2 left after different endodontic irrigation methods. Material and Methods Eighty-six human canine roots were prepared for obturation. Thirty teeth were filled with known but different amounts of Ca(OH)2 for 7 days, which were dissolved out and titrated to quantitate the residual Ca(OH)2 recovered from each root to produce a standard curve. Forty-eight of the remaining teeth were filled with equal amounts of Ca(OH)2 followed by gross Ca(OH)2 removal using hand files and randomized treatment of either: 1) Syringe irrigation; 2) Syringe irrigation with use of an apical file; 3) Syringe irrigation with added 30 s of passive ultrasonic irrigation (PUI), or 4) Syringe irrigation with apical file and PUI (n=12/group). Residual Ca(OH)2 was dissolved with glycerin and titrated to measure residual Ca(OH)2 left in the root. Results No method completely removed all residual Ca(OH)2. The addition of 30 s PUI with or without apical file use removed Ca(OH)2 significantly better than irrigation alone. Conclusions This technique allowed quantification of residual Ca(OH)2. The use of PUI (with or without apical file) resulted in significantly lower Ca(OH)2 residue compared to irrigation alone

Micro-CT Evaluation of Root Filling Removal after Three Stages of Retreatment Procedure

The aim of this study was to quantify the residual filling material after filling removal, re-preparation with rotary or reciprocating files and passive ultrasonic irrigation (PUI). Twenty maxillary molars were prepared using ProTaper instruments up to F1. The teeth were filled with AH Plus and ProTaper gutta-percha points using the single-cone technique. Thereafter, the specimens were scanned using a micro-computed tomography system (Micro-CT #1). Then, the root canal filling was removed using ProTaper Retreatment files, and a new scan was performed (Micro-CT #2). The specimens were divided into two groups according to the instrument used for re-preparation: ProTaper rotary or WaveOne reciprocating files (Micro-CT #3). Finally, PUI was performed, and a new micro-CT scan was performed (Micro-CT #4). Intragroup and intergroup analyses were performed using Friedman and Dunn’s post hoc test and the Kruskal-Wallis and Dunn post hoc tests, respectively. Palatal canal presented the highest volume of residual filling material in all stages of endodontic retreatment (p<0.05). The main reduction of filling volume was achieved after using ProTaper Retreament (p<0.05). The amount of remaining filling material after using ProTaper Retreatment was similar to that achieved with rotary and reciprocating files and after PUI (p>0.05). Rotary and reciprocating files achieved similar removal of the root canal filling (p>0.05). The greatest reduction in filling material was achieved after using ProTaper Retreatment files. Rotary and reciprocating instruments and PUI did not improve the removal of root canal filling materials.O objetivo dente estudo foi quantificar o material obturador residual após remoção da obturação, repreparo do canal com instrumentos de rotação contínua e reciprocantes e após irrigação ultrassônica passiva (IUP). Vinte molares superiores foram preparados usando instrumentos ProTaper sequencialmente até F1. Os dentes foram obturados com AH Plus e cones de guta percha ProTaper utilizando a técnica de cone único. Em seguida, os espécimes foram submetidos à microtomografia computadorizada (Micro- CT #1). Então, o material obturador foi removido utilizando instrumentos ProTaper Retratamento e novo escaneamento foi realizado (Micro-CT #2). Os espécimes foram divididos em dois grupos de acordo com o instrumento usado para o repreparo: de rotação contínua (ProTaper) ou reciprocante (WaveOne) (Micro-CT #3). Finalmente, IUP foi realizada e nova micro-CT foi conduzida (Micro-CT #4). As análises intra-grupo e inter-grupos foram realizadas utilizando os testes de Friedman e de Dunn e o teste de Kruskal- Wallis e Dunn, respectivamente. O canal palatino apresentou o maior volume de material obturador remanescente em todos os estágios do tratamento endodôntico (p<0,05). A maior redução do volume da obturação foi obtida após usar os instrumentos ProTaper Retratamento (p<0,05). A quantidade de material obturador remanescente após utilizar instrumentos ProTaper Retratamento foi similar àquela obtida após repreparo com instrumentos de rotação contínua e reciprocantes e após a IUP (p>0,05). Instrumentos de rotação contínua e reciprocantes proporcionaram similar remoção de material obturador (p>0,05). A maior redução do volume de material obturador foi obtida após utilizar os instrumentos ProTaper Retratamento. Instrumentos de rotação contínua e reciprocantes, assim como a IUP, não reduzíram o volume de material obturador remanescente

Effectiveness of different irrigation protocols on calcium hydroxide removal from simulated immature teeth after apexification

Aim: To evaluate the effectiveness of different irrigation solutions and ultrasonic activation of the irrigation solutions on the removal of calcium hydroxide (Ca(OH)2) from the simulated immature root canals after apexification. Materials and methods: One-hundred and one single-rooted teeth were used. The root canals were shaped with ProTaper rotary files up to F5. Simulation of roots with immature apices was carried out using size 4 Unicore drills. An injectable Ca(OH)2 was injected into each root canal, and packed to the working length. Then, cotton pellets were placed over canal orifices, and apical and coronal parts of the roots were sealed with resin-modified glass ionomer cement, and light cured. Specimens were stored in distilled water for 3 months at 37°C. After 3 months, the temporary coronal seal was removed and the samples were randomly divided into: (a) saline (n = 20), (b) ultrasonic activation of saline (n = 20), (c) sodium hypochlorite (NaOCl) (n = 20), (d) ultrasonic activation of NaOCl (n = 15), (e) chlorhexidine digluconate (CHX) (n = 20) and one positive control group (n = 3) and one negative control group (n = 3). The amount of remaining Ca(OH)2 on the canal walls was measured under stereomicroscope with 30× magnification. Comparisons between groups were made by the non-parametric Kruskal-Wallis test and Dunn post-test at a significance level of p  0.05) groups. Conclusions: Irrigation solutions and ultrasonic activation of the irrigation solutions could not completely remove Ca(OH)2 from the simulated immature root canals