Ji Wook Jeong

Ex vivo comparative analysis of retrievability among four calcium silicate-based sealers for regaining apical patency

A 57‐year‐old patient with temporomandibular disorder and toothache underwent root canal treatments on teeth 42–31 by an endodontist. Despite these treatments, the patient experienced persistent pain radiating to his ears and sought evaluation by another endodontist. No notable facial or intraoral swelling nor paresthesia was observed; however, he reported difficulty with swallowing and trismus. A large periapical radiolucent lesion was identified spanning from tooth 42 to 32, and root resorptions were observed at the apices of teeth 42, 41 and 31. The initial diagnoses for teeth 42, 41, and 31 were previously treated and symptomatic apical periodontitis. Root‐end surgery with biopsy was performed. One month later, the biopsy results revealed the lesion to be a carcinoma. The patient was immediately referred to a cancer centre, where a definitive diagnosis of adenoid cystic carcinoma was made. A prompt biopsy is critical for the definitive diagnosis of malignancies for timely treatment.

Background: Pulp tissue debridement and the eradication of microorganisms from an infected root canal system before obturation is a primary focus of endodontic treatment and the best predictor for the long-term success of endodontic treatment. Objective: The purpose of this in vitro laboratory study was to evaluate pulp tissue debridement and the disinfection efficacy of two different Er;Cr:YSGG laser units, with a 2790 nm wavelength, compared to ultrasonic-activated irrigation (UAI) in root canals infected with Enterococcus faecalis. Methods: Human non-infected mandibular first molars were extracted, disinfected, and cultured with Enterococcus faecalis. Different types of Er;Cr:YSGG laser irrigation and UAI were performed according to the manufacturers’ protocols. The teeth were then processed for bacteriological and SEM analyses. Results: The different laser-activated irrigation protocols showed multiple areas of remaining bacteria, biofilm, tissue, and thermal ablation. The laser fiber tips also displayed significant tip degradation after use, which might affect efficacy. Conclusions: In this in vitro study, laser-activated irrigation using Er;Cr:YSGG technology and UAI were inefficient in eliminating pulp tissue from difficult-to-reach areas and Enterococcus faecalis from infected root canals.

Recently, the single-cone hydraulic canal filling technique using bioceramic sealers was found to hinder retreatment due to the mechanical properties of the bioceramic sealers. This study assessed the effectiveness of four nickel–titanium rotary files in removing gutta-percha and bioceramic sealer from molar root canals in vitro. Eighty-eight root canals from extracted molars were instrumented with Vortex Blue rotary files and filled with gutta-percha and bioceramic sealer using a single-cone technique. After 30 days, the filled canals were randomly divided into four groups according to the file used for re-instrumentation: ProTaper Gold (PTG), Endo ReStart (ERS), XP-3D Shaper (XPD), and HyFlex Remover (HFR). This study assessed whether root canal filling material removal and patency were achieved within a 10-min time frame, recording the time required in seconds. The rate of regaining patency and the time required to achieve patency were compared among groups using a generalized linear model. Scanning electron microscopy was used to evaluate the mechanical changes to the files after use. The patency rate of XPD and HFR was significantly higher than PTG. ERS and XPD demonstrated shorter patency times than HFR and significantly shorter patency times than PTG. SEM images revealed a varied range of reverse windings across file groups. PTG and ERS exhibited microcracks and fractured tips, while XPD and HFR did not display these mechanical alterations. The four file systems in this study displayed varying levels of effectiveness in the retreatment of root canals filled with bioceramic sealers.

Pulp tissue debridement and eradication of microorganisms from an infected root canal system before obturation is a primary focus of endodontic treatment and the best predictor for the long-term success of endodontic treatment. The purpose of this in vitro laboratory study was to evaluate pulp tissue debridement and the disinfection efficacy of two different Er;Cr:YSGG laser units, with 2790 nm wavelength, compared to Ultrasonic Activated Irrigation (UAI) in root canals infected with Enterococcus faecalis. The different laser-activated irrigation protocols showed multiple areas of remaining bacteria, biofilm, tissue, and thermal ablation. The laser fiber tips also displayed significant tip degradation after use which might affect efficacy. While UAI showed similar results. In this in-vitro study, laser-activated irrigation using Er;Cr:YSGG technology and UAI were inefficient in eliminating pulp tissue from difficult-to-reach areas and Enterococcus faecalis from infected root canals.

Recently single-cone hydraulic canal filling technique using bioceramic sealers brought a difficulty of retreatment due to the mechanical properties of the bioceramic sealers. This study assessed the effectiveness of four nickel-titanium rotary files in removing gutta-percha and bioceramic sealer from molar root canals in vitro. Eighty-eight root canals from extracted molars were instrumented with Vortex Blue rotary files and filled with gutta-percha and bioceramic sealer using a single-cone technique. After 30 days, the filled canals were randomly divided into four groups according to the file used for re-instrumentation: ProTaper Gold (PTG), Endo ReStart (ERS), XP-3D Shaper (XPD), and HyFlex Remover (HFR). The study assessed whether root canal filling material removal and patency were achieved within a 10-minute time frame, recording the time required in seconds. The rate of regaining patency and the time required to achieve patency were compared between groups using a generalized linear model. Scanning electron microscopy were used to evaluate the mechanical changes on the files. The patency rate of XPD and HFR was significantly higher than PTG. ERS and XPD demonstrated shorter patency times than HFR and significantly shorter patency times than PTG. SEM images revealed a varied range of reverse windings across file groups. PTG and ERS exhibited microcracks and fractured tips, while XPD and HFR did not display these mechanical alterations. The four file systems in this study displayed varying levels of effectiveness in the retreatment of root canals filled with bioceramic sealers.

Objectives Currently, premixed putty-type bioceramic cements (PPBCs) have become popular materials for root-end fillings. This study investigated three root-end filling techniques using PPBCs and calcium silicate-based sealers including EDTA pretreatment. Materials and methods Ninety root segments were prepared and standardized with an artificial fin and lateral canal, and assigned to three groups (n = 30). Root-end fillings were placed using BC-RRM Putty alone (Group PA), injection of BC sealer followed by BC-RRM Putty (Lid Technique: Group LT) or BC-RRM Putty with BC sealer coating (Deep putty packing technique: Group DP). Half of each group was pretreated with 17% EDTA. The radiographic images of the specimens were assessed by five graders and push-out bond strength tests were conducted. The data were analyzed with a general linear model including two-way ANOVA and chi-square test at a significance level of 5%. Results DP approach demonstrated significantly higher bond strength than LT (P < 0.05). However, there was no statistically significant difference in bond strength between PA and either DP or LT. EDTA pretreatment had no significant effect on push-out bond strength. Radiographically, for the main canal, PA and DP scored significantly higher than LT. In the fin, PA scored significantly higher than others (P < 0.05). Conclusion Our study highlights variations in root-end filling techniques. Injecting a bulk of bioceramic sealer before the placement of PPBCs may reduce bond strength and radiopacity. The application of PPBCs alone or in the deep putty technique demonstrates potential for favorable outcomes. EDTA pretreatment did not enhance bond-strength. Clinical relevance Careful selection and application of bioceramic materials and techniques in root-end fillings may influence the outcome of endodontic root-end surgery. When PPBCs and calcium silicate-based sealers are used together for root-end fillings, sealer followed by deep putty application may offer improved bond strength and radiographic fill compared to the lid technique.

It is difficult to predict the outcomes of non-surgical root canal treatment (NSRCT) for mandibular second premolars with multiple root canals. In these teeth, the complicated anatomy with fin(s), or a C-shape, and possible secondary canal(s) varies unpredictably. The morphology of the root canals provides shelters for bacteria to remain, regrow, and form biofilms despite the endodontic treatment. Moreover, the prevalence of mandibular second premolars with multiple canals is extremely infrequent. Therefore, the clinical management of NSRCT in such cases is not sufficiently reported. This case report introduces two cases of NSRCT for mandibular second premolars with a radicular groove and also presents the appropriate clinical strategies and techniques. Cone-beam computed tomography (CBCT) imaging was used preoperatively. After the completion of NSRCT, CBCT was reused to review the completed procedures using the Nerve Canal tool in CS 3D Imaging v3.2.9 and v3.8.7. Five canals were obturated in case 1, and four canals in case 2 along with a C-shape morphology. Analyzing the configuration of the root canals by CBCT was critical to achieve successful NSRCT because the numbers, exits, configurations, and volumes of the secondary canals were not anticipated after reviewing 2D radiographs. Based on the interpretation, the advanced protocols of NSRCT were planned: first, augmentation of chemo-mechanical cleaning, but minimizing the loss of dentine; second, the tactile examination to locate and negotiate the orifices of the secondary canals; and lastly, the optimized plan and technique for root canal filling of the complex canal systems.

This review explores the field of retreatment strategies for cases filled with calcium silicate-based root canal sealers. Since the introduction of calcium silicate-based materials in dentistry, calcium silicate-based root canal sealers have become popular among dentists because of their biocompatibility, bioactivity, and sealing ability. Therefore, effective retreatment strategies are indispensable. This article aims to identify the challenges associated with the removal of calcium silicate-based sealers themselves and removal of gutta-percha with the sealers during retreatment, evaluate current techniques and materials, and provide future directions for research in this field. Regarding the strategies of removal of root canal sealers, calcium silicate-based sealers are still relatively new materials for clinicians compared with traditional sealers such as epoxy- or eugenol-based sealers. First, no clinically established solvents have been reported. Second, calcium silicate-based sealers are currently utilized by clinicians in either the cold sealer-based technique or the warm vertical condensation technique. Third, the setting process of calcium silicate-based sealers generates byproducts, primarily calcium hydroxide and secondarily hydroxyapatite, that could interact with dentine. Lastly, there is a lack of clinical studies evaluating the efficacy of retreatment protocols for teeth filled with calcium silicate-based sealers. Therefore, it is important to investigate the chemo-mechanical properties of calcium silicate-based sealers themselves and their reactions to solvents and/or mechanical instruments and identify the interfacial properties of calcium silicate-based sealers with respect to dentine and gutta-percha. In addition, researchers in the clinical field need to actively gather and report data on retreatments of teeth filled with calcium silicate-based sealers.

This review explores the field of retreatment strategies for the cases filled with calcium silicate-based root canal sealers. Since the introduction of calcium silicate-based materials in dentistry, calcium silicate-based root canal sealers have become popular among dentists because of their biocom- patibility, bioactivity, and sealing ability. Therefore, effective retreatment strategies are indispensable. This article aims to identify the challenges associated with the removal of calcium silicate-based sealers itself and gutta-percha with the sealers during retreatment, evaluate current techniques and materials, and provide future directions for research in this field. Regarding the strategies of removal of root canal sealers, calcium silicate-based sealers are still relatively new materials for clinicians compared with the traditional sealers such as epoxy- or eugenol-based sealers. First, no clinically established solvents have been reported. Second, calcium silicate-based sealers are currently utilized by clinicians in either cold sealer-based technique or warm vertical condensation technique. Third, the setting process of calcium silicate-based sealers generates byproducts primarily calcium hydroxide and secondarily hydroxyapatite, which could interact with dentine. Lastly, there is a lack of clinical studies evaluating the efficacy of retreatment protocols for teeth filled with calcium silicate-based sealers. Therefore, it is important to investigate chemo-mechanical properties of calcium silicate- based sealers itself and their reactions to solvents and/or mechanical instruments, and identify the interfacial properties of calcium silicate-based sealers in respect to dentine and gutta-percha. In addition, researchers in clinical field need to actively gather and report data on retreatments of teeth filled with calcium silicate-based sealers.