Disinfection and Shaping of Vertucci Class II Root Canals after Preparation with Two Instrument Systems and Supplementary Ultrasonic Activation of Sodium Hypochlorite

INFLUENCE OF THE FILLING TECHNIQUE ON ENDODONTIC RETREATMENT IN CURVED MESIAL CANALS OF MANDIBULAR MOLARS - AN IN VITRO STUDY

INTRODUCTION

The root curvature represents a challenge during the endodontic retreatment. Considering the different techniques to fill the root canals and the growing use of bioceramic sealers, this study aimed to evaluate the influence of the filling technique associated with a bioceramic sealer on the remaining filling material and the impact on the remaining dentin after the filling removal in the retreatment of curved mesial canals of mandibular molars.

METHODS

Eighteen curved mesial roots of mandibular molars with Vertucci type IV canals were prepared up to instrument 35/.05. Two groups were established according to the filling technique: single-cone (n=18) and continuous wave of condensation (n=18). Bio-C Sealer was used for both techniques. The filling was removed using the Reciproc Blue R25 instrument, and the repreparation was carried out using the Reciproc Blue R40 instrument. The samples were scanned by micro-CT before and after the filling removal and analyzed regarding the volume of the remaining filling material and dentin thickness for calculating transportation and centering ability. For statistical analysis, the data normality was checked, and parametric tests were used for normal distribution and non-parametric tests for non-normal distribution.

RESULTS

The remaining filling material was observed in both groups during retreatment, with no differences. Analyses of transportation and centering ability also indicated similarities between the two groups.

CONCLUSION

Endodontic retreatment in curved mesial canals of mandibular molars filled with single-cone or continuous wave of condensation technique and bioceramic sealer was similar. The use of reciprocating instruments for filling removal and repreparation was efficient in curved mesial canals of mandibular molars, with no complications.

Characteristics and Effectiveness of XP-Endo Files and Systems: A Narrative Review

Background: XP-endo files are composed of Max-Wire alloy, which was developed by FKG Dentaire (La Chaux-de-Fonds, Switzerland). This alloy, known as Martensite-Austenite Electropolish Flex, is the first NiTi alloy used in endodontics to combine the shape memory effect with superelasticity for use in clinical practice. Objective: This article aims to provide a comprehensive overview of the existing knowledge and evidence regarding different XP-endo files and systems, XP-endo Finisher (XPEF), XP-endo Shaper (XPES), XP-endo Retreatment (XPER), XP-endo Rise (XPE-Rise), and XPE-Rise Retreatment (XPE-Rise-R), to help clinicians understand their different properties and recommended clinical uses. Moreover, this review aims to identify future research opportunities in this field. Materials and Methods: A search was performed in the PubMed database using the keywords "XP endo" or "XP-endo". A total of 309 studies were identified during the initial search, and then initial abstract screening was conducted. The inclusion criteria included any study that aimed to evaluate XP endo files and systems on permanent teeth, either in vivo or in vitro. We excluded studies that were unrelated to the subject, literature reviews, case studies, and studies that employed deciduous teeth. Finally, we performed an extensive review of the selected 130 studies, which we assessed, summarized, and classified based on the specific XP-endo file used. Conclusion: Overall, XP-endo files offer significant improvements in endodontic treatment. XPEF excels in irrigation activation and medicament removal, and XPES succeeds in canal cleaning, shaping, and retreatment. The XPER system, which incorporates the XPEF-R file, shows promise in removing root-filling materials, but its performance is inconsistent compared to other retreatment systems. We have found limited information regarding the latest XPE-Rise and XPE-Rise-R systems, additional research is required to fully determine their comparative effectiveness and optimize their clinical application.

Effectiveness of supplementary antimicrobial procedures in disinfecting lateral canals as evaluated by a novel ex vivo analytical approach

This ex vivo study devised an analytical ex vivo method for infection/disinfection of simulated lateral canals located in the middle and apical segments of the root. The antibacterial effects of supplementary approaches were tested in this model. Extracted mandibular premolars had their main root canals enlarged and then two lateral canals (100 μm in diameter) were created in the root, one in the apical and the other in the middle portion. Micro-computed tomography was used for specimen selection and to confirm the quality of the simulated ramifications. The specimens were contaminated with a mixed bacterial culture from subgingival bacterial biofilm added to pure Enterococcus faecalis strain ATCC 29212 grown overnight, using special strategies to facilitate culture medium penetration within the lateral canals. The following procedures were tested for disinfection: NaOCl/passive ultrasonic irrigation (PUI), NaOCl/XP-endo Finisher, ozonated water/continuous ultrasonic irrigation (CUI), and NaOCl/conventional irrigation with 30-G needles (control). Bacteriological samples were taken from the main canal before (S1) and after (S2) each supplementary protocol, and also from each lateral canal after treatment (S3). DNA extracted from the samples was subjected to quantitative real-time polymerase chain reaction. All S1 main canal samples were positive for bacterial presence. Bacterial counts in the main root canal substantially decreased by 99.2% after PUI, 99.1% after ozone/CUI, 99% after XP-endo Finisher, and 96% in the control group (P < 0.01 for all groups). There were no significant differences between groups (P > 0.05). The same was observed when comparing the effects of the supplementary approaches in the apical and middle lateral canals (P > 0.05). Only a few lateral canals showed no detectable bacteria. The method proposed here proved effective for ex vivo infection/disinfection studies. All supplementary approaches induced a substantial bacterial reduction in the main canal, with no significant differences between them. However, in terms of lateral canal disinfection, none of the tested approaches showed significant effects when compared to the control group.

Evaluation of Minimally Invasive Preparation of Curved Mesial Canals of Mandibular Molars - An In Vitro Study

INTRODUCTION

Curved mesial roots can be challenging for different stages of endodontic treatment. Preparation aims to enlarge, clean, and shape the root canal system, and hundreds of systems are available to carry it out. Aiming to maintain pericervical dentin, minimally invasive preparation was proposed, and with it, instruments with lower tapers emerged. This study aimed to evaluate the increase in canal volume, the centering ability of the instruments, and root canal transportation of two different rotary systems with lower tapers.

METHODS

Eighteen curved mesial roots of extracted mandibular molars were scanned by micro-CT at 3 moments: initial and after the 2 stages of endodontic preparation. The canals were prepared using TruNatomy (TN) and ProDesign Logic 2 (PDL2) instruments up to sizes 25.04 and 26.04, respectively, and after 36.03 and 35.05, respectively. The data were analyzed using parametric and nonparametric tests with a significance level of 5%.

RESULTS

TN and PDL2 systems showed no difference regarding the increase in the volume of the canals with the first instruments, but after preparation with a diameter size of 35 or 36, there was a difference (P < .01) between the systems in the cervical and middle thirds.

CONCLUSION

Both systems shaped the mesial canals of mandibular molars while keeping low transportation and good centering ability in enlargements up to diameter size 35 or 36 with tapers of 3 or 5%.

Cleaning and disinfection of the root canal system provided by four active supplementary irrigation methods

This in vitro study evaluated the bacterial reduction provided by the EndoActivator (EA), Easy Clean (EC), passive ultrasonic irrigation (PUI), and XP-Endo Finisher. Eight-four mesial roots of mandibular first molars were instrumented, inoculated with Enterococcus faecalis, and divided into four groups (n. 20). Bacterial reduction in the main canals and dentinal tubules were respectively determined by MTT assays and Live/Dead BackLight technique through confocal laser scanning microscopy (CLSM) at 50, 100, and 150 µm in-depth (n. 10 per group). Statistical analyses were conducted following a significance level of 95% (P < 0.05). A significant statistical difference was just identified between XPF and EC in the main canals. In the dentinal tubules from the main root canals, at 100 and 150 µm in-depths, significant statistical differences were only observed between XPF and EC (P = 0.027) for the former and between XPF and EC (P = 0.011) and XPF and PUI (P = 0.021) for the latter. In the dentinal tubules from the isthmus, at 100 µm in-depth, statistically relevant differences did occur between XPF and EC (P = 0.038) and EC and EA (P = 0.029). At 150 µm in-depth, these differences were only significant by comparing XPF and PUI (P = 0.025) and XPF and EC (P = 0.036). Although no irrigation method could thoroughly disinfect the RCS, bacterial reduction indexes were generally better after using XPF.

Minimally invasive management of vital teeth requiring root canal therapy

The present study aimed to investigate the possible use of a non-instrumentation technique including blue light irradiation for root canal cleaning. Extracted human single rooted teeth were selected. Nine different groups included distilled water, NaOCl, intra-canal heated NaOCl, and NaOCl + EDTA irrigation after either instrumentation or non-instrumentation, and a laser application group following non-instrumentation technique. The chemical assessment of the root canal dentine was evaluated using energy dispersive spectroscopy (EDS) and Fourier transform infrared (FT-IR) spectroscopy. Surface microstructural analyses were performed by using scanning electron microscopy (SEM). The antimicrobial efficacy of different preparation techniques was evaluated using microbial tests. Light application didn't change the calcium/phosphorus, carbonate/phosphate and amide I/phosphate ratios of the root canal dentin. The root canal dentin preserved its original chemistry and microstructure after light application. The instrumentation decreased the carbonate/phosphate and amide I/phosphate ratios of the root canal dentin regardless of the irrigation solution or technique (p < 0.05). The application of light could not provide antibacterial efficacy to match the NaOCl irrigation. The NaOCl irrigation both in the non-instrumentation and instrumentation groups significantly reduced the number of bacteria (p < 0.05). The use of minimally invasive root canal preparation techniques where the root canal is not instrumented and is disinfected by light followed by obturation with a hydraulic cement sealer reduced the microbial load and preserved the dentin thus may be an attractive treatment option for management of vital teeth needing root canal therapy.

A review of the latest developments in rotary NiTi technology and root canal preparation

The introduction of nickel-titanium (NiTi) mechanical instruments dramatically changed clinical endodontics over the last few decades. Before NiTi, it was necessary to use more instruments to create an ideal root canal shape, and many approaches, sequences and techniques were developed over the years. Recently, NiTi endodontic instruments have undergone a series of changes brought about by modifications in design, surface treatments, and thermal treatments to improve their root canal preparation outcomes and reduce associated canal preparation risks during root canal treatment. Heat treatment is one of the most fundamental approaches to improving the fatigue resistance and flexibility of NiTi endodontic instruments. In addition, new kinematics have been developed to offer greater safety and efficiency. This narrative review describes the general properties and manufacturing of NiTi instruments, and the mechanical system evolution of NiTi instruments.