Influence of Needle Design and Irrigant Flow Rate on the Removal of Enterococcus faecalis Biofilms In Vitro.

This study aimed to evaluate the influence of needle design and irrigant flow rate on the removal of Enterococcus faecalis mature biofilms during sodium hypochlorite irrigation. Forty-eight single-rooted human teeth were instrumented (ProTaper F3), autoclaved and inoculated with Enterococcus faecalis to establish a two-week-old biofilm. E. faecalis biofilms were treated with Sodium hypochlorite that was injected in the root canals using three types of needles (NaviTip, ProRinse, IrriFlex). For the IrriFlex needle, one, two, or four bars of pressure was applied to the irrigating solution to increase flow rates. Bacteria were labeled with the LIVE/DEAD BacLight Bacterial Viability kit, and viability was assessed by flow cytometry (FCM). Results were statistically analyzed using one-way ANOVA and Tukey multiple comparison intervals (α = 0.05). Bacterial viability was significantly reduced after sodium hypochlorite passive irrigation but the number of viable bacteria retrieved from root canal specimens irrigated with the Pro-Rinse needle was significantly higher compared to NaviTip and IrriFlex needles (p < 0.05). When the irrigant flow rate was increased, the viability of bacterial biofilms was significantly reduced compared to passive irrigation using the IrriFlex needle (p < 0.05). Applying higher flow rates during irrigation using the IrriFlex needle did not further reduce bacterial viability.

Effect of a Modified Irrigation Protocol on the Cleanliness of Moderately Curved Canals.

OBJECTIVES: This study tested the hypothesis that modifying the sequence of sodium hypochlorite (NaOCl)/ethylene diamine tetra-acetic acid (EDTA) irrigation during root canal shaping would improve apical cleanliness in moderately curved canals. MATERIALS AND METHODS: Forty-five root canals were prepared using Protaper Gold with three irrigation protocols. Standard irrigation (SI) used 0.5 mL 3% NaOCl between each instrument, followed by 5 mL 17% EDTA manually agitated for 30 seconds. Reverse irrigation (RI) used 0.5 mL of 17% EDTA between each instrument, then 5 mL of 3% NaOCl, manually agitated for 30 seconds. Reverse irrigation plus (RI+) was similar to RI, except NaOCl (5 mL), used as a final rinse, was allowed to interact for 3 minutes with dentin before manual agitation (30 seconds).Root canal cleanliness was evaluated under the scanning electron microscope (SEM) (Hulsmann score); the chemical composition of dentin after irrigation was analyzed by energy dispersive X-ray (EDX). STATISTICAL ANALYSIS: Results were compared using Kruskal-Wallis ANOVA by ranks and Wilcoxon matched paired posthoc tests. A Chi-square test assessed whether the best cleanliness would demonstrate a significant association with one irrigation protocol; odds ratio calculation was performed using score "1" versus score "2 or more" (2+) (p < 0.05). RESULTS: In the apical region, cleanliness was better in RI+ than SI and both significantly better than RI. Odd ratios indicate that the cleanliness in RI+ was significantly better than RI and SI groups (p < 0.000 and 0.003, respectively). Independently of the irrigation protocol, EDX analyses showed no chemical alteration of root dentin. CONCLUSIONS: Using 17% EDTA during shaping, followed by 3% NaOCl rinse for 3 minutes, improved apical cleanliness without inducing erosion of dentin.

Comparative evaluation of the shaping ability of two different nickel-titanium rotary files in curved root canals of extracted human molar teeth.

AIM: The aim of the present study was to compare the shaping ability of two different nickel-titanium rotary files in the curved root canals of extracted human molar teeth. METHODS: Thirty root canals of 17 extracted human molars teeth were randomly assigned to two experimental groups (n = 15): ProTaper Next and ProTaper Universal (PTU), on the basis of the rotary files system used. The final size of all apical foramina was 0.25 mm in diameter. Standardized digital radiographs were taken before and after instrumentation in both clinical and proximal views, with a size 10 K-file inserted into the canal for the determination of the angle of curvature and apical transportation. Preparation time and fractured or deformed instruments were also recorded. The unpaired Student's t-test was used to compare results. RESULTS: There was no significant difference between the two instruments with respect to canal straightening and apical transportation before and after instrumentation (P > 0.05). The use of both instruments resulted in a significant reduction in the angle of curvature after instrumentation (P < 0.05). Instrumentation time was significantly greater for PTU (P < 0.05). CONCLUSIONS: The ProTaper Universal and ProTaper Next systems performed similarly with regard to the straightening of curved root canals and apical transportation. ProTaper Next was significantly faster than ProTaper Universal.

Randomized Clinical Trial of Intraosseous Methylprednisolone Injection for Acute Pulpitis Pain.

INTRODUCTION: The present study reports the results of a randomized clinical trial comparing local intraosseous methylprednisolone injection and emergency pulpotomy in the management of acute pulpitis on efficacy, safety, and efficiency end points. METHODS: After providing prior informed written consent, 94 patients consulting for acute irreversible pulpitis pain at university-affiliated teaching hospital dental clinics in Dakar, Senegal were randomly assigned to either the methylprednisolone treatment group (n = 47) or the pulpotomy treatment group (n = 47). Patients were followed up at 1 week and assessed 6 months later to evaluate the therapeutic outcome of their treatment. RESULTS: At day 7 the patients in the methylprednisolone group reported less intense spontaneous and percussion pain in the day 0-day 7 period than the patients in the pulpotomy group. Methylprednisolone treatment took approximately 7 minutes (4.6-9.3) less to accomplish than pulpotomy (or about half the time). No difference in the therapeutic outcome was found between the 2 treatment groups at 6 months (all credible intervals span 0). CONCLUSIONS: This study establishes that methylprednisolone injection for acute pulpitis is relieved by a minimally invasive pharmacologic approach more effectively than by the reference pulpotomy and conserves scarce dental resources (ie, endodontic equipment and supplies, dental surgeon's time).

Root canal shaping by single-file systems and rotary instruments: a laboratory study.

INTRODUCTION: The aim of this study was to compare the shaping ability of two single-file systems and conventional rotary instruments in severely curved root canals of extracted human molars. METHODS AND MATERIALS: Mesiobuccal canals of 120 mandibular molars with angles of curvature ranging between 25(°) and 35(°) and radii of curvature from 5 to 9 mm, were divided into three groups (n=40). In each group the canals were instrumented with either WaveOne (W), Reciproc (R) or ProTaper (P). The time required for canal shaping and the frequency of broken instruments were recorded. The standardized pre and post-instrumentation radiographs were taken to determine changes in working length (WL) and straightening of canal curvature. The presence of blockage or perforation was also evaluated. Data were analyzed using the one-way analysis of variance (ANOVA) and post-hoc Tukey's test. The level of significance was set at 0.05. RESULTS: Both single-instrument systems reduced the canal preparation time by approximately 50% (P<0.05). No incidence of broken instruments from single-file systems was reported; however, two F2 instruments in the P group were broken (P<0.05). Reduction in WL and straightening of canal curvature was observed in all three systems with the highest scores belonging to P system (P<0.05). No case of blockage or perforation was found during shaping in any group. CONCLUSION: Single-file systems shaped curved canals with substantial saving in time and a significant decrease in incidence of instrument separation, change in WL, and straightening of canal curvature.

Use of a new retrograde filling material (Biodentine) for endodontic surgery: two case reports.

Mineral trioxide aggregate (MTA) is considered at the present time as the gold standard for root-end filling in endodontic surgery. However, this biocompatible material presents several drawbacks such as a long setting time and handling difficulties. The aim of this article is to present a new commercialized calcium silicate-based material named Biodentine with physical improved properties compared to MTA in a clinical application. Two endodontic microsurgeries were performed by using specific armamentarium (microsurgical instrumentation, ultrasonic tips) under high-power magnification with an operatory microscope. Biodentine was used as a root-end filling in order to seal the root canal system. The two cases were considered completely healed at 1 year and were followed for one more year. The 2-year follow-up consolidated the previous observation with absence of clinical symptoms and radiographic evidence of regeneration of the periapical tissues.

Centering Ability and Influence of Experience When Using WaveOne Single-File Technique in Simulated Canals.

Introduction. WaveOne is a single endodontic instrument that reciprocates with a dedicated motor to shape root canal systems. The present study assessed the centering ability of this simplified protocol along with the effect of experience in simulated plastic canals. Methods. One experienced operator shaped two groups of simulated canals. Groups 1 and 3 each comprised 30 blinded L-shaped canals or S-shaped canals, respectively. Photographs were taken before and after shaping and digitally assessed centering after superimposition of the pictures. Time of shaping, number of passes, canal aberrations, and instrument degradation were recorded. In group 2 shaping was done on 30 blinded L-shaped canals by 30 different students with no prior experience with WaveOne. Results. All three groups yielded satisfactory, reproducible shaping. Centering ratios were low and homogeneous in all groups, with no significant differences between the experienced operator and the students. Apical transportation values were very low (≤0.138 mm) with no instances of blockage or separation. The average shaping time was short (43 to 101,6 sec). Conclusions. Within the limits of the study, the WaveOne instrument had excellent centering ability with a low risk of fracture or blockage and a short shaping time, regardless of the operator's level of experience.

Effectiveness of different final irrigant activation protocols on smear layer removal in curved canals.

INTRODUCTION: A final flush with chelating agents and antiseptic irrigating solutions is needed to remove the smear layer. The improvement of these protocols is possible by using specific delivery and agitation techniques. This study examined the effect of different final irrigation regimens and methods of activation on smear layer removal in curved canals after root canal instrumentation. METHODOLOGY: Mesial root canals of 50 extracted mandibular molars were prepared using ProTaper rotary files (Dentsply Maillefer, Ballaigues, Switzerland) and 3% NaOCl. Teeth were then allocated to two control groups and four experimental groups (n = 10) for final irrigation as follows: no-activation group (final rinse with a 27-gauge needle and 17% EDTA/3% NaOCl), manual-dynamic activation group (final rinse 17% EDTA/3% NaOCl + gutta-percha agitation), automated-dynamic activation group (final rinse 17% EDTA/3% NaOCl + RinsEndo [Dürr Dental GmbH & Co KG, Bietigheim-Bissingen, Germany]), and sonic-activation group (final rinse 17% EDTA/3% NaOCl + Endoactivator [Advanced Endodontics, Santa Barbara, CA]). All mesial roots were split with a new approach to allow visualization of every third of the canal, particularly the apical third. The samples were prepared for scanning electron microscopic observation to assess the smear layer removal. Blind scoring was performed by two calibrated observers using a five-score scale. The differences in smear layer scores between the experimental groups were analyzed with the Kruskal-Wallis test and the Mann-Whitney U test. The level of significance was set at p = 0.05. RESULTS: Very high levels of root canal cleanliness (< or = score 3) were found for each test group with activation. For the middle and apical third, the no-activation group was significantly less effective than the three other activation groups (p < 0.05). The manual-dynamic activation group (final rinse 17%EDTA/3%NaOCl + gutta-percha agitation) and the sonic-activation group (final rinse 17%EDTA/3%NaOCl + Endoactivator) showed significantly better smear layer removal (p < 0.05) in comparison with the other test groups in the apical third. CONCLUSION: Root canal cleanliness benefits from solutions activation (especially sonic activation and manual-dynamic activation) in comparison with no activation during the final irrigation regimen.

Trauma and dentinogenesis: a case report.

INTRODUCTION: After a traumatic injury to the upper central incisors of a 7-year-old patient, avulsion of tooth #9 and pulp exposure after crown fracture of tooth #8 were managed. METHODS: After immediate replacement of tooth #9 in its socket, teeth were splinted for 3 weeks. No endodontic treatment was performed on tooth #9, but pulp capping was performed with mineral trioxide aggregate (Pro Root MTA; Dentsply Maillefer, Ballaigues, Switzerland) on #8, and both teeth were restored with composite resin. The teeth were monitored every 3 months for 2 years. RESULTS: At 24 months, both teeth responded positively to electrometric tests and roots showed normal development, but an abnormal reduction in the size of the root canal space of tooth#8 was observed. CONCLUSION: Based on these observations, we discuss odontoblast behavior in the context of the stage of dentinogenesis and the probable disturbance of regulation of the physiologic dentinogenic secretory processes in the pathologic situation.

Apical limit and working length in endodontics.

UNLABELLED: Establishing the working length is an important step in endodontic treatment as inaccurate length determination may lead to failure. There is an ongoing debate regarding the extent of the apical limit of root canal preparation. This controversy is based upon different clinical opinions concerning the distance between the end point of the root canal preparation and the periodontal tissues. In this paper, we review the different schools of thought for working length determination, and how apex locators work and how they must be used for optimal accuracy. The reliability of these devices has been proven; the price is moderate and apex locators are now part of the basic armamentarium in the achievement of quality and predictable endodontic treatment. CLINICAL RELEVANCE: The technique of determining the working length from a single radiograph remains empirical, and apex locators should be considered an essential aid in establishing working length.

A novel platform for in vitro analysis of torque, forces, and three-dimensional file displacements during root canal preparations: application to ProTaper rotary files.

We proposed a new testing setup and in vitro experimental procedure allowing the analysis of the forces, torque, and file displacements during the preparation of root canals using nickel-titanium rotary endodontic files. We applied it to the preparation of 20 fresh frozen cadaveric teeth using ProTaper files (Dentsply Maillefer, Ballaigues, Switzerland), according to a clinically used sequence. During the preparations, a clinical hand motion was performed by an endodontist, and we measured the applied torque around the file axis and also the involved three-dimensional forces and 3-dimensional file displacements. Such a biomechanical procedure is useful to better understand the working conditions of the files in terms of loads and displacements. It could be used to analyze the effects of various mechanical and geometric parameters on the files' behavior and to get data for modelling purposes. Finally, it could contribute to studies aiming to improve files design in order to reduce the risks of file fractures.

Influence of fractured instruments on the success rate of endodontic treatment.

UNLABELLED: The fracture of an instrument is a recognized complication in endodontics. The immediate response to a fractured instrument is frequently to regard the treatment as a failure. Several factors must, however, be taken into account to evaluate the prognosis of the tooth in this situation. The objective of the endodontic treatment with or without a fractured instrument remains the same, namely to disinfect the root canal system and prevent its recontamination. The time at which file fracture occurred during treatment and the degree of canal infection should be considered when determining the potential effect of instrument fracture on treatment outcome. Patients must be informed about an instrument fracturing in their tooth for ethical and legal reasons. The aim of this paper is to attempt to place fractured instruments in context, not to provide an in depth description of fractured instrument management techniques. CLINICAL RELEVANCE: To understand the influence of fractured instruments on prognosis in endodontics.

Protaper--hybrid technique.

UNLABELLED: Crown down preparation is the most known and described technique since the introduction of Nickel Titanium (NiTi) rotary instruments in endodontics. This technique gives good results but has limitations, such as not addressing the initial anatomy of oval or dumb-bell shaped canals. The specific design of the Protaper instruments allows use of them with a different technique and, specifically, with a brushing motion in the body of the canal. The recent introduction of hand Protaper files has expanded the range of application of this system, especially in curved canals. The 'hybrid technique', using rotary and hand files, and the advantages of the combination of both instruments, are clearly described in this article. Used with this technique, the Protaper is a very safe system to use, and more controllable, for both inexperienced and experienced practitioners alike, than other systems. CLINICAL RELEVANCE: To understand the precautions needed with rotary files, and how to use them to preserve the anatomy of the canal and get a tapered shaping, even in severely curved canals.

[Advantages and limits of nickel-titanium instruments for root canal preparation. A review of the current literature]. / Avantages et limites des instruments en nickel-titane pour la préparation canalaire endodontique. Revue de la littérature récente.

In recent years, an important innovation in the field of dentistry has been the introduction of nickel-titanium alloy instruments. Superelasticity and shape memory are the main mechanical properties of this alloy which prompted its use in endodontics. Due to these characteristics, NiTi instruments have been demonstrated to preserve the original anatomy, the shape and position in space of the apical foramen. This literature review of mechanical properties of NiTi endodontic instruments aims to provide clinicians with a better understanding of their advantages and limits.