Dynamic recording of irrigating fluid distribution in root canals using thermal image analysis

The effects of aperture position and length in side-vented needles on root canal irrigation: A computational fluid dynamics study

INTRODUCTION

Root canal irrigation is crucial for infection control during root canal treatment. Side-vented needles for positive pressure irrigation are commonly used in clinical practice. However, variations in needle design among manufacturers can impact the fluid dynamics of irrigation. This study aims to use computational fluid dynamics to explore the flow characteristics of different needle aperture lengths and positions, and their effects on the effectiveness and safety of irrigation, using a validated passive scalar transport numerical model.

METHODS

The validation of the CFD irrigant model was achieved by comparing it with an in vitro irrigation experiment model. The CFD model used scalar concentration, while the in vitro experiment model used red dye tracing. Using a standard 30G side-vented needle as a reference, virtual needle models featuring four aperture lengths and three positions were created. These virtual irrigation needles were then placed in two root canal geometries for CFD simulation to evaluate fluid exchange capabilities and related fluid dynamic parameters.

RESULTS

The results of the CFD simulation, using a scalar transport model, closely matched the in vitro tracer tests for irrigation experiments across seven root canal geometries. The CFD analysis indicated that positioning the aperture lower increased the irrigant exchange distance. Notably, decreasing the aperture length to 0.25x, and positioning it at the lower end of the needle significantly increased exchange distance and shear stress, while reducing apical pressure.

CONCLUSIONS

These results indicate that the position and length of the aperture affect the exchange distance of irrigant flow, wall shear stress, and apical pressure. The CFD validation model for scalar transport, based on a steady state, can function as a valuable tool for optimizing the side-vented needle in research. Further research on the design of side-vented needles will enhance the understanding of flow characteristics beneficial for irrigation efficiency in clinical practice.

The Effect of Master Apical Preparation Size on Healing Outcomes in Endodontic Treatment: A Systematic Review and Meta-Analysis

INTRODUCTION

The aim of this systematic review was to assess the existing literature and examine whether or not the size of apical enlargement during mechanical preparation affects the outcome of treatment in patients undergoing nonsurgical root canal therapy (NSRCT).

METHODS

MEDLINE (PubMed), Embase, Cochrane Library, and gray literature were searched (January 2000-May 2023). Study selection and data extraction were performed in duplicate. Eligible studies were critically appraised for risk of bias and quality of evidence and were meta-analyzed to estimate the treatment effects.

RESULTS

Two studies were included in the meta-analysis. The overall pooled success rate was 75.8%. The success rates of treatment with an apical size ≥ 30 and < 30 were 80.9% and 52.9%, respectively. Cases with an apical size ≥ 30 demonstrated significantly more favorable results (RR = 0.63, 95% Confidence Interval 0.46-0.79, P < .05). The overall quality of evidence was low.

CONCLUSIONS

With a low certainty of evidence, master apical preparation size ≥ 30 may result in an increased healing outcome in terms of clinical and radiographic evaluations.

Effect of preparation size on the removal of accumulated hard-tissue debris from the mesial root canal system of mandibular molars using SWEEPS technology

OBJECTIVES

This study assessed the influence of preparation size on the efficacy of shock wave-enhanced emission photoacoustic streaming (SWEEPS) and conventional irrigation (CI) on removal of accumulated hard tissue debris (AHTD) from isthmus-containing mandibular molars using micro-computed tomographic analysis.

MATERIALS AND METHODS

Sixty extracted mandibular molars with two mesial canals connected by an isthmus were selected. Canals were shaped with Mtwo instruments (VDW, Munich, Germany) up to sizes 25/.06, 40/.04 or 40/.06 (n = 20), and specimens were distributed into 2 final irrigation groups (n = 10): SWEEPS and CI. Roots were scanned at a resolution of 10.5 µm before and after preparation and final irrigation. Data sets were co-registered, and the percentage reduction of AHTD calculated for each specimen was statistically compared using analysis of variance with a of 5% significance level.

RESULTS

The preparation size did not significantly influence the percentage reduction of AHTD (p < 0.05), whereas the final irrigation technique had a significant effect on debris removal (p < 0.05). A significant reduction of AHTD was achieved after final irrigation in all groups (p < 0.05); however, SWEEPS was associated with a significantly greater percentage reduction of debris than CI (p < 0.05). None of the specimens presented a completely clean isthmus.

CONCLUSIONS

Removal of AHTD was not significantly affected by the preparation size. SWEEPS was associated with significantly less debris than CI.

CLINICAL RELEVANCE

SWEEPS performed significantly better than CI regarding the removal of AHTD from isthmus-containing mandibular molars irrespective of the preparation size.

Emissivity evaluation of human enamel and dentin

Background: Human enamel and dentin temperatures have been assessed with non-contact infrared imaging devices for safety and diagnostic capacity and require an emissivity parameter to enable absolute temperature measurements. Emissivity is a ratio of thermal energy emitted from an object of interest, compared to a perfect emitter at a given temperature and wavelength, being dependent on tissue composition, structure, and surface texture. Evaluating the emissivity of human enamel and dentin is varied in the literature and warrants review. The primary aim of this study was to evaluate the emissivity of the external and internal surface of human enamel and dentin, free from acquired or developmental defects, against a known reference point. The secondary aim was to assess the emissivity value of natural caries in enamel and dentin.

Method: Fourteen whole human molar teeth were paired within a thermally stable chamber at 30°C. Two additional teeth (one sound and one with natural occlusal caries–ICDAS caries score 4 and radiographic score RB4) were sliced and prepared as 1-mm-thick slices and placed on a hot plate at 30°C within the chamber. A 3M Scotch Super 33 + Black Vinyl Electrical Tape was used for the known emissivity reference-point of 0.96. All samples were allowed to reach thermal equilibrium, and a FLIR SC305 infrared camera recorded the warming sequence. Emissivity values were calculated using the Tape reference point and thermal camera software.

Results: The external enamel surface mean emissivity value was 0.96 (SD 0.01, 95% CI 0.96–0.97), whereas the internal enamel surface value was 0.97 (SD 0.01, 95% CI 0.96–0.98). The internal crown-dentin mean emissivity value was 0.94 (SD 0.02, 95% CI 0.92–0.95), whereas the internal root-dentin value was 0.93 (SD 0.02, 95% CI 0.91–0.94) and the surface root-dentin had a value of 0.84 (SD 0.04, 95% CI 0.77–0.91). The mean emissivity value of the internal enamel surface with caries was 0.82 (SD 0.05, 95% CI 0.38–1.25), and the value of the internal crown-dentin with caries was 0.73 (SD 0.08, 95% CI 0.54–0.92).

Conclusion: The emissivity values of sound enamel, both internal and external, were similar and higher than those of all sound dentin types in this study. Sound dentin emissivity values diminished from the crown to the root and root surface. The lowest emissivity values were recorded in caries lesions of both tissues. This methodology can improve emissivity acquisition for comparison of absolute temperatures between studies which evaluate thermal safety concerns during dental procedures and may offer a caries diagnostic aid.

A critical analysis of research methods and experimental models to study irrigants and irrigation systems

Irrigation plays an essential role in root canal treatment. The purpose of this narrative review was to critically appraise the experimental methods and models used to study irrigants and irrigation systems and to provide directions for future research. Studies on the antimicrobial effect of irrigants should use mature multispecies biofilms grown on dentine or inside root canals and should combine at least two complementary evaluation methods. Dissolution of pulp tissue remnants should be examined in the presence of dentine and, preferably, inside human root canals. Micro-computed tomography is currently the method of choice for the assessment of accumulated dentine debris and their removal. A combination of experiments in transparent root canals and numerical modeling is needed to address irrigant penetration. Finally, models to evaluate irrigant extrusion through the apical foramen should simulate the periapical tissues and provide quantitative data on the amount of extruded irrigant. Mimicking the in vivo conditions as close as possible and standardization of the specimens and experimental protocols are universal requirements irrespective of the surrogate endpoint studied. Obsolete and unrealistic models must be abandoned in favour of more appropriate and valid ones that have more direct application and translation to clinical Endodontics.

Present status and future directions - irrigants and irrigation methods

Irrigation is considered the primary means of cleaning and disinfection of the root canal system. The purpose of this review was to set the framework for the obstacles that irrigation needs to overcome, to critically appraise currently used irrigants and irrigation methods, to highlight knowledge gaps and methodological limitations in the available studies and to provide directions for future developments. Organization of bacteria in biofilms located in anatomic intricacies of the root canal system and the difficulty to eliminate them is the main challenge for irrigants. Sodium hypochlorite remains the primary irrigant of choice, but it needs to be supplemented by a chelator. Delivery of the irrigants using a syringe and needle and activation by an ultrasonic file are the most popular irrigation methods. There is no evidence that any adjunct irrigation method, including ultrasonic activation, can improve the long‐term outcome of root canal treatment beyond what can be achieved by instrumentation and syringe irrigation. It is necessary to redefine the research priorities in this field and investigate in greater depth the penetration of the irrigants, their effect on the biofilm and the long‐term treatment outcome. New studies must also focus on clinically relevant comparisons, avoid methodological flaws and have sufficiently large sample sizes to reach reliable conclusions. Future multidisciplinary efforts combining the knowledge from basic sciences such as Chemistry, Microbiology and Fluid Dynamics may lead to more effective antimicrobials and improved activation methods to bring them closer to the residual biofilm in the root canal system.

The effect of various in-vitro and ex-vivo parameters on irrigant flow and apical pressure using manual syringe needle irrigation: Systematic review

BACKGROUND

Fluid dynamics is a majorly neglected aspect to be studied in root canal irrigation. The fundamental rule to understand mechanics is to observe patterns of flow during the process. Thus, this work is conducted to do a systemic assessment of the in-vitro and ex-vivo based studies to evaluate the effect of various parameters on the irrigant flow and apical pressure on using a manual syringe needle for root canal irrigation.

METHODS

The literature search was conducted through libraries such as PubMed (Medline), CINAHL, Embase, Scopus and other hand literature from Google Scholar, the British medical library etc. The systematic review was reported following the preferred reporting items for systematic reviews and meta-analyses (PRISMA) guidelines. As they include studies that were in-vitro and ex-vivo based, the risk of bias of the selected articles was assessed using a customized tool based on the previous literature and parameters evaluated in the studies included.

RESULTS

The literature search resulted in 101 items of which 19 records were included in this review. Results reported that multiple factors and parameters were assessed to evaluate the flow and apical pressures on using manual syringe needle irrigation.

CONCLUSIONS

Present systematic review gives insights in-depth about the irrigation dynamics of manual syringe needle irrigation. Besides, it is inconclusive to compile a single factor or a single parameter contributing to the enhanced irrigant flow and least apical pressures.

Syringe Irrigation in Minimally Shaped Root Canals Using 3 Endodontic Needles: A Computational Fluid Dynamics Study

INTRODUCTION

The aim of this study was to compare the irrigant flow in curved root canals prepared to various apical sizes by constant-taper or variable-taper instruments during syringe irrigation with 3 endodontic needles at 2 different flow rates.

METHODS

Two matched curved mesial root canals of human mandibular molars were imaged by micro-computed tomographic imaging after preparation to apical size 20, 25, and 30/.06 taper either by constant-taper or variable-taper instruments. A Computational Fluid Dynamics model was used to simulate the irrigant flow in the 2 root canals prepared to each apical size during syringe irrigation with a 30-G open-ended needle and 30-G and 31-G closed-ended needles at 0.05 and 0.15 mL/s.

RESULTS

The irrigant could not penetrate up to the working length in root canals prepared to apical size 20 or 25/.06 taper. The 30-G open-ended needle combined with the low flow rate allowed the irrigant to reach the working length in size 30/.06 taper root canals while maintaining a relatively low apical pressure, but the wall shear stress was very low. The 31-G closed-ended needle combined with the high flow rate also delivered the irrigant to the working length in size 30 root canals and developed higher wall shear stress, but the apical pressure was also higher.

CONCLUSIONS

Syringe irrigation using 30-G and 31-G needles was compromised in minimally shaped root canals.

Comparison of the Effect of Three Irrigation Techniques and Root Canal Preparation Size on Sodium Hypochlorite Penetration into Root Canal Dentinal Tubules

Objective

This study aims to compare the effects of conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI), and innovative sonic-powered irrigation (EDDY) on the penetration of sodium hypochlorite (NaOCl) solutions into root canal dentinal tubules at different levels of the root canal.

Materials and Methods

One hundred ninety-two extracted first mandibular premolars of 17- to 25-year-old patients were decoronated 13 mm from the root apices and separated into two groups according to apical preparation sizes (APS) 25 and 40. The root canals were dried with a paper point and stained in crystal violet for 72 hours. Each APS group was separated into three groups according to irrigation techniques, as follows: CSI, PUI, and EDDY. Roots were perpendicularly resected to the long axis at three levels (coronal, middle, and apical). Photomicrographs were taken of all three cross-sections of each tooth under a stereomicroscope. The depth of the bleached zone was measured with ImageJ software. The data were analyzed by Welch's analysis of variance and an independent t-test (p = 0.05).

Results

No penetration was found at the apical level in the CSI25, CSI40, and PUI25 groups. The EDDY25 and EDDY40 groups showed the most significant penetration at the middle and apical levels compared to the other groups (p < 0.05).

Conclusions

Within the limitations of this study, irrigation techniques and APS affect the penetration depth of NaOCl into the root canal dentinal tubules. In terms of irrigation techniques, the penetration was deepest when EDDY was used, followed by PUI and CSI. In terms of APS, NaOCl penetrated deeper into APS40 than APS25. The use of the EDDY irrigation technique in APS25 can improve the penetration of NaOCl into root canal dentinal tubules at the apical level.

Comparison of irrigant activation devices and conventional needle irrigation on smear layer and debris removal in curved canals. (Smear layer removal from irrigant activation using SEM)

AIM

To compare the effectiveness of smear layer and debris removal in the final rinse of curved canals of permanent molars using different commercially available irrigant activation devices.

METHODS

The mesial roots of 74 extracted maxillary and mandibular molars were instrumented using the Mtwo nickel-titanium rotary system (VDW GmbH, Munich, Germany). They were then randomly assigned to one of three groups, varying in their final rinse protocol. Group 1 (n = 15) - conventional needle irrigation with 4% NaOCl; Group 2 (n = 19) - EndoActivator® (Dentsply Tulsa Dental Specialties, Tulsa, OK, USA) with 4% NaOCl; Group 3 (n = 17) - XP-endo® Finisher (FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) with 4% NaOCl. After the final rinse, all canals were flushed with 1 mL 15% EDTA for 60 s and then flushed with saline. The roots were split longitudinally and prepared for scanning electron microscope imaging. ImageJ for Windows was utilised to assess the images for smear layer removal, while two blinded investigators assessed debris presence in the middle and apical thirds using a 5-point scale.

RESULTS

There was no significant difference in smear layer and debris removal between treatment and control groups in the same canal zones. A significant difference was noted across different canal zones both within and across the groups.

CONCLUSION

There is no statistically significant difference in effectiveness between activated irrigation techniques and manual activation. Further investigations are required to evaluate all methods available and determine the most efficient technique to irrigate successfully.

A laboratory study of root canal and isthmus disinfection in extracted teeth using various activation methods with a mixture of sodium hypochlorite and etidronic acid

AIM

To evaluate in a laboratory setting the antibiofilm activity of several irrigating protocols including conventional irrigation, ultrasonic activation and XP-endo Finisher, with a mixture of sodium hypochlorite and etidronic acid in infected isthmuses and root canals of extracted human mandibular molar teeth.

METHODOLOGY

Fifty-six mesial roots of mandibular molars, half of them with a continuous isthmus from the cervical to the apical third between the two root canals (type 1), and the other half with a continuous isthmus from the cervical to the middle third and one canal in the apical third (type 2), were included. The root canals were contaminated for 7 days with an Enterococcus faecalis suspension. There were three experimental groups plus a control group (n = 7 per type of root canal anatomy). All the root canals, except for the control group that was not treated, were chemomechanically prepared and then assigned to one of the experimental groups according to the final adjunctive procedure: conventional irrigation, ultrasonic activation or XP-endo Finisher activation. The irrigating solution used was a combination of 2.5% sodium hypochlorite and 9% etidronic acid, and the final protocols were applied for three cycles of 30 s with a 3 mL volume. The antibiofilm activity was evaluated at each location (root canal and isthmus) and third (cervical, middle and apical) using confocal laser scanning microscopy and the live/dead technique. Statistical analysis was performed using SPSS (descriptive statistics) and SUDAAN (P-value calculations).

RESULTS

Root canals had significantly lower biovolume values than the isthmuses (P < 0.05). The biovolume in the root canals was significantly reduced in all the experimental groups in all the thirds except for conventional irrigation in the apical third (P > 0.05). In the cervical and middle thirds, ultrasonic activation was associated with the lowest biovolumes (P < 0.05), followed by XP-endo Finisher. In the isthmus, disinfection was similar in all the thirds for all the protocols. Conventional irrigation was associated with intermediate values with no significant differences from the control group or from the activated protocols (P > 0.05), although the latter were significantly different from the control group (P < 0.05). No differences were found between ultrasonic activation and XP-endo Finisher in the middle and apical thirds (P > 0.05) in the isthmuses.

CONCLUSIONS

In this laboratory study on extracted teeth, the isthmus was more difficult to disinfect than root canals. In the root canals, ultrasonic activation and XP-endo Finisher had a greater effectiveness than conventional irrigation. In the isthmuses, no differences were observed between the two activation techniques and conventional irrigation.

CFD analysis on the effect of combining positive and negative pressure during the irrigation of artificial isthmuses

Fluid dynamics generated by irrigation needles have not been deeply analyzed in root canal irregularities such as apical ramifications or isthmus where the cleaning capacity of irrigants might be compromised and hence the treatment outcome. The goal of this study was to compare the key irrigation parameters (flow pattern, irrigant velocity, apical pressure, and shear stress) between two irrigation needles and the additional effect of aspiration cannulas through computational fluid dynamics. A 3D-model consisting of two canals linked by an isthmus was modeled. The abovementioned needles irrigated the primary canal, whereas an aspiration cannula was located inside the secondary canal. Both the geometry definition and spatial discretization were carried out with ANSYS 16.2, through which six different simulations were performed: lateral exit (LE) needle, frontal exit (FE) needle, LE and cannula in crown (LEC), FE and cannula in crown (FEC), LE and cannula in middle third (LEM), FE and cannula in middle third (FEM). FE and FEM showed that the irrigation flow only passes through the isthmus in the most apical section (maximum irrigant velocity / shear stress = 8.44 m/s / 1628.44 Pa and 8.63 m/s / 1185.69 Pa, respectively). However, the remaining simulations showed the irrigation flow passing through the isthmus twice, through the most apical section first and through the upper part of the isthmus later (maximum irrigant velocity / shear stress = 8.48 m/s / 1298.24 Pa (LE), 8.61 m/s / 1261.36 Pa (LEM), 8.61 m/s / 1355.24 Pa (LEC), 8.59 m/s / 1256.87 Pa (FEC)). Furthermore, the highest velocity values were detected when aspiration cannulas were added.

In Vivo Evaluation of Painful Symptomatology after Endodontic Treatment Performed Using Two Different Irrigation Needle Insertion Depths

Objective  The main purpose of this study was to evaluate pain symptoms in patients after endodontic treatment performed in a single session in teeth with vitality or pulp necrosis, comparing two depths of insertion of the NaviTip irrigation needle.

Materials and Methods  One-hundred upper uniradicular teeth were selected and divided into four groups ( n = 25), namely Bio group 1 (live pulp/1 mm from the foramen), Bio group 3 (live pulp/3 mm from the foramen), Necro group 1 (pulp necrosis/1 mm from the foramen), and Necro group 3 (pulp necrosis/3 mm from the foramen). All canals were instrumented with Wave One Gold System. Irrigation was performed using 2.5% NaOCl. The teeth were filled using the single-cone technique with AH Plus sealer using a McSpadden compactor. After treatment, patients answered a questionnaire with a visual analog scale scored from 0 to 10 at 1, 3, and 7 days after treatment.

Statistical Analysis  Data were analyzed using Mann–Whitney U, Wilcoxon, and Friedman tests.

Results  There was a decrease in average pain levels at the three time points for both vital and necrotic teeth ( p < 0.05). There were no significant differences in postoperative pain levels comparing needle depth, or vitality and pulp necrosis ( p > 0.05). The percentage of mild pain increased over time and moderate pain decreased, regardless of pulp condition. There was no incidence of acute pain at any time.

Conclusions  Post-treatment endodontic pain levels in upper uniradicular teeth with or without pulp vitality resulted in similar pain scores, regardless of the depth of insertion of the irrigation needle in relation to the apical foramen.

Reduction of an in vitro Intraradicular Multispecies Biofilm Using Two Rotary Instrumentation Sequences

Objective  The purpose of this research was to investigate the effect per se of two shaping and cleaning techniques on the reduction of an in vitro multispecies biofilm.

Materials and Methods  A total of 39 freshly extracted monoradicular teeth for periodontal reason were decoronated. Roots were sectioned longitudinally. After autoclaving, a specific stressed biofilm was grown on the root halves that were subsequently reassembled in a silicone index. Two treatments ( n = 9 each)—RaCe (Schottlander; Letchworth Garden City, United Kingdom) and ProTaper Gold ( PTG; Dentsply Maillefer, Baillagues, Switzerland)—were tested; three noninstrumented samples served as a control group and three were rinsed with saline. Posttreatment samples were taken at three different levels of the root. Colony-forming units were counted after incubations. Additionally, three treatments ( n = 5 each)—RaCe, PTG, and saline only—were evaluated under a confocal laser scanning microscope (CLSM).

Statistical Analysis  Statistical analysis was conducted using Tukey’s test and analysis of variance to evaluate the post-instrumentation bioburden.

Results  Both instrumentations were able to reduce the biofilm; however, differences were not present between them ( p > 0.05). CLSM showed biofilm killing and disruption through mechanical shaping alone.

Conclusions  Intraradicular biofilm is reduced with mechanical shaping. There was no difference between RaCe and PTG systems in biofilm reduction despite differences in design, file sequence, and rotational speed.

Ultrasonic Irrigant Activation during Root Canal Treatment: A Systematic Review

INTRODUCTION

The aim of this study was to systematically review the evidence on the cleaning and disinfection of root canals and the healing of apical periodontitis when ultrasonic irrigant activation is applied during primary root canal treatment of mature permanent teeth compared with syringe irrigation.

METHODS

An electronic search was conducted of the Cochrane Library, Embase, LILACS, PubMed, SciELO, and Scopus databases using both free-text key words and controlled vocabulary. Additional studies were sought through hand searching of endodontic journals and textbooks. The retrieved studies were screened by 2 reviewers according to predefined criteria. The included studies were critically appraised, and the extracted data were arranged in tables.

RESULTS

The electronic and hand search retrieved 1966 titles. Three clinical studies and 45 in vitro studies were included in this review. Ultrasonic activation did not improve the healing rate of apical periodontitis compared with syringe irrigation after primary root canal treatment of teeth with a single root canal. Conflicting results were reported by the in vitro microbiological studies. Ultrasonic activation was more effective than syringe irrigation in the removal of pulp tissue remnants and hard tissue debris based on both clinical and in vitro studies. Ultrasonic activation groups were possibly favored in 13 studies, whereas syringe irrigation groups may have been favored in 3 studies.

CONCLUSIONS

The level of the available evidence was low, so no strong clinical recommendations could be formulated. Future studies should focus on the antimicrobial effect and healing of apical periodontitis in teeth with multiple root canals.

Micro-CT evaluation of sonically and ultrasonically activated irrigation on the removal of hard-tissue debris from isthmus-containing mesial root canal systems of mandibular molars

AIM

To evaluate the efficacy of sonically and ultrasonically activated irrigation on removal of accumulated hard-tissue debris (AHTD) in mesial root canal systems of mandibular molars using micro-computed tomographic (micro-CT) analysis.

METHODOLOGY

Forty mesial roots of mandibular molars with two independent canals joined apically by an isthmus (Vertucci type II) were selected. The root canals were instrumented using Reciproc R25 instruments, and specimens were scanned at a resolution of 10.5 μm. Subsequently, n = 10 roots were assigned to each of the four final irrigation groups such that the group means and variances were almost identical: sonically activated irrigation with EndoActivator (EA) or EDDY (ED), ultrasonically activated irrigation (UAI) and manual irrigation without activation (MI). The final irrigation procedures were performed using a total of 5 mL 1% NaOCl and 5 mL 15% EDTA per canal over 5 min with activation time of 4 × 20 s. Reconstructed data sets were coregistered, and the mean percentage reduction of AHTD after final irrigation was compared statistically between groups using analysis of variance at a significance level set at 5%.

RESULTS

A significant reduction of AHTD was achieved after final irrigation in all groups (P < 0.05), ranging from 44.1% to 66.8%. The vol% of debris after irrigation was 3.7 ± 1.9% for EA, 3.3 ± 2.3% for ED, 2.1 ± 1.6% for UAI and 4.4 ± 2.3% for MI, with no significant difference between groups (P > 0.05).

CONCLUSIONS

None of the final irrigation protocols completely removed AHTD from mesial root canal systems in extracted human mandibular molars. Sonically and ultrasonically activated irrigation performed no better compared to manual irrigation.

Comparison of apical debris extrusion during root canal preparation using instrumentation techniques with two operating principles: An in vitro study

Aims:

The aim of this study was to quantify the debris extruded apically from teeth using rotary and reciprocation instrumentation systems.

Subjects and Methods:

Eighty extracted human mandibular premolars with single canals and similar lengths were instrumented using ProTaper Universal (40, 06; Dentsply Maillefer, Ballaigues, Switzerland), ProTaper Next (40, 06; Dentsply Maillefer, Ballaigues, Switzerland), WaveOne (40, 06; Dentsply Maillefer, Ballaigues, Switzerland), and Reciproc (R40; VDW GmbH, Munich, Germany). Debris extruded during instrumentation was collected into preweighed Eppendorf tubes, which were then stored in an incubator at 70°C for 5 days. The final weight of the Eppendorf tubes with the extruded debris was calculated after obtaining the mean of three consecutive weights obtained for each tube.

Statistical Analysis Used:

Statistical analysis was performed using SPSS version 16.0 software. The groups were compared using the Kruskal–Wallis test for all variables.

Results:

There was no statistically significant difference between the groups (P = 0.1114). However, the ProTaper Universal group produced more extrusion and ProTaper Next produced least debris extrusion among the instrument groups (P > 0.05).

Conclusions:

All instrumentation techniques were associated with extruded debris.

Efficacy of XP-Endo Finisher in the Removal of Triple Antibiotic Paste from Immature Root Canals

INTRODUCTION

The aim of this study was to evaluate and compare the effectiveness of the XP-Endo Finisher (FKG Dentaire, La Chaux-de-Fonds, Switzerland) with passive ultrasonic irrigation (PUI) and needle irrigation in the removal of triple antibiotic paste (TAP) from the straight immature root canals of extracted teeth.

METHODS

Thirty-four freshly extracted single-rooted teeth were used. All canals were prepared up to the ProTaper F5 file (Dentsply Maillefer, Ballaigues, Switzerland). Apices were drilled to simulate teeth with immature apices. The canals were filled with TAP, sealed, and incubated at 37°C and 100% humidity for 1 month. Samples were randomly assigned to 3 experimental groups according to the method used for TAP removal: XP-Endo Finisher, PUI, and needle irrigation (n = 10). Then, the roots were split into 2 halves. The amount of TAP residue in the apical portion of each segment was evaluated using a scanning electron microscopy and scored.

RESULTS

The amount of remaining TAP was significantly lower in the XP-Endo Finisher group compared with the needle irrigation and PUI groups (P < .05). Between the needle irrigation and PUI groups, there were no statistically significant differences (P > .05).

CONCLUSIONS

Within the limitations of this study, the XP-Endo Finisher removed significantly more TAP than needle irrigation and PUI.

Apical negative pressure irrigation versus syringe irrigation: a systematic review of cleaning and disinfection of the root canal system

The aim of this study was to systematically review and critically analyse the published data on the treatment outcome (primary outcome) and on the cleaning and disinfection of root canals (secondary outcomes) achieved by negative pressure irrigation as compared to syringe irrigation. An electronic search was conducted in EMBASE, LILACS, PubMed, SciELO, Scopus and Web of Knowledge using both free-text keywords and controlled vocabulary. Additional studies were sought through hand searching of endodontic journals and of the relevant chapters of endodontic textbooks. No language restriction was imposed. The retrieved studies were screened by two reviewers according to predefined criteria. Included studies were critically appraised and the extracted data were arranged in tables. The electronic search and hand search retrieved 489 titles. One clinical study and 14 in vitro studies were finally included in the review; none of these studies assessed treatment outcome, four studies assessed the antimicrobial effect, seven studies evaluated the removal of pulp tissue remnants, and four studies investigated the removal of hard tissue debris or both hard tissue debris and pulp tissue remnants. Poor standardization and description of the protocols was evident. Inconclusive results were reported about the cleaning and disinfection accomplished by the two irrigation methods. Negative pressure irrigation was more effective under certain conditions when compared to suboptimal syringe irrigation; however, the variability of the protocols hindered quantitative synthesis. There is insufficient evidence to claim general superiority of any one of these methods. The level of the available evidence is low, and the conclusions should be interpreted with caution.

Eradication of Intracanal Enterococcus Faecalis Biofilm by Passive Ultrasonic Irrigation and RinsEndo System

AIM

The aim of the study was to compare the antimicrobial efficacy of three irrigation techniques after the use of standardized volume of NaOCl and with standardized time and irrigation.

METHODOLOGY

Forty-eight single rooted teeth were inoculated with an Enterococcus faecalis suspension for 24 h. The remaining six canals served as negative controls. The 36 root canals were randomly distributed into three experimental groups; group 1, conventional syringe irrigation; group 2, automated-dynamic irrigation (RinsEndo); group 3, passive ultrasonic irrigation (PUI). In the first protocol, the standardized volume of 3% NaOCl (20 mL) was used and in the second protocol, and standardized irrigation time (45 seconds) was used. Samples from root canals were cultured and the colony-forming units (CFUs) were counted.

RESULTS

When the volume of the irrigant was standardized, RinsEndo was more effective than PUI (p<0.01). When the irrigation time was standardized, there were no significant differences between any irrigation techniques (p>0.05). The RinsEndo group had the highest percentage of minimal counts of E. faecalis CFUs.

CONCLUSIONS

RinsEndo was more effective than PUI only when the volume of the irrigant was standardized. However, the RinsEndo provided higher bacterial reduction in both protocols when using the least amount of the irrigant and providing longer contact time.

An in vivo assessment of the influence of needle gauges on endodontic irrigation flow rate

Aim:

The aim of this clinical study was to assess the influence of irrigation needle gauge on endodontic irrigation flow rates.

Settings and Design:

In vivo assessment.

Materials and Methods:

Five specialist endodontists performed intracanal irrigation procedures on 50 mesiobuccal canal of mandibular first molars using three different irrigation needle gauges. Data of time taken for irrigation was recorded by an irrigation testing system and analyzed using independent sample “T” test and one-way analysis of variance (ANOVA) test. The level of significance was set at P < 0.05.

Statistical Analysis Used:

The following tests were used for the statistical analysis: Independent sample “T” test, one-way ANOVA test, and post hoc multiple comparison was carried out using Tukey's honest significant difference (HSD) test using Statistical Package for the Social Sciences (SPSS) version 16 for Windows.

Results:

The average flow rate of 26 gauge was 0.27 mLs⁻¹, of 27 gauge was 0.19 mLs⁻¹, and of 30 gauge was 0.09 mls⁻¹. There was statistical significance among the gauges (P < 0.001). 26 gauge had highest flow rate when compared with other groups followed by 27 gauge and 30 gauge respectively. The operator variability for flow rate of three endodontic irrigation needle gauges (26 gauge, 27 gauge, and 30 gauge) was found to be not significant.

Conclusions:

Needle gauge has significant influence on endodontic irrigation flow rate.

Assessing root canal fillings on a radiograph--an overview

This article will discuss why a root filling that appears satisfactory on a radiograph may fail, and why one which appears unsatisfactory on a radiograph may succeed. In doing so, this article will also discuss the criteria of endodontic success and failure and its implications on the decision to retreat.

Effects of different instrumentation techniques on calcium hydroxide removal from simulated immature teeth

The aim of this study was to evaluate the effectiveness of endodontic instrument systems in the removal of calcium hydroxide [Ca(OH)(2)] from simulated immature teeth. The root canals of 106 human single-rooted teeth were shaped with ProTaper rotary files up to an F5 file size. Simulation of roots with immature apices was carried out using size 4 green 1.5-mm diameter Unicore drills. A non-setting Ca(OH)(2) was injected into each root canal and inserted into the working length using lentulo spiral, after which cotton pellets were placed over canal orifices. The apical and coronal side of the roots were then sealed with 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 five experimental groups according to the method used for Ca(OH)(2) removal (ProTaper, Reciproc, OneShape, WaveOne, and Manual) (n = 20), one positive control group (n = 3) and one negative control group (n = 3). The amount of remaining Ca(OH)(2) in the canal walls was measured under a stereomicroscope at 30× magnification. The data were analyzed using Kruskal-Wallis test and Mann-Whitney U test at a significance level of 0.05. Positive and negative control groups were found to be statistically different from all other groups (p < 0.05). There were no significant differences among the ProTaper, Reciproc, OneShape, WaveOne, and Manual groups (p > 0.05). As a conclusion, none of the techniques completely removed Ca(OH)(2) from simulated immature teeth.

A comparison of different irrigation systems and gravitational effect on final extrusion of the irrigant

BACKGROUND

The aim of this study was to compare manual needle irrigation (MNI), RinsEndo (RE), and passive ultrasonic irrigation (PUI), and assess the effect of gravity on extrusion from the apex in vitro.

MATERIAL AND METHODS

The distobuccal roots of molars were used and the canals were instrumented up to F2. Teeth were mounted on models, which permitted visualization and manipulation of the apices for necessary procedures. The models were placed in articulator to simulate the jaw. Six groups (G) were formed as: G1, G2 and G3 represented mandibular positioning of teeth and were irrigated with MNI, RE, and PUI, respectively, while G4, G5, and G6 represented maxillary positioning of teeth and were also irrigated in same sequence. Prior to the final irrigation, 72 cube-shaped foam pieces covered with aluminum foil were weighed and the values were recorded as the initial weights. The cubes were then placed on the apical part of each sample. Final irrigation was performed with distilled water and the cubes were weighed again to determine their final weight. Data were analyzed using Kruskal-Wallis and Mann-Whitney U post-hoc test (p<0.05).

RESULTS

Irrespective of the irrigation technique used, the amount of irrigant extruded from the apex showed a statistically significant difference related to the effect of gravity (p<0.05). There was no statistically significant difference between irrigation methods (p>0.05). When the irrigation systems were compared to examine the effect of gravity, the significant difference was found between G2 and G5 (p<0.05).

CONCLUSIONS

Within the limitations of this study, MNI and PUI were found to be reliable irrigation systems. Caution should be exercised when using RinsEndo. Key words:Final irrigation, manual needle irrigation, passive ultrasonic irrigation, RinsEndo.

Assessment of smear layer removal protocols in curved root canals

This study sought to assess if the final rinse protocol interferes with the smear layer removal in the apical area of curved canals. Sixty-four extracted human mandibular molars with curved mesial roots were instrumented with rotary files and divided into six experimental groups for final rinse: 1EDTA (syringe irrigation with 1 mL of 17% ethylenediaminetetraacetic acid (EDTA) ), 5EDTA (syringe irrigation with 5 mL of 17% EDTA), 1EDTA-P (syringe irrigation with 1 mL of 17% EDTA + pumping with gutta-percha point), 5EDTA-P (syringe irrigation with 5 mL of 17% EDTA + pumping with gutta-percha point), 1EDTA-EA (syringe irrigation with 1 mL of 17% EDTA + EndoActivator) and 5EDTA-EA (syringe irrigation with 5 mL of 17% EDTA + EndoActivator). Final rinsing was carried out over 3 min. The specimens were split lengthwise and observed under a scanning electron microscope using a score criterion. Comparison among the groups showed statistically significant difference only between the 5EDTA-EA group and the other groups (Kruskal-Wallis and Dunn's post-hoc tests, P < 0.05). The combination of 5 mL of 17% EDTA and 3 mL of 2.5% sodium hypochlorite (NaOCl) with the EndoActivator removed smear layer from the apical area of curved root canals more effectively than the other protocols used.

The investigation of gutta-percha temperature and compaction force change when using the vertical compaction of warm gutta-percha technique

The naturally occurring isoprene rubber component of gutta-percha has been used in dental root canal filling treatments for almost a hundred years owing to its stability and plasticity as a root canal filling material. The traditional warm gutta-percha vertical compaction technique is the major technique for warm gutta-percha root canal obturation. However, the relation between compaction force and temperature change in this technique is still unclear. The purposes of this study were to determine the ideal gutta-percha molding temperature for compaction and to evaluate single and double heating and compaction in the warm vertical compaction procedures using infrared thermography. Gutta-percha was placed in a digital dry bath incubator at temperatures ranging from 25°C to 62°C in order to analyze compaction forces using an Instron universal testing machine. Both single and double heating and compaction procedures were examined using an infrared thermograph model to monitor temperature change when performing the warm gutta-percha vertical compaction procedure. Our results demonstrate that 44–58°C is the ideal temperature to soften gutta-percha for excellent compaction. Heating and compacting gutta-percha twice at 3 mm from the apex can mold the gutta-percha completely.

Influência do diâmetro foraminal do canal radicular, do tipo e da penetração de agulha, e do fluxo da solução irrigadora na limpeza e na extrusão apical

Introdução: A irrigação do canal radicular visa a limpeza e desinfecção do sistema de canais radiculares, sem promover extrusão apical. Objetivo: Avaliar a influência do diâmetro foraminal do canal radicular, da penetração e do tipo de agulha, e do fluxo na limpeza e na extrusão apical da solução irrigadora. Material e método: Doze dentes incisivos inferiores humanos com canal único foram instrumentados e, após ampliação foraminal com diferentes diâmetros (LK #40 e 60), os canais radiculares foram preenchidos com solução de contraste radiológico espessada com propilenoglicol e óxido de zinco. Foram utilizados dois tipos de agulhas de irrigação 27G com diferentes designs (abertura apical ou lateral), dois fluxos correspondentes a 15 ou 25 mL/min, e com penetração das agulhas em duas profundidades (3 e 6 mm aquém do ápice). Antes e após irrigação, os dentes foram radiografados utilizando um sistema radiográfico digital. As áreas do canal radicular antes (preenchido pelo contraste) e após irrigação (remanescente do contraste) foram submetidas à subtração de imagens no programa Adobe Photoshop CS4 e mensuradas por meio do programa Image Tool 3.0, obtendo o percentual de limpeza e de extrusão. Os dados foram analisados por meio dos testes ANOVA e Tukey, com nível de significância de 5%. Resultado: Não houve diferença estatística entre o diâmetro foraminal, o tipo e a profundidade de penetração da agulha, e a velocidade do fluxo de irrigação nos parâmetros limpeza (acima de 97%) e extrusão apical (menor do que 0,38 mm2), com p>0,05. Conclusão: Todos os protocolos de irrigação avaliados proporcionaram limpeza do canal radicular e pequena extrusão apical da solução irrigadora.

Effectiveness of different intracanal irrigation techniques in removing intracanal paste medicaments

This study aimed to compare the effectiveness of different intracanal irrigation techniques in removing intracanal medicaments prior to obturation. A total of 168 single roots were prepared with ProTaper® rotary files and medicament pastes applied (Ledermix®, Odontopaste®, Doxypaste and Pulpdent®), left in for 2 weeks, then removed using filing followed by one of four methods: irrigation with an open-ended notched irrigation needle (Appli-Vac) either at the working length or 5 mm from the canal orifice, or the Max-I-probe or EndoActivator® at the working length. Following the removal of medicaments, the roots were split into two and the internal surfaces photographed, for digital image analysis of the overall percentage of residual medicament. With the exception of canals irrigated 5 mm apical to the root canal orifice, all four irrigation techniques achieved an average of 95% for removal of Ledermix®, Odontopaste® and Doxypaste. Calcium hydroxide paste was the most difficult medicament to remove, with no difference between irrigation techniques. Up to 27% of the Pulpdent® material remained after irrigation. No irrigation technique could completely remove all traces of medicaments. The position of the irrigational needle and the type of medicament used are key factors, which influence the effectiveness of irrigation in removing medicaments.

Irrigation of human prepared root canal--ex vivo based computational fluid dynamics analysis

AIM

To analyze the influence of the needle type, insertion depth, and irrigant flow rate on irrigant flow pattern, flow velocity, and apical pressure by ex-vivo based endodontic irrigation computational fluid dynamics (CFD) analysis.

METHODS

Human upper canine root canal was prepared using rotary files. Contrast fluid was introduced in the root canal and scanned by computed tomography (CT) providing a three-dimensional object that was exported to the computer-assisted design (CAD) software. Two probe points were established in the apical portion of the root canal model for flow velocity and pressure measurement. Three different CAD models of 27G irrigation needles (closed-end side-vented, notched open-end, and bevel open-end) were created and placed at 25, 50, 75, and 95% of the working length (WL). Flow rates of 0.05, 0.1, 0.2, 0.3, and 0.4 mL/s were simulated. A total of 60 irrigation simulations were performed by CFD fluid flow solver.

RESULTS

Closed-end side-vented needle required insertion depth closer to WL, regarding efficient irrigant replacement, compared to open-end irrigation needle types, which besides increased velocity produced increased irrigant apical pressure. For all irrigation needle types and needle insertion depths, the increase of flow rate was followed by an increased irrigant apical pressure.

CONCLUSIONS

The human root canal shape obtained by CT is applicable in the CFD analysis of endodontic irrigation. All the analyzed values -irrigant flow pattern, velocity, and pressure - were influenced by irrigation needle type, as well as needle insertion depth and irrigant flow rate.

Efficacy of four irrigation needles in cleaning the apical third of root canals

This study aimed to evaluate the influence of irrigation needle gauge and design, and the final root canal diameter on the apical cleaning efficacy. Twelve human mandibular incisors were used. At different stages of root canal widening (sizes 20, 30 and 40 K-files), root canals were filled with radiopaque contrast medium. Four different needles were evaluated: 23G with side opening, 22G with apical opening, 30G with side opening and 30G with apical opening. Irrigation was carried out with 2 mL distilled water. The same tooth was radiographed with a digital system several times to assess the four types of needle in those three stages of canal widening. Pre-irrigation (canals filled with contrast) and post-irrigation (canals with remaining contrast) images were submitted to digital subtraction using the Adobe Photoshop CS4 program. Pre-irrigation (filled with contrast) and subtracted (cleaned by irrigation) areas were outlined by a trained and blinded operator using the Image Tool 3.0 software. Their ratio was calculated to express the percentage of apical cleaning in each stage of canal widening (sizes 20, 30 and 40 K-files) with each of the four needles. Data obtained were subjected to one-way ANOVA and Tukey's tests. The 30G needles with side and apical opening promoted better apical cleaning at all stages of root canal widening (p<0.05). In conclusion, smaller diameter needles were more efficacious in cleaning the apical third of the root canals, regardless of their design.

Endodontic 'solutions' part 1: a literature review on the use of endodontic lubricants, irrigants and medicaments

Endodontic lubricants, irrigants and medicaments help prepare and disinfect root canal systems (RCS) but primary and secondary cases involve different microbes and therefore it is unlikely that one protocol will be effective for both case types. Each individual 'solution' or sequence of'solutions' could play a significant role in each case type, but there are no detailed published guidelines in existence. To help inform clinical practice it was decided to undertake a literature review followed by a UK and Republic of Ireland wide audit on current endodontic'solution' usage within dental schools. The literature review was undertaken under the following headings: pre-op oral rinse; file lubricants; root canal irrigants and intracanal medicaments and provides an evidence base for protocol development for both primary and retreatment cases.The audit project and the protocols developed from the findings of both the literature review and audit will be presented in Part 2.

Root canal debridement efficacy of different final irrigation protocols

AIM

To compare the smear layer and debris removal effectiveness of four root canal irrigation protocols as well as their effectiveness in removing remaining soft tissues in curved root canals.

METHODOLOGY

The mesiobuccal and mesial root canals of 107 extracted human maxillary and mandibular molars were instrumented using Mtwo rotary NiTi instruments then randomly divided into four groups according to a final rinse protocol: Group 1 (n = 28) - manual agitation of 1% NaOCl and 15% EDTA; Group 2 (n = 26) - CanalBrush agitation of 1% NaOCl and 15% EDTA; Group 3 (n = 26) - 3% H(2) O(2) alternated with 1% NaOCl; Group 4 (n = 27) - passive ultrasonic agitation of 1% NaOCl and 15% EDTA. All irrigation protocols were performed in a closed system. Eleven roots per group were prepared and histologically stained (H&E) to assess percentage of remaining pulpal tissues in the apical thirds. The remaining specimens were split longitudinally and examined under scanning electron microscope at ×2000 magnification to assess smear layer and debris removal. Image Pro Plus 6.0 software was used to analyse smear layer and remaining pulp tissue. Debris presence was scored by two blinded investigators using a five-point scale. Data were analysed using Univariate analysis of variance (GenStat 13, α = 0.05).

RESULTS

CanalBrush and passive ultrasonic irrigation were equally effective with significantly less smear layer and debris than manual agitation and H(2) O(2) alternated with NaOCl (P < 0.05). The H(2) O(2) alternated with NaOCl protocol was significantly more effective in removing pulp tissue remnants in the apical level than manual agitation (P = 0.009) and passive ultrasonic irrigation (P = 0.01).

CONCLUSIONS

CanalBrush was as effective as passive ultrasonic irrigation in smear layer and debris removal. Alternating H(2) O(2) with NaOCl was effective in removing soft tissues from root canal complexities. Further studies are required to evaluate effectiveness of this regimen taking into account irrigant volume differences and effect of root canal system configuration.

Curved versus straight root canals: the benefit of activated irrigation techniques on dentin debris removal

OBJECTIVE

The aim of this study was to compare the efficacy of hydrodynamic and ultrasonic-activated irrigation to conventional syringe irrigation in removing dentin debris in straight and curved root canals.

STUDY DESIGN

Twelve human teeth were selected for study. The root canals of 6 single-rooted premolars with straight canals and 6 molar roots with curved canals were prepared to a size of 45 and split longitudinally. To simulate canal irregularities, 3 standardized holes were cut in 1 canal wall. The canals and holes were then covered with debris. After reassembly, 3 irrigation techniques were compared: syringe irrigation, hydrodynamic irrigation, and ultrasonic irrigation. The amount of debris that remained was evaluated microscopically and graded with a 4-score system.

RESULTS

The hydrodynamic and ultrasonic irrigation techniques were significantly (P < .001) more efficient as compared with syringe irrigation in both the straight and curved root canals. Ultrasonic irrigation demonstrated a higher efficiency in the straight root canals (P < .01), whereas hydrodynamic irrigation was more efficient in the curved canals (P < .01).

CONCLUSIONS

In the straight canals, ultrasonic irrigation was the most effective, but in the curved root canals, hydrodynamic irrigation was superior.

Root canal preparation of maxillary molars with the self-adjusting file: a micro-computed tomography study

INTRODUCTION

The aim of this study was to describe the canal shaping properties of a novel nickel-titanium instrument, the self-adjusting file (SAF), in maxillary molars.

METHODS

Twenty maxillary molars were scanned by using micro-computed tomography at 20-μm resolution. Canals were shaped with the SAF, which was operated with continuous irrigation in a handpiece that provided an in-and-out vibrating movement. Changes in canal volumes, surface areas, and cross-sectional geometry were compared with preoperative values. Canal transportation and the fraction of unprepared canal surface area were also determined. Data were normally distributed and compared by analyses of variance.

RESULTS

Preoperatively, mean canal volumes were 2.88 ± 1.32, 1.50 ± 0.99, and 4.30 ± 1.89 μm(3) [corrected] for mesiobuccal (MB), distobuccal (DB), and palatal (P) canals, respectively; these values were statistically similar to earlier studies with the same protocol. Volumes and surface areas increased significantly in MB, DB, and P canals; mean canal transportation scores in the apical and middle root canal thirds ranged between 31 and 89 μm. Mean unprepared surfaces were 25.8% ± 12.4%, 22.1% ± 12.0%, and 25.2% ± 11.3% in MB, DB, and P canals, respectively (P > .05) when assessed at high resolution.

CONCLUSIONS

By using SAF instruments in vitro, canals in maxillary molars were homogenously and circumferentially prepared with little canal transportation.