Scanning electron microscope study comparing four root canal preparation techniques in small curved canals

Effect of Chemical Debridement and Irrigant Activation on Endodontic Treatment Outcomes: An Updated Overview

Chemical debridement is considered one of the most important steps during root canal treatment to target unreached areas and provide thorough disinfection of the canals. The efficiency of this step efficiency can be increased using different agitation and irrigation techniques/devices. This comprehensive review aimed to summarize the effect of various irrigant activation and agitation techniques/devices on endodontic treatment outcomes. Using mechanical active irrigation, which enables the activation or agitation of the irrigating solution, is beneficial in root canal treatment by increasing the efficiency of delivering the irrigant up to working length and ensuring isthmus cleanliness. However, considerable variation was noticed between the protocols used in each technique with a lack of well-designed randomized clinical trials to focus on the long-term outcome. Moreover, a low level of evidence was noticed regarding the effectiveness of certain activation techniques over others. Therefore, each study needs to be carefully weighed before using its results and embracing its conclusion. Future studies need to focus more on the antimicrobial effect of each technique and its effect on the healing of apical periodontitis. Also, recent advances, such as multisonic and laser activation, are promising tools that need more clinical investigations to show their efficiency.

Debris and Smear Layer Removal from Oval Root Canals Comparing XP-Endo Finisher, EndoActivator, and Manual Irrigation: A SEM Evaluation

Objective  This study aimed to assess and compare XP-Endo Finisher (XP) cleaning efficiency with respect to the amount of remaining debris and smear layer versus Max-I-Probe needle (CI), EndoActivator device (EA), and combination of XP-Endo Finisher file with EndoActivator device (XP+EA) in oval root canals.

Materials and Methods  This in vitro study was performed on 36 extracted single root/canal mandibular premolars. Radiographic images were taken in buccolingual and mesiodistal projections to evaluate the shape of the root canal and determine whether it met exclusion criteria. All teeth were decoronated and prepared using Reciproc (R40). The samples were divided randomly into four groups: CI, EA, XP, and XP + EA. The root canals were irrigated with 5 mL of 17% EDTA and 2.5% NaOCl, respectively. Apart from the CI group, both solutions were activated by using the tested techniques for 1 minute.

The teeth were split longitudinally, and the best visible identified sections of the roots were used as the representing samples for scanning electron microscope (SEM) evaluation. Each half was divided into the following three parts: 1 mm from the anatomic apex and a standardized photomicrograph with 500x and 1500x magnifications for debris and smear layer were obtained. A five-grade scoring system was utilized to quantify the results at the coronal, middle, and apical regions. Statistical analysis was performed by using the Kruskal–Wallis and Mann–Whitney U tests.

Results  Group differences in debris and smear layer scores were found statistically significant for all locations as well as for overall assessment, except for the coronal third. Intragroup comparison of debris and smear layer in CI, EA, and XP had the minimum score at the middle third, with no significant difference compared with the coronal and apical thirds. XP + EA had less debris and smear layer score at the coronal third, significantly different from apical third.

CI and EA had less debris and smear layer compared with XP and XP + EA at all locations with a significant difference at the middle and apical third ( p < 0.05).

Conclusion  EA and CI showed less debris and smear layer than XP and XP + EA in the middle and apical third. The use of the XP in conjunction with the present irrigation protocol failed to have debris-free dentin surface in the apical portion of most of the root canals.

Comparison of Five Different Irrigation Techniques on Smear Layer Removal in Apical Thirds of Root Canals of Mandibular First Premolar: A Scanning Electron Microscopic Study

Aim:

This study was conducted to compare smear layer removal by five different irrigation techniques—conventional needle irrigation (CI), manual dynamic activation (MDA), passive ultrasonic irrigation (PUI), sonic irrigation (SI), and negative apical pressure (NAP).

Materials and Methods:

Fifty freshly extracted mandibular first premolars were cleaned and shaped by One Curve rotary files and 3% sodium hypochlorite and 17% ethylenediaminetetraacetic acid. The samples were divided into five equal groups (n = 10), according to the final irrigation activation technique: Group I, CI; Group II, MDA; Group III, PUI; Group IV, SI; and Group V, NAP. The samples were prepared and observed under a scanning electron microscope. The photomicrographs were recorded and evaluated with a scoring system.

Results:

Group I and Group II had the highest scores, which showed a statistically significant difference between the other groups (P < 0.05). This was followed by PUI, NAP, and SI.

Conclusion:

Final irrigation activation with SI and NAP resulted in the better removal of smear layer when compared to that with other groups.

Cleaning Efficiency of Root Canal after Irrigation with New Irrigation Technique: A Scanning Electron Microscopic Study

Introduction:

The aim of this study was to evaluate the ability of pressurized water irrigation technique (AquaPick Device) as an intra-canal irrigation technique and compare it with sonic irrigation device (Endoactivator) for their ability to remove smear layer from canals.

Methods and Materials:

Total number of 80 single rooted teeth (premolars) were prepared, divided into eight main groups, Group 1: Aquapick with apically vented needle/18 mm depth, Group 2: Aquapick with apically vented needle/15 mm depth, Group 3: Endoactivator device/18 mm depth, Group 4: Endoactivator device/15 mm depth, Group5: Aquapick with 2 side vented needle/18 mm depth, Group 6: Aquapick with 2 side vented needle/15 mm depth and two control groups. Then all samples were tested by SEM in 3, 6 and 9-mm distances from the apical foramen. The data were statistically analyzed using Kruskal Wallis and Mann-Whitney U tests.

Results:

There was a high significant difference among the tested groups with the best removal of smear layer by the use of pressurized water irrigation device with apical vented needle especially at the 3 mm area.

Conclusion:

Pressurized water irrigation technique could be used as intra-canal irrigation technique with good results.

Canal Aberration Assessment in Simulated Root Canals: a Comparative Study

Aim:

The aim of this study was to compare time of preparation and canal aberrations in a simulated root canals after using three different rotary systems: Endostar E5, Endostar E3 and T One File Gold.

Materials and Methods:

A total of 90 endodontic training blocks were used in this study and divided into three groups consisting of 30 each (n = 30). Blocks processing was performed by thirty dentists without any prior experience in rotary instrumentation techniques. In the first group blocks were prepared using Endostar E5, in second one with Endostar E3 and in third one with T One File Gold system. The preparation time was measured. The postoperative image of each block was taken by stereomicroscope and canal aberrations (ledge and instrument fracture) was recorded. Statistical analysis was done by SPSS software.

Results:

Instrumentation with T One File Gold system is significantly faster compared to instrumentation with Endostar E5 and Endostar E3 systems (p <0.05). There are no statistically significant differences in the type and number of procedural errors between Endostar E5, Endostar E3 and T One File Gold systems when the operators have no previous experience in rotary instrumentation techniques.

Conclusion:

Under the conditions of this study, the incidence of examined canal aberrations were similar for all tested systems. The preparation time was significantly shorter with single file system.

FESEM evaluation of smear layer removal using different irrigant activation methods (EndoActivator, EndoVac, PUI and LAI). An in vitro study

OBJECTIVES

This study was to compare the efficacy of EndoActivator, EndoVac, PUI, and LAI methods in removing the smear layer from root canals.

MATERIALS AND METHODS

Eighty single-rooted mandibular premolars were decoronated to a standardized length of 15 mm. Specimens were shaped to ProTaper F4 (Dentsply Maillefer) and irrigated with 5.25% NaOCl at 37 °C. Teeth were divided into six groups (two control groups [n = 10] and four test groups [n = 15]) according to the final irrigation activation/delivering technique (sonic irrigation [EndoActivator], passive ultrasonic irrigation [PUI], negative apical pressure [EndoVac], and laser activated irrigation [LAI]). Root canals were then split longitudinally and observed with field emission scanning electron microscopy to evaluate the presence of smear layer at 1, 3, 5, and 8 mm from the apex. Scores were analyzed by Kruskal-Wallis and Mann-Whitney U tests.

RESULTS

The EndoActivator was significantly more efficient than PUI, LAI, and control groups in removing the smear layer at 3, 5, and 8 mm from the apex. The EndoVac System removed statistically significantly more smear layer than all groups at 1 mm from the apex. At 5 mm from the apex, EndoActivator and EndoVac removed more smear layer than LAI and control groups. At 5 and 8 mm from the apex, PUI and EndoVac did not differ statistically, but both performed statistically better than the control groups.

CONCLUSION

In our study, none of the activation/delivery systems completely removed the smear layer from the root canal walls; nevertheless, EV and EA showed, respectively, statistically significant better results at 1, 3, 5, and 8 mm and 3, 5, and 8 mm from the apex.

Comparative evaluation of demineralization of radicular dentin with 17% ethylenediaminetetraacetic acid, 10% citric acid, and MTAD at different time intervals: An in vitro study

Background:

The smear layer has the capability to protect the bacteria within the dentinal tubules from intracanal medicament. After removal of the smear layer from infected root canals, it allows disinfection of the entire root canal. The smear layer compromising the seal between the root canal sealer and root canal wall also decreases the penetration of irrigants into dentinal tubules.

Aims:

This study compares the amount of phosphorous liberated and demineralization of the radicular dentin with 17% ethylenediaminetetraacetic acid, 10% citric acid and mixture of doxycycline, citric acid, and a detergent at different time intervals.

Materials and Methods:

Extracted maxillary single-rooted teeth were prepared by using a combination of passive step-back and rotary 0.04 taper nickel-titanium files. Sodium hypochlorite 5.25% and sterile distilled water were used as an intracanal irrigant. The canals were then treated with 5 mL of one of the following solutions such as final rinse sterile distilled water, 5.25% sodium hypochlorite, 17% ethylenediaminetetraacetic acid (EDTA) or mixture of doxycycline, citric acid, and a detergent. The presence or absence of smear layer and the amount of erosion on the surface of the root canal walls at the coronal, middle, and apical portions of each canal were examined under a scanning electron microscope.

Statistical Analysis:

Data were analyzed by one-way analysis of variance (ANOVA) to determine whether there were significant differences between the groups.

Results:

The results show that mixture of doxycycline, citric acid, and a detergent is an effective solution for the removal of the smear layer and does not significantly change the structure of the dentinal tubules.

Conclusions:

In this study, 10% citric acid shows the maximum amount of dimeneralization of radicular dentine followed by mixture of doxycycline, citric acid, and a detergent, and 17% ethylenediaminetetraacetic acid. When all the subgroups were compared, it was seen that the maximum amount of phosphorus liberation was performed by 10% citric acid >mixture of doxycycline, citric acid, and a detergent >17% EDTA at a different time interval.

Effectiveness of different irrigation techniques on smear layer removal in apical thirds of mesial root canals of permanent mandibular first molar: A scanning electron microscopic study

Aim:

The aim of this study was to compare smear layer removal after final irrigant activation with sonic irrigation (SI), manual dynamic agitation (MDA), passive ultrasonic irrigation (PUI), and conventional syringe irrigation (CI).

Materials and Methods:

Forty mesial canals of mandibular first molars (mesial roots) were cleaned and shaped by using ProTaper system to size F1 and sodium hypochlorite 3% and 17% ethylenediaminetetraacetic acid. The specimens were divided into 4 equal groups (n = 10) according to the final irrigation activation technique: Group 1, PUI; group 2, manual dynamic activation (MDA); group 3, SI; and group 4, control group (simple irrigation). Samples were split longitudinally and examined under scanning electron microscope for smear layer presence.

Results:

Control groups had the highest smear scores, which showed the statistically significant highest mean score at P < 0.05. This was followed by ultrasonic, MDA, and finally sonic, with no significant differences between them.

Conclusions:

Final irrigant activation with sonic and MDA resulted in the better removal of the smear layer than with CI.

A comparative evaluation of different irrigation activation systems on smear layer removal from root canal: An in-vitro scanning electron microscope study

AIM

The aim of the following study is to compare the evaluation of different irrigation activation system-F-File, CanalBrush (CB) and EndoActivator (EA) in removing smear layer from root canal.

MATERIALS AND METHODS

Root canals of eighty single rooted decoronated premolar teeth were instrumented using crown-down technique and then equally divided into four groups on basis of irrigation activation methods used: Without irrigation - control group, irrigation with F-File, CB, EA into Group I, II, III respectively. Samples were then longitudinally sectioned and examined under scanning electron microscope by three qualified observers using score from 1 to 4. Data was analyzed using Statistical Package for Social Sciences (SPSS), version 15.0 (SPSS Inc., Chicago IL) at significance level of P ≤ 0.05.

RESULTS

Minimum mean score was observed in Group II at coronal, apical locations. Group III had minimum score at middle third. Groups difference in score were found to be significant statistically for all three locations as well as for overall assessment (P < 0.001).

CONCLUSION

CB remove smear layer more efficiently from the root canal than F-File and EA in coronal and apical region.

Effect of Duration of Irrigation with Sodium Hypochlorite in Clinical Protocol of MTAD on Removal of Smear Layer and Creating Dentinal Erosion

Background and aims

The aim of the present study was to compare 1.3% sodium hypochlorite (NaOCl) in MTAD (mixture of tetracycline isomer, acid, and detergent) for the removal of the smear layer and induction of canal erosion.

Materials and methods

38 maxillary incisors were divided in three experimental groups of 10 and two positive and negative control groups of each 4 teeth, and prepared using rotary files. In test groups, 1.3% NaOCl was used for 5, 10 and 20 minutes during preparation followed by MTAD as the final rinse. In negative control group, 5.25% NaOCl was used for 10 minutes followed by 17% Ethylenediamine Tetra-Acetic Acid (EDTA) as the final rinse. In positive control group, dis-tilled water was used for 10 minutes during preparation and then as the final rinse. The samples were examined under scan-ning electron microscope, and the smear layer and dentinal erosion scores were recorded.

Results

Five and 10 min groups had significant differences with 20 min group (p < 0.05). In apical third, 5 and 10 min groups had also significant differences with 20 min (p < 0.05). In the coronal thirds, when the time of irrigation with 1.3% NaOCl increased from 5 min to 20 min, erosion also increased significantly. However, 5 and 10 min groups had no signifi-cant differences with negative control group.

Conclusion

The use of 1.3% sodium hypochlorite for 5 and 10 minutes in the MTAD protocol removes the smear layer in the coronal and middle thirds but does not induce erosion.

Histological analysis of cleaning efficacy of hand and rotary instruments in the apical third of the root canal: A comparative study

AIM

To compare the cleaning efficiency of manual and rotary instrumentation in the apical third of the root canal system.

MATERIALS AND METHODS

In group 1 (n=10), instrumentation was performed with stainless steel K-file; in group 2 (n=10), it was done with hand ProTaper files; and in group 3 (n=10), instrumentation was done with ProTaper rotary. Distilled water was used for irrigation. The apical third was sectioned transversally and histologically processed. The cross sections were examined under optic microscope and debris was measured using Motic software.

RESULTS

Instrumentation with stainless steel K-files showed minimum amount of debris, followed by ProTaper hand files, and rotary ProTaper files were least effective with maximum amount of debris; however, there were no significant differences between the three experimental groups.

CONCLUSIONS

Both the manual and rotary instrumentation are relatively efficient in cleaning the apical third of the root canal system and the choice between manual and rotary instrumentation should depend on case to case basis.

Comparison of the percentage of gutta-percha-filled area obtained by Thermafil and System B

The aim of this study was to determine the percentage of gutta-percha-filled area (GPFA) obtained by Thermafil and System B techniques using light microscopy and digital image processing. Forty-five human mandibular first molars were prepared and obturated as follows: Group 1: lateral condensation (n = 15); Group 2: System B (n = 15); and Group 3: Thermafil system (n = 15). Horizontal sections were cut 4 and 6 mm from the apical foramen of each tooth. The samples were metallographically prepared and taken through photomicrographs. Using digital analysis, the cross-sectional area of the canal and the gutta-percha areas were measured. The GPFA data obtained for the three groups were analysed using the non-parametric Friedman and Wilcoxon Signed-Ranks tests. Significant differences were found between Group 3 and Group 2-Group 1. No significant difference was found between Group 2 and Group 1. The Thermafil system produced significantly higher GPFAs than lateral condensation and System B techniques (P < 0.01). This result suggests that the Thermafil system can reduce sealer and voids.

Passive ultrasonic irrigation of the root canal: a review of the literature

Ultrasonic irrigation of the root canal can be performed with or without simultaneous ultrasonic instrumentation. When canal shaping is not undertaken the term passive ultrasonic irrigation (PUI) can be used to describe the technique. In this paper the relevant literature on PUI is reviewed from a MEDLINE database search. Passive ultrasonic irrigation can be performed with a small file or smooth wire (size 10-20) oscillating freely in the root canal to induce powerful acoustic microstreaming. PUI can be an important supplement for cleaning the root canal system and, compared with traditional syringe irrigation, it removes more organic tissue, planktonic bacteria and dentine debris from the root canal. PUI is more efficient in cleaning canals than ultrasonic irrigation with simultaneous ultrasonic instrumentation. PUI can be effective in curved canals and a smooth wire can be as effective as a cutting K-file. The taper and the diameter of the root canal were found to be important parameters in determining the efficacies of dentine debris removal. Irrigation with sodium hypochlorite is more effective than with water and ultrasonic irrigation is more effective than sonic irrigation in the removal of dentine debris from the root canal. The role of cavitation during PUI remains inconclusive. No detailed information is available on the influence of the irrigation time, the volume of the irrigant, the penetration depth of the instrument and the shape and material properties of the instrument. The influence of irrigation frequency and intensity on the streaming pattern as well as the complicated interaction of acoustic streaming with the adherent biofilm needs to be clarified to reveal the underlying physical mechanisms of PUI.

A quantitative analysis of rotary, ultrasonic and manual techniques to treat proximally flattened root canals

Objective:

The efficiency of rotary, manual and ultrasonic root canal instrumentation techniques was investigated in proximally flattened root canals.

Material and Methods:

Forty human mandibular left and right central incisors, lateral incisors and premolars were used. The pulp tissue was removed and the root canals were filled with red die. Teeth were instrumented using three techniques: (i) K3 and ProTaper rotary systems; (ii) ultrasonic crown-down technique; and (iii) progressive manual technique. Roots were bisected longitudinally in a buccolingual direction. The instrumented canal walls were digitally captured and the images obtained were analyzed using the Sigma Scan software. Canal walls were evaluated for total canal wall area versus noninstrumented area on which dye remained.

Results:

No statistically significant difference was found between the instrumentation techniques studied (p<0.05).

Conclusion:

The findings of this study showed that no instrumentation technique was 100% efficient to remove the dye.

Effectiveness in cleaning oval-shaped root canals using Anatomic Endodontic Technology, ProFile and manual instrumentation: a scanning electron microscopic study

AIM

To compare in vitro the cleanliness of root canal walls in oval-shaped root canals following automated or manual instrumentation.

METHODOLOGY

Forty-five oval-shaped single-rooted maxillary and mandibular premolars with straight canals were divided into three groups of 15. Automated canal preparation was performed using Anatomic Endodontic Technology (AET, group 1) and the ProFile system (group 2). Manual instrumentation (group 3) was performed with K-Flexofiles. Irrigation was performed using alternately 5.25% NaOCl and 17% EDTA, followed by rinsing with saline. The roots were split longitudinally into halves and the canals examined at x200 and x400 in a scanning electron microscope. The presence of debris and smear layer was recorded at distances of 1, 5 and 10 mm from the working length using a three-step scoring scale and a 300 mum square grid. Mean scores for debris and smear layer were calculated and statistically analysed for significance (P < 0.05) between and within groups, using the Kruskal-Wallis nonparametric anova and Dunn's tests.

RESULTS

At 1, 5 and 10-mm levels the root canals prepared with AET had significantly less surface debris and smear layer on the canal walls compared with canals prepared with ProFile or manual instrumentation. For all three groups significantly lower mean smear layer scores (P < 0.05) were recorded at 5 and 10-mm levels compared with the 1 mm level. Significantly lower mean debris scores (P < 0.05) were also recorded at 5 and 10-mm levels for the AET group whereas no significant differences were found between the three levels for the ProFile and manual instrumentation groups.

CONCLUSIONS

Although better instrumentation scores were obtained in canals prepared with AET, complete cleanliness was not achieved by any of the techniques and instruments investigated.