|Year : 2018 | Volume
| Issue : 4 | Page : 383-387
|Comparisons by microcomputed tomography of the efficiency of different irrigation techniques for removing dentinal debris from artificial grooves
Francine Cesario1, Marco Antonio Hungaro Duarte1, Jussaro Alves Duque1, Murilo Priori Alcalde1, Flaviana Bombarda de Andrade1, Marcus Vinicius Reis So2, Bruno Carvalho De Vasconcelos3, Rodrigo Ricci Vivan1
1 Department of Restorative Dentistry, Dental Materials and Endodontics, Bauru Dental School, University of Sao Paulo, Bauru, Sao Paulo, Brazil
2 Department of Operative Dentistry, Federal University of Rio Grande do Sul, Porto Alegre, Rio Grande do Sul, Brazil
3 Department of Dentistry Campos Sobral, Federal University of Ceara, Sobral, Ceara, Brazil
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|Date of Submission||25-Aug-2016|
|Date of Decision||15-Nov-2017|
|Date of Acceptance||28-Feb-2018|
|Date of Web Publication||27-Jul-2018|
| Abstract|| |
Aim: The aim of this study was compare the capacity of different irrigation protocols for debris removal from artificial grooves and assess the effectiveness of Easy Clean used in different kinematics by means of micro-CT.
Methodology: Fifty acrylic prototyped maxillary incisors were instrumented and included in a muffle. The specimens were longitudinally sectioned, and a longitudinal groove was made on the inner surface of the root canal in one of hemisections, and the dentin debris was inserted into the grooves. The specimens were divided into five groups (n = 10): G1: Conventional with open-ended needle; G2: Conventional with double side-vented needle; G3: Easy Clean in reciprocating movement; G4: Easy clean in continuous rotation (ECCR); and G5: Passive ultrasonic irrigation (PUI). All specimens were scanned using microcomputed tomography before and after the irrigation technique and calculated the volume (mm3) of dentin debris. The paired t-test and post hoc Tukey test were the statistical tests used, with significance set at 5%.
Results: There were no significant difference (P > 0.05) between PUI and ECCR. ECCR was significantly (P < 0.05) more effective than the groups of conventional irrigation techniques.
Conclusions: PUI and ECCR favored the removal of a larger volume of dentin debris from the groove.
Keywords: Dentin debris; endodontic irrigation; microcomputed tomography; ultrasonics
|How to cite this article:|
Cesario F, Hungaro Duarte MA, Duque JA, Alcalde MP, de Andrade FB, Reis So MV, De Vasconcelos BC, Vivan RR. Comparisons by microcomputed tomography of the efficiency of different irrigation techniques for removing dentinal debris from artificial grooves. J Conserv Dent 2018;21:383-7
|How to cite this URL:|
Cesario F, Hungaro Duarte MA, Duque JA, Alcalde MP, de Andrade FB, Reis So MV, De Vasconcelos BC, Vivan RR. Comparisons by microcomputed tomography of the efficiency of different irrigation techniques for removing dentinal debris from artificial grooves. J Conserv Dent [serial online] 2018 [cited 2019 Jul 22];21:383-7. Available from: http://www.jcd.org.in/text.asp?2018/21/4/383/237733
| Introduction|| |
The main goal of endodontic therapy is to remove organic and inorganic tissue from the root canal system for later root canal obturation. However, due to the complex anatomy of the root canal system, inaccessible areas cannot be mechanically cleaned with endodontic instruments. Thus, the remains of organic tissues, infected dentin debris, and microbial biofilm in the root canal system can contribute to endodontic treatment failure.
Conventionally, root canal system cleaning is accomplished by a chemical-mechanical preparation using endodontic instruments and copious irrigation of the area with disinfectant chemical solutions. Conventional irrigation is performed by using a syringe and cannula although this irrigation technique has limited effectiveness in eliminating microbial biofilms and organic tissues in highly complex anatomical areas.,
During the chemical-mechanical preparation, dentin debris accumulates within any complex area, hindering the flow of the irrigating solution., Accumulated dentin debris harbors microorganisms, and the biofilm in the root canal system limits effective root canal obturation.
In recent years, new irrigation techniques have been proposed to optimize cleaning and disinfection of the root canal system. Passive ultrasonic irrigation (PUI) has been widely used for helping to distribute the irrigating solution, improving the cleaning efficiency and thus disinfecting any hard to access areas in the root canal system.,,,,,
A new instrument called Easy Clean (Easy Dental Equipment, Belo Horizonte, MG, Brazil) was recently introduced on the market by a Brazilian company. It is an instrument #25/0.04, made of plastic that is coupled to an electric motor using reciprocating motion. Kato et al. showed that Easy Clean promoted a better degree of cleanliness in the apical third of curved root canal walls than PUI. There are no reports assessing the effectiveness of this irrigation technique on cleaning the anatomically complex areas of the root canal system and whether the type of kinematics (using reciprocating movement or continuous rotation) would promote a more effective cleaning.
A variety of methodologies have been proposed to quantify debris removal after using different mechanized systems and irrigation techniques, with most of them using scores to assess removal.,,,, An alternative would be to use microcomputed tomography (CT), but the difficulty of quantifying the debris in human teeth by this method arises because both the debris and teeth have the same radiopacity. Therefore, previous studies has been used acrylic teeth to evaluate the solubility of retro-filling materials and intracanal dressings by means of microCT, favoring a suitable diferentiation of the radiopacity between the endodontic materials and acrylic teeth.,,
Therefore, the aim of the present study was to use micro-CT to compare the capacity of different irrigation protocols for debris removal from artificial grooves made in acrylic teeth and verify whether the type of kinematics used in the Easy Clean system has any influence on its effectiveness. The null hypothesis tested was that there would be no difference in the capacity for removing debris promoted by the different techniques used and that the kinematic would not interfere in the efficiency of Easy Clean.
| Methodology|| |
Preparation of artificial grooves
Fifty acrylic maxillary incisors with straight prototyped root canals were used. The authors used the acrylic teeth because, in a pilot study, we used human teeth and it was not possible to differ and quantify the dentin debris into the artificial groove, by the micro-CT, because of a similar radiopacity between human dentin and the debris. Therefore, the acrylic teeth were used due to provide lower radiopacity than human dentin, which allowed quantify the volume of the dentinal debris pre and post the irrigation protocols. The root canal preparation was performed with a Reciproc R40 file (VDW GmbH, Munich, Germany) establishing a working length 1.0 mm short of the final opening, which would be compatible with the apex. For each root canal preparation, a new instrument was used. During the preparation, 6.0 ml of 2.5% sodium hypochlorite was used as the irrigating solution that was inserted into the root canal with a 30-gauge needle (Navitip; Ultradent Products, South Jordan, USA) coupled to a disposable syringe (Ultradent Products) placed 1.0 mm from the working length. Subsequently, by means of a diamond disc, two longitudinal grooves were made on the external surface of the teeth: one on the buccal side and the other on the lingual side, without reaching the root canal.
After the root canal preparation, all samples were molded with condensation silicone (Clonage, DFL, Rio de Janeiro, RJ, Brazil) and inserted into a metal muffle to avoid extravasation of the irrigating solution. After molding, the acrylic teeth were removed from the oven and cleaved, following the direction of the grooves created earlier. After this, in the hemisections of all the acrylic teeth used, a longitudinal groove 4.0 mm long, 0.2 mm wide, and 0.54 mm deep were made on the internal surface of the canal up to 2.0 mm from the apex; for this purpose, a diamond disc measuring 0.8 cm in diameter and 0.2 mm thick (Komet, Saint Andre, SP, Brazil) was used as described by Martins Justo et al.
The grooves were then treated with 10% hydrofluoric acid (Maquira Ldta Dental Products Industry, Maringá, Parana, Brazil) for 10 min to obtain a rougher surface and allow greater retention of dentin debris. Dentin debris, obtained from worn bovine roots, was extracted using spherical drill steel No. 8 (KG Sorensen, Cotia, SP, Brazil) and was mixed with sodium hypochlorite at a concentration of 2.5% and compressed into the grooves. Excess debris and that on the wall of the root canal were removed with the aid of a microbrush (FGM, Joinville, Brazil).
Microcomputed tomography scanning procedures
The hemisections with the groove containing the dentin debris were scanned according to the following parameters: 19-mm voxel size, 50 kV, 800 mA, 0.8 rotation step size, and 1024 × 1304 resolution. Slices were reconstructed with the software (NRecon v. 1.6.3, Bruker micro-CT) and saved in axial slices in BMP format. Thus, pretreatment images were obtained, in which it was possible to observe the groove completely filled with debris; then, the images were analyzed with CTAn v. 1.12 software (Bruker micro-CT, CTAN v220.127.116.11, SkyScan, Aartselaar, Bélgica) to establish the initial volume.
After the first scanning procedure, the hemisections were regrouped and placed in the muffle before performing the final irrigation techniques. The acrylic teeth were randomly divided into five groups (n = 10): G1: Conventional with open-ended needle (OEN); G2: Conventional with double side-vented needle (DSVN); G3: Easy Clean in reciprocating movement; G4: Easy Clean in continuous rotation (ECCR); and G5: PUI.
In all groups, the canals were irrigated with 6.0 ml of 2.5% sodium hypochlorite divided into 3 applications of 20 s each. In G1 and G2, conventional irrigation was performed, only differing in the type of needle used; in G1, a standard 30-gauge OEN (Navitip; Ultradent Products) was used; while in G2, a DSVN (endo-Irrigation; Transcodent, Neumunster, Germany) was used. In both cases, the needle, coupled to a disposable syringe, was positioned 1 mm from the working length, and no agitation was performed. The irrigating solution in G3 was agitated with the Easy Clean instrument adjusted 1 mm from the working length and driven by an electric motor in the reciprocal movement mode (X-Smart Plus, Dentsply-Maillefer, Ballaigues, Switzerland). The acrylic teeth allocated to G4 were treated in a similar manner to those in G3; however, continuous rotation was used, driven by a contra-angle at a speed of up to 20.000 rpm. Finally, in G5, PUI was performed using an irrisonic ultrasonic insert (Helse Dental Technology, Santa Rosa de Viterbo, SP, Brazil) directly coupled to a piezoelectric ultrasonic unit (200 Piezon ® master, EMS, Switzerland) set at power 2 with movement of the insert toward the groove and positioned 1 mm from working length.
After using these techniques, all the hemisections containing the groove were removed and then scanned again using the same parameters as those of the first scan. The volume of debris before and after the final irrigation technique was recorded, and the percentage of debris removal was then calculated.
The normality of the data was not confirmed by the Shapiro–Wilks test. Statistical analysis was performed using the Wilcoxon test to compare the intragroup volume of debris (initial × final). For comparing the initial volume and percentage of debris removal among the groups, the Kruskal–Wallis followed by the Dunn test was used. The level of significance was set at 5%.
| Results|| |
The results showed that there were no statistically significant differences (P > 0.05) in initial dentin debris volumes (pretreatment) among the five groups studied, indicating an appropriate pairing of the initial volume of debris. No irrigation technique completely removed dentin debris from the grooves [Table 1]. In all groups, there were statistically significant differences in the intragroup comparisons of the volume of debris before and after irrigation treatment (P< 0.05). Comparing the percentage of debris removal among the groups, PUI was significantly more effective than conventional irrigation with OEN, DSVN, and Easy Clean used in reciprocating movement (P< 0.05). Easy Clean operated in a continuous rotation mode resulted in a statistically significant difference when compared with conventional irrigation with OEN and DSVN (P< 0.05). PUI and ECCR showed no statistical significant difference (P > 0.05). [Figure 1] shows illustrative images of results obtained in the five groups where the line “A” represents the preoperative tooth and the line “B” represents the tooth after the irrigation technique.
|Table 1: Median, minimum, and maximum debris volumes pre- and post-irrigation and percentage debris reduction in each group|
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|Figure 1: Representative image of the groups. The green color shows the debris present before and after irrigation protocols. OEN: Open-ended needle; DSVN: Double side-vented needle; ECRM: Easy Clean in reciprocating movement; ECCR: Easy Clean in continuous rotation; PUI: Passive ultrasonic irrigation|
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| Discussion|| |
The present study used micro-CT to evaluate the capacity of different irrigation methods for debris removal from artificial grooves in prototyped acrylic teeth. Furthermore, two distinct kinematics (reciprocating movement and continuous rotation) were compared using the Easy Clean instrument. The null hypothesis tested was rejected in part because there were statistically significant differences in the percentage of debris removed by different techniques tested, and there was no statistically significant difference between the types of kinematics used in the Easy Clean system.
The methodology using acrylic teeth with artificial grooves promoted good visualization and measurement of volume using micro-CT. This was due to the difference in radiopacity that made debris more evident and easier to measure before and after any irrigation technique. Previous studies analyzed irrigation techniques and irrigating solutions for removing debris from inside grooves made in human and bovine teeth by means of scores, which is a subjective analysis that does not provide objective data., Other studies have analyzed the volume of debris removed from human teeth.,, However, the radiopacity of the debris is the same as that of dentin, and this makes the measurement and subsequent analysis difficult. The use of acrylic teeth and grooves constructed in a standardized way with the same force and depth allowed for a greater homogeneity of the samples between groups.
In this experiment, micro-CT was used to assess the volume of dentin debris in the five groups. There was no statistical difference among the five groups before treatment, indicating an appropriate distribution of initial debris among the groups. The standardized grooves (d × h × l) were made between the middle and apical thirds,,, allowing insertion of the same amount of debris before the irrigation technique. To improve the adherence of debris (dentin powder + sodium hypochlorite) to the grooves, the teeth were treated with 10% hydrofluoric acid for 10 min. It should be noted that the use of spurs and grooves with these measurements simulated the flattening present in anatomic conditions corresponding to the mandibular incisors.
During root canal instrumentation, the volume and frequency of the irrigating solution can be specified to clean the root canal system. In the present study, 6.0 mL of sodium hypochlorite was used during the irrigation steps in all groups.
The results of this study showed that conventional irrigation technique using irrigation needles with double side vent and front vent presented lowest effectiveness of debris removal. These results are in agreement of previous studies, which showed that conventional irrigation has limited effectiveness to clean flatted areas.,,
The Easy Clean group using a reciprocating movement promoted similar results to those of the conventional irrigation techniques although the results were worse than those obtained by using PUI. These results differed from those reported in the study of Kato et al. who concluded that the Easy Clean in reciprocating motion favored better results than PUI for removing the debris from the dentin walls in the apical third. The results of this aforementioned study could be related because it was used curved canals and no flattened areas were assessed, factors that were analyzed in our study. However, when Easy Clean was used in continuous rotation, the results were statistically superior to those of conventional irrigation and similar to those of the PUI group, which demonstrated the best results. The differences in the results of the Easy Clean used in reciprocating movement and continuous rotation could be explained due to differences in kinematics and rotation speed, thus altering the distribution of the irrigating solution throughout the flattened areas, resulting in better debris removal.
The Easy Clean in continuous rotation provided greater debris removal in comparison with reciprocating motion and conventional irrigation technique are in agreement with Duque et al. In addition, the ECCR has similar efficiency in comparison with the PUI
PUI has been widely studied and recommended by several authors to improve the cheaness and disinfection of root canal system.,, In the present study, PUI was performed by directing the ultrasonic device toward the groove, which favor better debris removal.
The irrigation method using the ultrasonic device provided the best results, corroborating those of other studies published in the literature.,, The ultrasonic activation of the irrigantsolution induces a physical phenomenon on the irrigant, which promotes an intensive agitation and pushing the irrigant toward of flattened areas, favoring better cleaness.
The phenomena of transient cavitation, microstreaming and shock waves  favor the distribuition of the irrigant solution toward anatomical complexities, wich are inaccesible for endodontic instruments, promoting greater debris removal.,,
| Conclusions|| |
None of the irrigation techniques were able to completely remove the dentin debris from the artificial grooves. PUI and ECCR favored the removal of a larger volume of dentin debris from the groove. The type of kinematics did not interfere statistically in the efficiency of the Easy Clean system; however, a higher percentage of debris removal was observed when the continuous rotation kinematics was used.
Financial support and sponsorship
This work was supported by the State of São Paulo Research Foundation (FAPESP 2014/19499-8).
Conflicts of interest
There are no conflicts of interest.
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Dr. Francine Cesario
Al. Octavio Pinheiro Brisola No. 9-75, 17012-901 Bauru, Sao Paulo
Source of Support: None, Conflict of Interest: None