|Year : 2015 | Volume
| Issue : 2 | Page : 44-48
A comparison of different irrigation/agitation methods for the removal of calcium hydroxide medicament from the root canal walls
Erhan Tahan1, Buket Tug Kilkis2, Mehmet Tanriver3, Mustafa Sadik Akdag4
1 Department of Endodontics, Faculty of Dentistry, Recep Tayyip Erdogan, Rize, Turkey
2 Department of Endodontics, Faculty of Dentistry, Necmettin Erbakan University, Konya, Turkey
3 Department of Pediatric Dentistry, Faculty of Dentistry, Sifa University, Izmir, Turkey
4 Department of Restorative Dentistry, Faculty of Dentistry, Karadeniz Technical University, Trabzon, Turkey
|Date of Web Publication||8-May-2015|
Department of Endodontics, Faculty of Dentistry, Recep Tayyip Erdo?an University, Rize 53100
Source of Support: None, Conflict of Interest: None
Aim: To compare the removal efficiency of calcium hydroxide (CH) medicament from the root canal walls with different irrigation/agitation methods. Materials and Methods: Forty human mandibular premolars were selected. Root canals of these teeth were prepared up to F4 file using ProTaper rotary system and then filled with CH. All root specimens were stored at 37C and 100% relative humidity for 7 days. Teeth were randomly divided into four different groups (n = 10). For the removal of the medicaments from the canal walls, roots were subjected to the final irrigation/agitation methods used as follows: Conventional syringe irrigation with side-vented needle (Group 1), passive ultrasonic irrigation (PUI; Group 2), manual dynamic agitation (Group 3), and apical negative pressure irrigation (Group 4). The negative control did not receive CH placement. The positive control received the intracanal medication, but no subsequent removal. Roots were split longitudinally into two halves. Digital images of the root canal walls were acquired by a digital camera and assessed for residual amount of medicament. Cervical, middle, and apical third of each canal was assessed by using a scoring system. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey's multiple comparison tests, at 95% confidence interval (P < 0.05). Results: There were no statistically significant differences between all experimental groups and the negative group in each canal third (P > 0.05). However, there were statistically significant differences between the experimental groups and the positive control (P < 0.05). None of the experimental groups totally removed CH medicaments from root canal walls. Conclusions: In the limitations of this in vitro study, all experimental groups produced similar removal efficiency in terms of canal cleanliness.
Keywords: Apical negative pressure, calcium hydroxide removal, irrigation, ultrasonic agitation
|How to cite this article:|
Tahan E, Kilkis BT, Tanriver M, Akdag MS. A comparison of different irrigation/agitation methods for the removal of calcium hydroxide medicament from the root canal walls. J Res Dent 2015;3:44-8
|How to cite this URL:|
Tahan E, Kilkis BT, Tanriver M, Akdag MS. A comparison of different irrigation/agitation methods for the removal of calcium hydroxide medicament from the root canal walls. J Res Dent [serial online] 2015 [cited 2019 Dec 13];3:44-8. Available from: http://www.jresdent.org/text.asp?2015/3/2/44/156644
| Introduction|| |
The microbial existence in root canal system has a crucial role for endodontic infection.  A major goal of root canal treatment is getting a bacterial reduction and subsequent elimination of their byproducts from the root canal system.  However, chemomechanical debridement cannot completely clean the bacteria from the root canal.  Therefore, the use of intracanal dressings has been advocated. 
Calcium hydroxide (CH) is widely used in endodontic treatment of infected root canals between multiple sessions because of its antibacterial activity. Its effectiveness mainly depends on its alkaline pH and ability to rapidly dissociate into hydroxyl and calcium ions.  However, before obturating the root canal with permanent obturating materials, it has to be entirely removed. It has been shown that CH remnants can prevent the penetration of the sealers into the dentinal tubules,  hinder the sealer adhesion to dentin, and may increase the apical leakage of the canal obturation. 
Gu et al.,  showed that various techniques and devices have been developed for increasing the agitation of the irrigation solution. Manual dynamic agitation is a cost-effective technique in which a well-fitting gutta-percha cone is repeatedly inserted into the root canal up to the working length (WL). It has been demonstrated in several studies that ultrasonic agitation can enhance the disinfection of the root canal system. ,
The EndoVac system (Discus Dental, Culver City, CA, USA) uses apical negative pressure irrigation contrary to the traditional syringe irrigation. It creates a negative pressure to aspirate the irrigating solution and debris in the root canal. It has been demonstrated that this system can provide a better cleaning efficiency, especially at the most apical part of the prepared canal walls;  and increases the intracanal disinfection. 
The aim of this study was to compare the interappointment medicament removal efficiency of conventional syringe irrigation, passive ultrasonic irrigation (PUI), manual dynamic agitation, and apical negative pressure irrigation methods.
| Materials and methods|| |
Forty freshly extracted noncarious human mandibular premolars with completely formed apex were used in this in vitro study. A # 10 K-file was inserted into the mesiobuccal canal and radiographs were taken to ensure that the degree of curvature determined by Schneider's  method was mild (< 20). Roots considered straight according to this method with same external size were selected to provide standardization. Teeth were stored in 2.5% NaOCl solution at room temperature to remove organic debris for 48 h. External root surfaces were debrided with hand scalers and washed under tap water. Teeth were then immersed in 0.9% NaCl solution supported with 0.02% sodium azide until use. The roots were decoronated 1 mm above the cementoenamel junction using a diamond bur and the specimens with 16 mm standard length from the root apex were obtained. The pulp tissue was removed using barbed broaches. Roots were radiographed from mesiodistal and buccolingual aspects with placing a # 10 file in each one to ensure that each contained only one root canal. WL was established 1 mm short of the apical foramen. All canals were prepared by the same operator. The cervical canal portions were enlarged with Gates Glidden burs # 2-3 and the root canals were instrumented with ProTaper Ni-Ti rotary instruments (Dentsply Maillefer, Ballaigues, Switzerland) up to F4 (40 size,.06 taper). Root canals were irrigated with 5 mL of 2.5% NaOCl solution between instrumentations. A plastic syringe with a 30-gauge side-vented irrigation needle (KerrHawe SA, Bioggio, Switzerland) inserted up to the WL for irrigation. A final rinse was performed with 5 mL of 17% ethylenediaminetetraacetic acid (EDTA) and 5 mL of 2.5% NaOCl. Root canals were dried with multiple paper points and dressed with CH medicament by using a lentulo spiral. Medicament used was mixed to a creamy consistency using a CH powder (Henry Schein Company, Melville, NY, USA) and sterile saline solution. The access cavities were temporarily sealed with a cotton pellet and a temporary filling (Coltosol; Colten, Langenau, Germany). Root specimens were stored at 37C and 100% relative humidity for 7 days. After this storage period, the temporary filing material and the cotton pellet was removed with an excavator. The specimens were randomly assigned to four experimental groups (n = 10) according to the following irrigation/agitation methods: Group 1- conventional syringe irrigation with side-vented needle; Group 2- PUI; Group 3- manual dynamic agitation; and Group 4- apical negative pressure irrigation (EndoVac system). Each group had the same total post-instrumentation irrigation/agitation time of 6 min (3 min active and 3 min passive) with different techniques.
In Group 1, CH was removed from root canals using a 30-gauge side-vented endodontic needle. The root canals were irrigated with 5 mL of 2.5% NaOCl, followed by using an F4 instrument in a circumferential filing action and were irrigated again with 5 mL of 2.5% NaOCl for 1 min. Then the irrigant was left undisturbed in the canal space for 1 min. This was followed by irrigation with 5 mL of 17% EDTA for 1 min and left untouched in a full canal for 1 min. The last cycle was performed again with 5 mL of 2.5% NaOCl solution for 1 min and followed by leaving the canal full of irrigant for 1 min. In Group 2, root canals were irrigated with agitation of 5 mL of 2.5% NaOCl using a piezoelectronic unit (NSK Varios 750; Nakanishi, Inc., Tochigi, Japan), which was achieved at the full WL for 1 min by using size 15 Varios U files (Nakanishi Inc, Tochigi, Japan). Afterwards the irrigant was left undisturbed in the canal space for 1 min. This was followed by irrigation with 5 mL of 17% EDTA and ultrasonic activation for 1 min, and then the solution left untouched in a full canal for 1 min. The final rinse was achieved with 5 mL of 2.5% NaOCl in conjunction with ultrasonic agitation, followed by leaving the canal full of irrigant for 1 min. In Group 3, 5 mL of 2.5% NaOCl was delivered to the root canal with the side-vented needle and agitated with a gutta-percha cone (size 40, 0.06 taper) well-fitted to the WL and moved for 1 min in a coronoapical direction using back-and-forth strokes of approximately 1 mm with a frequency of 100 movements/min, followed by leaving the irrigant undisturbed in the canal space for 1 min. Then root canals were irrigated with 5 mL of 17% EDTA and agitated for 1 min again with a well-fitted cone similar to the first cycle. The irrigant was left undisturbed in the canal space for 1 min. For the last agitation cycle, a final rinse was received with 5 mL of 2.5% NaOCl followed by the agitation via the gutta-percha cone with the same size and taper. Root canal was left undisturbed again for 1 min with the irrigant inside in it. In Group 4 (EndoVac system), a macro-irrigation cycle was performed with 5 mL of 2.5% NaOCl for 30 s, followed by a micro-irrigation cycle for 30 s again. The microcannula alternated coronoapical movements remaining 6 s at WL and 6 s 2 mm short of the WL until completing 30 s. This was followed by leaving the canal full of irrigant for 1 min. A second micro-irrigation cycle was performed with 5 mL of 17% EDTA for 1 min and the irrigant was left undisturbed in the canal space for 1 min. The last cycle was performed with 5 mL of 2.5% NaOCl irrigation by using microcannula for 1 min, followed by leaving the canal full of irrigant for 1 min.
Additional roots were prepared and used as control groups. In the negative control group (n = 3), samples did not receive any medicament to ensure the proper analysis of cleaning attempts. Whereas, canals were filled with CH but no subsequent removal attempts were performed in the positive control group (n = 3). This ensured that CH was uniformly delivered throughout the entire canal length and in the experimental groups the initial amount of medicament was significantly reduced when compared with the positive control group.
After each technique, root canals were irrigated with 5 mL of sterile saline and dried with multiple paper points. Two longitudinal grooves on the buccal and lingual aspects were prepared along the external root surface at the maximum buccolingual diameter to facilitate subsequent splitting of the root to expose the instrumented canal. For this purpose, a cylindrical diamond bur and a diamond disk were used in a high-speed handpiece under copious water cooling with utmost caution to avoid iatrogenic perforation of the canal space. A new razor blade was placed in the buccal or lingual groove; and while the root secured between two fingers, gentle tapping of the razor blade caused the splitting of the root into two longitudinal halves.
Appropriate half of each canal with visible canal lumen was selected and photographed. Digital images were acquired by a digital camera (Canon EOS 350D, Kiss Digital N, Japan), at 72 dpi and 24-bit resolution and 150% magnification in a macro mode. All images were photographed from a constant distance, with the digital camera fixed on a tripod to ensure the standardization of images captured. Images were screened on a 21.5-27 inches monitor (Dell monitors, Dell S Series, US). Three observers jointly evaluated the amount of the residual medicament of each canal third using a 4-grade scoring system defined by Lambrianidis et al.  When disagreements existed between the observers during the scoring of the images, they argued, so that an agreement was achieved on the scores. The difference in scoring never exceeded one score, and in such a case the higher score was recorded. The scoring criteria of canal cleanliness degree and removal of medicament were as follows: Score 1- no visible remnants, score 2- scattered remnants, score 3- distinct masses, score 4- densely packed remnants. The highest scores of cervical, middle, and apical areas of root canals were recorded. The results were statistically analyzed with one-way analysis of variance (ANOVA) and Tukey's multiple comparison tests at a 95% confidence interval (P < 0.05).
| Results|| |
The CH removal scores and mean and standard deviation values of each group according to the canal third levels are shown in [Table 1]. There was no statistically significant difference between all experimental groups and negative control (P > 0.05). Medicament remnants were found on the canal walls regardless of the technique used. On the contrary to the experimental groups and negative control, positive control group displayed complete coverage of the entire canal lumen with the densely packed remnants (P < 0.05). [Figure 1] shows representative images of removal scores from different groups.
|Figure 1: Representative images of removal scores from different groups. (a) score 1 (negative control), (b) score 2, (c) score 3, (d) score 4 (positive control)|
Click here to view
| Discussion|| |
There are several methods available for measuring residual remnants on root canal walls such as direct visualization, digital microscopy, scanning electron microscopy, and volumetric analysis by using spiral CT. In several studies, the removal efficiency of different techniques was evaluated with calculation of the percentage ratio of medicament coated surface area to the total canal surface area. ,, Whereas, a scoring system was used in the present study to facilitate the comparison among groups evaluated. This scoring system was considered to be a more reliable technique because of the difficulties in automatically selecting the areas covered with CH remnants by using an appropriate software as previously reported.  Moreover, digital image analysis for quantitative assessment of the residual CH evaluates only the superficial layer of CH remnants and does not allow to the three-dimensional evaluation. In the present study, the scoring of the images was made jointly by three observers because of the attempts for the highest agreement. Following thorough calibration, the observers argued and determined one score for every image.
It has been emphasized in the literature that beside the irrigant delivery system used, the effectiveness of the irrigation procedure depends on both the mechanical flushing action and the chemical ability to dissolve dental tissue. , Therefore, to compare the effectiveness of the techniques evaluated, same irrigation periods were attempted to be used during different irrigation/agitation procedures. The results of the present study were in agreement with studies that found most of the CH remnants were removed. ,, When total canal areas were considered in all experimental groups, mean values of scores were found to be recorded as 2.0 or down, closer to the negative control group. This may be explained by the specimens with mild degree of canal curvature that caused to increase the canal cleanliness efficiency. Moreover, post-instrumentation irrigation/agitation time up to 6 min was totally performed in each group during the agitation of the irrigant. Thanks to this period of time used and mixing the CH powder with the saline solution instead of oil-based vehicles,  the overall cleaning effect of the techniques evaluated was surprisingly high.
Regardless of the irrigation/agitation methods used in the present study, medicament remnants were found on canal walls, especially in the most apical part of the canal lumen. None of the techniques evaluated entirely removed CH remnants from the canal walls as previously reported. , Although the presence of CH remnants as an apical plug in the apical region has been advocated for its prolonged antimicrobial activity, it is preferable to remove it because of the possible increase of apical leakage when contacted with tissue fluids. 
When the overall canal areas were considered, the worst results on the removal of CH remnants were found in conventional syringe irrigation and manual dynamic irrigation groups than the other two irrigation techniques. Depending on the anatomy of root canal in conjunction with penetration depth and diameter of the needle, the conventional syringe irrigation has a relatively weak flushing action.  These results in the present study may be explained by the fact that the higher velocity and volume of irrigant flow achieved by PUI  and apical negative pressure irrigation.  PUI creates a transmission of energy from an ultrasonic device to the irrigant via a file oscillating inside the root canal and allows to clean the canal walls by forming a microstreaming. Thereby, it provides the agitation of the irrigating solution. The EndoVac system's effectiveness may be attributed to the use of apical negative pressure irrigation concept. During microdebridement, placement of the microcannulas directly at the apical end of the root canal provides more irrigant volume and flow than other techniques in the apical region. While using the irrigation only technique could not penetrate well into the apical third of root canals, different agitation techniques such as PUI and/or EndoVac system showed significantly better results. Furthermore, better scores of canal cleanliness were found in the cervical and middle thirds in comparison with the apical third. However, there were no statistically significant differences between the experimental groups or the canal thirds evaluated.
In conclusion, it seems that all the techniques evaluated in this study did not remove the medicament from root canal walls completely. The canal's cleanliness efficiency of all experimental groups was similar.
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