|Year : 2021 | Volume
| Issue : 11 | Page : 1662-1668
The effectiveness of ethylenediaminetetraacetic, etidronic, and peracetic acids activated with ultrasonics or diode laser on calcium hydroxide removal from root canal walls
IG Savur, OI Ulusoy
Department of Endodontics, Dental Faculty, University of Gazi, Ankara, Turkey
|Date of Submission||31-Aug-2020|
|Date of Acceptance||16-Apr-2021|
|Date of Web Publication||15-Nov-2021|
Prof. O I Ulusoy
Endodontics Department, Dental Faculty, University of Gazi, 06510, Ankara
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Background: To assess the efficiency of ethylenediaminetetraacetic acid (EDTA), etidronic (HEBP), and peracetic (PAA) acids agitated with ultrasonic energy or diode laser on removing calcium hydroxide (CH) dressings from root canal walls. Material and Methods: Single root canals of eighty extracted human teeth were chemomechanically instrumented and filled with CH. Sixty teeth were divided into six experimental groups (n = 10) according to the applied irrigation regimens for the removal of CH: Group 1: 5.25% NaOCl—17% EDTA, Passive ultrasonic irrigation (PUI); Group 2: 5.25% NaOCl + 9% HEBP, PUI; Group 3: 5.25% NaOCl—2% PAA, PUI; Group 4: 5.25% NaOCl—17% EDTA, Diode laser-activated irrigation (LAI); Group 5: 5.25% NaOCl + 9% HEBP, LAI; Group 6: 5.25% NaOCl—2% PAA, LAI. The other 20 teeth were served as negative (n = 10) and positive controls (n = 10). The residuary amount of CH was scored in coronal, middle, and apical thirds of the root canals by using scanning electron microscope. The data were statistically analyzed using Kruskal-Wallis H with Bonferroni adjusted Mann-Whitney U test with a significance level of 0.05. Results: Etidronic acid activated with ultrasonics or diode laser removed the highest amount of CH from the middle third of root canals, compared to the other irrigation regimens (P < 0.001). Although the residual CH scores of PAA-PUI, PAA-LAI, and EDTA-PUI, EDTA-LAI groups were not statistically different from each other (P > 0.05), lower amount of CH was observed in the PAA-PUI and PAA-LAI groups. Conclusions: Use of etidronic acid activated with ultrasonics or diode laser can be an appropriate irrigation regimen for CH removal from root canal system.
Keywords: Diode laser, etidronic acid, laser-activated irrigation, passive ultrasonic irrigation, peracetic acid
|How to cite this article:|
Savur I G, Ulusoy O I. The effectiveness of ethylenediaminetetraacetic, etidronic, and peracetic acids activated with ultrasonics or diode laser on calcium hydroxide removal from root canal walls. Niger J Clin Pract 2021;24:1662-8
|How to cite this URL:|
Savur I G, Ulusoy O I. The effectiveness of ethylenediaminetetraacetic, etidronic, and peracetic acids activated with ultrasonics or diode laser on calcium hydroxide removal from root canal walls. Niger J Clin Pract [serial online] 2021 [cited 2022 Nov 26];24:1662-8. Available from: https://www.njcponline.com/text.asp?2021/24/11/1662/330470
| Introduction|| |
Elimination of microorganisms from the root canal system is accepted as one of the major objectives of root canal treatment. Calcium hydroxide (CH) is widely used for disinfection of the root canals and was suggested to kill the most common endodontic bacterial pathogens. However, the CH dressings should be completely removed from the root canal system prior to obturation.
Remaining CH on the root canal walls was stated to hinder the infiltration of root canal sealers into the dentin tubules and affect their adhesion to the root canal walls., CH residues were also shown to increase the apical microleakage of the gutta-percha fillings when a zinc oxide–eugenol-based sealer was used.
CH removal from the root canal system is usually performed by sodium hypochlorite (NaOCl) irrigation combined with mechanical instrumentation and a final rinse with 17% ethylenediaminetetraacetic acid (EDTA). However, this technique has previously been demonstrated to be insufficient for the total elimination of CH from the root canal walls., Therefore, in recent years agitation of irrigants for the removal of CH from the root canals has gained popularity.,, For this purpose, ultrasonic energy is commonly preferred to activate the irrigation solution. It has been shown that the use of ultrasonically activated NaOCl-EDTA is more effective in removing CH from root canal walls compared to conventional syringe irrigation.
Laser-activated irrigation (LAI) has recently been introduced as an activation method of irrigation solutions.,, Near-infrared diode laser, a solid-state semiconductor type, was suggested to be effective for the activation of the irrigants in the removal of smear layer. Gallium, aluminum, and arsenic were used during the production process of near-infrared diode laser. Diode laser, which is poorly absorbed by water, generally has wavelengths ranged from 655 to 980-nm in endodontic usage., Diode laser device has a flexible thin fiber facilitating access into irregular root canal anatomy, and this results in enhanced elimination of microorganisms from the deep radicular dentin., Although there are studies that evaluated the leftover debris and smear layer on root canal dentine after use of diode LAI,, to date no study has investigated the effect of irrigation solutions agitated with diode laser on CH removal from the root canal walls.
Grawehr et al. 2003 suggested that NaOCl cannot maintain its antimicrobial property and organic tissue dissolution capacity when used with EDTA, because the free available chlorine tends to decrease due to the interaction between these two irrigants. Therefore, different chelating agents that do not interact with NaOCl are being investigated. Peracetic acid (PAA) is known as one of the strongest disinfectants and possesses antimicrobial, sporicidal, and antiviral properties. The acetic acid in PAA is a weak decalcifying agent forming dissoluble compounds with calcium and it was supposed to eliminate inorganic material. Use of PAA with a concentration of 0.5–2.25% was shown to be efficient in the elimination of inorganic material from root canal dentinal walls.,
A 1-hydroxyethylidene-1, 1-bisphosphonate (HEBP), also known as etidronic acid, is a biocompatible decalcifying agent. Etidronic acid has previously been reported to achieve smear layer removal when used with NaOCl and suggested as a possible alternative irrigation solution to EDTA.,
The aim of this in-vitro study was to evaluate the residual CH in the root canal walls after use of 17% EDTA, 9% HEBP, 2% PAA activated with ultrasonics or diode laser by scanning electron microscope (SEM). The null hypothesis tested that there is no difference between the irrigation techniques regarding CH removal from the root canal system.
| Material and Methods|| |
The ethical issues regarding this research were approved by a local institutional ethics committee (No: 36290600/39). Human upper incisor teeth with similar dimensions and extracted for periodontal reasons were selected. Teeth with root caries, fractures, cracks, internal or external resorptions, and calcifications were excluded from this study. Periapical radiographs were obtained to confirm similar root canal morphology. Thus, a total of 80 teeth meeting these criteria was used. The external root surfaces were cleaned from superficial debris using ultrasonic instruments. The teeth were kept in 0.1% thymol solution prior to the experiment. The teeth were decoronated to obtain a 14 mm standardized root length using a diamond disc. The melted wax was used to cover the root apices to simulate a closed-end canal system. After access cavity preparation using diamond burs, a size of 15-K file (Dentsply, Maillefer, Ballaigues, Switzerland) was placed in the root canal up to that it was visible at the apical foramen, to ensure the patency of the canals. The working length was established to be 1 mm short of the apical foramen. The root canals were mechanically instrumented with the ProTaper System (Dentsply, Maillefer) in a crown-down sequence to an apical preparation size #40 (F4). The root canals were rinsed with 2.5% NaOCl using a 30G needle (Navi-Tip; Ultradent, USA) after each instrument change and finally irrigated with 3 mL 17% EDTA for 60 s. Then root canals were washed using 5 mL distilled water and dried with paper points. The teeth were randomly divided into one positive, one negative control group, and six experimental groups including ten teeth each. The root canals were filled with CH powder (Merck, Darmstadt, Germany) that was mixed with glycerin at a powder to liquid ratio of 1:2, using a lentulo spiral (Dentsply, Maillefer, Ballaigues, Switzerland) until the root canal was completely filled up to canal opening. The confirmation of CH filling quality was provided with radiographic evaluation for each sample [Figure 1]. A temporary restorative material (Cavit; 3M ESPE, MN, U. S. A) was used to close the root canal orifices. All the samples were finally kept in 37°C and high moisture environment for seven days. The coronal accesses were then reopened, and the CH dressings inside the root canals were removed by different irrigation solutions activated by different techniques as follows:
|Figure 1: Representative radiographic image after placement of calcium hydroxide inside the root canal|
Click here to view
Group 1 (NaOCl-EDTA, passive ultrasonic irrigation (PUI) [n = 10]): The root canals were passively irrigated with 3 mL 5.25% NaOCl for 30 s using a 30G needle (Navi-Tip), which was positioned at 1–2 mm short of the working length. A size of #20 ultrasonic tip (NSK Varios E4D, Tochigi, Japan) was fixed on an ultrasonic unit (NSK Varios 750) and activated in the NaOCl-filled root canal at a power setting of 4, for 30 s. Afterward, the root canals were irrigated with 3 mL 17% EDTA for 30 s, which was then agitated for 30 s using identical protocol.
Group 2 (NaOCl + HEBP, [PUI] [n = 10]): The root canals were passively irrigated with a 3 mL mixed solution containing 5.25% NaOCl + 9% HEBP for 30 s using a 30G needle (Navi-Tip), that was placed at 1–2 mm short of the working length. The solution was activated for 30 s with ultrasonics using the same technique in group 1. A 3 mL NaOCl + HEBP solution was prepared again and applicated into the root canals for 30 s, which was then activated by ultrasonics for another 30 s. For the preparation of 9% (w/v) HEBP solution, sixty percent aqueous HEBP (Sigma-Aldrich, St Louis, USA) was diluted. A dark-colored glass bottle was used to preserve the solution before the experiment.
Group 3 (NaOCl-PAA, [PUI] [n = 10]): The root canals were passively flushed with 3 ml 5.25% sodium hypochlorite for 30 s, and PUI was performed in the same manner as in Group 1. 3 mL 2% PAA was introduced to the root canals for 30 s and ultrasonically agitated for 30 s as in group 1. 36–40% peracetic acid solution was purchased from a chemical company (Sigma-Aldrich). Deionized water was used for diluting the solution to have a resulting 2% weight/volume ratio.
Group 4 (NaOCl-EDTA, [LAI] [n = 10]): 3 mL 5.25% NaOCl was used for rinsing the instrumented samples for 30 s. Then this solution was activated for 30 s using an 808-nm wavelength diode laser system (AMD Lasers, İndianapolis, İndiana, US) in the pulse mode at 1.5 W power setting. For this purpose, the straight fiber tip with 200-μm diameter was placed into the root canal 2 mm short of the apex. The root canals were then rinsed using 3 mL 17% EDTA for 30 s, activated by diode laser for 30 s as described above.
Group 5 (NaOCl + HEBP, [LAI] [n = 10]): A 3 mL single solution containing 5.25% NaOCl + 9% HEBP was passively applied into the root canals for 30 s using a 30G needle (Navi-Tip) and activated for 30 s by diode laser as described in group 4. Freshly prepared NaOCl + HEBP (3 mL) was used for flushing the root canals for 30 s, which was then activated by diode laser for another 30 s.
Group 6 (NaOCl-PAA, [LAI] [n = 10]): The root canals were rinsed by 3 mL 5.25% NaOCl for 30 s without any activation, and diode laser-activated irrigation was carried out using the protocol in group 4 for 30 s. Then 3 mL 2% PAA was used to irrigate the samples for 30 s, activated using diode laser for 30 s.
Positive control (n = 10): The root canals were obturated with CH. Any irrigation procedure was not performed.
Negative control (n = 10): The instrumented root canals did not have any CH filling.
The 30G irrigation needle was placed inside the root canals at 1–2 mm short of the working length and calibrated at this level with a rubber stop in all experimental groups.
The total application time of the irrigants was 2 min and the total irrigant volume was 6 mL in each group, except for the control groups.
Scanning electron microscope (SEM) evaluation
Grooves that were parallel to the long axis of the teeth were created on the root surfaces using a diamond disc and the roots were separated longitudinally into two halves. Samples were dehydrated in ethanol solution. The tooth halves were sputter-coated using 20-nm gold and observed using an SEM (FEI Quanta 400F, Philips, Netherlands). Representative areas for each group were photographed with SEM at X1000. Two calibrated examiners independently analyzed the amount of residual CH in the photographs in a blind manner and scored it at three-thirds of the root canals for each specimen using a 5-grade scale as suggested by Ruddle 2008:
Score 1: Percentage of clean tubules: 80–100
Score 2: Percentage of clean tubules: 60–80
Score 3: Percentage of clean tubules: 40–60
Score 4: Percentage of clean tubules: 20–40
Score 5: Percentage of clean tubules: 0–20
SPSS 15.0 statistical package (SPSS Inc, Chicago, USA) was used to analyze the present data. Data were described as mean and standard deviations. The data were analyzed regarding normal distribution using the Shapiro-Wilk test. Kruskal-Wallis H test with Bonferroni adjusted Mann-Whitney U was used to compare differences between the groups. A P value less than 0.05 was considered to be statistically significant.
| Results|| |
The median values and interquartile ranges for the residual CH at coronal, middle, and apical thirds of the root canal walls were shown in [Table 1]. None of the irrigation methods achieved complete elimination of the CH from root canals. The teeth in positive control group showed complete coverage of the canal walls with CH remnants in three-thirds of the root [Figure 2]a. Use of HEBP activated with ultrasonics or diode laser resulted in the lowest scores of CH residues compared to the other irrigation regimens in the middle third of the root canals (p < 0.001) [Figure 2]b. Cleaner dentinal walls were observed after the use of NaOCl + HEBP, PUI and NaOCl + HEBP, LAI [Figure 2]c, compared to NaOCl-EDTA, PUI, and NaOCl-EDTA, LAI [Figure 2]d in the apical thirds of the root canals (P < 0.001). Although the residual CH scores of NaOCl-PAA, PUI and NaOCl-PAA, LAI and NaOCl-EDTA, PUI and NaOCl-EDTA, LAI groups were not different from each other statistically (P > 0.05), less CH residues were observed in the NaOCl-PAA, PUI and NaOCl-PAA, LAI groups in all thirds of the root canal walls [Figure 2]e. When the same irrigation protocol was used, no statistically significant difference was detected between the coronal, middle, and apical regions regarding residual CH (P > 0.05).
|Table 1: The median and interquartile ranges (IQR) of residual CH at the coronal, middle, and apical thirds of the root canals for all groups|
Click here to view
|Figure 2: Representative scanning electron microscope images (×2000) showing (a) Calcium hydroxide remnants covering all the dentin tubules in apical third of root canal walls (positive control) (b) Clean dentinal walls free of calcium hydroxide remnants in the middle third of root canals after irrigation with 9% etidronic acid activated by ultrasonics (c) Dentin tubules in the apical third of the root canal irrigated with 9% etidronic acid activated by diode laser (d) Dentinal tubules blocked with calcium hydroxide in the apical third of the root canal after irrigation with 17% ethylenediaminetetraacetic acid activated by diode laser (e) Removal of calcium hydroxide from coronal third of root canal walls after irrigation with 2% peracetic acid activated by ultrasonics|
Click here to view
| Discussion|| |
The results of the current research demonstrated that any irrigation protocol could not have achieved total removal of CH from root canal dentine. However, cleaner dentinal walls were observed after the use of NaOCl + HEBP, PUI and NaOCl + HEBP, LAI compared to the NaOCl-EDTA activated with laser or ultrasonics. Therefore, the null hypothesis stating that there is no difference between the irrigation techniques in terms of CH removal from the root canal system was rejected.
Previous research has shown that CH could not be removed from the root canals by conventional syringe irrigation., Agitation of the irrigation solutions was suggested to increase the diffusion of solutions to the dentinal tubules and root canal irregularities, and enhance the CH removal capacity of them.,, This may be related to the high irrigation flow rate and volume provided by PUI in the root canals. Therefore, in this research, irrigation solutions activated using different methods were evaluated for their removing capacity of CH. CH removal before the root canal obturation was suggested to be performed with a chelating agent following NaOCl irrigation. Therefore, NaOCl was used for initial flushing in all groups in the present study, before application of demineralizing agents.
Although there are many studies regarding the smear layer and debris removal efficiency of diode laser-activated irrigation,, to the authors' knowledge there is no information about its impact on removing CH dressings from root canals. Our results demonstrated that, when the same irrigation solution was used, CH removal efficiency of LAI and PUI were similar in all thirds of the root canal. Therefore, LAI can be used alternatively to the PUI. However, use of HEBP activated either with laser or ultrasonics resulted in cleaner dentinal walls compared to the use of EDTA and PAA. This means, the type of irrigation solution has a greater influence on the CH removal other than the type of activation method. Unlike HEBP, EDTA-LAI and EDTA-PUI irrigated samples exhibited the worst scores regarding the removal of CH from the middle and apical parts of the root canals. Our results support those of the previous studies that reported higher chelating capacity of HEBP compared to EDTA with regards to elimination of smear layer from apical region of root canals, although the compositions of smear layer and CH are different. Higher demineralizing effect of the HEBP can be attributed to its lower surface tension which may increase its wettability, contact with dentinal walls, and penetration ability to the dentinal tubules., Therefore, HEBP can be considered as a promising alternative to EDTA in removing CH from root canal walls.
The calcium in peracetic acid shows continuity of its existence in the solution and does not precipitate again due to its acidic property. Despite its weak chelating capacity and different decalcification dynamics from EDTA, PAA exhibits similar efficiency with EDTA for calcium removal from the root canal. Accordingly, no statistical difference was observed regarding CH removal capacity between PAA and EDTA used with PUI and LAI in the present work. Considering the results of previous research,,, and the present ones, PAA can be suggested as a possible alternative to EDTA with respect to CH removal from root canals.
It has previously been stated that, when using closed-canal system model, the apical section of root canal could not be cleaned sufficiently by irrigation solutions. However, closed-canal model simulates real clinical conditions more successfully than the open-canal system model. In the current study, using closed-canal model, we detected more CH in the apical part of the root canals compared to the other regions, although the difference was not statistically significant. This could be attributed to the fact that irrigation solutions have an inadequate penetration to this area due to the narrow diameter and the vapor lock effect., Even if a great effort has been given to simulate real clinical conditions in the present laboratory study, the effects of the irrigation protocols on CH removal from root canals could be different in real clinical conditions. We have removed the crowns of the sample teeth in order to achieve standardization in the placement of CH fillings and removal procedures. However, in a clinical setting, serving as a reservoir, the clinical crowns can influence the movement of the irrigation solutions, thereby affecting their cleaning ability. This issue can be evaluated as a limitation.
The vehicle mixed with CH powder is another important factor that influences its effective removal from root canal walls. We used glycerin as a CH vehicle in all experimental groups of the present research. It was stated that penetration of glycerin into dentinal tubules is deeper compared to distilled water. In addition, CH—water mixture was removed from the root canal walls more efficiently compared to CH—glycerin mixture. Therefore, if distilled water was used as a vehicle, CH could be removed easier from root canals in this current research.
| Conclusion|| |
Within the limitations of this present study, it can be concluded that use of 810-nm wavelength diode laser can be rated as an alternative method to PUI for the activation of irrigants in terms of CH removal from the root canal system. Use of etidronic acid activated by ultrasonics or diode laser removed the highest amount of CH remnants from root canal thirds. Further research should be conducted in real clinical conditions to assess the impact of root canal irrigation techniques on complete removal of CH from the root canal walls.
Use of 9% HEBP activated with 810 nm wavelength diode laser can be regarded as an effective irrigation protocol for eliminating CH from the root canal system.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2]