|ORIGINAL RESEARCH - BASIC AND CLINICAL
|Year : 2022 | Volume
| Issue : 1 | Page : 37-43
The effect of different irrigants on sealer penetration into dentinal tubules with and without activation, using confocal scanning microscope
Helayl A Alshaibani, Shibu Thomas Mathew
Department of Endodontics, Riyadh Elm University, Riyadh, Kingdom of Saudi Arabia
|Date of Submission||28-Apr-2021|
|Date of Acceptance||13-Jan-2022|
|Date of Web Publication||4-Jul-2022|
Dr. Shibu Thomas Mathew
Department of Endodontics, Riyadh Elm University, Riyadh
Kingdom of Saudi Arabia
Source of Support: None, Conflict of Interest: None
| Abstract|| |
Purpose: To compare the effectiveness of three root canal irrigants with the influence of activation technique on the depth of sealer penetration into dentinal tubules using a confocal laser scanning microscope (CLSM). Materials and Methods: Sixty recently extracted human mandibular premolars with single straight canals (n = 60) were prepared with ProTaper Next NiTi rotary files up to X3. The samples were divided into three groups according to the final irrigation solution (n = 20), 5.25% sodium hypochlorite, 2% chlorhexidine digluconate, 17% ethylene-diamine-tetraacetic acid (EDTA). Each group was further subdivided into two groups according to the ultrasonic activation protocol and then obturated with a single gutta-percha size X3 and labeled sealer mixed with 0.01% fluorescent rhodamine B after the final irrigation protocol. Transverse sections were obtained at 2, 5, and 8 mm from the apex and observed under CLSM. It recorded the maximum penetration depth of both irrigant and sealer. Data were analyzed using a three-way analysis of variance and Tukey test (P = 0.05). Results: 17% EDTA exhibited significantly higher penetration depth with ultrasonic activation than the other groups and also determined (P < 0.011) statistically significant differences at root canal third (coronal, middle, apical; P < 0.011). Conclusions: The dentinal tubule penetration was significantly affected by selecting a root canal irrigant, an ultrasonic activation protocol, and root canal third. 17% EDTA with ultrasonic activation seemed beneficial in dentinal tubule penetration. Hence, the depth of sealer penetration might influence the outcome or success rate of endodontic therapy.
Keywords: Chlorhexidine, confocal laser scanning microscope, ethylene-diamine-tetraacetic acid, irrigant activation, sodium hypochlorite
|How to cite this article:|
Alshaibani HA, Mathew ST. The effect of different irrigants on sealer penetration into dentinal tubules with and without activation, using confocal scanning microscope. J Int Clin Dent Res Organ 2022;14:37-43
|How to cite this URL:|
Alshaibani HA, Mathew ST. The effect of different irrigants on sealer penetration into dentinal tubules with and without activation, using confocal scanning microscope. J Int Clin Dent Res Organ [serial online] 2022 [cited 2022 Aug 7];14:37-43. Available from: https://www.jicdro.org/text.asp?2022/14/1/37/349750
| Introduction|| |
The success of root canal treatment depends on the canal anatomy, appropriate diagnosis, treatment plan, and proper obturation of the root canal system. To obtain complete disinfection without recontamination, which can be achieved through a combination of chemo-mechanical disinfection of the canal spaces followed by sealing of entry and exit portals. However, accomplishing complete debridement and disinfection of the canal space is futile.
Sodium hypochlorite (NaOCl), ethylene-diamine-tetraacetic acid (EDTA), and chlorhexidine digluconate (CHX) are the widely used root canal irrigants in endodontic therapy. NaOCl, with its ideal antimicrobial properties, is the most commonly used irrigant to dissolve necrotic tissues. Root canal sealers are luting agents with an antibacterial effect and are used to fill spaces between the core materials, the canal walls, and between the gutta-percha points. They penetrate the dentinal tubules to avert colonization of residual bacteria and thereby prevent recontamination of the root canal by serving as an indicator on the amount of smear layer removed.
Studies have been done to analyze the action of irritants such as NaOCl, CHX, and EDTA to remove the smear layer and debris from the canals.,, Still, to date, no study has been done on dentinal tubular penetration using BioRoot sealer with different irrigation solutions and techniques. Therefore, this study aimed to compare the effectiveness of three root canal irrigants and their influence of activation technique on the depth of sealer penetration into dentinal tubules using a confocal laser scanning microscope (CLSM). A null hypothesis was that using the irrigant ultrasonic activation method will be more effective in facilitating the depth of sealer penetration into dentinal tubules than without activation.
| Materials and Methods|| |
The study was approved by the Institutional Review Board of Riyadh Elm University, Kingdom of Saudi Arabia, under the registration number: (FPGRP/43733005/224).
Sixty randomly selected, freshly extracted human permanent mandibular premolars with a single, straight, and fully formed root were selected based on clinical and radiographic examination. Extraneous tissue was cleaned with an ultrasonic scaler and then stored in 0.5% sodium azide solution. A tooth with open apices, cracks, resorptive defects, and calcifications was excluded using preoperative radiographs. Teeth were then stored in an alcohol solution and glycerin, mixed in a 1:1 ratio to keep the sample moist until the experiment was completed.
Tooth selection and preparation
Teeth were marked at 16 mm from the apex with a marker pen and measured using a digital caliper. The crown of the teeth was embedded in a chemical cured acrylic resin block and then decoronated using a low-speed saw at 300 rpm under water cooling. After access cavity preparation, the working length and patency were verified by inserting #10 K-file until it reached the apical foramen; then subtracted 1 mm from this measurement. All samples were wrapped with 0.05-mm thickness aluminum tin foil and then embedded in silicone mold filled with chemical cured acrylic resin block by using a surveyor to determine the long axis of the roots during molding. After resin polymerization, a trimming machine trimmed the excess and removed the foil from the root surface and resin block “alveolus.” For periodontal ligament simulation, Vinyl polysiloxane (elastomeric material) was placed in the resin block, and the roots were re-inserted into it. The excess material was removed with a scalpel blade.
Samples were instrumented using crown down technique, with ProTaper Next NiTi rotary system at 300 rpm and torque of 2 N cm connected to tri-auto mini endodontic motor, up to size X3. Canals were then irrigated using 2.5% NaOCl with a 27-G needle inserted to 1 mm short of the working length.
After completing chemo-mechanical preparation, the teeth were randomly divided into three groups based on the irrigants used. Each group was further subdivided based on the ultrasonic activation technique. The irrigation groups were as follows:
Group 1A: (n = 10), canals were irrigated with 5 mL (intermittent flush method) of 5.25% NaOCl and filled with 5.25% of NaOCl then activated (passive ultrasonic irrigation PUI) with a size 20, 0.02 taper oscillating ultrasonic device 1 mm short of the working length for 30 s at power level 1. The canals were then filled again with 5.25% NaOCl after PUI activation.
Group 1B: (n = 10), canals were irrigated with 5 mL (continuous flush method) of 5.25% NaOCl positive pressure irrigation for 1 min by using a syringe and a side-vented 27-gauge needle.
Group 2A: (n = 10), canals were irrigated with 5 mL (intermittent flush method) of 2% CHX and filled with 2% CHX, then activated (PUI) with a size 20, 0.02 taper oscillating ultrasonic device 1 mm short of the working length [Figure 6] for 30 s at power level 1. The canals were filled again with 2% CHX after PUI activation.
Group 2B: (n = 10), canals were irrigated with 5 mL (continuous flush method) of 2% CHX positive pressure irrigation for 1 min by using a syringe and a side-vented 27-G needle.
Group 3A: (n = 10), canals were irrigated with 5 mL (intermittent flush method) of 17% EDTA and filled with 17% EDTA then activated (PUI) with a size 20.,02 taper oscillating ultrasonic device 1 mm short of the working length [Figure 6] for 30 s at power level 1. The canals were filled again with 17% EDTA after PUI activation.
Group 3B: (n = 10), canals were irrigated with 5 mL (continuous flush method) of 17% EDTA positive pressure irrigation for 1 min by using a syringe and a side-vented 27G needle.
At the end of the irrigation procedures, the canals were dried with size 30, 0.02 taper paper points, and used size X3 ProtaperNext Guttapercha cones to test the point where “tugback” at the working length was first achieved.
Root canal filling was performed by a single operator, using a single cone method with BioRoot Bioceramic sealer with size X3 Protaper Next Gutta Percha cones. A modified sealer was used by incorporating RhodamineB at a proportion of 0.01% for improving CLSM and then filled into the canals using the master cone. Excess material was removed with a heated instrument and vertically condensed with a plugger. Specimens were stored at 37°C and 100% humidity for 24 h in an incubator, corresponding to the setting time of the sealer.
The elastomeric material was removed from the root surface and resin block, and the roots were superglued to the league. Each sample was sectioned horizontally using a low speed 0.6 mm thickness diamond disk at speed 300 rpm to obtain a 1 mm thickness section. Three 1 mm thick slices were obtained from each root for the analysis.
Quadrants were divided into the mesial, distal, buccal, lingual quadrant, and measured each quadrant for the maximum penetration depth. The quadrant that was penetrated maximum by the dye was recorded and analyzed the image. The slices were examined under a CLSM and a method of epifluorescence with wavelengths of absorption and emission for Rhodamine B at 514/585 nm. In contrast, sealer penetration depth measurements were performed and did magnification with a 10 × zoom lens which captured photographs with a resolution of 1024 pixels. Image analysis was performed using NIS-AR, v4.0 software. The maximum depth of sealer penetration in the dentinal tubules was measured and recorded.
Statistically compared the extent of dye penetration in the groups to find significant differences between them. A three-way ANOVA test was performed based on location (coronal, middle, apical) in the canal to measure the value of depth of penetration. Evaluated data on quantitative response variables (depth of penetration) for the assumptions of normality using Levene's test of equality of error variance based on means. Data on the depth of penetration revealed a normal distribution (P > 0.05). Interaction between dependent (depth of penetration) and independent variables (location, type of irrigation, and activation/without activation) was evaluated. Tukey test was used for the breakdown of interactions. The significance level was set at 5%, and all statistical calculations were performed on SPSS version 25 (IBM, USA).
| Results|| |
Levene's test based on the mean (P = 0.112), median (P = 0.444), median and with adjusted degrees of freedom (0.447), and trimmed mean (0.156) did not show any significant differences [Table 1]. Equal variances across samples are called homogeneity of variances.
A significant interaction between the factors irrigation, activation, and location (P ≤ 0.001) was shown in the three-way ANOVA for penetration depth. There was also a significant effect on irrigation-activation (P ≤ 0.001), irrigation-location (P ≤ 0.001); however, no significant effect between activation-location (P = 0.076). Similarly, the main effects of irrigation (P ≤ 0.001), activation (P ≤ 0.001), and location (P ≤ 0.001) also showed a statistically significant difference in depth of the penetration of sealer after the use of irrigants [Table 2].
|Table 2: Three-way analysis of variance for the root canal sealer, Irrigation technique, activation, and location|
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The mean depth of sealer penetration with NaOCl, CHX, and EDTA did not differ significantly after activation (P = 0.909). While without activation, it showed a statistically significant difference in depth of the penetration (P ≤ 0.001). Multiple comparison tests indicated significantly higher sealer penetration in EDTA with activation when compared to CHX and NaOCl with or without activation; whereas CHX showed considerable sealer depth even without activation.
In the central location, canal irrigants showed a significant difference in sealer penetration depth with activation (P ≤ 0.001) and without activation (P ≤ 0.001) by ultrasonic. Higher depth penetration was observed in EDTA with activation compared to CHX (P ≤ 0.001) and NaOCl (P = 0.002). Furthermore, EDTA showed significantly notable sealer depth without activation.
EDTA showed significantly higher penetration in apical location than CHX (P ≤ 0.001) and NaOCl with or without activation. Thus, it was observed in the multiple comparison test that with ultrasonic activation, irrigants displayed higher sealer penetration than without activation as shown in [Figure 1].
|Figure 1: multiple comparisons of sealer depth of penetration of different irrigants based on location and ultrasonic activation. WA = With activation; WOA = Without activation; NaOCl = Sodium hypochlorite; CHX = Chlorhexidine digluconate; EDTA = Ethylene-diamine-tetraacetic acid|
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NaOCl demonstrated significantly higher sealer depth penetration with ultrasonic activation (P ≤ 0.001) in coronal, compared to middle (P = 0.004) and apical (P = 0.001) locations [Figure 2] and [Figure 3]. While no significant difference in locations without activation (P = 0.964)
|Figure 2: CLSM picture of sealer penetration using (a) NaOCl, (b) CHX, (c) EDTA. CLSM = Confocal laser scanning microscope; NaOCl = Sodium hypochlorite; CHX = Chlorhexidine digluconate; EDTA = Ethylene-diamine-tetraacetic acid|
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|Figure 3: intercomparison between NAOCL, CHX, and EDTA with/without activation based on coronal, middle, and apical location.WA = With activation; WOA-without activation; NaOCl = Sodium hypochlorite; CHX = Chlorhexidine digluconate; EDTA = Ethylene-diamine-tetraacetic acid|
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CHX showed significant differences in sealer depth of penetration in different locations with ultrasonic activation (P ≤ 0.001). Significantly higher sealer depth in the coronal and middle locations (P ≤ 0.001) than apical location (P ≤ 0.001) without activation was observed, whereas activation was required to bring significant sealer depth penetration in the apical location [Figure 2] and [Figure 3].
EDTA showed significantly higher sealer depth penetration without or with ultrasonic activation (P ≤ 0.001) compared with other irrigants (CHX and NaOCl). Better sealer depth penetration was observed in all locations with activation [Figure 2] and [Figure 3].
Thus, comparing the data obtained from the comparison tests and CLSM using different irrigants (NaOCl, CHX, EDTA) with or without activation; EDTA demonstrated statistically significant sealer depth penetration with activation than without activation when compared to other irrigants (CHX and NaOCl) as shown in [Table 3]. Furthermore, it was observed that in the apical location, when compared with other irrigants, EDTA showed maximum sealer penetration with ultrasonic activation.
|Table 3: Comparison of sealer depth penetration after irrigation with different irrigants|
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| Discussion|| |
The purpose of this study was to measure the effect of each irrigating solution and activation technique on sealer penetration into dentinal tubules using a CLSM.
The depth of sealer penetration is influenced by different irrigant agitation systems and physical-chemical characteristics of root canal sealers. Root canal sealer penetration into the dentinal tubules till the apical location is clinically significant as it prevents bacterial repopulation inside the tubules and acts as a blocking agent. It improves filling material retention within the root canal, creates mechanical interlocking between sealer and root dentin by forming sealer tags into the dentin, then entombs remaining bacteria within dentinal tubules.
Calcium silicate-based bioceramic sealers interact with dentin through the chemical uptake of calcium and silicon in the presence of a phosphate buffer solution, which allows penetration of collagen fibers.,
BioRoot™ root canal sealers gained popularity as they provided higher dentinal tubule penetration than AH 26, even in the presence of calcium hydroxide. It is a water-based sealer that forms an interfacial calcium phosphate (apatite) layer when it comes in contact with the physiologic solution to release calcium; thereby developing a chemical bond with the dentinal walls.
In the present study, three different irrigants, 5.25% NaOCl, 2% CHX, and 17% EDTA were used with and without activation to observe sealer depth penetration through CLSM. It was observed that irrigants influenced higher sealer penetration in the coronal followed by middle and apical location with activation than without activation. Zou et al. stated that temperature, contact time, and concentration influenced the penetration of NaOCl into tubules when it is activated. Furthermore, studies show that the PUI was associated with the three-dimensional penetration of irrigant up to the working length and into lateral canals; which was confirmed in the present study that showed sealer penetration in the apical third of the root canal under CLSM. According to a study, NaOCl is known to dissolve magnesium and phosphate ions while increasing the amount of dentinal carbonate, and it significantly altered the Ca/P ratio of the root dentin surface.
CHX showed a minor depth of sealer penetration at the apical section without activation when compared to other irrigants; which might be due to factors like vapor lock effect in the apical third of the canal or ineffective activation of irrigating solutions as per the studies conducted by El Hachem et al. and Mamootil and Messer. Smaller diameter, reduced number of dentinal tubules, and more significant tubular sclerosis can also be the reason for poor dentinal tubule penetration in the apical third. The results obtained are per the study by Vadhana et al., which indicated that PUI aided in deeper penetration of 2% CHX into dentinal tubules than conventional syringe irrigation at all three levels. Studies showed that CHX improves the wetting ability of root canal sealers.
17% EDTA irrigant with ultrasonic activation produced higher penetration of sealer in coronal, middle, and apical sections compared to without activation sections, similar to the findings by Ballal and Mancini,, indicating that the 17% EDTA is effective in smear layer removal from the coronal, middle thirds and the apical third, compared to other solutions. Hence, with activation, EDTA showed higher sealer depth penetration even in the apical location. Thus it can be used as an indicator to show that the smear layer can be removed using sonically activated irrigation and PUI., The chelating action of EDTA solution induced softening of the calcified components of dentin, thereby reducing the microhardness and allowing better sealer penetration.
The present study highlights the importance of the final irrigation protocol for complete debridement of the canal for better canal seal and to prevent re-infection. This study indicates that ultrasonic activation showed significant differences in penetration depth of sealer after irrigation with activation at different locations of the root canal when compared with irrigants without activation. Ultrasonic activation of 17% EDTA showed significantly higher penetration depth of sealer at the apical section, per another study that stated ultrasonic activation might be attributed to the acoustic micro streaming that can adequately activate the endodontic irrigants and remove organic content in the root canal system.
Therefore, from the observations, the null hypothesis that effective sealer penetration can be achieved using ultrasonic activation on different irrigating solutions was accepted.
| Conclusions|| |
Ultrasonic activation could enhance the penetration of root canal irrigant and sealer into dentinal tubules. The highest level of sealer penetration was found in the coronal third and lowest in the apical third in all experimental groups.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]