| Abstract|| |
Aim: The aim of the study is to quantify the amount of debris extrusion after instrumentation with single-file rotary and reciprocating systems used either with conventional irrigation (CI) or passive ultrasonic irrigation (PUI) systems.
Methodology: Sixty extracted human mandibular incisors were randomly assigned to two groups (n = 30); rotary single-file system, One Shape (OS-Group 1) and reciprocating single-file system, WaveOne (WO-Group 2) instruments. The two groups were further subdivided into two subgroups (n = 15); (A) PUI and (B) CI. The apically extruded debris was collected in preweighed glass vials as per the Myers and Montgomery method. After drying, the mean weight of debris was assessed with a microbalance and statistically analyzed using analysis of variance and Student's t-test.
Results: The reciprocating file system produced significantly more debris compared to the rotary file system using either of the irrigation systems (P = 0.04). CI produced significantly more (P = 0.02) debris extrusion compared to PUI irrespective of the file system used.
Conclusion: Under the conditions of this study, both systems caused apical debris extrusion. Rotary single-file system produced less debris extrusion compared to reciprocating single-file system. Use of PUI may be advocated as an alternative to CI, as it causes lesser apical debris extrusion.
Keywords: Apical debris extrusion; passive ultrasonic irrigation; reciprocating instrumentation; single-file system
|How to cite this article:|
Gummadi A, Panchajanya S, Ashwathnarayana S, Santhosh L, Jaykumar T, Shetty A. Apical extrusion of debris following the use of single-file rotary/reciprocating systems, combined with syringe or ultrasonically-facilitated canal irrigation. J Conserv Dent 2019;22:351-5
|How to cite this URL:|
Gummadi A, Panchajanya S, Ashwathnarayana S, Santhosh L, Jaykumar T, Shetty A. Apical extrusion of debris following the use of single-file rotary/reciprocating systems, combined with syringe or ultrasonically-facilitated canal irrigation. J Conserv Dent [serial online] 2019 [cited 2020 Jul 11];22:351-5. Available from: http://www.jcd.org.in/text.asp?2019/22/4/351/270508
| Introduction|| |
Chemomechanical debridement of the root canal system is an indispensable step in contemporary root canal treatment. Irrespective of the various techniques and instruments used, biomechanical preparation results in extrusion of intracanal debris into the periradicular tissues even while maintaining the area of preparation short of the apical terminus. Extrusion of infective material from the root canal system during instrumentation was first documented by Chapman et al. This extrusion has been associated with the induction of pain and/or edema due to the inflammatory response. The incidence of these undesired consequences reportedly range between 1.4% and 16%.
In recent years, the advent of single-file systems has exceedingly simplified the multistep rotary instrumentation into a single-step procedure. WaveOne (WO) (Dentsply, Maillefer, Ballaigues, Switzerland) and One Shape (OS) (Micro-Mega, Besancon, France) are designed to complete biomechanical preparation with only one instrument. While WO works in reciprocal motion, the latter works in a continuous rotation.
Van de Visse and Brilliant attempted to compare apical extrusion of debris in root canals with or without irrigation and concluded that irrigation was a procedure that facilitated the extrusion of intracanal debris periapically and that instrumentation without irrigants resulted in no collectible debris. The type of root canal irrigation system may also affect the frequency and amount of apically extruded debris. Needle irrigation is the basic technique, used on a daily basis for root canal irrigation. Passive ultrasonic irrigation (PUI) of the root canals has been suggested as a means of improving canal debridement, canal disinfection.
To date, the effect of PUI on apical extrusion of debris when used in conjunction with single-file systems has not been studied. Hence, this study aims to quantify the amount of debris extrusion after root canal instrumentation with two single-file systems – WO and OS, combined with either PUI or conventional irrigation (CI). The null hypothesis is that there is no difference in the amount of apically extruded debris between the two instrumentation techniques and the two irrigation techniques.
| Methodology|| |
With ethical consent from the Institution's Ethics Committee, sixty extracted human mandibular incisors were selected. Teeth with complete root formation and straight root canals with <10° curvature were included in the study. The degree of curvature was calculated using the methodology described by Schneider. Teeth with a single canal and a single apical foramen were included in the study by verifying the buccal and proximal radiographs. Apical region of the roots was inspected using a stereomicroscope under ×20. In addition, other exclusion criteria were: teeth with any signs of cracks, internal and/or external resorption, root caries, root canal calcification or obstruction, pulp stones, and previous endodontic treatment. The teeth were disinfected in a solution of 0.1% thymol for 24 h and stored in saline until use. The crowns were sectioned such that all specimens had a length of 16 mm from the root apex. Coronal access was refined using diamond burs, and the canals were checked for apical patency with a size 10 K file (Mani. Inc., Tochigi, Japan). The file with a rubber stopper was then carefully introduced into each canal until it was just visible at the apical foramen. The working length (WL) of all teeth was established 1 mm short of this measurement and was confirmed with a radiograph. A size 15 K file was inserted until the WL was reached. Teeth which exhibited a snug fit at the WL were selected and divided randomly into two groups of thirty teeth each based on the file system to be used (OS and WO). The two groups were further subdivided into two subgroups (n = 15) depending on the irrigation system to be employed (PUI and CI).
Preweighing the eppendorf tubes
Each Eppendorf tube was weighed by the electronic microbalance (Sartorius, Germany Model-CP225D) of 10-5g sensitivity. Three consecutive weighings were conducted for each tube and their arithmetic mean was regarded as the weight of each empty Eppendorf tube.
Experimental model design
The experimental model used to evaluate debris extrusion in the present study was similar to that described by Myers and Montgomery. Each individual tooth was held in a preweighed Eppendorf tube by a rubber stopper, and this assembly was fixed inside a glass vial. It was made sure that no possible contact was made between the Eppendorf tube and the glass vial. The Eppendorf tube was then vented with a 30G needle (Ammdent, India) to equalize internal and external pressure within the tube [Figure 1].
Root canal preparation
All instruments were used in VDW Gold Reciproc Endo motor (VDW GmbH, Munich, Germany, Ref-V041173000000). The pulp chamber and the root canal were filled with 2 ml of distilled water. After three passes, the instrument flutes were cleaned with sterile gauze. The canal was irrigated with 2 ml of distilled water and a size 10 K file was used to maintain apical patency. These procedures were repeated until the file reached the WL. Total volume of irrigant was limited to 8 ml per tooth.
Group 1 One Shape
Classic OS rotary file, size 25, and 0.06 taper was used according to the manufacturer's instructions with a rotational speed of 400 rpm and torque of 4Ncm.
Group 2 WaveOne
Instrumentation was done with WO reciprocating (CW/CCW 30°/150°) primary file, size 25, and 0.08 taper as per the manufacturer's guidelines in preset WO mode of the endomotor.
Both the above groups were further subdivided into two subgroups based on the irrigation system used.
Subgroup A-passive ultrasonic irrigation
A U-file ultrasonic tip of size 15, 0.02 taper, and 33 mm length (Mani Inc., Tochigi, Japan) was placed in the canal 2 mm short of the WL. It was activated at a frequency cycle of 28–32 kHz/sec for 1 min using the BioSonic S1 Piezo Ultrasonic Scaler System (Coltene/Whaledent, Cuyahoga Falls, USA, Ref: 0911S1148B) after preparation of the canal.
Subgroup B-conventional irrigation
In this subgroup, irrigation was carried out with an open-ended 30G needle syringe positioned 2 mm short of the WL. Syringe was used in back and forth movements after canal preparation.
Quantifying the debris
The teeth were removed from the Eppendorf tubes, and their roots apices were washed with 1 ml of distilled water, to collect the debris that had adhered to their outer side. All tubes were incubated at 37°C for 15 days to allow the evaporation of the remaining irrigant from the tubes. After the incubation period, each Eppendorf tube with debris was weighed. Three consecutive weights were obtained for each tube, and the mean value was calculated. The dry weight of extruded debris was calculated by subtracting the weight of the empty tube from the weight of the tube containing debris.
The difference between the mean weights was calculated and statistically evaluated using two-way analysis of variance (ANOVA) and Student's t-test with the level of significance set at P < 0.05.
| Results|| |
Results of ANOVA test indicated highly significant difference among the four groups (P < 0.001). As depicted in [Graph 1] OS file system with PUI showed the least amount of debris extrusion. The highest amount of debris extrusion was displayed by WO with CI followed by WO with PUI [Graph 2].
| Discussion|| |
Many factors such as root canal anatomy, instrument size, type, canal preparation technique, apical enlargement, apical stop, irrigation solution, and irrigation delivery system determine the amount of debris and irrigant extrusion. Intergroup comparison between the instrumentation systems showed that, the WO reciprocating file system exhibited significantly higher debris extrusion as compared to OS rotary file system [Table 1]. Hence, the null hypothesis stating that there is no difference between the instrumentation systems was rejected. While a study by Koçak et al. depicted that reciprocating instrumentation produces lesser apical debris, Küçükyilmaz et al. observed no significant difference in debris extrusion between single-file rotary and reciprocating systems., On the contrary, studies conducted by Bürklein and Schäfer and Nayak et al. showed that single-file reciprocating systems extruded higher debris compared to their counterpart rotary systems., Variation in tooth, length, diameter, and volume of tooth instrumented could be the reason for such differences among studies.
|Table 1: Pair-wise comparison among instrumentation technique and irrigation systems|
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The differences between the instruments may be due to (i) the canal preparation technique, (ii) the cross-sectional design of the instruments, and (iii) the different tapers of the instruments.
Comparing the canal preparation technique, WO files due to their reciprocating and in-and-out filing motion, act like a piston, extruding more debris than OS instrumentation technique. In contrast, OS file with continuous rotation portrays a screw conveyor improving transportation of dentin chips and debris coronally. Owing to its cross-sectional design of three cutting edges with radial lands and a relatively small chip space, WO file system extrudes more debris apically. This design, when blended with reciprocating motion, may enhance transportation of debris toward the apex. OS instrument with its variable cross-section along the length of the blade accommodates more space for better elimination of debris as opposed to WO which has a triangular cross-section. It might also be considered that the greater taper of WO at the tip compared to OS is another possible reason for the greater amount of debris extrusion. A recent article stated that WO group extruded the highest amount of debris per unit of time, time for canal preparation being a relatively new variable used.
Intragroup comparison between the irrigation systems showed that CI caused significantly higher debris extrusion compared to PUI in both the instrumentation systems [Table 1]. Hence, the null hypothesis stating that there is no difference between the irrigation systems also was rejected. The results are in accordance with a study by Mitchell et al., where CI extruded more debris apically compared to EndoVac, EndoActivator, Rispisonic, and PUI techniques. Similarly, a study conducted by Shetty et al. also concluded that ultrasonic irrigation extruded lesser debris in comparison with conventional syringe irrigation. Open-ended needles generate positive pressures in excess of central venous pressure, as stated by Khan et al. A study by Boutsioukis et al. concluded that, there is an increased mean pressure at the apical foramen during open-ended needle irrigation, indicating increased risk of extrusion toward the periapical tissue. There is a general consensus that PUI is more effective than conventional syringe and needle irrigation in eliminating pulp tissue and dentin debris. PUI can remove debris and bacteria adhered on the root surface by action of acoustic streaming which produces shear stresses along the root canal wall.
In the present study, straight root canals with a single canal were chosen for standardization. Mature teeth were included in this study, while excluding teeth with incomplete root development as dentin mineralization is less intense in young teeth as compared to mature teeth, making them more susceptible to wear, resulting in increased extrusion. During the instrumentation procedure, irrigant volume was standardized to 8 ml. Needles of 30G were used for irrigation as the design allows it to freely fit to a point just short of the physiologic terminus facilitating efficient irrigation. Open-ended needles were used in the present study, as they have better irrigant replacement. They were placed 2 mm short of the WL to ensure adequate irrigant exchange and high shear stress against the root canal wall. Distilled water was chosen instead of NaOCl to reduce the chance of particulate precipitates.
A limitation of the study is that the crown was resected for standardization, but this is not representative of the true clinical situation where the presence of the clinical crown could affect the amount of debris extruded. Second, gravity may have played a crucial role in carrying the irrigant out of the canal due to the lack of backpressure in this study. Therefore, the results of this study are to be assessed with caution as the clinical scenario could not be replicated.
| Conclusion|| |
Within the limitations of the present study, it can be concluded that, both the single-file systems caused apical debris extrusion using either of the irrigation systems. Use of rotary single-file system resulted in lesser amount of debris extrusion compared to the reciprocating single-file system. PUI resulted in lesser debris extrusion than CI in both the groups. In this context, use of PUI over CI can be advocated.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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Dr. Ankita Gummadi
10-2-289/120, Flat No 502, Royal Homes Siena Grand, Shanti Nagar, Mallepally, Hyderabad - 500 028, Telangana
Source of Support: None, Conflict of Interest: None