Journal of Orofacial Sciences

: 2022  |  Volume : 14  |  Issue : 2  |  Page : 93--99

A Comparative Evaluation of Apically Extruded Debris using Three Rotary and One Reciprocating Instrumentation Ni‑Ti Systems: An in Vitro Study

Maha Adnan Habeeb 
 College of Dentistry, University of Uruk, Ziuna, Baghdad, Iraq

Correspondence Address:
Maha Adnan Habeeb
College of Dentistry, University of Uruk, Ziuna, Baghdad, 10001


Introduction: Chemomechanical preparation of root aims to eliminate the inflamed and necrotic tissue with infected dentine. This process may produce some debris extruded apically. The aim of our study was to compare and to assess the amount debris extruded apically by using four different single files systems. Materials and methods: Forty mandibular premolars which were cut to the cementoenamel junction with a diamond disk to similar lengths. Glass vials were pre-weighed and used to collect debris. The samples were divided into four groups: Group A (HyFlex EDM), Group B (AF Blue S-One), Group C (WaveOne Gold) and Group D (XPS). We used distilled water for irrigation. All canals were prepared to the size #25, then the vials were placed in hot air oven at 180°C for 5 h for evaporation of debris. Then vials containing dry debris were weighed again. The final mass of the extruded debris was calculated by subtracting the weight of initial empty vial from vial containing dry debris. ANOVA and LSD tests were applied to analyse data. Results: According to the results obtained in this study, all the tested files caused extrusion of debris apically. A highly significant difference was observed between all groups (P < 0.01). The highest value for debris extrusion was observed in rotary HyFlex EDM (0.03693 gm), whereas reciprocating C group (WaveOne Gold) showed the lowest value (0.01938 gm). Conclusion: The continuous rotary files caused less debris when compared with reciprocating one. Also all systems caused some degree of apical extrusion.

How to cite this article:
Habeeb MA. A Comparative Evaluation of Apically Extruded Debris using Three Rotary and One Reciprocating Instrumentation Ni‑Ti Systems: An in Vitro Study.J Orofac Sci 2022;14:93-99

How to cite this URL:
Habeeb MA. A Comparative Evaluation of Apically Extruded Debris using Three Rotary and One Reciprocating Instrumentation Ni‑Ti Systems: An in Vitro Study. J Orofac Sci [serial online] 2022 [cited 2023 Jan 30 ];14:93-99
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One of the most important goals of root canal instrumentation is to debride and disinfect the canal system, and creating the 3D shape for complete obturation.[1] After mechanical preparation, the dentin chips with the remaining of pulpal tissue, microorganisms, and their endotoxins and sometimes irrigating material are often introduced into periapical tissues through the apex. The outcome of this extrusion beyond the apex could be postoperative pain, inflammation, and flare-ups which might lead to delayed healing.[2] The innovation of nickel–titanium (Ni‑Ti) endodontic instruments has led to many advantages including saving time, decreasing operator fatigue, and minimizing instrumentation errors. But these rotary files have some drawbacks because of their high flexural and torsional stresses which increase the chance of instrument breakage.[3] In all techniques of instrumentation, there is some degree of apical extrusion that could be more or less according to the system used. One of the most important factors that affect the amount of extruded material apically is the number and design of instruments, their motion kinematics, irrigation protocol, and complexity of root canals.[4] Recently, single-file systems with different designs and motion kinematics (rotary and reciprocating) have been introduced by manufacturers. Studies have given contradictive results regarding which file system to choose that would extrude less debris.[5],[6] One of the single‑file systems which is used in a rotation movement is the HyFlex EDM File (COLTENE/Whaledent AG, Switzerland), it has a variable cross‑section with asymmetrical pitch, noncutting tip, and negative rake angle. The process of manufacturing these files is unique which is named “electric discharging machine.” This technique implies spark erosion on the file surface and this process increases fracture resistance and decrease cyclic fatigue.[7],[8] Another unique single-file system is the XP-endo Shaper (FKG Dentaire SA, Switzerland). This file is made of MaxWire alloy technology which means the file is changed from the martensite phase at room temperature to the austenite phase at body temperature. The diameter of apical part is 0.30 mm with 1% fixed taper. When the file is activated in rotation movement, the 1% taper increases to 4% because it expands at body temperature moving up and down causing turbulence of the irrigant.[9],[10] AF Blue S-One (Fanta Dental Materials Inc., Shanghai, China) is a continuous rotation heat-treated single file. Its flutes is safe sided which means only one side with an inactive tip and a flat surface design with 0.04 and 0.06 taper. The manufacturer claims that this instrument allows quick and safe preparation, especially in curved root canals due to high flexibility.[11] To reduce the number of files needed while still achieving appropriate canal cleaning and shaping, the reciprocating systems were innovated. Although these systems are able to complete canal instrumentation in shorter time than the usual rotation systems, there were contradictive studies on the amount of extruded debris created by these systems.[12],[13] One of the most popular reciprocating rotary systems used in clinical practice is the WaveOne Gold files (Dentsply Maillefer, Ballaigues, Switzerland). These files have increased flexibility, have shape memory that minimize canal transportation with high resistance to cyclic fatigue, and also have variable pitch and increased helical angle.[14],[15]. The null hypotheses were that there would be no significant difference between these files on the amount of apically extruded debris. So the aim of our in vitro study was to assess and compare the performance of WaveOne Gold, XPS, HyFlex EDM and AF Blue S-One in terms of extrusion of debris apically.

 Materials and Methods

Ethical clearance

The ethical approval for this study (protocol no. 556/ IEC/ URUK) was provided by the Ethical committee of the College of Dentistry/University of Uruk on 21 February, 2021.

In this study, we collected 40 mandibular premolars with single straight canal which were extracted for orthodontic purpose in patients aged 20 to 30 years. They had complete root formation, no curvatures, and absence of external and internal resorptions. A cumine scaler was used to clean the teeth calculus and soft tissue and then they were immersed in 6% NaOCl for 2 hours to remove any remnant of soft tissue and organic material.[16] Teeth length was measured using a digital calliper and then marker pen was used to mark the crown so that only 15 mm will be left after decoronation of teeth using a diamond disk with abundant water cooling [Figure 1]. Before instrumentation, all root canals were examined using a #10 stainless steel K-file (Dentsply Maillefer) to inspect the canals for calcifications and obstructions.[17] In our study, we used the Myers and Montgomery method. A 10-mL glass vial which was covered with a stopper was used for collection of debris [Figure 2]. Each glass vial was preweighed three times without stopper and before instrumentation and collection of debris using sensitive electronic balance that had a precision of (0.0001) [Figure 3]. Then we made a perforation at the center of the rubber cap of each glass vial using hot instrument. Each tooth was placed in the hole of the rubber cap with pressure to the level of the cementoenamel junction.[18] To prevent the leakage of irrigant outside from the gap between the rubber stopper and the tooth, we used adhesive to fill the space and a rubber dam with dental floss was used to cover the vial to prevent coronal extrusion of debris to the external surface which may have negative impact on the result [Figure 4]. For equalizing the air pressure outside and inside of the vial, we used a 25-gauge needle which was inserted into the rubber cap [Figure 5].[19]{Figure 1}{Figure 2}{Figure 3}{Figure 4}{Figure 5}

Sample grouping

In this study, all the teeth were divided into four groups according to the file system used: group A (n = 10): HyFlex EDM OneFile (COLTENE/Whaledent AG) #25; group B (n = 10): AF Blue S-One (FANTA, Shanghai Fanta Dental Materials Inc., Shanghai, China); group C (n = 10): WaveOne Gold group (Dentsply Maillefer) primary files (25.07); and group D (n = 10): XP-endo Shaper (FKG Dentaire SA). The enlargement of the apical foreman for all the groups was reached to size 15 prior to the beginning of instrumentation with each file system. All the files were used with an endodontic motor (WoodPecker, GoldenDent, USA) [Figure 6]. For the WaveOne Gold, after adjusting the working length and reaching to size 15 using a #15 stainless steel K-file (Dentsply Maillefer), a primary file with the size 25 and 7% taper was used according to the manufacturer instructions (150° counter‑clockwise and 30° clockwise). The file was introduced into the canal with a brushing in and out motion until the full working length was attained. For AF Blue S-One, after adjusting the working length and reaching to size 15 using a #15 stainless steel K-file, we used (#25/0.06) file in a pecking motion with 500 rpm speed and torque of 2.6 Ncm until the full working length was attained. For the HyFlex EDM group, after reaching to size 20 using a #20 stainless steel K-file (Dentsply Maillefer), the size 25 primary file was introduced with 500 rpm speed and torque of 2.5 Ncm. In the XPS group, after reaching size 15, the air motor was programmed on continuous rotation at 800 rpm speed and 1 Ncm torque with gentle strokes until reaching the estimated length. For all groups, irrigation protocol was 8 mL of distilled water as total volume with a 4-mL during instrumentation and 3 mL as a final flush using a disposable side vented 30-gauge navi tip needle which was inserted passively 2 mm from the apex. Then the external surface of root was washed with 1 mL distilled water to remove any debris attached to the root externally.[17] Then all the glass vials were placed in hot-air oven at 180°C for 5 hours so that all the irrigating solution would be evaporated.[20] The electronic balance was placed on a table in the corner of a single quiet and isolated room with only one door to avoid air current, and shaded windows avoiding direct sunlight; and any source of air drafts was switched off. We calculated the weight of glass vial containing dry debris by taking the mean of three readings of the glass vial using the electronic balance. The temperature during weighing procedure was 25°C with (58–65%) humidity to prevent the negative effect of fluctuating temperature on the result. The final result was obtained by subtracting weight of empty glass vial from the weight of glass vial containing dry debris.[21]{Figure 6}


The results of the descriptive statistics which include minimum, maximum, mean values (in gram), and standard deviation of apically extruded debris and irrigants for all groups are shown in [Table 1] and [Figure 7]. Group C (WaveOne Gold) showed the lowest mean value of apically extruded debris and irrigants (0.01938) in comparison with AF Blue S-One, XPS, and HyFlex EDM, whereas group A (HyFlex EDM) has showed the highest mean value (0.03693). Analysis of variance test was performed to identify the presence of any statistically significant difference among groups. [Table 2] summarizes a highly significant difference between tested groups (P ≤ 0.001). The least significance difference (LSD) test was performed for multiple comparisons between groups [Table 3]. The result of LSD test showed that group A (HyFlex EDM) had a nonsignificant difference with group B (AF Blue S-One) and group C (WaveOne Gold) (P ≥ 0.05), whereas it showed a significant difference with group D (XPS) (P ≤ 0.05). Group B (AF Blue S-One) showed a nonsignificant difference with group C (WaveOne Gold) (P ≥ 0.05) and highly significant difference with group D (XPS) (P ≤ 0.001). Group C (WaveOne Gold) showed a highly significant difference with group D (XPS) (P ≤ 0.001).{Table 1}{Figure 7}{Table 2}{Table 3}


One of the most causative factors for delayed healing or flare-ups in endodontically treated teeth is the extrusion of apical debris, filling materials, and irrigants that can provoke foreign body reaction due to disruption in the microbial balance.[2] The virulence and volume of the microorganisms are considered key factors for the degree of acute infection or flare-ups. The factors that affect the amount of apical extrusion could be classified into: (i) physical factors such as the amount and velocity of irrigant, size of apical constriction, hardness of dentin, and tooth position; _and (ii) mechanical factors such as the amount of irrigant used, final size of file, motion kinematics, and file design.[8] To decrease operation time and simplify root canal instrumentation, a single file was applied in the endodontic treatment.[22] Hence in the present study, the amount of apical extrusion of debris was evaluated using three continuous rotation single file systems (XPS, HyFlex EDM, and AF Blue S-One) and one reciprocating single-file WaveOne Gold. In our study, we chose mandibular premolars with single-wide canals to minimize the pumping effect of the file apically so that little amount of debris would be extruded.[1] The working length was adjusted at 1 mm from the apical constriction to minimize extrusion of debris. Also using a side-vented syringe for irrigation could decrease material pumping apically. The mean apical foramen diameter in mandibular premolars is approximately 25 mm, so we used a #25 file as a final apical size during chemomechanical preparation for all systems.[23] In this study, we considered the extrusion of irrigants in addition to the intracanal dentinal debris because the solutions of irrigants can be extruded into the periapical tissue. We used distilled water instead of sodium hypochlorite for irrigation to avoid any crystallization which might affect the accuracy of the recordings.[24] The model of Myers and Montgomery was used which is a known and well-accepted apparatus for measuring the amount of apical extruded debris.[18] For the results of our study, there was a highly significant difference between tested groups. HyFlex EDM file system showed the greatest amount of apically extruded debris among tested groups, although the difference was insignificant except with S-One file system which was highly significant. One possible cause of the high amount of debris extrusion of Hyflex EDM file system is the unwinding of file flutes which increases the length of pitch and subsequently increases extrusion.[8] Elmsallati et al.[25] compared apical extrusion made by short, medium, and long pitch of files and found the greatest amount of debris associated with longest pitch design. Also in our study, the reciprocating WaveOne Gold showed the least amount of debris compared to the rotary systems used in the study. These observations are in agreement with previous findings that proved the reciprocating systems are associated with less debris.[7],[23],[26] However, some researchers found less debris associated with rotary systems when compared with reciprocating files.[27],[28] Ozsu et al.[29] showed that the WaveOne extruded less debris than the ProTaper system. These conflicting results could be due to the differences in the design of the file cross section, tip, cutting efficacy, motion kinematics, flexibility, alloy, and number of files. The reason for the low debris extrusion created by WaveOne Gold system could be attributed to the triangular cross section of the tip which is modified with radial lands that produce less cutting power which means less debris extrusion.[14] Furthermore, the manufacturing process of WaveOne Gold files consists of thermally treating the surface with Ni-Ti alloy which is named “Gold,” where the file is treated with heat then cooled slowly and this process increase the resistance and flexibility so that the file can prepare curved canals without excessive shaping.[15] XPS significantly produced less amount of debris than HyFlex EDM and this may be due to the MaxWire technology that gives XPS file the shape memory and the off-centered design which preserves the dentine and produce minimum debris apically. This might explain the decreased amount of debris extrusion.[10] One of the studies has proved that XPS produced significantly less debris extrusion when compared with Reciproc blue and other rotary systems.[30] In addition to that Azim et al.[31] reported that XP extruded the least amount of debris in retreatment cases. The low volume of debris extruded by AF Blue S-One file produced in our study could be explained by the application of blue heat technology which creates a highly flexible file and resistant to fracture and these features lower the cutting efficiency of the instrument and produce less debris,[11] and also the S-shaped cross-section and noncutting tip with variable pitch provide a large space for escape of debris coronally and thus less extrusion apically.[13] The most important limitation of our study is the inability to simulate the periapical tissue physical pressure, so the debris extruded apically could not be limited. Hence further studies are required to evaluate apical extrusion patterns of these file systems under the presence of periapical tissues. According to the result of this study, we can limit the use of XPF and Hyflex EDM rotary file to vital cases where we have less infected to prevent future flare-ups. On the other hand, for the chronic cases such as heavily infected teeth with resorbed canals, we can use the AF Blue S-One and WaveOne Gold. The null hypotheses were rejected because we found highly significant difference between tested groups in terms of apical extrusion.


Based on the results of our study, we concluded that all the single-file systems used on our study created some amount of debris extrusion apically and there was a highly significant difference between tested groups. Also the reciprocating single-file WaveOne Gold created the least amount of debris followed by S-One then XPS and HEDM, respectively.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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