|Year : 2022 | Volume
| Issue : 2 | Page : 136-143
Assessment of pain intensity after instrumentation by MPRo and Hyflex rotary files in molars with irreversible pulpitis: A randomized single-blind clinical trial
Maram Farouk Obied1, Sara Samir El Mallah2, Hala Fayek Khalil3
1 Endodontic Department, Faculty of Dentistry, Ain Shams University, Cairo, Egypt
2 Endodontic Department, Faculty of Dentistry, Fayoum University, Fayoum, Egypt
3 Endodontic Department, Faculty of Dentistry, The British University in Egypt, Cairo, Egypt
|Date of Submission||12-Sep-2021|
|Date of Decision||15-Jan-2022|
|Date of Acceptance||17-Jan-2022|
|Date of Web Publication||26-Apr-2022|
Dr. Hala Fayek Khalil
Endodontic Department, Faculty of Dentistry, The British University in Egypt, El Shrouk City, Suez Road, Cairo 11837
Source of Support: None, Conflict of Interest: None
Aim: To assess the intensity of postoperative pain after endodontic treatment using full-sequence rotary Ni–Ti system either MPro or Hyflex in mandibular molars with irreversible pulpitis. Materials and Methods: This was a randomized, prospective, single-blind clinical trial. Fifty patients were randomly assigned into two equal groups according to rotary system used: Hyflex CM or MPro (n = 25). Both groups were mechanically prepared. Patients were asked to assess their postoperative pain using the numerical rating scale (NRS) at 3, 6, 24, 48, and 72 h after instrumentation. Data were presented as mean, standard deviation, median, and interquartile range values to be statistically analyzed with R statistical analysis software using Friedman’s test followed by Nemenyi post hoc test at different time intervals within each rotary system. Mann–Whitney U test was conducted to compare NRS values between both rotary systems. Results: The intensity of pain postoperatively was low significantly in Hyflex group in all observation periods. MPro group showed a decreasing mean from 3 h to 72 h time intervals. 3 h recorded the highest mean (3.72 ± 1.88). Statistically, there was a significant difference between all intervals except after 48 and 72 h. Hyflex group showed the same. 3 h recorded the highest mean (1.72 ± 1.34). Statistically, there was a significant difference between 3 h and the rest time intervals, but no significant difference was found between the 6, 24, 48, and 72 h. For both groups, there was no significant association between gender and pain and there was no significant correlation between age and painConclusion: Both Hyflex and Mpro systems resulted in postoperative pain with a different degree but Hyflex system represented lower postoperative pain intensity when used for mechanical instrumentation of mandibular molars with irreversible pulpitis.
Keywords: Clinical Trial, Hyflex Files, Irreversible Pulpitis, MPro Files, Pain Assessment
|How to cite this article:|
Obied MF, El Mallah SS, Khalil HF. Assessment of pain intensity after instrumentation by MPRo and Hyflex rotary files in molars with irreversible pulpitis: A randomized single-blind clinical trial. J Int Oral Health 2022;14:136-43
|How to cite this URL:|
Obied MF, El Mallah SS, Khalil HF. Assessment of pain intensity after instrumentation by MPRo and Hyflex rotary files in molars with irreversible pulpitis: A randomized single-blind clinical trial. J Int Oral Health [serial online] 2022 [cited 2022 May 19];14:136-43. Available from: https://www.jioh.org/text.asp?2022/15/2/136/344057
| Introduction|| |
Pain is an unpleasant sensory experience with emotional and cognitive components, which occurs due to authentic or probable damage to tissues. Postoperative pain is a recurrent impediment in endodontic treatment with a prevalence of 1.4%–16%. Postoperative endodontic pain is essentially caused by extrusion of debris from the apical foramen during instrumentation., However, the capacity of some rotary systems to reduce the extrusion of debris was verified in different studies, leading to an obvious decline in postoperative pain level particularly with full-sequence rotary instrumentation.,,
One of the lately used full-sequence rotary systems is the MPro IMD (Guangdong, China), which is made from a specially treated X-wire. It has the pre-bending ability, great flexibility, and high resistance to cyclic fatigue, with a convex triangle cross-section, but its effect on the level of postoperative pain was not addressed.
Hyflex CM (Coltene-Whaledent, Altstätten, Switzerland) is a full-sequence Ni–Ti rotary system with an exclusive process to control the material memory (heating and cooling treatment). The CM-wire is almost equiatomic alloy constituted of 52%wt Ni, whereas the mass of commercially available Ni–Ti rotary systems is constituted of 54.5–57%wt Ni. The producer dues that the used alloy, besides the exclusive design features, provides better flexibility allowing more preservation of the original canal curvature. The outcome of its usage on postoperative pain intensity is yet to be assessed.
Consequently, the rationale of the present prospective randomized controlled clinical trial was about comparing the intensity of postoperative pain after endodontic treatment using a full-sequence rotary NI–TI system either MPro or Hyflex. The null hypothesis was that the used rotary Ni–Ti system does not influence the level of pain postoperatively.
| Materials and Methods|| |
Setting and design
A presented randomized clinical trial was performed at the Department of Endodontics, Faculty of Dentistry, Ain Shams University over a period of 4 months from February 2019 to the end of August 2019. Patients with ages ranging from 25 to 40 years were recruited to partake in this study and one investigator (MS) examined and enrolled all the partakers.
The sampling criteria
Sample size calculation was conducted using G*Power 188.8.131.52 software based on data obtained from a previous study. It was estimated that a minimum sample size of 19 subjects per group for a total of 38 subjects would be essential for an effect size of 0.97 with an alpha error of 0.05 and a power beta of 0.90 to achieve 95% confidence of a true difference between the groups. Sample size was increased by 25% to 25 subjects per group for a total of 50 subjects to compensate for drop-outs.
Eighty patients who had at least one mandibular molar (first or second) with acute irreversible pulpits and regular periapical radiographic views requiring root canal treatment were suitable to join. Moreover, to be qualified for our study the participant should be able to use the pain scale and abide by the follow-up time of the study. Preoperative periapical radiographs were taken to select molars with four canals and to assure the absence of apical radiolucency, internal, or external resorption. Female patients were excepted in presence of pregnancy or lactation; also if patients demand special health-care requirements or have systemic disorders. Molars that had three canals, acute periapical or periodontal abscess, destructed molars, or severely-curved roots also were excluded. Patients who administered analgesic medication preceding the treatment by 12 h were excepted from this study.
Prior to beginning the study, the purpose of the study, the treatment procedures, the benefits, and distress or risks that might be faced were fully explained to the subjects and only patients who decided to partake in the study and signed informed consent were registered and randomly divided into two groups [Figure 1]. Participants were free to withdraw from the trial at any step. Regular care was guaranteed to the participant even if he or she withdraws. At last, 50 patients were registered in the study.
|Figure 1: CONSORT flowchart showing flow of participants along the study|
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For randomization and allocation concealment, the patients were randomly allocated using a coin toss. This was performed by a second operator (OM) who was totally blind to the treatment procedure. After that, all diagnoses and endodontic treatment were performed by one operator (MS).
In addition to the approval of the Research Ethical Committee, Faculty of Dentistry, Ain Shams University with an approval code (FDASU-RECR 09181) the protocol of this prospective, two-arm, parallel-group, single-blind, randomized, clinical trial and the informed-consent format was registered in www.clinicaltrials.gov (ClinicalTrials.gov Identifier: NCT04216940). Our study reporting followed the Consolidated Standards of Reporting Trials (CONSORT) guidelines.
In this study, patients were divided randomly into two groups (n = 25) according to the rotary Ni–Ti system used in canal preparation as follows: Hyflex group and MPro group. After proper isolation and access cavity preparation, apical patency was assured in all canals with a size 10 K-File. The working lengths were measured using an apex locater (MM Control, Micro-Mega) then a glide path was prepared inside the root canals by using no. 15 and 20 K-files. In both groups, apical preparation was completed with a size 30/0.04 instrument by using the instrument order specified by the manufacturer. Mechanical preparation was performed in following the manufacturers’ recommendations in a matter of torque and speed by means of an electric motor with torque control (IEndo dual, Acteon, Merignac, France). File size 10 K-file was used to maintain Apical patency and instruments were removed once reached full canal length and rotated freely. Each instrument was used to mechanically prepare only four canals. Cleaning of instruments’ flutes was done after three pecks. Irrigation was accomplished using 5 mL of 2.5% NaOCl irrigation solution with a 27-gauge, notched-tip needle (Monoject needle, Tyco Healthcare Group LP, Kendall, Massachusetts) after each instrument. The used needle depth was adjusted by rubber stoppers to be 3 mm shorter than the measured working length. 5-mL saline was used as a final flush. At the end of the first visit, paper points were used to dry the canals (Protaper Universal, Dentsply Sirona), a dry cotton pellet was positioned in the pulp chamber followed by temporary filling (Cavit, 3M ESPE, Germany) to seal the access cavity without adding any intracanal medication.
One week later, the second visit was done in which a rubber dam was placed before removing the temporary filling then all root canals were irrigated using the same irrigant as in the first visit. Finally, canal filling was finished using a continuous wave of condensation using a carrier that can fit shorter than working length by 3 mm. For adequate thermoplasticization of apical gutta-percha, a single cone with matched-size gutta-percha cones (Protaper Universal, Dentsply Sirona) and an epoxy resin-based sealer (AH Plus, Dentsply DeTrey, Germany) were used. Again, the tooth was temporized. None of the patients was absent in the second visit; therefore, the total number of included patients was the same.
Evaluation of postoperative pain
The participants were asked to rate their pain on a defined scale from 0 to 10 scales (numeric rating scale [NRS]), where 0 is no pain and 10 is the worst pain imaginable before the dental treatment and at 3, 6, 24, 48, and 72 h after instrumentation. Patients documented their preoperative pain levels in the presence of the clinician to ensure that they understood the instructions. The patient got the NRS form along with them. Telephonic reminder was given to them to note their pain readings and return the form duly filled in the second visit. Each patient was given a prescription for 600 mg of Ibuprofen three times a day for 4 days with instructions to take only in case of severe pain that is not tolerable. The patients were instructed to record that in their sheet and to call the operator at once.
Statistical analysis was performed with R statistical analysis software version 4.1.1 for Windows (R Core Team (2021). R: A language and environment for statistical computing. R Foundation for Statistical Computing, Vienna, Austria. Available from: https://www.R-project.org/). Data were presented as mean, standard deviation (SD), median, and interquartile range (IQR) values. The significance level was set at P ≤ 0.05. Kolmogorov–Smirnov and Shapiro–Wilk tests were used to assess data normality. Friedman’s test followed by Nemenyi post hoc test was performed to compare NRS mean values between different time intervals within each rotary system. Mann–Whitney U test was conducted to compare NRS values between both rotary systems at each time interval, and to test the association between gender and pain. Spearman’s rank-order correlation coefficient was used to study the correlation between age and pain.
| Results|| |
Sample size calculation was conducted using G*Power 184.108.40.206 software based on data obtained from a previous study. It was estimated that a minimum sample size of 19 subjects per group for a total of 38 subjects would be essential for an effect size of 0.97 with an alpha error of 0.05 and a power beta of 0.90 to achieve 95% confidence of a true difference between the groups. Sample size was increased by 25% to 25 subjects per group for a total of 50 subjects to compensate for drop-outs. To calculate sample size, we used IBMVR SPSSVR Sample PowerVR Release 3.0.1 (IBM SPSS Statistics, Armonk, New York).
Among 80 patients evaluated for eligibility, 50 were involved, randomized, and their data analyzed without dropouts or exclusions [Figure 1]. None of the study partakers took analgesics. Mean values of NRS for all groups are presented in [Table 1] and [Figure 2]. MPro group showed a decreasing mean from 3 h to 72 h time intervals. 3 h recorded the highest mean (3.72 ± 1.88) followed by 6 h (2.0 ± 1.29), 24 h (1.16 ± 1.21), 48 h (0.6 ± 1.04), and the lowest mean (0.56 ± 1.04) after 72. Statistically, there was a significant difference between all intervals except after 48 and 72 h in which the differences were insignificant at P ≤ 0.05.
|Table 1: Mean ± SD and P-value of numerical rating scale (NRS) of MPro and Hyflex systems at different time intervals|
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|Figure 2: Line chart showing the mean of numerical rating scale (NRS) of MPro and Hyflex systems at different time intervals|
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Results of Hyflex group showed a decreasing mean from 3 h to 48 h intervals. 3 h recorded the highest mean (1.72 ± 1.34) followed by 6 h (0.56 ± 0.87), 24 h (0.16 ± 0.37), and the lowest mean recorded was after 48 and 72 h (0). Statistically, there was a significant difference between 3 h and the rest time intervals, but no significant difference was found between the 6, 24, 48, and 72 h at P ≤ 0.05. When comparing the two systems, results showed that Mpro had higher mean values in all observation periods than Hyflex and this was statistically significant at P ≤ 0.05.
Results of the association between gender and postoperative pain are presented in [Table 2] and [Figure 3]A, whereas results of the correlation between age and postoperative pain are presented in [Figure 3]B and C. For both groups, there was no significant association between gender and pain and there was no significant correlation between age and pain (P > 0.05).
|Figure 3: (A) Bar chart showing the association between postoperative pain and gender. (B) Scatter plot showing the correlation between postoperative pain and age in MPro group. (C) Scatter plot showing the correlation between postoperative pain and age in Hyflex group|
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| Discussion|| |
Postoperative pain is believed to have a considerable influence on quality of life, consequently appropriate controlling of it is a major issue. Even though postoperative pain is multifactorial, the instrumentation method is deemed to have a chief role.,,,
Quite a lot of studies accomplished concluded that the manifestation of postoperative pain was dropped when using rotary Ni–Ti systems., Nevertheless, little was completed to compare different rotary system clinically. Thus, the purpose of the present prospective randomized controlled clinical trial was to compare the influence of root canal treatment with MPro and Hyflex rotary files on the intensity of postoperative endodontic pain.
The MPro system is a novel one in the market with few studies in the literature evaluating its action or its effect on postoperative pain. It was used in this study as an intervention owing to its economic popularity and its innovative technology in metallurgy as it is made from specially treated raw X-wire material allowing pre-bending of the files and adding advantages to their stiffness and strength. The manufacturer claims that this will reduce the risk of breakage and will minimize the screw in effect.
The second used system is the Hyflex, which also represents a modern metallurgy technology that comprises a lesser percentage of nickel than other systems. The decline in the nickel content creates a metal that is softer, that is, shows lower hardness and less possibility for canal transportation. Moreover, the size and taper of it were like MPro which aid in standardizing such factors in the study.
This study was a randomized, single-blind, clinical trial with subject-reported result measures to diminish selection favoritism and in which the contributors, who are also the result evaluators, were blinded to the interferences applied, thus diminishing implementation and recognition favoritism. Moreover, participants with a contributing history, who took analgesic medication during the preceding 12 h before treatment, were excepted to evade drug interaction that may influence the results of the study. Mandibular molars were chosen because they have the greatest incidence of postoperative pain,, thus speaking to the direst outcome imaginable.
As standardizing our work protocols is a must to decrease the effects of intraoperative variables on outcomes, a double visit endodontic treatment was using in this study without the application of intracanal medicaments to remove their chemical effects and the effect of canal filling that may affect our results.,
In this study, the working length, the type, and volume of irrigant were the same in both groups as these things may cause debris extrusion, which may disturb the periodontal ligament reaction. Over-preparation was avoided mainly through using an apex locator and radiographs in all steps of treatment in all cases. The use of a side vented needle for irrigation helped the irrigation solution to safely reach the apex.
Pain is always difficult to study because it is very subjectively evaluated and measured by the patient, this makes the methodology used in evaluating pain level very critical. Several methods can be used for assessing pain., In our study we used a 10-point NRS because it is easy to use and more sensitive than verbal rating scales (VRSs). Patients were coached to use the scale to assure accurate outcome data assembly.,,
When comparing the used systems, postoperative pain was recorded in both with a different degree. This agreed with the previous study and can be attributed to chemomechanical preparation, in which infected debris can be moved to periapically, where they will induce an acute inflammatory response in the periapical area.
Postoperative pain was significantly low in the HyFlex group in comparison to the MPro group in all time intervals. This was in accordance with the data found by Kocak et al. who recorded lower postoperative pain with the Hyflex system and he referred to the decrease of the amount of apical extrusions which usually affect the periapical area due to unwinding of the spiral of the files during instrumentation. Moreover, Diemer and Calas highlighted the presence of an increasing variable pitch in Hyflex which diminishes the screw in tendency and consequently again reduces the apical extrusion of debris which in turn decreases the possibility of apical inflammation and pain. The same was concluded by Kocak et al. and Labbaf et al.
Regarding time intervals, our results recorded the highest postoperative pain score within the first 24 h. All patients had the highest level of pain after 3 h in both groups and gradually decreased over time through the first day and decreased over time in both groups. This was in accordance with previous studies., None of the patients reported an increase in pain intensity with time which is in harmony with Ramamoorthi et al.
Results of our prospective randomized controlled clinical trial proved that the rationale chosen in comparing the intensity of postoperative pain after endodontic treatment using Full-sequence rotary NI–TI system either MPro or Hyflex proved that both systems caused postoperative pain with different degrees. The null hypothesis was rejected.
It is recommended for further studies to may be work on finding techniques to decrease the apical debris extrusion associated with the MPro system that may have increased the postoperative pain results in our study.
Limitations of this trial might be the inclusion of mandibular molars with four canals, a limited number of samples per group and involving a broad spectrum of subject might have affected the trial outcomes. Upcoming studies are advised to evaluate the effects of different rotary designs on the short- and long-term results with special consideration of gender and number of trial participants per group
Under the limitations of this study, we concluded that both Hyflex and Mpro systems resulted in postoperative pain with a different degree but Hyflex system represented lower postoperative pain intensity when used during mechanical instrumentation of mandibular molars with irreversible pulpitis. Our null hypothesis was rejected.
Financial support and sponsorship
This research was independently funded by the authors, no university of company or funding institute collaborated in the research. All tests performed were paid for by the researchers.
Conflicts of interest
There are no conflicts of interest.
MO contributed to design, intellectual content, literature search, data acquisition, manuscript preparation, manuscript editing, and review. HF contributed to intellectual content, literature search, methodology, data analysis, manuscript preparation, manuscript editing, and review. SEM contributed to intellectual content, validation; visualization, manuscript editing, and resources.
Ethical policy and Institutional Review board statement
In addition to the approval of the Research Ethical Committee, Faculty of Dentistry, Ain Shams University with an approval code (FDASU-RECR 09181) dated September 2018 the protocol of this prospective, two-arm, parallel-group, single-blind, randomized, clinical trial and the informed-consent format was registered in www.clinicaltrials.gov (ClinicalTrials.gov Identifier: NCT04216940).
Patient declaration of consent
The authors certify that all participants have provided their written consent to participate in the research and to publish the analyzed data. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed.
Data availability statement
Data are available upon a valid request to the corresponding author.
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[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2]