| Abstract|| |
Background: Endodontic instrumentation is liable to cause some postinstrumentation pain (PIP). Rotary endodontic instruments differ in their design, metallurgy, surface treatment, etc.
Aim: This randomized clinical trial aimed to assess the incidence of PIP after root canal instrumentation with three different rotary endodontic systems which differ in their design, namely, ProTaper, Mtwo, and K3.
Materials and Methods: A total of 150 patients between the ages of 25 and 50 were chosen for the study. Teeth with asymptomatic irreversible pulpitis due to carious exposure were selected. The patients received local anesthesia by inferior alveolar nerve block. After preparing the access cavity, root canal instrumentation was done with one of the three instruments (n = 50) and closed dressing was given. PIP was assessed every 12 h for 5 days, and tenderness to percussion was analyzed at the end of 1, 3, and 7 days.
Statistical Analysis: Mann–Whitney U-test to determine significant differences at P < 0.01.
Results: The PIP and tenderness were less in Mtwo group when compared to ProTaper and K3 groups up to 84 h and 72 h respectively and statistically significant (P < 0.05). There was no statistically significant difference between ProTaper and K3 both in PIP and tenderness.
Conclusion: Rotary endodontic instrumentation causes some degree of PIP and tenderness to percussion. Among the instruments used, Mtwo causes less PIP and tenderness when compared to ProTaper and K3, and there was no difference between ProTaper and K3.
Clinical Relevance: PIP is highly subjective and may vary among different subjects. The apical (3 mm) taper of ProTaper was 0.08 followed by a smaller taper, whereas, the other two files were of a constant 0.06 taper, which means there could have been a greater apical extrusion and therefore more PIP. Despite, the mean of the age was similar, there could have been a difference in the size of the canal and therefore a difference in apical extrusion and PIP.
Keywords: Apical extrusion; pain intensity; postinstrumentation pain; randomized control trial
|How to cite this article:|
Subbiya A, Cherkas PS, Vivekanandhan P, Geethapriya N, Malarvizhi D, Mitthra S. Effect of three different rotary instrumentation systems on postinstrumentation pain: A randomized clinical trial. J Conserv Dent 2017;20:467-73
|How to cite this URL:|
Subbiya A, Cherkas PS, Vivekanandhan P, Geethapriya N, Malarvizhi D, Mitthra S. Effect of three different rotary instrumentation systems on postinstrumentation pain: A randomized clinical trial. J Conserv Dent [serial online] 2017 [cited 2021 Sep 17];20:467-73. Available from: https://www.jcd.org.in/text.asp?2017/20/6/467/223198
| Introduction|| |
The objective of root canal therapy is not only to preserve a tooth which may otherwise be lost due to pulpal or periradicular pathosis but also to prevent intra- and post-operative pain. Such pain may arise after endodontic instrumentation or obturation. The reasons for postinstrumentation pain (PIP) include extrusion of various irritants such as dentin debris, necrotic tissue, microorganisms, and irrigants toward the periapical area during canal preparation.,,
The prevalence of postoperative pain after endodontic treatment has been reported to be in the range from 3% to 58%. Various suggestions have been given to prevent PIP which includes maintenance of asepsis throughout endodontic procedure, selection of endodontic instruments that produce less apical extrusion, completion of the chemomechanical procedures in a single visit to prevent re-growth and colonization of bacteria and usage of intracanal medicaments between appointments.
Various studies have been conducted to understand the effect of different clinical approaches such as use of different local anesthetics,, premedication, and irrigants and irrigation devices on the intra- and post-operative pain. Root canal preparation technique and cross-sectional design of the instruments play a role in the extrusion of debris.
The study by Reddy and Hicks was one of the earliest to compare the effect of hand and rotary NiTi instruments on apical extrusion of debris which concluded that both hand instrument and rotary NiTi instrument techniques caused debris extrusion. Other studies have shown that extrusion varies with different rotary instruments.,, Another study that evaluated the expression of neuropeptides, substanceP and calcitonin gene-related peptide in periodontal ligament after root canal preparation with different instruments revealed that neuropeptide release was different for each of the instruments tested showing that the periradicular inflammation after instrumentation can vary with different instruments.
ProTaper has a convex triangular cross-section with no radial land with a variable taper along the length of the instrument. K3 has a variable core diameter, positive rake angle, three radial lands, and peripheral blade relief to reduce friction. Mtwo has a smaller core diameter with an italic S-shaped cross-section and enough flute space to accumulate debris.
Since the instrument design could influence the PIP, the purpose of this study was to assess the incidence of postoperative pain and tenderness to percussion after instrumentation with three rotary endodontic systems of different cross-sectional design such as ProTaper (Dentsply-Maillefer, Ballaigues, Switzerland), Mtwo (VDW, Munich, Germany), and K3 (Sybron Endo, Orange, CA, USA). The null hypothesis of this study was that there will be no difference in the postoperative pain between the instruments studied.
| Materials and Methods|| |
This prospective double-blind randomized clinical trial was approved by Sree Balaji Dental College and Hospital Ethical Committee, Bharath University (protocol Reference no. SBDCECM 104/13/06). Endodontic treatment was performed on patients who came for routine endodontic therapy at the Department of Conservative Dentistry and Endodontics of Sree Balaji Dental College and Hospital, Chennai, India. The trial adhered to the Consort statement.
From the outpatient Department of Conservative Dentistry and Endodontics, Sree Balaji Dental College and Hospital with a patient inflow of approximately 40/day a total of 2522 patients were screened for this study. Of these 204 patients who were meeting the inclusion criteria and willing to participate in the study were included and written informed consent was obtained after explaining the aim and nature of the study. The recruitment was done for 14 months from June 2015 to July 2016. Although only 150 patients received the allocated intervention and were analyzed for the study, all the 204 patients willing to participate were included in the study. This was done considering the exclusion which may happen after access opening due to the anatomical reasons as mentioned below in the inclusion/exclusion criteria.
Diagnostic radiographs were taken at two different angulations to determine root canal configuration and periapical pathosis. Teeth with carious pulpal exposure and without widening of periodontal ligament were selected. The status of pulp whether it is vital or necrotic was determined by cold stimulation with ethyl chloride spray and presence of bleeding from the pulp chamber during access cavity preparation. Teeth showing positive response during cold stimulation and presence of bleeding during access cavity preparation were considered vital and were selected for our study.
- Healthy adult patients requiring endodontic treatment in mandibular first molars between the ages 25 and 50 years
- Mandibular first molars with asymptomatic irreversible pulpitis
- Mandibular first molars with mesial and distal roots having Vertucci-type IV and type I canal configurations, respectively.
- Patients with previous contributory medical history, pregnancy, and patients not defined as American Society of Anesthesiologists I
- Patients with preoperative pain
- Patients under antibiotics, analgesics, or nonsteroidal anti-inflammatory drugs for the past 1 month
- Mandibular first molars with supernumerary roots
- Presence of root canals with extreme canal curvature (>30°)
- Teeth with internal and external resorption, open apices
- Presence of periapical pathosis, sinus tracts, and history of trauma
- Patients requiring endodontic retreatment.
Although the patients were informed about root canal instrumentation in general, the patients were blinded about which system was used for the treatment.
Randomization and allocation concealment
To minimize allocation bias, the patients were randomly assigned to three balanced groups using random table numbers. ProTaper, Mtwo, and K3 were assigned as Group 1, Group 2, and Group 3, respectively. The instruments were packed in separate opaque packs and numbered according to the randomization schedule. The randomization and the packing were done by one of the authors (PV) who was not the operator (AS).
All patients received local anesthesia by inferior alveolar nerve block of 1.8 ml lignocaine with1: 1,00,000 epinephrine (Septanest, Septodont, India). After anesthesia was confirmed by the feel of lip numbness and the tooth of interest did not respond to cold test, the rubber dam was placed. The carious tooth structure was excavated using a hand excavator before accessing the pulp to prevent the introduction of microorganisms into the root canal. Then, the cavity was disinfected with 2% chlorhexidine wipe and the pulp chamber was accessed with a sterile bur. After establishing a glide path with #15 K-file, the coronal third of the root canal was enlarged with Gates Glidden burs #4, #3, and #2 (Dentsply, Maillefer, Ballaigues, Switzerland). The working length to the apical constriction was confirmed by an electronic apex locator (Root ZX; Morita, Japan) and periapical radiographs. The canals were prepared with the instruments as decided by the randomization. The final apical size was established as ISO size 25/.06 for mesial canals when K3 and Mtwo were used and F2 (size 25/.08) when ProTaper was used. For distal canals, 40/.06 was used for K3 and Mtwo, and F4 (40/.06) where ProTaper was used. A solution of 4% sodium hypochlorite and normal saline was used as an intracanal irrigant throughout the procedure with chlorhexidine as final irrigant. The volume of irrigant used for each canal was the same in all the groups (a total of 30 ml of NaOCl was used during the instrumentation, in addition to that 10 ml of saline, followed by 10 ml of 2% chlorhexidine were used as the final irrigant). A size 20 K-file was placed at the established working length, and a radiograph was taken to confirm that the file was within the root canal to rule out any possibility of violation of apical constriction. Intracanal dressing was not given and closed dressing was given with Cavit-G (3M, St Paul, MN, USA). The patient was recalled after 24 h for evaluation of postoperative pain and tenderness. The patient was advised to take analgesic (Ibuprofen 400 mg, Abbot India Ltd, India) if there was an intolerable pain and were asked to mention on the pain score sheet. The patients were again recalled at the end of the third and the 7th day for the assessment of tenderness to percussion. At the end of the 7th day, if there was no pain or tenderness, temporary coronal filling was removed and the root canals were irrigated with 17% ethylenediaminetetraacetic acid and sodium hypochlorite to remove the smear layer. The root canals were then obturated with gutta-percha and AH-26 sealer by cold lateral compaction technique and temporary coronal filling was given.
Sample size, analysis of postoperative pain, and statistical analysis
The sample size calculation was performed using N-master sample size calculator (Christian Medical College, Vellore, India) based on a pilot study of 10 patients/group. The sample size was 21 per group (α-error = 0.01; power [1-β] = 99). The sample size was decided as 50 per group taking into consideration possible dropouts.
During the follow-up recall, the responses were recorded as no pain, slight, mild, severe, very severe, and extremely severe and scores from 0 to 5 were attributed to each kind of pain [Table 1]. The pain scoring sheet along with the pain scale (HP VAS) was given to the patient and directed to score every 12 h. The patients were followed up by the nurse to ensure that they scored every 12 h. Tenderness was evaluated to mild percussion and was recorded from 0 to 3 representing no pain, mild pain, moderate pain, and severe pain. Tenderness to percussion was recorded at the end of the 1st, 3rd, and 7th day. The findings were recorded on an Excel spreadsheet (Microsoft Corp, Redmond, WA) for statistical evaluation using Mann–Whitney U-test to determine significant differences at P < 0.01. The evaluation of tenderness was done by the third investigator (NG) who did not know which group the patient belonged to. In this study, double blinding was done as both the patient and pain/tenderness assessor (NG) was blinded. The operator could not be blinded about the instrument used for obvious reasons.
| Results|| |
Of the enrolled 204 patients, only 150 patients (n = 50/group) received the intervention. Seven were lost (number of patients in Group 1, 2, 3 were 2, 3, 2, respectively) as they did not report for the follow-up visits due to personal reasons. The details of the number of patients enrolled, allocated, and analyzed is represented in the consort flow diagram [Figure 1]. The gender distribution of male/female was 84/59 [Table 2]. The detail of patients in each group is shown in [Table 3]. No patient experienced more than level-3 pain, and the number of patients who had to take analgesic to alleviate pain was seven out of the total of 143 patients. The mean of age of the patients, gender distribution and the number of patients who took analgesic are shown in [Table 3]. The PIP and tenderness were significantly less (P < 0.01) in Mtwo group when compared to ProTaper and K3 groups up to 84 h and 72 h, respectively. There was no significant difference (P > 0.01) between ProTaper and K3 both in PIP and tenderness [Figure 2] and [Figure 3]. The number of patients who experienced no pain was also higher for Mtwo group when compared to ProTaper or K3 groups. Tenderness to percussion also showed a similar pattern (i.e.,) with Mtwo group exhibiting less tenderness when compared to ProTaper and K3 between 24 h and 84 h (P < 0.01) but no difference at 168 h (P > 0.01).
|Table 3: Descriptive analysis of patient age, gender and analgesic intake|
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| Discussion|| |
In the present study, instrumentation with Mtwo showed a lower incidence of PIP and tenderness when compared to ProTaper and K3, though there was no difference between the instrumentation with the latter. The null hypothesis was therefore rejected as there was a difference between the PIP experienced with the instruments studied.
The number of patients who did not experience PIP in the first 24 h was also significantly more in Mtwo group when compared to ProTaper or K3, which were 14, 3, and 5, respectively. Similarly, the number of patients who took analgesics was 1, 3, and 2, respectively. Only the patients who experienced level-3 pain took analgesics and two patients in ProTaper group did not take analgesic despite experiencing a level-3 pain. Results of patients who took analgesics were also included for statistical analysis as leaving them out could alter the real number and level of pain experienced in that group.
ProTaper, Mtwo, and K3 rotary systems were selected for this study because of the difference in design characteristics. Instrument design can affect the apical debris extrusion, mechanical stress on the root canal wall, etc. Although the PIP can be multifactorial, in the present study, sufficient care was taken to rule out preoperative factors and to minimize any intraoperative causes of PIP. The inclusion criteria in this study were stringent to prevent any possible bias in the result, as preoperative pain is an important indicator for PIP. Only those teeth with asymptomatic irreversible pulpitis without apical periodontitis were selected in this study. Care was taken to avoid the difference in the age of the patient, the anatomy of root canal both in terms of number of canals, canal type, maintenance of working length, prevention of violation of apical constriction, etc.
Although endodontic instrumentation is aimed at the elimination of endodontic microflora and prevention of apical periodontitis, a mild PIP in the form of apical periodontitis is inevitable.,, Apical periodontitis may be influenced by several features of root canal preparation such as mechanical stress, apical debris, irrigant extrusion, and apical patency verification.,,,, Such interappointment pain will be more often a result of an imbalance in host-bacteria relationship induced by intracanal procedures. An interappointment pain of moderate-to-severe intensity with/without swelling is rather unusual. Nevertheless, studies establishing the amount of PIP induced by instrumentation are important to enable operators to reduce discomfort to their patients.
The factors in PIP can be microbial and nonmicrobial. Sufficient care was taken in this study to avoid nonmicrobial causes such as over-instrumentation or a difference in irrigants that could have extruded into the periapical area. The microbial factors include apical debris extrusion, incomplete instrumentation and secondary intraradicular infection, of which only the difference in debris extrusion could have arisen as a factor in this study. Although previous studies have proven that placement of intracanal medication is important to eradicate the residual bacteria from the root canal system in addition to chemomechanical procedures, interappointment medication was not used in our study to reduce the number of confounding variables on postoperative pain.
The less PIP in Mtwo could be related to its S-shaped profile section, which gives the instrument a smaller core diameter, providing enough space to accumulate debris. These instruments also have a positive rake angle, which makes it more efficient, and in conjunction with their variable helical angle and pitch, the debris would tend to move coronally. On the other hand, the ProTaper group showed the highest PIP, and this could be explained by the convex triangular cross-section and reduced depth of flutes in the shaping files and F1. This design limits the accommodation of debris produced during instrumentation and therefore decreases coronal movement of debris. The cross-section in these ProTaper instruments do not provide sufficient space for the accumulation of debris, and along variable tapers the instrument facilitates apical extrusion by acting like a piston. Although previous studies have shown different conclusions on the apical extrusion of ProTaper and K3, there was no statistically significant difference in this study in terms of PIP.,
When the periapical area is challenged with extruded debris, the host immune system responds with an increase in acute inflammatory reaction to reestablish the equilibrium at the periapical area. The severity of periapical inflammation is directly proportional to the quantity of apically extruded debris, and the mechanical stress exerted on the tooth. A study on neuropeptide release has shown that root canal instrumentation increases substance-P and calcitonin gene-related peptide expression in periodontal ligament, which could generate an inflammatory process in the periapical tissues resulting in PIP. This neuropeptide release was reportedly highest with ProTaper and least with Mtwo system. Moreover, it is known that root canal instrumentation significantly influenced the incidence of dentinal defects., The higher incidence of cracks in ProTaper when compared to Mtwo in another study shows that there is a greater incidence of stress on root canal wall, resulting in higher incidence of cracks. These defects may be caused by the stress generated during mechanical instrumentation. Such stress on the root canal wall could also be a contributing factor to a greater inflammatory response and therefore the PIP.
Although the stringent selection criteria, care should be taken in application of the result in every clinical situation because of the following reasons:
First, the experience of pain is highly subjective and may vary among different subjects. Second, the apical (3 mm) taper of ProTaper was 0.08 followed by a smaller taper, whereas, the other two files were of a constant 0.06 taper, which means there could have been a greater apical extrusion and therefore more PIP. Third, despite the fact that the mean of the age was similar, there could have been a difference in the size of the canal and therefore a difference in apical extrusion and PIP.
| Conclusion|| |
Within the limitations of this study, it can be concluded that endodontic instrumentation causes some degree of PIP and tenderness to percussion. Among the instruments used Mtwo causes significantly less PIP and tenderness when compared to ProTaper and K3, and there was no statistically significant difference between ProTaper and K3.
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Conflicts of interest
There are no conflicts of interest.
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Source of Support: None, Conflict of Interest: None
[Figure 1], [Figure 2], [Figure 3]
[Table 1], [Table 2], [Table 3]