Influence of Three Different Instrumentation Techniques on the Incidence of Postoperative Pain After Endodontic Treatment

Objective: To evaluate the influence of three different instrumentation techniques on the incidence of postoperative pain after endodontic treatment. Material and Methods: Ninety permanent single rooted mandibular premolar with sign and symptoms of nonvital teeth were selected. Patients were randomly divided into three different groups according to the type of instrumentation: Group 1= Reciproc; Group 2= Twisted File in continuous motion and Group 3= WaveOne. Oburation was done with corresponding guttapercha points using zinc oxide eugenol sealer. The intensity of pain was recorded by the patient using visual analogue scale, after 2hr, 6hr, 12hr, 48hr and 3 days of completion of obturation. Data analysis was done using Wilcoxon signed-ranks test. The level of significance was set at 5%. Results: For Group 1 at 12 hours mean was 4.53 + 1.9 and median was 5. The mean value increased from 2 hours to 6 hours upto 12 hours and decreased after 48 hours till 3rd day. For Group 2 at 12 hours mean was 2.80 + 0.71 and median was 3.00. The mean value increased from 2 hours to 6 hours upto 12 hours and decreased after 48 hours till third day. For Group 3 at 12 hours mean was 4.77 + 1.81 and median was 5.00. Mean value increased from 2 hrupto 12 hr and decreased from 12 hours upto third day. At interval from 2-48 hours there is no significant difference seen between 3 groups and at 2 hours-3 days interval significant difference was seen in first group, but no significant results were seen between group 2 and group 3. There was no significant difference seen between all the groups at the interval of 6-12 hours (p>0.05). Conclusion: Pain score was less in case of Twisted File continuous motion technique while it was more in WaveOne and Reciproc technique.


Introduction
Endodontic treatment can be completed in either single or multiple visits [1,2].Previous study has shown that better performance of single visit root canal therapy over multiple root canal therapy.So when compared to multiple visit endodontics single sitting is preferred [3].
The latest instrumentation technique to improve the simplicity and treatment safety [4][5][6].
Biomechanical preparation plays an important role in endodontic therapy.During this phase little, inadvertent extrusion of debris and irrigants into periapical tissues may occur both with manual stainless steel or nickel titanium rotary instrument techniques.Latest studies have shown that reciprocating instrumentation technique significantly increases the amount of debris extruded periapicallywhich may result in postoperative pain [7][8][9].
Therefore, this in-vivo study evaluated and compared the influence of three different instrumentation techniques on the incidence of postoperative pain after endodontic treatment.

Study Design and Sampling
This study was conducted in the Department of Conservative Dentistry and Endodontics, Bhojia Dental College and Hospital, India.Ninety permanent single rooted mandibular premolar with sign and symptoms of non-vital teeth were selected for the study.
The following inclusion criteria were adopted: single rooted mandibular premolars in healthy patients ranging age group of 18-45 years were selected.The teeth showed signs of necrotic pulp / irreversible pulpitis required endodontic treatment.Asteeth with periapical radiolucency, root or bone resorption, and poor periodontal support were excluded from the study.

Data Collection
Detailed history and thorough clinical examination were done before treatment procedure was started.Preoperative radiographic examination was performed before proceeding with the actual procedure.Procedure started with inferior alveolar nerve block followed by rubber dam application, caries excavation and access preparation.Pulp was extirpated using # 10 K file (Dentsply Maillefer, Ballaigues, Switzerland) and a glide path was made using #20 hand K files (Dentsply Maillefer, Ballaigues, Switzerland).Working length was determined using # 15 K file (Dentsply Maillefer, Ballaigues, Switzerland) with apex locator and was verified with radiovisiography.
Patients were randomly divided into three groups: Group 1 (n = 30): cleaning and shaping was done with # 25/8% Reciproc file VDW (VDW GmbH, Munich, Germany) using reciprocating motion till the working length; Group 2 (n = 30): cleaning and shaping was done with # 30/4% Twisted File TF (Sybron Dental Specialties Inc., Orange, CA, USA) using continous motion till the working length and Group 3 (n = 30): cleaning and shaping was done with #25/8% WaveOne file (Dentsply Maillefer, Ballaigues, Switzerland) using reciprocating motion followed by copious irrigation with 3% NaOCl and 0.9% normal saline.Canals were dried with paper point and obturation was done with corresponding guttapercha point (Tanariman Industrial LTDA., Manaus, AM, Brazil) using zinc oxide eugenol sealer (Dental Products of India -DPI, New Delhi, India).
The intensity of pain was recorded by the patient using visual analog scale, after 2hr, 6hr, 12hr, 48hr and 3 days of completion of oburation by the patient himself.

Data Analysis
The comparison of mean standard deviation and median of pain score within the three groups on all the days was done using Wilcoxon Signed-Ranks Test (p<0.05).

Ethical Aspects
Approval was granted by Ethical Committee and consent form was obtained from each patient prior to treatment.

Results
For Group 1 at 12 hours mean was 4.53 + 1.9 and median was 5.The mean value increased from 2 hours to 6 hours upto 12 hours and decreased after 48 hours till 3rd day.On third day mean was 0.50 + 0.77 and median was 0.00.For Group 2 at 12 hours mean was 2.80 + 0.71 and median was 3.00.The mean value increased from 2 hours to 6 hours upto 12 hours and decreased after 48 hours till third day.Mean value 0.20+ 0.40 and median value 0.00 on third day.For Group 3 at 12 hours mean was 4.77 + 1.81 and median was 5.00.Mean value increased from 2 hr upto 12 hr and decreased from 12 hours upto third day.On third day it became 0.40 + 0.621 with median value 0.00 (Table 1 and Figure 1).At interval from 2-6 hours, 2-12 hours, 2-48 hours there is stastical significant difference between three groups (p<0.05).At time interval of 2 hours-3 days, no significant difference was seen in first and third group (p>0.05),but significant results were seen in Group 2 (p<0.05).There was significant difference seen between all the groups at the interval of 6-12 hours (p<0.05).The results were significant in Groups 1 and 2 from 6 hours to 48 hours, but non-significant in Group 3.After that significant difference was seen between 3 groups at the interval of 6 hours to 3 days, 12 hours to 48 hours, 12 hours to 3 days and 48 hours to 3 days (p<0.05)(Table 2).

Discussion
Managing pain is a challenge in clinical practice of endodontics, and the main aspect by which the skill of the clinician is often judged.Post-endodontic pain has been associated with mechanical factors, including root canal instrumentation techniques, over-instrumentation or extrusion of root-filling materials [1].
Root canal treatment can be performed either in a single or multiple visits.Historically, single-visit procedure can be traced through the literature for at least 100 years.Yet most practitioners practice multiple visit approach [10].Previous authors compared single visit root canal therapy and multiple visit root canal therapy and observed no statistical difference in postoperative sequelae in both therapies [7].A previous study showed that single-visit root canal therapy had better performance than the multiple visit, which had as disadvantages the loss of provisional restoration, inter appointment leakage, fracture of tooth and loss of time [3].
A previous study histologically evaluated cleaning effectiveness of two reciprocating singlefile systems in severely curved root canals i.e.Reciproc versus WaveOne.Both systems presented similar effectiveness for root canal cleaning [11].One study compared the available reciprocating systems, Reciproc and WaveOne, using a meta-analysis with different parameters.A comprehensive electronic literature search for Reciproc and WaveOne using PubMed and Google scholar was initially conducted in September 2014 and updated in September 2016.This study supports the finding that Reciproc is more resistant to cyclic fatigue than WaveOne.However, with regard to other parameters, mixed results were obtained [12].
Some authors evaluated the amount of apically extruded debris following root canal preparation with ProTaper Next (PTN), Twisted File and WaveOne Gold.They concluded that the PTN system extruded more debris than the TF and WOG systems.The TF and WOG systems were faster than the PTN system [13].
There are various factors that reduces the post-operative discomfort viz prevention of apical transportation, preservation of original shape and lack of canal obliterations.Besides these anatomical factors, the mechanical factors i.e. instrument design speed experience and irrigants also affect the post-endodontic pain.New instrumentation techniques have been recently commercialized to improve simplicity and safety of treatment by using reciprocation motion instead of continuous rotation and by reducing the number of nickel titanium (NiTi) instruments and consequently instrumentation time [7,8].
More precisely, a few years ago Dentsply-Maillefer and VDW GmbH have developed two different nickel titanium instruments of greater tapers which are designed to be used with an innovative, proprietary reciprocating movement, and allow root canals to be prepared with one single instrument: in majority of cases a taper #25/8% instrument is selected.The two abovementioned instruments are slightly different in design and motion, but performance is quite similar [5,6].In this study we have used three rotary systems i.e Reciproc and WaveOne in reciprocating motion, also twisted files using continuous motion.Instrumentation with Reciproc and WaveOne using reciprocating showed more apical extrusion of debris as compared with twisted files using continuous rotation motion.A probable reason finding is that reciprocating motion tends to pull dentinal debris into the flutes of the files directs it toward the apical aspect of the canal.
This study showed that twisted files resulted in less postoperative pain.It could be because twisted files shape the canals better than the single file system that is WaveOne and Reciproc as its cutting flutes are manufactured by twisting the files not grinding.Also files are made by advance surface conditioning treatment.Twisted file when used in continuous motion require less inward pressure and remove the debris out of canal, which results in lesser incidences of postoperative pain.
The other reason might be attributed to the three proprietary processes to deliver and surpassed strength flexibility and cleaning efficiency.
The number of instruments within the sequence canal varies and adapt to canal anatomy, being the last instrumentof the sequence used only when a greater apical enlargement is needed due to larger original canal dimensions and/or enhanced final irrigation techniques.It is well known that a small, inadvertent extrusion of debris and irrigants into periapical tissues is a frequent complication during the cleaning and shaping procedures, both with manual stainless steel and nickel-titanium rotary instrumentation techniques [7,8].However, recent studies have shown that reciprocating instrumentation techniques seem to significantly increase the amount of debris extruded beyond the apex and, consequently, the risk of postoperative pain [8].A previous clinical study comparing Reciproc and NiTi rotary instruments has also confirmed these findings [14].
The present study was carried out in ninety patients.It is a small sample size to evaluate the various techniques.Further studies need to be carried out on a larger sample size and for a longer duration to further explore Visual Analogue Scale in various root canal techniques.

Conclusion
Pain score was less in case of Twisted File continuous motion technique while it was more in WaveOne and Reciproc technique.Reciprocating movement mimics the hand technique resulting in less file separation but it tends to extrude the debris past apical constriction, which may result in past endodontic pain.

a
Based on negative ranks; b Based on positive ranks; c The sum of negative ranks equals the sum of positive ranks; Wilcoxon Signed-Ranks Test; *Statistically significant.

Figure 1 .
Figure 1.Comparison of mean of all groups.
WaveOne and Reciproc are specially design NiTi files which work in similar but reverse, balanced force action using a pre programmed motor to move the files in back and forth reciprocating motion.The files are manufactured using M wire technology, improving strength and resistance to cyclic fatigue by upto nearly four times in comparison with other brands of rotary NiTi files.