This research was conducted with the approval of the Institutional Review Committee (IRC number 077/19) in the duration from April 2019 to December 2019.
Endodontic treatment was performed in single or multiple visits of either vital or non-vital tooth and anterior or posterior tooth. Each patient was explained about the aims and design of the study, and informed written consent were obtained before their inclusion. The exclusion criteria were: complex cases such as pulp canal obliteration, procedural accidents, variable anatomy where maintaining patency is difficult, retreatment cases, teeth with periapical radiolucency and swelling, pregnancy patients who are medically compromised and patients under analgesic medication within last 3 days.
Sample size determination: The sample size calculation for each group was 36.8 with level of significance of 0.05, a power of 0.9, an effect size of 0.8 and standard deviation of 1.2 (15). One hundred seventy-eight subjects were included in the study after careful screening of patients reporting to Department of Conservative Dentistry and Endodontics, Universal College of Medical Sciences, Bhairahawa, Nepal.
The preoperative radiographic examination and clinical records were collected from all the patients, like preoperative pain, pulpal status, periapical status and group of the teeth (anterior or posterior teeth of any of the arch). The pulpal status was checked with electric pulp tester (Digitest™ Parkell Inc., USA) and Endofrost (Coltene/Whaledent GmbH and Co.KG). This was later reconfirmed upon access opening i.e presence of bleeding and on sensibility tests positive response implied for vital tooth similarly for non-vital tooth absence of bleeding and negative response on sensibility tests. The periapical status was checked by percussion, palpation and bite test. The cases diagnosed as symptomatic /asymptomatic irreversible pulpitis, pulp necrosis without periapical radiolucency and symptomatic apical periodontitis without periapical radiolucency were included in this study. Whereas symptomatic apical periodontitis with periapical radiolucency, asymptomatic apical periodontitis (which always shows periapical radiolucency), acute apical abscess and chronic apical abscess were excluded. The preoperative pain scores for eligible cases were recorded and noted in Numeric pain rating scale (NRS-11).
The 0-10 Numerical Rating Scale (NRS-11) was used in which patients were asked to mark the number between 0 and 10 that matched best to their pain intensity. Zero represents ‘no pain at all’ 1-3 mild pain, 4-6 moderate and 7- 10 severe pain. Preoperative pain scores were rated in the clinic and postoperative pain scores at 1st, 2nd and 7th day were recorded by patients at home. Patients were instructed to record pain scores before analgesic intake if required. The response proforma was collected on 7th day of follow-up.
The patients visiting the Department of Conservative dentistry and Endodontics were assessed for inclusion and exclusion criteria. Among those, 178 patients were preselected with almost equal subjects on the basis of group of teeth (anterior and posterior) and pulp status (vital and non-vital) and were enrolled in the study. These subjects were randomly allocated to one of the two groups: patency (Group A) and non-patency (Group B). An equal proportion of randomization allocation ratio for the two groups was done by shuffled deck of cards with number assigned (i.e. even number for patency group and odd number for non-patency group). Number of visits were allocated by another set of equal proportion of envelopes containing concealed assignment codes. After the start of the procedure, 18 cases were excluded again due to drop out (n=5), procedural difficulties (n=9) and to make equal cases in subgroups (n=4). The final sample was 160 patients. Endodontic treatments were performed by one endodontist in single and multiple visits and another blinded investigator evaluated and compiled the data.
Group Stratification:
Group A: Patency group (n=80)
- Sub-group A1: Single Visit(n=40)
Sub-division A1V: Vital teeth (n=20)
Division A1Va: Anterior teeth (n=10)
Division A1Vp: Posterior teeth (n=10)
Sub-division A1NV: Non-vital teeth (n=20)
Division A1NVa: Anterior teeth (n=10)
Division A1NVp: Posterior teeth (n=10)
- Sub-group A2: Multiple Visits(n=40)
Sub-division A2V: Vital teeth (n=20)
Division A2Va: Anterior teeth (n=10)
Division A2Vp: Posterior teeth (n=10)
Sub-division A2NV: Non-vital teeth (n=20)
Division A2NVa: Anterior teeth (n=10)
Division A2NVp: Posterior teeth (n=10)
Group B: Non-patency group (n=80)
- Sub-group B1: Single Visit(n=40)
Sub-division B1V: Vital teeth (n=20)
Division B1Va: Anterior teeth (n=10)
Division B1Vp: Posterior teeth (n=10)
Sub-division B1NV: Non-vital teeth (n=20)
Division B1NVa: Anterior teeth (n=10)
Division B1NVp: Posterior teeth (n=10)
- Sub-group B2: Multiple Visits(n=40)
Sub-division B2V: Vital teeth (n=20)
Division B2Va: Anterior teeth (n=10)
Division B2Vp: Posterior teeth (n=10)
Sub-division B2NV: Non-vital teeth (n=20)
Division B2NVa: Anterior teeth (n=10)
Division B2NVp: Posterior teeth (n=10)
Local anesthesia (2% lidocaine hydrochloride and epinephrine 1:200,000; Neon laboratories Ltd., India) using conventional nerve block techniques was given to all patients for ease of discomfort. Root canal procedure was started as per standard protocol under rubber dam isolation for all teeth. The access cavity preparation was done using round bur (SS White, USA) and Endo Z bur (Dentsply Maillefer, Switzerland) with high‑speed handpiece. Number 8 and 10 K‑file (Dentsply Maillefer, Switzerland) was used to negotiate the canals with the help of Glyde (Dentsply Maillefer, Switzerland). The WL was determined using Propex II apex locator (Dentsply Maillefer, Switzerland) and then confirmed radiographically with 15 K file. If there was disagreement between radiographic and electronic working length measurements, reading of the apex locator was selected.
The root canal treatment was done in either single or multiple visits. Cleaning and shaping of canals were done with hand K-files (Dentsply Maillefer, Switzerland) using step-back technique. For patency group (i.e. Group A), a size 10 K-file was passed 1 mm beyond the working length. The patency technique was done after each file used for step-back technique (i.e. sequential apical preparation files as well as sequential coronal preparation files). Likewise, for non-apical patency group (i.e. Group B) filing was done cautiously to prevent surpassing of patency file beyond the working length at all times during treatment. For both patency and non-patency groups, irrigation was performed with 5 ml of 5% sodium hypochlorite (NaOCl) solution (Dentpro, India) followed by sterile 0.9% saline (Axa Parenterals Ltd, India), and 2% chlorhexidine (Dentochlore, Ammdent, India) after each instrument change. For multiple visit (Group A2 and B2) cases, canal was medicated with calcium hydroxide (RC CAL Prime Dental products ltd,India), temporarily sealed with cavit (3M ESPE) and recalled after a week for follow-up. In single visit (Group A1 and B1) and asymptomatic multiple visit (Group A2 and B2) cases, the obturation was done in following steps: The master cone radiograph was taken to re-confirm the length. Canals were dried using paper points. AH Plus sealer (Dentsply Maillefer, Ballaigues, Switzerland) was applied on the walls of the canal. After that, obturation was done with lateral condensation technique and access cavity was restored using direct composite resin. Postoperative pain scores were recorded on Numeric pain rating scale forms by the patients on 1st, 2nd and 7th day.
Normality of the data was tested using Kolmogorov Smironov test. The data were not distributed normally hence, non-parametric test i.e Mann-Whitney U test was used. The relation between pre-operative pain and post-operative pain was evaluated by Spearman correlation test. Multiple linear regression analysis was done to assess the predictor of postoperative pain in patency maintained group.