Successful local anesthesia is the basis of endodontic management of symptomatic teeth. However, the dental anesthetic injections have a limited success rate in the first attempt. The success rate decrease in the presence of a preoperative pain. The inferior alveolar nerve block (IANB) is particularly notorious with high anesthetic failure rates especially in teeth associated with symptomatic pulpitis .^1-10  To achieve painless treatment in patients with a failed primary IANB, supplementary anesthesia has been advised . Supplementary intraligamentary (or periodontal injections) and intraosseous injections have shown promising results .^1,2,11  The aim of the supplementary injections is to deposit the local anesthetic solution in the cancellous bone close to the root apex . An intraligamentary injection is actually a form of intraosseous injection since the local anesthetic solution is forced via perforations in the dental socket to the cancellous bone around the root . ^11-14

Review of literature: Endodontic treatment can cause the release of inflammatory mediators into the surrounding periapical tissues.¹ Thus, pain fibers are directly stimulated or sensitized by prostaglandins in situ.^3-5 In addition, the vascular dilation and increased permeability as consequences of periradicular inflammation cause edema and increased interstitial tissue response. ^3-5 Considering the role of prostaglandins on endodontic pain, a possible strategy for reduction of postoperative endodontic pain might be the local use of an anti-inflammatory agents adjacent to the inflamed tooth to decrease the production of inflammatory mediators and improve the efficacy of local anesthetics. The intraligamentary injection was introduced by Malamed in 1982 as an alternative to the conventional inferior alveolar nerve block.¹² Since then it has been evaluated both as primary injection and as a supplementary injection.^15-18 Kaufman et al compared the anesthetic efficacy of plain 2% lidocaine with 2% lidocaine with 1:50,000 epinephrine.¹⁹ The authors reported that duration of anesthesia with plain lidocaine was 1.02 min, while lidocaine with epinephrine had pulpal anesthesia of 27.05 min. Majority of the studies evaluating intraligamentary injections have been performed on asymptomatic teeth. ^18-21  Very limited research has been dedicated to the evaluation of different variables in intraligamentary injections in patients with symptomatic irreversible pulpitis.

Aim :

To comparatively evaluate the anesthetic efficacy of intraligamentary injection of 0.8mL of diclofenac sodium (75mg/3ml) vs. active placebo (0.8ml of 2% lidocaine) after a failed inferior alveolar nerve block (IANB), in patients with symptomatic irreversible pulpitis.

Objective :

 1. To achieve painless treatment in patients with a failed primary IANB. during the endodontic management of symptomatic mandibular first/second molar.

 2. To evaluate the heart rate during and after intraligamentary injections.

The null hypothesis will be that different anesthetic solutions have no effect on the anesthetic success rate or the heart rate.

Materials and Methods:

Methodology:  Prospective, randomized, double-blind clinical trial

Site               :  Conservative Dentistry, Faculty of Dentistry, Jamia Millia Islamia 

              N    : 30 patients each group

 Patients experiencing a failed primary IANB shall be enrolled for the study. The initial failure will be defined as pain (score more than 54 on Heft Parker Visual  Analog Scale (VAS) during access cavity preparation or at root canal instrumentation stage.²² The primary outcome (endpoint) will be defined as “success or failure” which will be indicated as the ability to undertake pulp access and canal instrumentation with no or mild pain. The secondary outcome will be the evaluation of heart rate after supplementary intraligamentary injections.

                   A tentative sample size calculation has been performed using data from a previous study , keeping the α level type I error at 0.05 for a single-tailed test and β level type II error at 0.20.¹⁹ The analysis indicated that a sample size of 30 subjects would give 80% power to detect a 25% difference in the success rates of the two different supplemental intraligamentary injections. For heart rate analysis, it has been calculated that a minimum of 23 patients per group shall be required to detect a difference of 10 beats per minutes (with the baseline heart rate of 72 beats per minutes).

                 The treatment procedure and the use of pain scales will be explained to the patients. A combined VAS, Heft-Parker scale (HP VAS), will be used in the present study. ²²

Inclusion criteria :

1. Symptomatic carious exposed mandibular first or second molars.
2. Positive and prolonged response to thermal sensitivity tests and electric pulp test.
3. Vital coronal pulp on access cavity preparation.
4. American Society of Anesthesiologists class I or II medical history.
5. Ability to understand the use of pain scales.

Exclusion criteria

a.       Active pain in more than 1 teeth.

b.      Teeth with fused roots.

c.       Radiographic evidence of an extra root.

d.      Large restorations with overhanging margins.

e.       Full crowns or deep periodontal pockets.

f.       Known allergy or contraindications to any content of the local anesthetic solution or NSAIDs

g.      History of known or suspected drug abuse.

h.      Taking any drugs which could affect the pain perception, e.g, opiods, antidepressants, anticonvulsants, muscle relaxants, anxiolytics, sedatives, nsaids. ²³

i.        Pregnant or breastfeeding patients.

j.        Patients with asthma, gastric ulcers, bleeding disorders.

All patients will receive a primary IANB injection using 1.8 mL of 2% lidocaine with 1: 80 000 epinephrine using a direct Halsted approach. The needle will be inserted until bony resistance will be felt. After reaching the target area, aspiration will be performed, and the solution will be deposited over a period of 60 seconds. After 10 minutes, the patients will be asked about the lip numbness. Patients without profound lip numbness will be excluded from the study since the block will be considered as ‘missed’. A conventional access opening will be initiated after isolation with a rubber dam. Patients will be instructed to raise their hand if any pain will be felt during the procedure. In case of pain during treatment, the procedure will be stopped, and the patients will be asked to rate the pain on the HP VAS. The patients with failed primary IANB will receive supplementary intraligamentary injections of 0.8mL of diclofenac sodium (75mg/3ml) or 0.8ml of 2% lidocaine. The injections will be masked with an opaque tape and will be coded with an alpha-numeric code. The code will be broken only after the completion of the study. The patients will be randomly allocated to two treatment groups (n=30per group) with the help of an online random generator. The rubber dam will be removed and the site of the injection will be cleaned with an antiseptic solution. The resting heart rate will be monitored with a finger pulse oximeter by a faculty member. The first group will receive intraligamentary injections of 0.8mL of diclofenac sodium (75mg/3ml). The injections will be administered using a pressure type syringe (Osung Deosy, Pearland, Tx, USA) and 30 gauge short needles (Septojet needles, Septodont). The second group will receive intraligamentary injections of 2% lidocaine with 1 : 200 000 epinephrine. In both the groups, a total of 0.8 mL of anesthetic solution will be deposited. The heart rate will be measured at 15-second interval till 5 minutes after intraligamentary injections. Success will be again defined as no pain or faint/weak/mild pain during endodontic access preparation and instrumentation.²¹

Statistical analysis: The results will be tabulated in contingency tables. The age of patients will be analyzed using Mann-Whitney U test at P < .05. The gender and distribution of teeth will be analyzed using 2X2 contingency tables and chi-square tests. The anesthetic success rates will be analyzed with Pearson chi-square test. The heart rate changes will be analyzed using t-test.

Source of funding: None

Conflicts of interest: None

Work schedule        : the study is expected to be completed in 2 months

Technical support required: None