Condition category
Oral Health
Date applied
Date assigned
Last edited
Retrospectively registered
Overall trial status
Recruitment status
No longer recruiting

Plain English Summary

Background and study aims
Root canal treatment is a common dental procedure used to treat an infection at the centre of a tooth in an area called the root canal system. The infection can be extremely painful, and the only way of treating it is to remove the bacteria from the root canal system (root canal treatment) or to remove the tooth. Root canal treatment is generally considered to be an extremely painful procedure, and so modern research into root canal treatment generally focusses on decreasing the pain for patients who may already be nervous of the treatment. The aim of this study is to investigate the pain relieving qualities of a new combination of clonidine (an anti-anxiety medication used in general surgery) with 2% lidocaine (the typical numbing medication used in the dental office) compared to normal treatment.

Who can participate?
Adults who require root canal treatment.

What does the study involve?
Participants are randomly allocated to one of two groups who each receive a different numbing treatment before having their root canal surgery. Those in the first group receive an injection into the gum (inferior alveolar nerve block) to numb the mouth using lidocaine (a local anaesthetic used by dentists) with epinephrine (adrenaline), which is the usual solution used for this procedure. Those in the second group receive the injection with the new solution made up of clonidine (an anti-anxiety medication used in general surgeries) and lidocaine. In both groups, their level of pain is assessed using a scale before the injection and then 6, 12, 24, 36, 48, and 72 hours afterwards.

What are the possible benefits and risks of participating?
The benefits to the patient include receiving a root canal performed by a root canal specialist. The risks involved are minimal as the patient requires the root canal to remove the dental pain and infection, and the novel anesthetic (clonidine + 2% lidocaine) has been proven to be safe in other studies.

Where is the study run from?
Isfahan University of Medical Sciences (Iran)

When is the study starting and how long is it expected to run for?
September 2014 to January 2016

Who is funding the study?
Isfahan University of Medical Sciences (Iran)

Who is the main contact?
Professor Elham Shadmehr

Trial website

Contact information



Primary contact

Prof Elham Shadmehr


Contact details

School of Dental Medicine
240 Squire Hall
3435 Main St
United States of America
+98 (0)716 829 6225

Additional identifiers

EudraCT number number

Protocol/serial number


Study information

Scientific title

The effect of clonidine as an adjunct to lidocaine on postoperative pain control following root canal treatment: a prospective randomized double-blind study


Study hypothesis

Addition of clonidine to 2% lidocaine will reduce postoperative pain after root canal treatment.

Ethics approval

Isfahan University of Medical Sciences, 14/04/2014, ref: 142287

Study design

Randomized controlled double-blind clinical trial

Primary study design


Secondary study design

Randomised controlled trial

Trial setting


Trial type


Patient information sheet

Not available in web format, please use contact details to request a participant information sheet


Postoperative pain after root canal treatment


Patients are randomised to one of two groups.

Group 1: Patients receive 1.8 mL of 2% lidocaine with clonidine (15 µg/mL) using a conventional inferior alveolar nerve block (IANB).
Group 2: Patients receive 1.8 mL of 2% lidocaine with epinephrine (1:80,000) using a conventional inferior alveolar nerve block (IANB).

All treatments are completed in a single-visit appointment. Pain scores are recorded preoperatively and at 6, 12, 24, 36, 48, and 72 hours after endodontic treatment using a Heft-Parker visual analog scale (VAS). Also, the total number of tablets of analgesics consumed by the patient are also recorded and analyzed by chi-squared, paired t-test and repeated measure of ANOVA (p<0.05).

Intervention type



Not Applicable

Drug names

Clonidine, lidocaine

Primary outcome measure

1. Pain scores, recorded using a Heft-Parker visual analog scale (VAS) preoperatively and at 6, 12, 24, 36, 48, and 72 hours after endodontic treatment
2. Number of pain medications consumed are recorded continuously for 72 hours postoperatively

Secondary outcome measures

Duration of postoperative pain is assessed using a visual analog scale (VAS) preoperatively and at 6, 12, 24, 36, 48, and 72 hours

Overall trial start date


Overall trial end date


Reason abandoned (if study stopped)


Participant inclusion criteria

1. Adult patients (18 years of age or older)
2. In good medical condition (American Society of Anesthesiologists classification 1)
3. Diagnosed with symptomatic irreversible pulpitis and normal/symptomatic apical periodontitis at the mandibular first or second molars

Participant type


Age group




Target number of participants


Participant exclusion criteria

1. Patients with active signs of oral infections or inflammation
2. History of addiction or use of ß blockers
3. Patients taking any medications that could affect anesthetic assessment (analgesics or opioids at least one week before treatments)
4. Patients with allergies or contraindications to the use of clonidine, epinephrine or ibuprofen
5. Female patients who were pregnant or breastfeeding
6. Patients with no response to cold testing
7. Perirapical pathosis (other than a widened periodontal ligament)
8. No vital coronal pulp tissue upon access cavity preparation (partial necrosis)

Recruitment start date


Recruitment end date



Countries of recruitment


Trial participating centre

Isfahan University of Medical Sciences
Hezar Jarib Street

Sponsor information


Isfahan University of Medical Sciences

Sponsor details

Hezar Jarib Street

Sponsor type




Funder type


Funder name

Isfahan University of Medical Sciences

Alternative name(s)


Funding Body Type

government organisation

Funding Body Subtype

government non-federal



Results and Publications

Publication and dissemination plan

Planned publication in the Journal of Dental Research.

IPD Sharing plan:
The datasets generated during and/or analysed during the current study are/will be available upon request from Dr Elham Shadmehr (

Intention to publish date


Participant level data

Available on request

Basic results (scientific)

Publication list

Publication citations

Additional files

Editorial Notes

29/01/2019: The intention to publish date has been changed from 25/12/2017 to 31/07/2019