Pre-operative Analgesics for Postoperative Pain Relief After Dental Treatment
Phase: EARLY_PHASE1
Conditions: Pain, Postoperative, Analgesia
Sponsor: Hadassah Medical Organization

 
 
 
 
Pre-operative analgesics for postoperative pain relief after 
dental treatment 
 
 
NCT02393339 
 
Research protocol       29.12. 2014 
 
 

Background:  
Patients associate dental treatment with pain. An experience of poorly managed pain 
related to dental procedure can cause avoiding looking for further treatment, and 
make patients more challenging to treat (1). The management of pain is of particular 
importance in pediatric dentistry where patient's perceptions of dental treatment are 
being established. 
Pain control is routinely achieved through the use of local anesthetic (LA) solutions 
injected into the soft tissues during treatment. However, pediatric studies have shown 
that 38% of treated children still reported postoperative dental pain, with the highest 
being after root canal therapy, stainless steel crowns and extractions (2). 
There may be a role for preoperative analgesics in the management of pain in 
children. 
Several studies found that preoperative use of Ibuprofen and Paracetamol may 
provide a pre-emptive analgesic effect in pediatric patients following extraction 
treatments under local LA and following orthodontic separator placement without LA 
(3-5). 
The use of preoperative analgesics postoperative pain in adults is well established in 
medicine. Use of preoperative oral analgesics for children undergoing dental 
treatment under general anaesthesia (GA) is also routine. 
A Cochrane review conclusions from the available evidence couldn't determine 
whether or not preoperative analgesics are of benefit in pediatric dentistry for 
procedures under local anesthetic, and further randomized controlled clinical trials are 
needed (6). 
 
Objective: to compare the efficacy of the pre-operative administration of Paracetamol 
and placebo in reducing postoperative pain after routine dental treatment in children. 
 
Rationale: Use of preoperative oral analgesics for children undergoing dental 
treatment under GA is routine. Use of preoperative analgesics in children undergoing 
dental treatment with LA has the potential to reduce postoperative discomfort and 
pain. Prediction and treatment of post-operative pain should be an integral part of 
professional pediatric care. 
 
Materials and methods:  

This study will be a prospective, placebo-controlled, randomized, double-blind trial. 
400 boys and girls 5-12 years old, healthy, in need of dental treatment with local 
anesthesia of Lidocaine 2% with adrenalin 1:100,000 in the Hadassah School of 
Dental Medicine will take part in the study. Exclusion criteria: preoperative pain, 
patients taking analgesics within 5 h prior to the dental treatment, allergic reaction or 
adverse effect to paracetamol, not available (by phone) at least 2 hours after 
treatment. 
Study group: 200 children will receive paracetamol (15 mg/kg) 15 min before the 
dental treatment. 
Control group: 200 children will receive placebo 15 min before dental treatment. 
Randomization: every day a different unnamed but numbered bottle of 
medication/placebo (1-paracetamol or 2-placebo) will be available at the dental clinic. 
The bottles will look the same and will be marked 1 or 2. The patients will be 
assigned to the study group or the control according to the day of the treatment.  
Blindness: the patient, the treating dentist, and the interviewer will be blind to the 
medication. 
Data collection:  age, gender, type of treatment, type of LA (infiltration /block), time 
of taking the preoperative analgesic, type of preoperative analgesics ( 1 or 2), time at 
the end of the treatment and baseline apprehension.  Baseline anxiety will be recorded 
prior to the procedure using Facial Image Scale (FIS) (7). FIS is a valid means of 
assessing child dental anxiety status in a clinical context. It comprises a row of five 
faces ranging from very happy to very unhappy. Each face has a numerical value, 
from 1 to 5. The children will be asked to point at which face they feel most like at 
that moment, before the beginning of dental treatment. 
 
 
 
Main outcome measure: one of the main investigators will interview the patient at 
three time points:  immediately at the end of the treatment, one hour after taking the 
pre-operative analgesic and by phone 2.5 hours after taking the pre-operative 
analgesic. The patient and his parents will be asked if the child is crying (yes/no), 
complaining about pain (yes/no), needed a different kind of analgesics after the 

treatment (yes/no). In addition, each child will describe his ⁄ her feelings regarding 
postoperative pain, using the Wong-Baker Facial Rating Pain Scale (8). This scale 
measures the unpleasantness or affective dimension of a child’s pain experience, and 
is used with children aged 3–17 years old. The child is shown a set of six cartoon 
faces with varying facial expressions from smile ⁄ laughter to tears. Each face has a 
numerical value, from 0 to 5. The child selects the facial expression that best 
represents his ⁄ her experience of discomfort, the face ‘which look like how you feel 
deep down inside, not the face you show to the world’. The facial pain scale shows 
good construct validity as a self-report pain measure.  
The first two parts of the questionnaire (time 0, 1 h) will be answered in the clinic and 
the last part (time 2.5 h) by phone; the children will have the scale with the faces with 
them. 
 
 
 
 
Statistical analysis plan 
McNemar test - to analyze categorical variables difference (Wong-Baker Facial 
Rating Pain Scale) at two-time points. Chi-square and Fisher's exact test- for 
correlations between two categorical variables (between gender/ local anesthesia 
method/ baseline anxiety/ type of dental treatment/ type of behavior management 
technique/ Wong-Baker Facial Rating Pain Scale and group, and between type of 
behavior management technique/ type of dental treatment and Wong-Baker Facial 
Rating Pain Scale). Student's t-test was - for comparison of quantitive variables 
among two groups (participants' age, treatment length). Kruskal-Wallis test - for 
comparing different age groups and the Wong-Baker Facial Rating Pain Scale. 
Spearman's rank correlation coefficient - to assess the relationship between baseline 
anxiety and Wong-Baker Facial Rating Pain Scale. 
 

References:  
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2. Ashkenazi M, Blumer S, Eli I. Post-operative pain and use of analgesic agents 
in children following intrasulcular anaesthesia and various operative 
procedures. British Dental Journal 2007;202(5):E13.  
3. Baygin O, Tuzuner T, Isik B, Kusgoz A, Tanriver M. Comparison of pre-
emptive ibuprofen, paracetamol, and placebo administration in reducing post-
operative pain in primary tooth extraction. International Journal of Paediatric 
Dentistry 2011;21(4):306–13.  
4. Primosch RE, Nichols D, Courts FJ. Comparison of preoperative ibuprofen, 
acetaminophen and placebo administration on parental report of postextraction 
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TT.  
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