Abstract
Objective: The
aim of this study was to evaluate the analgesic efficacy of preoperative versus
postoperative administration of diclofenac sodium in the prevention of the
postoperative pain following a lower third molar surgery.
Methods: A
prospective randomized clinical trial was conducted on 73 patients who
underwent surgical extraction of bilateral fully impacted lower third molars.
Patients were randomised into two groups: group I were started on diclofenac
sodium postoperatively, and group II were
started on diclofenac sodium preoperatively, both groups were then prescribed a
diclofenac sodium regimen for three days postoperatively and were advised to
resort to an additional analgesic (paracetamol/codeine tablets) as a rescue
medication when adequate relief from pain was not achieved. The analgesic
efficacy of both regimens was tested.
Results: Results showed a significant difference between the
two groups in terms of the analgesic efficacy in the first postoperative
day. Significantly less pain and less need for additional analgesia was
recorded in group II (p<0.05).
Conclusion: Preoperative treatment with diclofenac
sodium provides effective relief from
acute mild to moderate pain following third molar surgery compared to its
postoperative administration.
Key
words: Third molar surgery, Postoperative pain, Diclofenac
sodium, Pre-emptive analgesia.
JRMS
December 2009; 16(3): 26-30
Introduction
Third molar surgery is often performed on an
ambulatory basis, and postoperative pain is a common complaint following this
type of surgery. The trend towards day case surgery, with discharge on oral
medication has highlighted the need for effective and safe analgesics using
regimens that facilitate a rapid and swift recovery and quick discharge of
patients. The ideal analgesic regimen for day case surgery management should
provide good analgesia in the immediate period and enable early discharge
without sedation, dizziness, or psychomotor impairment commonly found with
opiates. This fact may need to be considered more seriously when we know that
the standard of postoperative pain management on surgical wards is inadequate
according to 50% of anesthesiologists, and 60% of inpatients report
pain-related problems on hospital discharge.(1)
Excellent pain control following third molar surgery
is essential for the delivery of optimal dental care and for the well-being of
patients. Although the current armamentarium of local anesthesia and analgesic
drugs are generally adequate, failure to control the immediate postoperative
pain is frustrating to both patients and clinicians.(2)
It is well known that the natural metabolites of
arachidonic acid, prostaglandins, and leukotrienes play a key role in the
inflammatory process, since they act as mediators and modulators of that
reaction by causing vascular dilatation, by increasing capillary permeability,
by producing hyperalgesia, and by promoting the migration of leukocytes and
macrophages to the site of inflammation. Since nonsteroidal anti-inflammatory
drugs (NSAIDs) inhibit the enzyme cycolooxygenase and thus reduce the synthesis
of prostaglandins PGE2 and PGI2, those drugs can be used for the control of
pain, trismus, and swelling.(3,4)
The NSAIDs are considered the optimum choice for the
management of postoperative pain following the surgical removal of third
molars. The short acting opioids such as fentanyl or alfentanil are often used
intra-operatively for more painful procedures; while the longer-acting opioids
such as morphine are best avoided in the day case patients, as their side
effects (nausea, vomiting, constipation and respiratory depression) are
deleterious and expensive and may be more common than generally believed.
Moreover the NSAIDs are superior to opioids in their anti-inflammatory action.(5,6)
Because pain after surgical removal of wisdom teeth is
expected, prevention of pain is a better management strategy than treating the
pain once it has occurred. Treating
patients before they develop pain is considered a more humanitarian and enlightened
approach to patient care and is consistent with the current trends toward more
aggressive, preventive, and systemic approach to pain management. This approach
will prevent or reduce the hyperalgesia state and inhibit inflammation and pain
by reducing the synthesis of prostaglandins in response to surgical trauma.
Moreover, it has become recognized that the longer pain remains uncontrolled,
the more sensitive the patient becomes to painful stimuli. Once nociception is
unregulated through both central and peripheral mechanisms, perception of pain
is altered, and hyperalgesia can occur. Also, the rapid or preoperative
analgesic intervention may prevent the upregulation (wind-up) of the nociceptve
system within the central nervous system.(7,8,9)
The aim of this study is to compare the analgesic
efficacy of preoperative versus postoperative administration of diclofenac
sodium in the prevention of the postoperative pain following lower third molar
surgery.
Methods
A prospective randomized clinical trial was conducted
on 73 patients who underwent surgical extraction of bilateral fully impacted
lower third molars at Prince
Ali Military
Hospital during the
period between March and December 2003. All cases involved bone removal as part of the surgical procedure
and were evaluated preoperatively by radiographs. All cases that showed only soft tissue
impaction were excluded from our trial. All patients were verbally consented
for the proposed surgical procedure and a full explanation was provided to
them.
Patients were divided randomly into two groups in a
simple alternate pattern. Group I (n=36)
patients were given 100mg of a sustained
release diclofenac sodium tablet one hour after surgery before leaving the day
case ward, and advised to take another 50mg tablet of diclofenac sodium 8 hours
later. On the second day they were
requested to take 150mg of diclofenac in three divided doses for three consecutive
days. Group II (n=37) patients received the same regimen except that they were
given their first dose of 100mg sustained release diclofenac sodium tablet two
hours prior to surgery, and then continued on the same analgesic regimen as the
first group. Patients in both groups were requested to resort to an additional
analgesic (paracetamol/ codeine tablets) as a rescue medication when adequate
relief from pain was not achieved.
All surgeries were performed in the operating theatre
by the same surgeon under local anesthesia and intravenous sedation. A
standardized technique involving the classical envelope flap with a sulcus
incision was used. All patients were discharged on the same day of surgery. The
study was conducted in the morning so as to allow for a long evaluation period.
The estimation of the complexity of the surgical procedure was based on
duration of the operation.
Patients with history of peptic ulcer disease, asthma,
haemorrhagic diathesis, or renal impairment were excluded from the study. All
patients were given the same antibiotic regimen of 500mg oral amoxicillin three
times daily, or erythromycin one gram twice daily.
Table I. Pain intensity in the two groups at different time
points
|
 Time Point
Pin
Score
|
6 hrs. Post Op.
|
12 hrs. Post Op.
|
|
Pain
score
|
0 & 1
|
2 & 3
|
0 & 1
|
2 & 3
|
|
Group
I
|
11 (30.55%)
|
25 (69.44%)
|
14 (38.88%)
|
22 (61.11%)
|
|
Group
II
|
19 (51.35%)
|
18 (48.64%)
|
22 (59.45%)
|
15 (40.54%)
|
Table
II. Need for additional analgesia in
both groups
|
Rescue Analgesia
Group
|
Yes
|
No
|
|
Group
I
|
19 (53.0%)
|
17 (47.0%)
|
|
Group
II
|
11(29.7%)
|
26 (70.3%) |
The patients were requested to provide an overall evaluation of the pain intensity in a form of 4-point numerical
scale, when pain is absent “0”, slight “1”, moderate “2”, or intense “3” at the
two time points: 6 hours following completion of surgery (the expected peak of
pain in the first postoperative day) and 12 hours following completion of
surgery. Each patient was given a special form to fill the pain score at the
two above mentioned time points, besides recording any additional analgesia
taken. All patients were reviewed on the
second postoperative day in our outpatient clinics, and data of their pain
scores was collected from them.
The pain-relieving efficacy for both regimens was
tested by comparing the number of patients experiencing severe or moderate pain
to the number of patients who reported slight or no pain at the two time
points. Nonparametric statistical analysis of the results was done by means of
a chi-square test.
Pain-relieving efficacy of each regimen was also
assessed by comparing the number of patients who resorted to the additional
rescue analgesia.
Results
In this trial we enrolled 73 patients (five patients were
dropped from the study for failure to fill the pain score forms properly) who
underwent surgical extraction of bilateral fully impacted lower third molars
who managed to fill the pain score forms correctly and were reviewed on the second
postoperative day; among them there were 32 male and 41 female patients. Their
age range was 18-39 years (mean = 28).
There was no significant difference between the two
groups in terms of the duration of the operations, which was used as an
indicator for the complexity of the surgical procedure; the mean duration in
minutes was 32 minutes for group I, and 30 in group II.
Table I summarizes data on the analgesic efficacy in
both groups throughout the 12-hour period after surgery. The mean pain
intensity scores at the first time point for the post treated group I was 2.45
and for the pretreated group II was 1.62, and at the second time point it was
2.40 for the post treated group, and 1.35 for the pretreated group. Statistical
analysis of these results shows that patients pretreated with diclofenac sodium
experienced significantly less pain throughout the 12-hour investigation period
compared to those who received the diclofenac sodium only postoperatively (p<0.05).
The number of patients who resorted to rescue
medication in both groups is shown in Table II. Among the pretreated group,
70.3% survived the first 12 hours following surgery without any need for rescue
medication, while only 47.2% in the post treated group managed without the need
for a rescue medication. Again these results show a significant difference
(p<0.05) between the two groups in terms of the analgesic efficacy in case
of preoperative administration of the nonsteroidal analgesic drug.
Discussion
Postoperative pain is
considered a main reason for the delayed discharge and unanticipated hospital
admission of outpatients. Efforts should be made to develop effective
strategies for the prevention and treatment of postoperative pain in the
ambulatory surgical patient.(10)
The debate on preoperative
administration of analgesics is not new, but unfortunately it is not common
practice among surgeons to start their patients on analgesia prior to surgery,
Ong et al. in their study comparing the effectiveness of preoperative
administration of a selective COX
2 inhibitor demonstrated a significant reduction in both the total analgesic
consumption and the need for rescue medications when it was administered
preoperatively compared to the postoperative treated group.(11) This supports the concept
of nociceptive upregulation of both peripheral and central nervous systems
leading to more intense postoperative pain.(11,12)
In this clinical trial we
focused on the operative day of surgery as there is a general consensus that
this is the critical period during which the pain peak occurs and most patients
tend to improve by the following days. The pain in this type of procedure
usually starts two hours after the procedure as the effect of the residual
local anesthetic wears off and the full inflammatory response to surgery evolves,
usually becoming most severe between 6-8 hours following surgery. Futhermore,
we excluded patients with serious diseases such as uncontrolled hypertension,
diabetes mellitus, blood diathesis, or any illness that might confound the
results of the study, as it is
speculated that pain existing prior to surgery may lead to central
sensitization, thus affecting postoperative pain evaluation.(13)
This study demonstrated that
pre-emptive administration of diclofenac sodium one hour preoperatively
resulted in lower pain experience compared to postoperative administration. The
preoperative administration of diclofenac sodium allowed the drug to reach
maximal plasma levels before the surgical incision, allowing enough time for
large concentration of the drug to be achieved at the target tissues before the enzyme cyclooxygenase was expressed as a result to
tissue injury. This is in agreement with previous research that studied the
effect of preoperative administration of indomethacin, that resulted in
significant reduction of postoperative pain and swelling.(14)
There is a lot of literature that contradicts the
results of this study or similar studies that support the importance of
pre-emptive analgesia. Campbell et al.
who found no clinical significance between patients taking preoperative
tenoxicam and alfentanil compared with those who did not take any in bilaterally
symmetrical oral surgery,(15) however Katz explained this as
failure of he surgeon to achieve a sufficient peri-operative nerve blockade or
to the development of central sensitization once the pharmacological action of
pre-emptive analgesia has worn off.(16)
Conclusion
NSAIDs are considered
excellent analgesics for preventing postoperative pain in third molar surgery.
Diclofenac sodium is an example of this group of analgesics. Preoperative
treatment with diclofenac sodium provides effective relief from acute mild to
moderate pain following third molar surgery.
We strongly recommend
preoperative administration of diclofenac sodium for prevention of postoperative
pain, as the analgesic and anti-inflammatory properties of non steroidal
anti-inflammatory drugs are best employed when given preoperatively before
tissue damage occurs and the whole inflammatory process takes place.
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