effects of preoperative ibuprofen, anxiety...
TRANSCRIPT
EFFECTS OF PREOPERATIVE IBUPROFEN, ANXIETY AND GENDER ON POST
SEPARATOR PLACEMENT PAIN
By
CURTICE KARY MARRIS
A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE
UNIVERSITY OF FLORIDA
2004
ACKNOWLEDGMENTS
I thank my husband, Rod, for his love and support. I would not be where I am
today without his belief in me. I thank Dante and Mikey for their unconditional love over
the last seven years. I thank my son, Luke, for understanding all the extra time Mommy
had to spend on this project.
I thank the members of my committee Drs. Timothy Wheeler, Henrietta Logan,
Robert Yezierski, Roger Fillingim and Sue McGorray for their mentorship and guidance
throughout this project. I would also like to thank Marie Taylor for her help in
coordinating the development of my research.
ii
TABLE OF CONTENTS Page ACKNOWLEDGMENTS .................................................................................................. ii
LIST OF TABLES............................................................................................................. iv
LIST OF FIGURES .............................................................................................................v
ABSTRACT....................................................................................................................... vi
CHAPTER
1 INTRODUCTION ..........................................................................................................1
2 MATERIAL AND METHODS......................................................................................6
3 RESULTS .....................................................................................................................10
4 DISCUSSION...............................................................................................................15
LIST OF REFERENCES...................................................................................................20
BIOGRAPHICAL SKETCH .............................................................................................24
iii
LIST OF TABLES
Table page 1 Sample Size, Dosing and Dosing Times........................................................................6
2 Treatment Timeline........................................................................................................9
3 Baseline Characteristics. Mean (s.d.) for Groups A, B and C. ...................................10
4 Change in Pain between Day 1 and 2 for Masticatory Performance Index .................14
iv
LIST OF FIGURES
Figure page 1 Example of Visual Analog Scale used in pain diary, test of evoked pain and
anticipation of pain.....................................................................................................7
2 Mean VAS scores and standard error for chewing ......................................................11
3 Mean VAS scores and standard error for biting ..........................................................12
4 Mean VAS scores and standard error for fitting back teeth together. .........................13
5 Mean VAS scores and standard error for fitting front teeth together. .........................13
v
Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science
EFFECTS OF PREOPERATIVE IBUPROFEN, ANXIETY AND GENDER ON POST
SEPARATOR PLACEMENT PAIN
By
Curtice Kary Marris
May 2004
Chair: Timothy Wheeler Major Department: Orthodontics
A common experience during orthodontic treatment is that of pain. A significant
number of patients experience moderate to severe pain as a result of initial orthodontic
treatment. The purpose of this study was to assess the effectiveness of adding
preoperative ibuprofen to an ibuprofen regimen administered after separator placement in
reducing the incidence and severity of post-separator placement pain and to assess the
contribution of psychological factors and gender to the pain experience. Subjects were
selected from patients presenting for orthodontic treatment at the University of Florida
orthodontic clinics. This is an ongoing study with a current n=21 (10 female, 11 male).
Each subject was randomly assigned to one of three experimental groups: Group 1:
received 400mg ibuprofen 1 hour prior to separator placement (D1), 3 hours after
separator placement (D2) and 7 hours after separator placement (D3); Group 2: received
placebo at D1, 400mg ibuprofen at D2 and D3; Group 3: control group received placebo
at D1, D2 and D3. The investigator was blinded to the groups. Prior to separator
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placement, subjects completed a State and Trait Anxiety Inventory (STAI), Positive and
Negative Affect Scale (PANAS), a Masticatory Performance Index and a Visual Analog
Scale (VAS) for expected pain and pain experienced with the Masticatory Performance
Index. A pain diary was kept for 24 hours. A follow up Masticatory Performance Index
was performed at 24 hours.
Significantly less pain was experienced at 6 hours and at bedtime when ibuprofen
was administered both before and after separator placement. Pain with Masticatory
Performance Index showed a significant increase on day 2. Lack of significant
differences with regard to gender and psychological factors could be due to small sample
size.
vii
CHAPTER 1 INTRODUCTION
A common experience during orthodontic treatment is that of pain. A significant
number of patients experience moderate to severe pain as a result of initial orthodontic
treatment. 1-4 Although great inter-individual variation exists in orthodontic pain, 3 most
patients will experience the greatest amount of pain within the first three days following
initiation of orthodontic treatment. 2, 3 A study by Wilson et al.5 found that following the
placement of separators or arch wire, pain is present within 4 hours and continues until at
least 24 hours 1, 5 dissipating by day 7. 1, 5, 6
Pain is one of the leading reasons for the desire to discontinue orthodontic
treatment.7 Studies considering the factors associated with compliance have found pain
to be negatively correlated to compliance.6, 8, 9 Egolf et al. 8 asked an open-ended
question as to the reason noncompliant patients did not wear their headgear or rubber
bands. Pain was the most frequent reason cited for lack of compliance. The long-term
effects of poorly managed pain in childhood and adolescence produce anxiety in
subsequent pain situations, which in turn will amplify pain.10 For these reasons, control
of orthodontic pain should be a primary concern for the clinician and the patient.
Pain is a multi-dimensional sensation with contributions from cultural
background, past experience and psychological factors.1, 3, 11-13 A large inter individual
variation in reaction to noxious stimuli has been noted. 1-3
In a study by Firestone et al.,14 assessments were made of expectation of pain and
related side effects prior to orthodontic treatment and were compared to the perception of
1
2
pain during treatment. Standardized psychometric measures for pain and anxiety were
not used and, therefore, difficulties may exist in comparing data across studies.
However, the visual analog scale (VAS) was used which is valid and reliable, 1, 15 as well
as simple enough for children to respond to without adult help.16 Results of this study
find the expectation of pain is significantly correlated to perceived pain during treatment.
Commonly, women are thought to experience pain at a greater intensity, more
frequently and for a longer period of time than men.17, 18 However, some recent studies
on orthodontic pain have not seen this gender difference in pain.1-3, 6, 19 Anxiety has been
found to be a major factor in incidence and intensity of post-operative pain.14 The
expectation of greater amounts of pain is associated with greater amounts of reported
pain.14 An investigation into the reasons patients may avoid orthodontic treatment found
that in patients less than 18 years old, anxiety increases with age and is reported more
often by girls than boys.20 In support of this finding, Brown and Moerenhout report
adolescents to have lower scores of psychological well being and that they correlate with
higher levels of pain.13 Sergl et al. 6 have suggested that patients with an internal locus of
control, where the patient attributes treatment outcome to personal efforts, have a lower
pain perception.
Application of noxious stimuli initiates conduction of sensation through primary
afferent sensory neurons ultimately resulting in an increased sensitivity of nociceptors at
the site of application. This is called peripheral sensitization. The decreased threshold of
nociceptors leads to an increase of neuronal activity into the central nervous system
(CNS). This causes changes in the CNS that contribute to persistent pain. This is called
central sensitization. Both peripheral sensitization and central sensitization lead to
3
hyperalgesia. Hyperalgesia is an increased response to a stimulus that is normally
noxious.11, 17 Preemptive analgesia is an attempt to block central and peripheral
sensitization, thereby decreasing postoperative hyperalgesia.12
Studies into the effects of prostaglandin application on tooth movement 21, 22 have
found prostaglandins to enhance tooth movement in a nearly 2 to 1 ratio. Studies
assessing the effect of NSAIDs on tooth movement 23-25 have found that these drugs
cause a decrease in tooth movement due to their action in blocking prostaglandin
production. On the basis of these findings, it has been suggested that to avoid a decrease
in tooth movement, and subsequently an increase in treatment time, NSAID medications
should be avoided when controlling pain due to orthodontic treatment.23, 24 However,
prostaglandins are not the only mediators of bone resorption. Leukotrienes, cytokines
and growth factors may contribute to bone resorption.26 Saito et al.26 found that
indomethacin slowed tooth movement but did not stop it. Studies suggest that ibuprofen
has both a direct initial analgesic effect and an indirect delayed analgesic effect via
prostaglandin inhibition.27, 28 Tyrovola and Spyropoulos25 suggest only avoiding the
long-term administration of NSAID drugs. Short-term use of NSAIDs will only
temporarily reduce the levels of prostaglandins.29
A limited number of studies have focused on the control of pain in orthodontics.
In 1984, White 30 found that 63% of patients that chewed aspergum after an arch wire
change reported a decrease in discomfort. However, a placebo gum was not used and
therefore the effects of chewing gum alone cannot be separated from the effects of
chewing aspergum.
4
Ngan et al.,29 in a study comparing a pre-separator placement dose of ibuprofen
with aspirin and placebo, found ibuprofen and aspirin to provide significantly less pain
than placebo. Ibuprofen provided significantly less pain at 24 hours than aspirin. This
study concluded that ibuprofen is the analgesic of choice to control orthodontic pain.
Law et al.31 evaluated the effect of the administration of ibuprofen before
separator placement or after separator placement on reported pain over 7 days. At 2
hours, those subjects who took preoperative ibuprofen reported less pain than placebo or
postoperative ibuprofen groups. A small sample size may be a reason why no other
significant differences were detected. A relatively high number of placebo group
subjects sought rescue medication.
Bernhardt et al.32 compared the effectiveness of preoperative ibuprofen
administration to postoperative ibuprofen administration and a combination of pre and
postoperative therapies. At 2 hours, both groups that received preoperative ibuprofen
were found to have a significant decrease in pain severity. No significant differences
were found between the pretreatment group and the combined therapy group. Again,
small sample size may have contributed to the lack of significant findings.
Due to the effects of poorly managed pain and the importance of compliance to
orthodontic treatment, determining a method to block or lessen pain in orthodontic
patients is a worthwhile endeavor. Current standard of care in orthodontics is to decrease
pain once it has occurred by means of an over the counter analgesic. Recent
studies 27, 29, 30 have indicated that administering analgesic prior to provoking pain with
separator placement could be beneficial in decreasing orthodontic pain. However, due to
5
a lack of significant findings possibly due to small sample size, further investigation is
warranted.
The purpose of this study is to assess the effectiveness of adding preoperative
ibuprofen to an ibuprofen regimen administered after separator placement in reducing the
incidence and severity of post-separator placement pain and to assess the contribution of
psychological factors and gender to the pain experience. Specifically, the purposes are 1)
to evaluate the effectiveness of anti-inflammatory medication (ibuprofen) administered
prior to and after placement of spacers on evoked orthodontic pain, 2) to evaluate the
effectiveness of anti-inflammatory medication (ibuprofen) administered after placement
of spacers on evoked orthodontic pain, 3) to evaluate the effectiveness of placebo
administration prior to and after placement of spacers on evoked orthodontic pain, 4) to
examine associations between psychological factors and pain experienced after
placement of spacers, 5) to examine sex differences in pain induced by placement of
spacers and in ibuprofen analgesia.
CHAPTER 2 MATERIAL AND METHODS
This was a double blind, parallel arm, prospective clinical trial. Criteria for
inclusion in this study were: 1) at least 13 years of age and no older than 30 years, 2) not
pregnant, 3) starting orthodontic treatment for the first time, 4) require the placement of
at least one separator in each of four quadrants as part of his/her orthodontic treatment, 5)
no contraindications or adverse reactions to ibuprofen, 6) no contraindications or adverse
reactions to nuts, and 7) give written informed consent for participation in the study.
The 21 subjects meeting the above inclusion criteria were selected from patients
presenting for orthodontic treatment at the University of Florida orthodontic clinics.
Each subject was randomly assigned to one of three groups stratifying for gender (Table
1).
Table 1. Sample Size, Dosing and Dosing Timesa
Groups n D1 D2 D3 A 7 400mg ibuprofen 400mg ibuprofen 400mg ibuprofen B 7 Placebo 400mg ibuprofen 400mg ibuprofen C 7 Placebo Placebo Placebo aD1, one hour prior to separator placement; D2, three hours after separator placement; D3, seven hours after separator placement
We randomized in blocks of 10, with 3 assigned to Group A, 3 assigned to Group
B, and 4 assigned to Group C. The first group of 7 subjects (5 female, 2 male) received
400mg ibuprofen at D1 (1 hour prior to separator placement) D2 (3 hours after separator
placement) and D3 (7 hours after separator placement), the second group of 7 subjects (3
female, 4 male) received placebo at D1, 400mg ibuprofen at D2 and D3 and the third
6
7
group of 7 subjects (2 female, 5 male) were the control group and received a placebo at
all three dosing times.
Ibuprofen tablets of 200mg were re-encapsulated and placebos were made to
match. At each dosing time 400mg or two tablets were administered. In order to blind
the investigator to the groups, the investigational drug pharmacy at Shands Hospital
dispensed the tablets.
All subjects completed the following instruments immediately prior to time D1
(time of first dosing):
1. Expectation of pain: subjects were asked to rate their expectation of pain consequent to separator placement using a 100mm Visual Analog Scale (VAS) (figure 2). Anchors of “no pain at all” (0mm) and “worst pain imaginable” (100mm) were used .33
2. Pre-existing affective state was assessed using the State and Trait Anxiety Inventory (STAI) 34 and the Positive and Negative Affect Scale (PANAS).35
3. Mastication Performance Index:36 the subjects were asked to chew a bagged almond five times on the right side of the mouth without swallowing. This was repeated on the left side of the mouth. The protocol has been modified from Al-Ali, Heath and Wright, 1999.36 Subjects were asked to rate pain as a consequence of chewing the almond on a VAS for both right and left sides.
4. If patient is female and is of childbearing potential (i.e., post-menarche), a pregnancy test will also be administered at this time.
Please make a check ( ) on each of the lines below so as to show how much pain you are having in the following areas.
Example
no pain at all worst pain imaginable Figure 1. Example of Visual Analog Scale used in pain diary, test of evoked pain and
anticipation of pain
8
Separators were placed (T0) one hour after the first dosing and administration of the
above tests. Ormco posterior separators were used unless the clinical situation warranted
the use of metal separators. At least one separator was placed in each quadrant. The
methods of placement, either over or under contact, and type of separator, were recorded
for each subject. Pain on placement of separator was recorded on a VAS.
Over 24 hours, subjects recorded discomfort when biting, chewing, fitting front
teeth together and fitting back teeth together in a VAS pain diary, similar to that used in
other studies.1, 29, 31, 32 Subjects recorded in the pain diary at: T1 (2 hours post separator
placement), T2 (6 hours post separator placement), T3 (at bedtime), T4 (upon awakening)
and T5 (24 hours post separator placement). At 24 hours (T5), the subject self-
administered the Masticatory Performance Index with VAS (Table 2). The completed
pain diary and the chewed bagged almonds were returned by mail.
The Visual Analog Scale (VAS) was used in this study to assess expectation of
pain, pain on placement, and evoked pain (via pain diary and known force test). The
VAS has been shown to be reliable and valid.1, 15, 16, 29, 33, 37
The State and Trait Anxiety inventory (STAI) was used to assess situational anxiety
(state anxiety), and anxiety as part of personality (trait anxiety).34 The STAI has been
used to assess dental anxiety reliably.38-40
The Positive and Negative Affect Scale (PANAS) provides a brief, easy to administer
measure of mood state, characterized along the separate dimensions of positive and
negative affect. The PANAS has demonstrated reliability and discriminant validity.35 It
is widely used in clinical and experimental pain research.
9
Table 2. Treatment Timelineb
bT0, prior to dosing; Tx, separator placement; T1, 2 hours after separator placement; T2, 6 hours after separator placement; T3, bedtime; T4, awakening, T5, 24 hours after separator placement; D1, time of first dosing; D2, time of second dosing; D3, time of third dosing
To D1 Tx T1 D2 T2 D3 T3 T4 T5 Group A: 400mg Ibuprofen
Group A: 400mg Ibuprofen
Group A: 400mg Ibuprofen
Group B: Placebo
Group B: 400mg Ibuprofen
Group B: 400mg Ibuprofen
Consent Randomize Expected pain rating STAI, PANAS Masticatory Performance Index and Experienced Pain Rating
Group C: Placebo
Experienced Pain Rating
Pain
Dia
ry
Group C: Placebo Pa
in D
iary
Group C: Placebo Pa
in D
iary
Pain
Dia
ry
Masticatory Performance Index and Experienced Pain Rating
-1.25 hr -1hr Separator +2hr +3hr +6hr +7hr Bed Wake 24hr
The Masticatory Performance Index was described in the literature by Manly and
Braley in 1950.41 Modifications to the method have been made throughout the years.36, 42,
43, 44 The protocol used in this study has been modified from Al-Ali, Heath and Wright
(1999),36 using microwaved and bagged almonds to reduce oil and saliva. This makes a
dry sieving process possible increasing the efficiency of the analysis.
One investigator did all data collection and separator placement. A Fisher Exact
test was performed for differences in sex. Analysis of Variance tests were performed for
differences between groups for STAI, PANAS, chewing performance index and VAS
scales for chewing performance index, expected pain, pain on separator placement, and
pain diary time points. Exact Wilcoxon Rank Sum Tests were performed to identify
which groups differed if p<.05. Wilcoxon Rank Sum tests were also used to assess
change between expectation of pain and pain on placement, as well as, differences
between day 1 and day 2 for chewing efficiency index and VAS scores for chewing
efficiency index.
CHAPTER 3 RESULTS
Baseline data showed no difference between groups with regard to gender, STAI,
PANAS, expected pain and pain on separator placement (Table 3).
Table 3. Baseline Characteristics. Mean (s.d.) for Groups A, B and C.c
Group A Group B Group C p-value gender(% Female) 71.4 42.9 28.6 .42 age 15.7 (3.2) 14.9 (2.4) 16.0 (3.7) .78 sanx 37.7 (7.0) 34.7 (8.8) 31.3 (7.8) .34 tanx 37.3 (5.3) 33.6 (7.0) 34.0 (8.9) .58 panasp 32.3 (5.7) 33.3 (6.9) 33.0 (9.0) .97 panasn 15.1 (5.9) 16.6 (3.0) 14.1 (3.7) .59 vasexp 5.1 (1.8) 5.3 (1.8) 4.6 (1.5) .77 vasplace 3.2 (2.9) 4.9 (3.4) 4.4 (2.2) .53 csanx, state anxiety; tanx, trait anxiety; panasp, positive affect; panasn, negative affect; vasexp, expectation of pain; vasplace, pain on placement
Three time points for the 24-hour pain diary showed significant differences
(Figures 2-5). At 2 hours, fitting front teeth together and fitting back teeth together were
significantly different between groups (p<.05). Group A (ibuprofen at all 3 dosing times)
was significantly different (p<.05) from both group B (ibuprofen after separator
placement only) and group C (placebo) for fitting front teeth together. For fitting back
teeth together, group A was significantly different (p<.05) from group B but not group C.
At 6 hours, chewing on the left side, biting on the left side and fitting front teeth
together were significantly different (p<.05). Group A was significantly different (p<.05)
from both group B and group C for biting on the left side. For chewing on the left side
and fitting front teeth together, group A was significantly different (p<.05) from group B
but not group C.
10
11
A) Chewing Right
0
2
4
6
8
10
12
2hrs 6hrs bedtime awakening 24 hrs
Time
Mea
n V
AS S
core
Group AGroup BGroup C
*
A) Chewing Left
0
2
4
6
8
10
12
2hrs
Mea
n V
AS S
core
Figure 2. Mean VAS scsides of the m
*
6hrs bedtime awakening 24 hrs
Time
Group AGroup BGroup C*
ores and standard error for chewing on the a) right and b) left outh. *p<.05
12
A) Biting Right
0
2
4
6
8
10
12
2hrs 6hrs bedtime awakening 24 hrs
Time
Mea
n V
AS S
core
Group AGroup BGroup C
B) Biting Left
0
2
4
6
8
10
12
2hrs 6hrs bedtime awakening 24 hrs
Time
Mea
n V
AS S
core
Group AGroup BGroup C* *
*
Figure 3. Mean VAS scores and standard error for biting on the a) right and b) left sides of the mouth. *p<.05
13
Fitting Back Teeth
0
2
4
6
8
10
12
2hrs 6hrs bedtime awakening 24 hrs
Time
Mea
n V
AS S
core
Group AGroup BGroup C
*
Figure 4. Mean VAS scores and standard error for fitting back teeth together.
Fitting Front Teeth
0
2
4
6
8
10
12
2hrs 6hrs bed
Tim
Mea
n V
AS S
core
Group A*
Figure 5. Mean VAS scores and standard e
*
Group BGroup C*
time awakening 24 hrs
e
rror for fitting front teeth together.
14
At bedtime, chewing on the right and left side, biting on the right and left side and
fitting front teeth together were significantly different (p<.05). Group A was
significantly different (p<.05) from both group B and group C for chewing on the left
side and biting on the left side. For biting on the right side and chewing on the right side,
group A was significantly different (p<.05) from group B but not group C. For fitting
front teeth together, group B was significantly different (p<.05) from group A and C.
Comparing gender for baseline variables, no significant differences were found.
However, a trend exists (p=.06) toward more pain on placement with males.
Masticatory Performance Index and VAS for Masticatory Performance Index
showed no differences between groups for both day 1 and day 2. Change in pain rating
between day 1 and day 2 for Masticatory Performance Index was significantly different
(p<.0001) despite no differences between groups (Table 4). Gender was compared for
difference in change in pain rating for Masticatory Performance Index but was not
significant.
Table 4. Change in Pain between Day 1 and 2 for Masticatory Performance Index Mean s.d. Median p-values Right -6.92 2.59 -7.30 <.0001 Left -6.94 2.81 -7.80 <.0001
CHAPTER 4 DISCUSSION
This study was undertaken with the aim of assessing the effectiveness of adding
preoperative ibuprofen to an ibuprofen regimen administered after separator placement in
reducing the incidence and severity of post-separator placement pain and assessing the
contribution of psychological factors and gender to pain. The principle findings of this
study indicate that if ibuprofen is administered both before and after separator placement,
less pain is experienced at 2 hours after separator placement when fitting front teeth
together, 6 hours after separator placement when biting, and at bedtime when biting and
chewing. Also, a significant increase in pain exists from day 1 to day 2 when performing
the chewing efficiency index with no differences seen between the different dosing
regimens. No contributions to pain could be determined for psychological factors and
gender.
Ngan, et al.1 assessed pain after separator placement without analgesic at 4 hours,
24 hours and 7 days. Increases in pain were found for 4 hours and 24 hours. Our study
found no significant difference between groups for pain at 24 hours. However,
differences in pain between groups at 6 hours in our study are somewhat consistent with
the increase in pain found in the Ngan et al. study at 4 hours. Also, consistent with our
study, the Ngan et al. study found no differences between genders.
Law et al.31 assessed pain after separator placement using ibuprofen as an
analgesic. Subjects were assigned to 1 of 3 groups: 1) ibuprofen before separator
placement, 2) ibuprofen after separator placement and 3) placebo. Pain was assessed at 2
15
16
hours, 6 hours, 24 hours, as well as at 2 days, 3 days and 7 days. Significantly less pain
was observed at 2 hours. Our study found a difference between groups at 2 hours after
separator placement only when fitting front teeth together.
Bernhardt et al.32 also assessed pain after separator placement using ibuprofen as
an analgesic. The three experimental groups were slightly different from our study: 1)
ibuprofen before separator placement, 2) ibuprofen after separator placement and 3)
ibuprofen both before and after separator placement. Pain was assessed at 2 hours, 6
hours, at bedtime, upon awakening, at 2 days, 3 days and 7 days. Differences were found
for the time points 2 hours and bedtime. Our study similarly found differences at 2 hours
and at bedtime. Lack of additional significant findings for Bernhardt et al.32 could be
contributed to by small sample size, high incidence of subjects turning to rescue
medication and uneven distribution of gender among groups.
Although previous studies of this type31, 32 had a high incidence of subjects
resorting to rescue medication, this study had no medication requests. This is perhaps
due to the protocol followed in instructing the subjects and parents about rescue
medications. Subjects and parents, if the subject was under 18 years old, were told to call
anytime day or night if the subject was experiencing enough pain to need medication. At
this time, the investigator would instruct the subject or parent on what medication could
be taken and the dosage.
Geographic sampling bias may exist in this study. Subjects were chosen from
patients presenting to the University of Florida graduate and faculty clinics. Patients
presenting themselves to a teaching facility may have a scientific curiosity, which may
not represent the true population of all orthodontic patients.
17
A socioeconomic bias may also exist. Subjects participating in this study were
offered a reduction in their orthodontic fee of $200. Socioeconomic need may have been
a significant motivator in consent to participate.
Differences may exist between those who will sign an informed consent and those
who will not. A person’s refusal to participate in this study may be a reflection of the
desire to avoid pain, an expectation of pain or the anticipated reaction to pain.
Previous pain experience may influence the pain response. We controlled this
extraneous factor by not accepting individuals who have prior experience with
orthodontic treatment. Bergius et al.45 assessed pain after separator placement by
telephone interview over 7 days. Previous pain experience was found related to VAS
assessments made on days 3 through 7.
The most important limitation of the current study is small sample size. The lack
of differences found for gender, psychological factors, expected pain and pain on
separator placement might be due to small sample size. With regard to gender, percent
female is 71% in group A, 43% in group B and 29% in group C. While this is not
particularly well distributed, not enough power exists to say that it is statistically
significant.
For five data points, fitting back teeth together at 2 hours after separator placement,
chewing on the left side and fitting front teeth together at 6 hours after separator
placement and chewing on the biting on the right side at bedtime, experimental groups A
and B differ but neither differs from the placebo group. For one data point, fitting front
teeth together at bedtime, group B experienced more pain than group A or the placebo
group. Again, small sample size could contribute to these unlikely occurrences. Other
18
possible contributions could be from the method of placement of the separator, whether
over or under the contact, and need for use of metal separator. Both the use of a metal
separator and the placement of an elastic separator under the contact could generate more
pain than an over the contact placement of an elastic separator.
Despite no differences between groups with regard to chewing efficiency and pain
with Masticatory Performance Index, a significant increase in pain exists from day 1 to
day 2. The lack of differences between groups could be because no ibuprofen was in the
bloodstream at the time of the assessments. The last dose of ibuprofen was taken 7 hours
after separator placement and the second Masticatory Performance Index is taken at 24
hours.
Modifications made to methods used in previous studies are among the strengths of
this study. Ibuprofen administered before and after separator placement was compared to
both ibuprofen administered after separator placement and placebo. This essentially is
adding a preoperative dose of ibuprofen to the current standard of care, administration of
ibuprofen after the noxious insult, and comparing both to placebo. Previous studies
collected data over time points covering 7 days. Since significant differences were only
seen over the short term in these studies, the protocol was modified to cover several time
points within 24 hours. The Masticatory Performance Index was added as a measure of
function relating pain to the ability to chew food. In addition, this study added
psychometric measures as experimental factors.
The current study is ongoing and, therefore, the sample size will increase. At the
current sample size of 21 with 7 per group, no definitive conclusions can be made, only
observations. The first observation is that the use of pre-emptive analgesia is effective in
19
reducing pain at 6 hours after separator placement and at bedtime. The second
observation is that despite the use of analgesics a significant increase in pain exists when
chewing on day 2 compared to day 1.
Several directions for future research in this area are apparent. Differences in
chewing efficiency at 24 hours may be seen if the ibuprofen regimen is continued through
24 hours. If a higher dosage of ibuprofen is used, greater differences may be seen
between groups. Medications besides ibuprofen, such as COX-2 inhibitors or
acetaminophen, may be more effective with fewer side effects. While most patients
would not discontinue orthodontic treatment due to pain caused by separators, pain does
influence compliance 6-9 which is crucial to many aspects of orthodontic treatment.
Therefore, continued research into orthodontic pain will hopefully yield a method to
decrease pain, thereby, increasing compliance producing more favorable orthodontic
outcomes.
LIST OF REFERENCES
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2. Jones ML. An investigation into the initial discomfort caused by placement of an archwire. European Journal of Orthodontics 1984; 6: 48-54.
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BIOGRAPHICAL SKETCH
Curtice Kary Marris was born in Rochester, New York, in 1967. She graduated
cum laude from University of Central Florida in 1997 with a B.S. in microbiology and
molecular biology. Kary attended the University of Florida for her dental education and
graduated with honors in 2001 obtaining a Doctor of Dental Medicine degree. She is a
Hinman Scholar and a member of Omicron Kappa Upsilon. Kary continued her dental
education at the University of Florida to complete a degree of Master of Science with a
certificate in orthodontics. She plans to complete her residency in May of 2004 and then
enter private practice in Orlando, Florida.
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