Pain reduction after initial archwire placement in orthodontic patients: A randomized clinical trial

Introduction

The aim of this study was to compare the efficacy of ibuprofen, viscoelastic bite wafers, and chewing gum in reducing orthodontic pain.

Methods

This randomized clinical trial included 50 girls between the ages of 13 and 18 years classified into 5 groups of 10 each: placebo, ibuprofen (400 mg), chewing gum, soft viscoelastic wafer, and hard viscoelastic wafer. The patients in each group received 1 method immediately after placement of the initial archwires and every 8 hours if they experienced pain. Pain perception was recorded by the patients while chewing, biting, fitting front teeth, and fitting posterior teeth at 2 hours, 6 hours, bedtime, 24 hours, 2 days, 3 days, and 7 days after archwire placement, using a visual analog scale. Analysis of variance (ANOVA) and Tukey tests were used for data analysis.

Results

There were significant differences in pain perception of chewing function between the placebo group and the chewing-gum group at 24 hours and 7 days, and between the placebo group and the hard-viscoelastic group on the day 7 ( P <0.05). Also, there were significant differences between the placebo group and the soft-viscoelastic group, and between the placebo group and the hard-viscoelastic group in pain severity when fitting posterior teeth at 6 hours ( P <0.05). At other times and with other functions, no significant differences were recorded.

Conclusions

Both chewing gum and viscoelastic bite wafers are effective for pain reduction in orthodontic patients and can be recommended as suitable substitutes for ibuprofen.

Pain is a common experience in orthodontic patients, and fear of pain and discomfort is a concern for many. Orthodontic pain arises from ischemia, inflammation, and edema in the compressed periodontal ligament. In an inflamed and ischemic periodontal ligament, mediators such as histamine, bradykinin, prostaglandins, serotonin, and substance P are released. These mediators irritate the nerve ends of the pain receptors, thus causing pain. Orthodontic pain usually begins at 2 hours after force application and reaches its maximum intensity at bedtime or at 24 hours, and lasts approximately 5 to 7 days.

Various methods have been suggested for pain control in orthodontic patients, including low-level laser therapy, transcutaneous electrical nerve stimulation, vibratory stimulation of the periodontal ligament, and nonsteroidal anti-inflammatory drugs (NSAIDs). Until now, the use of NSAIDs has been reported as the most successful modality in orthodontic pain reduction; in most studies, this method has been called the gold standard. Briefly, NSAIDs block the formation of arachidonic acid in the prostaglandin production cycle, so the concentration of prostaglandins, which are important pain mediators, will be reduced.

However, in recent years, the side effects of NSAIDs such as thrombocytopenia, skin rashes, headaches, and so on, have been considered issues of concern, particularly in young orthodontic patients. Consequently, nondrug methods of pain control such as chewing gum or plastic wafers have been recommended. The mechanism of these methods is to loosen the tightly grouped periodontal ligament fibers around the nerves and blood vessels, restoring the normal vascular and lymphatic circulation of the periodontal ligament, thus preventing or relieving inflammation and edema, and finally relieving pain and discomfort.

This study was designed because of the scarcity of research evaluating the efficacy of nondrug methods in orthodontic pain control. The aim of this study was to compare the efficacy of ibuprofen, chewing gum, and viscoelastic bite wafers in pain reduction during the first week after initial archwire placement.

Material and methods

This was a randomized placebo-controlled clinical trial approved by the research ethic committee of Mashhad University of Medical Sciences in Iran. The study took place at the orthodontic clinic of its dental school. Fifty female orthodontic patients between 13 and 18 years of age, scheduled for fixed orthodontic treatment, participated in this research.

The patients had no systemic diseases and were not receiving analgesic therapy. They had moderate crowding (4-8 mm) according to Little’s irregularity index. All patients needed extraction of the 4 first premolars for orthodontic reasons, and the extractions were scheduled to be finished at least 2 weeks before the placement of the orthodontic appliances. The patients and their parents were informed about the details of the study, and informed consent was obtained from each patient.

The subjects were randomly assigned to 1 of 5 parallel groups in a 1:1:1:1:1 ratio according to their clinic entrance number and a random number table. In all groups, the orthodontic appliances, including bands, brackets (0.018-in standard edgewise system) and archwires (0.016-in nickel-titanium) were placed during 1 appointment.

In the placebo group, the patients were asked to take a B 6 vitamin tablet as a placebo immediately after archwire placement and at 8-hour intervals for a week if pain persisted.

In the ibuprofen group, the subjects took a 400-mg ibuprofen tablet immediately after archwire placement and at 8-hour intervals for a week if pain persisted.

The subjects in these 2 groups were blinded about the drug that they took.

In the chewing-gum group, the patients chewed a sugar-free gum (Orbit; The Wrigley Company, Chicago, Ill) for 5 minutes immediately after archwire placement and at 8-hour intervals for 1 week if they experienced pain.

In the soft-viscoelastic and hard-viscoelastic groups, the patients used horseshoe-shaped viscoelastic bite wafers with moderate and low toughness, respectively. These blocks were made of polyvinyl siloxane, and their mechanical properties are shown in Table I . Subjects in these 2 groups chewed or bit down on the bite wafers for 5 minutes at 8-hour intervals for 1 week if pain persisted.

Table I
Mechanical properties of the viscoelastic blocks in this study
Soft viscoelastic Hard viscoelastic
Pressure resistance in 10% reduction of thickness (MPa) 3.2 6.1
Pressure resistance in 30% reduction of thickness (MPa) 4.7 7.3
Pressure resistance in 50% reduction of thickness (MPa) 5.8 8.5

The subjects were asked to complete a visual analog scale questionnaire at 2 hours, 6 hours, and bedtime on the day of archwire placement, and at 24 hours, 2 days, 3 days, and 7 days after the first appointment. The format of the questionnaire was a 10-cm line, and the patients were expected to mark a location on the line corresponding to the amount of pain they experienced, with 0 indicating no pain and 10 indicating unbearable pain. The severity of pain was recorded during 4 oral functions including chewing, biting, fitting back teeth, and fitting front teeth. For fitting the front and back teeth, the patients did not eat anything and were instructed to bring the front teeth edge to edge with light force and to fit the back teeth with light force, and then score their pain in each function. For the biting and chewing functions, the subjects used a slice of a yellow apple; they bit and chewed the slice and scored their experienced pain.

The patients were instructed not to use any additional analgesics. All patients returned their questionnaires, and none had used any analgesics.

After data collection, the normal distribution of variables was confirmed by the Kolmogorov-Smirnov test, and the differences between the groups were analyzed with analysis of variance (ANOVA) and Tukey tests using SPSS software (version 11.5; SPSS, Chicago, Ill). The level of significance for all tests was determined at P <0.05.

Results

ANOVA demonstrated no significant differences in the mean ages among the groups. The descriptive statics for the 5 groups are shown in Table II . The differences in pain perception are presented individually for each function.

  • 1.

    Chewing. The 1-way ANOVA showed significant differences in pain at chewing at hour 24 and day 7 after initial archwire placement ( Table II ). The results of the Tukey test ( Table III ) showed significant differences between the placebo group and the chewing-gum group at hour 24 ( P = 0.029) and day 7 ( P = 0.031), and between the placebo group and the hard-viscoelastic group ( P = 0.025) on day 7. There was no significant difference in pain levels while chewing between the other groups at any time interval.

    Table III
    Tukey test results of chewing function at hour 24 and day 7 and fitting posterior teeth at hour 6 after archwire placement in the 5 groups
    Tukey HSD
    Group n Chewing function at hour 24 Chewing function at day 7 Fitting posterior teeth at hour 6
    Subset for alpha = 0.05 Subset for alpha = 0.05 Subset for alpha = 0.05
    1 2 1 2 1 2
    Chewing gum 10 3.4700 1.2200 3.1000 3.1000
    Hard VE 10 4.2200 4.2200 1.1400 1.9300
    Ibuprofen 10 4.4500 4.4500 1.9300 1.9300 3.0900 3.0900
    Soft VE 10 7.1500 7.1500 1.5500 1.5500 2.4000
    Placebo 10 7.4700 4.0200 6.0000
    Means for groups in homogeneous subsets are displayed.
    VE , Viscoelastic.
  • 2.

    Biting. Based on ANOVA, there was no significant difference in pain at biting between the groups at any time interval.

  • 3.

    Fitting front teeth. The 1-way ANOVA demonstrated no significant differences between the groups in pain at fitting front teeth at any time interval.

  • 4.

    Fitting back teeth. The 1-way ANOVA showed significant differences in pain at fitting back teeth at hour 6 after archwire placement ( Table II ). The Tukey test showed significant differences between the placebo group and the soft-viscoelastic group ( P = 0.017), and between the placebo group and the hard-viscoelastic group ( P = 0.005).

Table II
Descriptive information of the 5 study groups and ANOVA results
Function Group Pain index values
2 h 6 h At night 24 h 2 d 3 d 7 d
Chewing Placebo 4.80 ± 3.06 6.45 ± 2.58 6.96 ± 2.13 7.47 ± 2.73 6.64 ± 3.11 5.04 ± 3.07 4.02 ± 2.77
Ibuprofen 5.10 ± 2.20 4.18 ± 2.47 4.90 ± 2.75 4.45 ± 2.07 4.76 ± 3.42 3.08 ± 2.69 1.93 ± 1.73
Chewing gum 4.88 ± 3.98 5.70 ± 3.75 6.45 ± 3.42 3.47 ± 3.83 3.80 ± 3.39 3.15 ± 3.75 1.22 ± 2.11
Soft VE 2.87 ± 2.42 4.40 ± 2.51 5.23 ± 2.78 7.15 ± 2.83 5.32 ± 2.01 3.18 ± 1.84 1.55 ± 1.72
Hard VE 5.29 ± 2.75 5.25 ± 3.28 4.85 ± 3.24 4.22 ± 2.83 3.34 ± 3.16 2.50 ± 2.90 1.14 ± 1.75
P value 0.369 0.422 0.366 0.008 0.144 0.374 0.018
Biting Placebo 5.11 ± 4.19 7.51 ± 2.75 7.92 ± 2.25 8.54 ± 1.99 8.22 ± 2.22 6.59 ± 2.30 5.11 ± 3.14
Ibuprofen 3.87 ± 2.57 6.19 ± 2.73 5.91 ± 1.75 6.65 ± 2.16 5.80 ± 2.01 4.39 ± 2.38 2.11 ± 2.12
Chewing gum 5.00 ± 4.18 5.19 ± 3.58 5.90 ± 3.50 6.45 ± 3.57 5.53 ± 3.53 4.78 ± 3.32 2.78 ± 3.06
Soft VE 4.07 ± 2.71 5.50 ± 2.36 6.40 ± 2.58 7.98 ± 2.66 6.67 ± 2.41 5.25 ± 3.04 3.66 ± 2.73
Hard VE 5.97 ± 3.36 6.27 ± 3.00 6.78 ± 1.62 6.31 ± 1.80 6.09 ± 2.57 4.96 ± 2.56 3.10 ± 1.82
P value 0.664 0.448 0.363 0.191 0.170 0.455 0.136
Fitting front teeth Placebo 4.45 ± 3.18 6.32 ± 2.95 5.80 ± 2.48 4.27 ± 3.07 4.05 ± 2.64 3.59 ± 2.68 2.68 ± 3.14
Ibuprofen 2.50 ± 2.53 3.67 ± 2.48 3.88 ± 2.68 4.65 ± 3.03 3.02 ± 2.60 2.77 ± 2.76 1.61 ± 1.71
Chewing gum 5.67 ± 4.00 5.42 ± 3.37 5.52 ± 3.46 6.05 ± 4.15 4.90 ± 4.09 3.55 ± 3.06 2.45 ± 3.18
Soft VE 2.91 ± 2.26 5.02 ± 3.54 6.38 ± 2.61 7.28 ± 2.96 5.42 ± 3.58 4.09 ± 2.82 1.90 ± 1.09
Hard VE 4.15 ± 3.55 4.73 ± 3.09 5.58 ± 2.60 5.36 ± 3.05 4.64 ± 3.59 3.74 ± 3.03 2.80 ± 2.41
P value 0.190 0.433 0.363 0.275 0.564 0.909 0.806
Fitting back teeth Placebo 3.87 ± 3.34 6.00 ± 2.49 5.69 ± 2.33 4.00 ± 2.69 3.25 ± 2.49 2.87 ± 2.89 2.27 ± 3.02
Ibuprofen 4.05 ± 2.40 3.09 ± 2.10 3.37 ± 2.30 3.43 ± 2.58 2.10 ± 1.91 2.37 ± 1.90 1.45 ± 1.42
Chewing gum 3.35 ± 3.09 3.10 ± 3.08 3.72 ± 3.04 3.48 ± 3.86 2.85 ± 3.75 2.08 ± 3.02 1.55 ± 2.67
Soft VE 2.58 ± 2.02 2.40 ± 1.63 3.55 ± 1.77 4.69 ± 3.66 2.95 ± 2.86 1.53 ± 1.80 0.30 ± 0.42
Hard VE 2.03 ± 2.03 1.93 ± 1.69 2.55 ± 2.09 1.84 ± 2.14 1.84 ± 2.67 1.00 ± 1.92 0.33 ± 0.64
P value 0.436 0.006 0.154 0.333 0.768 0.449 0.124
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Apr 8, 2017 | Posted by in Orthodontics | Comments Off on Pain reduction after initial archwire placement in orthodontic patients: A randomized clinical trial
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