Placebo Modulation of Orthodontic Pain

Study Overview
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Brief Summary
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How placebo modulates orthodontic pain remains largely unknown. The present study aimed to investigate the placebo modulation of brain activity associated with orthodontic pain using fMRI.

Detailed Description
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How placebo modulates orthodontic pain remains largely unknown. The present study aimed to investigate the placebo modulation of brain activity associated with orthodontic pain using fMRI. 23 voluneers were recruited in a longitudinal fMRI experiment. At both the baseline and the one-month follow-up, orthodontic separators were placed between right lower molars 24 hours before MRI scans. At baseline, the subjects were scanned without placebo while all subjects took placebos half an hour before the scan at follow-up. Scans include a bite/non-bite task fMRI and a followed resting state fMRI. A generalized linear model was used to identify pain-regulating network from task fMRI, and functional connectivity analysis of pain related brain regions was performed to study the possible modulation of placebo on connectivity of pain-regulating networks using resting-state fMRI.

Official Title
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Placebo Modulation of Orthodontic Pain: a Single-blind Functional MRI Study

Conditions
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Pain

Intervention / Treatment
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* Other: placebo
* Device: orthodontic elastic separators


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Female, 20-25 years old; Right handed; Understand the Visual Analog Scale; No history of serious illness, surgery, psychiatric disorders or neurological; No history of drug or alcohol abuse; No Maxillofacial diseases, agomphiasis, caries, metal filling material or crown; Individual normal occlusion with no orthodontic treatment history. Exclusion Criteria: claustrophobic or experienced obvious adverse reactions including fear, nausea, vomiting discomfort during the scan process or during menstruation.

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 25 Years

Sexes Eligible for Study
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Female

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: placebo arm<br>Orthodontic pain was introduced by placement of orthodontic elastic separators to the mesial and distal sides of the right mandibular first molar. Participants took placebos (pills made by starch) that were told to be an effective analgesic | Other: placebo<br>* participants took placebos (pills made by starch) that were told to be an effective analgesic.<br>Device: orthodontic elastic separators<br>* Orthodontic pain was introduced by placement of orthodontic elastic separators to the mesial and distal sides of the right mandibular first molar.<br>|
| Sham Comparator: sham arm<br>Orthodontic pain was introduced by placement of orthodontic elastic separators to the mesial and distal sides of the right mandibular first molar. But participants do not take placebos | Device: orthodontic elastic separators<br>* Orthodontic pain was introduced by placement of orthodontic elastic separators to the mesial and distal sides of the right mandibular first molar.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| fMRI data change during MRI scan | The fMRI data were collected with a Siemens 3.0T MRI system at West China Hospital. Scans include a bite/non-bite task fMRI and a followed resting state fMRI. Through MRI data we can investigate the modulation of brain activity associated with orthodontic pain using fMRI. | Day 1 | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| The chronological changes of anxiety level | Secondary outcomes concerning chronological changes of anxiety were assessed before and after orthodontic treatments through state-trait anxiety inventory (ST-AI). A higher score indicates higher anxiety level. | Day 1 |