Mechanisms of Acupuncture Analgesia on Experimental Dental Pain - A Psychophysical Study (Phase1)

Study Overview
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Brief Summary
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The investigators will assess the effects of manual acupuncture on experimental dental pain in 36 healthy subjects by means of subjective pain intensity ratings and pain-specific autonomic nervous system (ANS) reactions.

Detailed Description
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This psychophysical and -physiological study is the first part of a two-phase project which pursues to explore how acupuncture-induced pain modulation interacts with pain-specific brain processing patterns by means of functional magnetic resonance imaging (fMRI) and by using an experimental dental pain model. In this preceding study, the characterization of manual acupuncture effects on the experimental dental pain model will be tested under laboratory conditions and without restrictions of an fMRI-measurement in order to provide a sound foundation for the following fMRI-experiment. Pain modulating effects of the manual acupuncture intervention (4 points: needle manipulation of bilateral large-intestine 4 (LI4), stomach 6 and 7 (ST6, ST7) ipsilateral to the stimulated tooth) will be compared to sham-acupuncture (insertion and manipulation of 4 non-acupuncture points) and a control intervention (no acupuncture) which will each be performed at 3 different days in a randomized order. Intervention effects on experimental dental pain will be assessed by testing of 36 healthy volunteers by means of subjective pain intensity ratings and pain-specific ANS reactions such as electrodermal activity and heart rate/respiratory changes. Besides laying the groundwork for the following fMRI experiment, this study could provide valuable basic insights into the dynamics of the tested manual acupuncture effects and further provide important knowledge for the planning of future clinical studies encompassing dental conditions and development of acupuncture treatments.

Official Title
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Mechanisms of Acupuncture Analgesia on Experimental Dental Pain - A Randomized, Single Blinded, Sham-controlled Psychophysical Study (Phase1)

Conditions
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Experimental Dental Pain

Intervention / Treatment
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* Procedure: Acupuncture
* Procedure: Sham-Acupuncture
* Procedure: No Acupuncture


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: right-handed Written informed consent Fluent in German language Sufficient dental sensitivity for the tooth stimulation No acupuncture treatment in the previous 12 months No medical knowledge about acupuncure Exclusion Criteria: Alcohol, drug, and analgesics consumption within the last 24 hours Complaints of diseases of the oral cavity Pre-existing neurological and(or psychiatric conditions History of severe dental pain Regular intake of pain medication History of brain injuries Alcohol and drug abuse Chronic diseases that require a permanent intake of drugs

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 40 Years

Sexes Eligible for Study
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Male

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
Intervention Model: Single Group Assignment
Masking: Single


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Healthy subjects<br>All subjects participate at 3 experimental conditions (Acupuncture, Sham-Acupuncture and No Acupuncture) at 3 different days in a randomized order. | Procedure: Acupuncture<br>* Needle insertion and manipulation at 4 acupuncture points (bilateral LI4, right ST6 and ST7).<br>* Other names: Verum Acupuncture;Procedure: Sham-Acupuncture<br>* Needle insertion and manipulation at 4 non-acupoints<br>Procedure: No Acupuncture<br>* Control intervention: No needle insertion and manipulation<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Comparison of the - mean post-pre acupuncture intervention pain intensity rating differences - and mean post-pre control intervention (no acupuncture) rating differences |  | 15 minutes | 
| Comparison of the - mean post-pre acupuncture intervention pain intensity rating differences - and mean post-pre sham-acupuncture rating differences | In case of a significant effect in outcome 1, outcome 2 will be tested using a hierarchical procedure in order to avoid multiple testing. | 15 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Longer lasting effects of acupuncture on subjective intensity ratings | Besides the pre-post intervention comparisons (primary outcome), 2 additional timepoints (Total: pre-intervention, post-intervention, 15 min post-intervention, 30 min post-intervention) will be examined to test differences in temporal dynamics between the 3 intervention effects on subjective pain intensity. | 50 minutes | 
| Longer lasting effects of acupuncture on pain-specific changes in heart rate. | Besides the pre-post intervention comparisons (primary outcome), 2 additional timepoints (Total: pre-intervention, post-intervention, 15 min post-intervention, 30 min post-intervention) will be examined to test differences in temporal dynamics between the 3 intervention effects on pain-specific heart rate alterations. | 50 minutes | 
| Longer lasting effects of acupuncture on pain-specific changes in skin conductance. | Besides the pre-post intervention comparisons (primary outcome), 2 additional timepoints (Total: pre-intervention, post-intervention, 15 min post-intervention, 30 min post-intervention) will be examined to test differences in temporal dynamics between the 3 intervention effects on pain-specific skin conductance alterations. | 50 minutes | 
| Longer lasting effects of acupuncture on pain-specific changes in respiratory frequency. | Besides the pre-post intervention comparisons (primary outcome), 2 additional timepoints (Total: pre-intervention, post-intervention, 15 min post-intervention, 30 min post-intervention) will be examined to test differences in temporal dynamics between the 3 intervention effects on pain-specific changes in respiratory frequency. | 50 minutes | 
| Changes in skin conductance during the three intervention types (acupuncture, sham-Acupuncture, no acupuncture). | Comparison of changes in the skin conductance measured during the acupuncture/sham-acupuncture and no acupuncture | 10 minutes | 
| Changes in heart rate variability (HRV) during the three intervention types (acupuncture, sham-Acupuncture, no acupuncture). | Comparison of changes in the HRV measured during the acupuncture/sham-acupuncture and no acupuncture | 10 minutes | 
| Changes in respiratory frequency during the three intervention types (acupuncture, sham-Acupuncture, no acupuncture). | Comparison of changes in respiratory frequency measured during the acupuncture/sham-acupuncture and no acupuncture. | 10 minutes | 
| Frequency of SAEs | Serious adverse event (SAEs) occurrences will be recorded and their frequency will be calculated. | 1 month | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Manual acupuncture, Experimental dental pain, Psychophysics, Autonomic nervous system, Subjective pain ratings