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The Pain and Neurosensory Mechanisms Branch, National Institute of Dental and Craniofacial Research, National Institutes of Health, Building 10, Bethesda, MD 20892-1258, USA ∗Tel.: +1-301-496-5483, ext.405; fax: +1-301-402-4347 E-mail: email protected
Mitchell B. Max (Mon,) studied this question.