Acute mandibular osteomyelitis is an intractable dental infection with severe pain, fever, and general malaise in the maxillofacial region. It is classified into four stages according to the degree, and spontaneous pain is remarkable in the advanced stage （Ⅱ）. It is said that specific pathological conditions such as Yumikura symptom and Vincent symptom are observed, but there has been no report of a case with allodynia in the same part. We report a case of acute mandibular myelitis with allodynia in the mental nerve region of the apical periodontitis of the right mandibular first molar reaching the mental foramen via the mandibular canal.
