A severe periodontal destruction was found on the left mandibular second molar which revealed poor prognosis. Extraction of the tooth was carried out and an orthodontic elastic band was found . The direct etiology of this severe periodontal destruction was determined. The third molar was autotransplanted to the extraction socket of the edentulous region. Close professional supervision during orthodontic treatment period when using elastic band is highly recommended to avoid this hazardous situation.