Five and a half years old loose teeth if it is caused by inflammation or trauma is an abnormal phenomenon, if the permanent teeth are about to erupt and cause loose teeth, it is a normal phenomenon. 1. Abnormal phenomenon. Five and a half years old loose teeth, if it is periodontal inflammation or endodontitis, apical periodontitis caused by a single or multiple teeth have different degrees of looseness, often abnormal conditions need to carry out dental root canal treatment, the looseness will slowly disappear. If the teeth are loosened due to external impact, it is also an abnormal phenomenon and needs to be fixed. 2. Normal phenomenon. Five and a half years old loose teeth, may be close to the tooth replacement period, a single milk teeth naturally loose, if the film check the bottom of the permanent embryo is about to erupt, this time the teeth loose is a normal phenomenon. Five and a half years old loose teeth is normal or not, it is recommended to go to the hospital according to the history of oral examination and X-ray film comprehensive judgment to confirm.