In the sentence extracted from biomedical literature, identify all the chemical entities. The required answer format is the same sentence with HTML <span> tags to mark up specific entities. 
### Entity Markup Guides:
Use <span class="chemical"> to denote a chemical.

### Input Text: SUMMARY : The patient ' s medical and dental histories along with radiographic and clinical findings lead to a diagnosis of " meth mouth . " Although three different dental treatment modalities ( either conventional or implant - supported ) have been offered to the patient since August 2007 , the patient has yet to initiate any treatment .
### Output Text:
SUMMARY : The patient ' s medical and dental histories along with radiographic and clinical findings lead to a diagnosis of " meth mouth . " Although three different dental treatment modalities ( either conventional or implant - supported ) have been offered to the patient since August 2007 , the patient has yet to initiate any treatment . 