1627
These discoloration ' s can be treated in several ways but up to lately tooth structure had to be removed in an irreversible manner in order to provide sufficient bulk for the new restorative material .
 None
Given options, please tell me the categories of all the listed entity words.Output format is "type1: word1; type2: word2". 
Option: GENE 
Text: {0} 
 Entities:  
Answer:
 None