8972
The in vivo study demonstrated the biocompatibility and biodegradability of bare colloidal gelatin gels , and did not show any adverse effects on the process of bone healing after 4 week of implantation since the volumes of new bone formation were comparable to empty control defects .
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Please list all entity words in the text that fit the category.Output format is "type1: word1; type2: word2". 
Option: Chemical 
Text: {0} 
Answer:
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