This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
Guided tissue regeneration (GTR) is done in: 
Select and explain. 
A. Vestibular deepening procedures, B. Frenectomy, C. Flap surgeries, D. Gingivectomy
C: Flap surgeries
Answer: C: Flap surgeries 
Explanation: None