Final answer:
Gutta-percha is the permanent thermoplastic material used to obturate the pulpal canal during RCT. It is derived from the Palaquium tree and is heated to make it soft and pliable before being used to seal the canal.
Step-by-step explanation:
The permanent thermoplastic material used to obturate the pulpal canal during Root Canal Treatment (RCT) is Gutta-Percha. Gutta-percha is a natural latex derived from the Palaquium tree and is used as a filling material to seal the root canal.
During an RCT, the infected pulp is removed and the pulp chamber and root canals are shaped and cleaned. The gutta-percha is then heated to make it soft and pliable, and it is then compacted tightly into the cleaned canal to seal it.
Gutta-percha is preferred because it has a good biocompatibility, is durable, and can be easily manipulated to fill the irregularities of the root canal system.