Final answer:
In dentistry, the master cast is slightly carved around the vibrating line to create more acrylic thickness for strength and durability of the dental appliance.
Step-by-step explanation:
When creating a master cast in dentistry, the vibrating line is a reference point used to determine the desired thickness of the acrylic material that will be used to fabricate a dental appliance. The master cast is slightly carved around the vibrating line to create more thickness of the acrylic material, which is important for the strength and durability of the appliance.