Internal finish line for the mandible should be located relative to the external finish line?

Internal finish line for the mandible should be located relative to the external finish line?

• A. Mesial to the external finish line
• B. Distal to the external finish line
• C. Buccal to the external finish line
• D. Occlusal to the external finish line

Answer: (A)

The idea is that the inner boundary of the mandibular denture border (the internal finish line) should sit closer to the midline than the outer boundary (the external finish line). Placing the internal finish line mesial to the external one keeps the border within the functional sulcus and within the denture’s envelope, which helps maintain a good border seal, reduces tissue irritation, and allows the tongue and floor of the mouth to move without interference. If the internal finish line were distal, buccal, or occlusal to the external finish line, the denture border could overextend into soft tissue or onto the occlusal plane, leading to irritation, poor fit, and seating problems.

The idea is that the inner boundary of the mandibular denture border (the internal finish line) should sit closer to the midline than the outer boundary (the external finish line). Placing the internal finish line mesial to the external one keeps the border within the functional sulcus and within the denture’s envelope, which helps maintain a good border seal, reduces tissue irritation, and allows the tongue and floor of the mouth to move without interference. If the internal finish line were distal, buccal, or occlusal to the external finish line, the denture border could overextend into soft tissue or onto the occlusal plane, leading to irritation, poor fit, and seating problems.