The imaginary line extended through all the buccal cusp tips of the mandibular posterior teeth is called what?

• A. Plane of occlusion
• B. BO line
• C. LO line
• D. CF line

Answer: (B)

In occlusal analysis we use reference lines to describe how the teeth align, and the line that runs through the buccal cusp tips of all mandibular posterior teeth is called the buccal-occlusal line. This line provides a simple, straight reference across the lower back teeth to assess buccal cusp alignment. It differs from the plane of occlusion, which is a broader concept describing a surface plane formed by multiple points (incisal edges and cusp tips) rather than a single line. The other lines refer to different cusp-tip groupings, so the line through the buccal cusp tips best matches the description.