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

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

Answer: (B)

In occlusion analysis, there is a specific reference line that runs through the buccal cusp tips of the mandibular posterior teeth. This line is the BO line. It serves as a simple transverse reference to evaluate how the buccal cusps align across the lower arch and how the occlusal surfaces relate to each other. The plane of occlusion, by contrast, is a surface that represents the overall functional occlusal plane, not a single line. The LO line would refer to a line through lingual cusp tips, and CF line represents a different reference line not defined by the buccal cusps. So the imaginary line through all buccal cusp tips of the mandibular posterior teeth is the BO line.