The imaginary line extended through all the lingual cusp tips on the maxillary posterior teeth is known as which line?

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

Answer: (C)

The line being described is a reference line that runs along the lingual cusp tips of the maxillary posterior teeth. This line is used as the lingual reference in occlusal analysis, often called the lingual line of occlusion. It provides a simple way to assess how the lingual cusps of the upper molars and premolars align with the opposing teeth and helps in planning occlusal contacts and adjustments from the lingual aspect.

This is different from the plane of occlusion, which is a three-dimensional plane that typically relates incisal edges and buccal cusp tips to describe overall occlusal orientation, rather than a single line through the lingual cusps. The other options refer to different reference concepts and do not describe a line that passes specifically through the lingual cusp tips.