Curve of occlusion touching the buccal and lingual surfaces of mandibular buccal cuspal teeth is called as:
Curve of Wilson
Curve of Spee
Curve of Monsoon
Catenary curve
CURVE OF WILSON
It is a curve that contacts the buccal and lingual cusp tips of the mandibular posterior teeth. The curve of Wilson is mediolateral on each side of arch. It results from the inward inclination of the lower posterior teeth.
The curve helps in two ways:

Teeth aligned parallel to the direction of medial pterygoid for optimum resistance to masticatory forces.
The elevated buccal cusps prevent food from going past the occlusal table.