First to classify malocclusion on structural basis:

 # First to classify malocclusion on structural basis:

A. Salzmann

B. Kingsley

C. Angle

D. Katz

The correct answer is A. Salzmann.

Salzmann in 1950 was the first to classify malocclusion based on skeletal structures. 

• Skeletal Class I: These are purely dental malocclusions. The jaws are in harmony with one another. The profile is orthognathic. 

• Skeletal Class II: Subnormal and distal mandibular development in relation to maxilla 

• Skeletal Class III: Overgrowth of the mandible with a prognathic mandible.