A 40-year-old man complains of constant decementation of the porcelain fused-to-metal crown on tooth 11. The crown was made for him one year ago. How must the stump of the prepared tooth look like for proper functioning of this type of dental crown?

Answer options

1. Cylindrical shape, single-plane preparation, no ledge
2. Conical shape, convergence angle of 15-20 degrees, single-plane preparation, circular ledge
3. Conical shape, convergence angle of 10-15 degrees, single-plane preparation, circular ledge
4. Cylindrical shape, two-plane preparation, circular ledge
5. Conical shape, convergence angle of 5-7 degrees, two-plane preparation, circular ledge