[Stress on cast dowel constructions dependent on various means of preparation]

Comparative tests of stress exerted on dowel constructions with secondarily attached crowns were carried out in 60 plastic roots. With one half of the roots, the final preparation was first determined after the dowel construction was inserted; a circular shoulder was uniformly sunk. The margin of the crown and the dowel construction therefore were not at the same level. The remaining half was not reprepared; the margin of the crown and dowel construction were at the same level. The test teeth were loaded palatally as far as the fracture. Most fractures were characteristic oblique fractures in the region of the gingiva. The differences between the two groups were impressive. The load capacity for constructions with level crown margins and dowel constructions as far as the fracture was 6 kp less in the middle than those not at the same level.