[The behavior of pin-stump constructions with and without circular stump rings in a loading experiment]

On 60 identical resin roots comparative loading experiments with two pin-stump constructions were carried out. One half of the roots was supplied with pin constructions with and the other half with pin constructions without a circular ring cap. With both constructions the secondary crowns were inserted separately. The teeth were loaded up to breaking at their palatinal crown surfaces. There were two types of fractures. In both groups a small number of total fractures was located in the region of the tip of the pin. There were no longitudinal fractures. The most frequent fractures were oblique ones in the gingival region and a marked difference between both groups was noted. Pin constructions with a circular ring cap broke with a load of 10 kp less on the average than those without a circular ring cap.