The purpose of this investigation is to ascertain if small slots cut with inverted cone burs are an acceptable alternative to the presently used threaded pins in the restorative treatment of badly broken down teeth. To achieve this purpose it has been necessary to design and make a machine that will apply simulated chewing stresses to extracted teeth that have been restored with dental Amalgam and Composite resins. Such a machine has been built, and the necessary transducers to measure strain in the restorations under test. Investigation of the optimum slot design has shown that the smallest slot that can be cut with dental burs is the best. Slots cut with the #33 1/2 bur are ideal and a greater strength per unit area is obtained in the restorative material with these than when larger slots are used. Initial results in the study using the new simulated chewing machines indicate that the slots are comparable with pins as a retentive mechanism. When the laboratory phase of this study is completed a clinical study is planned.