Fracture resistance of four different restorations for cuspal replacement

The purpose of this study was to compare the fracture resistance of four po sterior restorations involving an entire cusp replacement. Four groups were established, each containing eight caries-free mandibular molars, similar in size and anatomic form. A mesio-occlusal preparation including the lingu al cusp was prepared on all teeth. Group A were restored with a pin-retaine d amalgam. Group B were restored with amalgam and a meta adhesive. Group C were restored with a composite resin with a beta-glass quartz insert. Group D were restored with composite resin and a HEMA adhesive. All specimens we re mounted in acrylic and stored in artificial saliva for 30 days. Each spe cimen was loaded in compression at a 90 degrees angle in an Instron testing machine with a crosshead speed of 0.5 cm/min. Results demonstrated the mea n (SD) failure loads in kilograms for each group to be: A, 1155 (388); B, 1 232 (436); C, 1345 (375); D, 1595 (373). Analysis of variance indicated no significant difference among groups at P < 0.05. Although the values for th e composite resin restoration with the adhesive were higher than the other restorative techniques.