Fracture resistance of four different restorations for cuspal replacement

The purpose of this study was to compare the fracture resistance of four posterior 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 lingual cusp was prepared on all teeth. Group A were restored with a pin-retained 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 were mounted in acrylic and stored in artificial saliva for 30 days. Each specimen 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 mean (SD) failure loads in kilograms for each group to be: A, 1155 (388); B, 1232 (436); C, 1345 (375); D, 1595 (373). Analysis of variance indicated no significant difference among groups at P<0.05. Although the values for the composite resin restoration with the adhesive were higher than the other restorative techniques.