Abstract
The impact fracture resistance of crowned endodontically treated teeth with composite cores but without posts, that had either no coronal dentin remaining or a 1mm dentin collar was compared to that of unrestored, caries free teeth. The teeth were struck mid-labially to simulate a common trauma situation using a pendulum device and fracture resistance determined by calculation of absorbed energies. No significant difference was found between the intact teeth and the crowned root treated teeth with composite core and a 1mm dentin collar. Crowned root treated teeth with a composite core but no coronal dentin had significantly reduced fracture resistance (p < 0.05). Teeth with the dentin collar mainly fractured obliquely from the buccal crown margin to a point coincident with the simulated alveolus, representing a clinical situation which would allow retention rather than extraction of the tooth.