Effect of endodontic access preparation on resistance to crown-root fracture

This investigation involved the creation of coronal-radicular fractures in vitro and compared the fracture resistance of intact human mandibular molars, with molars after varied tooth preparation. Forty freshly extracted, non-carious, nonrestored human mandibular molars were randomly divided into four treatment groups. The molars were subjected to constantly increasing occlusal load until coronal-radicular fracture occurred. Tooth preparations significantly diminished resistance to coronal-radicular fracture.