Odontologia

0099-2399/92/1807-0332/$03.00/0 JOURNAL OF ENDODONTICS Copyright © 1992 by The American Association of Endodontists

Printed in U.S.A.

VOL. 18, NO. 7, JULY 1992

Are Endodontically Treated Teeth more Brittle?
Christine M. Sedgley, BDS, MDSc, FRACDS, and Harold H. Messer, MDSc, PhD

This study compared biomechanical properties (punch shear strength, toughness, hardness, and load to fracture) of 23 endodontically treated teeth (mean time since endodontic treatment: 10.1 yr) and their contralateral vital pairs. Analyses using paired t tests revealed no significant differences in punch shear strength, toughness, and load to fracture between the two groups. Vital dentin was 3.5% harder than dentin from contralateral endodontically treated teeth (p = 0.002). The similarity between the biomechanical properties of endodontically treated teeth and their contralateral vital pairs indicates that teeth do not become more brittle following endodontic treatment. Other factors may be more critical to failure of endodontically treated teeth.

The endodontic and prosthodontic literature contains repeated references to the widely held clinical perception that endodontic treatment weakens teeth, resulting in increased brittleness (i-4). While Rosen (1) described the dentin of endodontically treated teeth as "desiccated and inelastic," Johnson et at. (2) additionally speculated that the elasticity of dentin decreased with time following endodontic treatment. Alternatively, it has been suggested that, rather than endodontic treatment, loss of tooth structure associated with restorative procedures was the major factor in weakening teeth. Recently, it was shown that endodontic procedures reduced the relative cuspal stiffness of premolar teeth by only 5%, in contrast to an occlusal cavity preparation (20%) and an MOD cavity preparation (63%) (5). The purported brittleness of endodontically treated teeth has been attributed to decreased moisture content. The supporting evidence