Root dentin hardness of endodontically treated teeth

Effect of sodium hypochlorite on dentine mechanical properties. A review

“…The main causes that may predispose teeth to fracture have been identified as the loss of tooth tissue due to caries or access cavity preparation 29 ; the altered mechanical properties of dentine due to the action of irrigants, medicaments, or root canal-filling materials 7,25 ; and the duration of endodontic treatment. 30 It is probable that these factors interact cumulatively to influence tooth loading and that the distribution of stresses ultimately increases the possibility of failure. 7 Flexural strength is defined as the ability of the material to resist deformation under load.…”

The role of organic tissue on the punch shear strength of human dentin

“…Lewinstein and Grajower measured Vicker's hardness of root dentin and also observed that the dentin hardness was unaltered after endodontic treatment. 15 To overcome the challenge presented by the especially small quantity of human dentin entailed in experimentation, some authors applied punch shear tests to accurately determine the mechanical property changes of pulpless dentin. The test results revealed that the punch shear strength and toughness of endodontically treated teeth were about 14% lower than those of vital teeth.…”

Effect of restoration type on the stress distribution of endodontically treated maxillary premolars; Three-dimensional finite element study

“…Similiarly, punch shear testing on endodontically treated teeth showed only a small (although statistically significant) reduction in strength of 14%. This suggests that the total effect of endodontic procedures is not great and is in fact comparable to an occlusal cavity preparation 3,22) . Lewinstein and Grajower 22) in their study of 16 vital and 32 root-filled teeth which had been extracted, indicated that root canal therapy did not affect vickers hardness of dentine, even after periods of 5-10 years.…”

“…As these stabilizing elements are removed during cavity preparation, the cusps are more easily deformed and forced apart during occlusal loading and become more susceptible to cusp or crown fracture 8,11,21) . Since dentinal hardness and moisture content in the pulpless teeth are similar to those in the vital teeth 1,22) , the susceptibility to fracture is believed to be increased due to the cumulative loss of tooth structure during restorative and endodontic procedures 5) , not the effect of endodontic treatment itself.…”