Piezoelectricity in cementum, dentine and bone.

Unlike the dental hard tissues, bone remodels when subjected to orthodontic forces. Bone is also piezoelectric (generates a surface electrical charge upon application of force). In dentine and cementum from sperm whale teeth (which gave samples of sufficient size), the existence and magnitude of piezoelectricity were examined and compared with human bone. Both dental tissues were found to be piezoelectric with coefficients of 0.027 and 0.028 pC/N, respectively; the coefficient of human bone was eight times greater (0.22 pC/N). Thus the strength of the piezoelectric effect was correlated with the known capacities of the tissues to undergo adaptive remodelling. This result is consistent with the theory that piezoelectricity mediates orthodontically induced alveolar remodelling.