Piezoelectricity in dental materials, a conceivable cause of postrestorative sensitivity

With the increased use of tooth-colored posterior inlays reports of postrestorative sensitivity have also increased. One of the symptoms the patients complain of is a sharp pain when the inlays are loaded through chewing and biting. Many explanations for the causes of dissimilar types of postrestorative sensitivity have been offered, but one conceivable explanation that has not hitherto been studied is the direct piezoelectric effect in dental materials. Direct piezoelectric effect means that when certain anisotropic crystals are mechanically loaded, a charge is generated on the surface. The aim of the present study was to examine whether this physical phenomenon occurs in certain materials intended for dental use. Specimens of four different dental ceramics and one indirect composite resin for inlays were mechanically loaded with various forces, and the current was directly recorded. Currents of up to 0.9 microA with a pulse duraton of 0.4 msec were extracted, and it cannot be excluded that the piezoelectric phenomenon and related properties may cause postrestorative sensitivity. This has to be taken into consideration when posterior inlays of the types concerned are used.