OBJECTIVE: The dentin-enamel junction (DEJ) plays a crucial role in dental biomechanics; however, little is known about its structure and mechanical behavior. Nevertheless, natural teeth are a necessary model for prosthetic crowns. The mechanical behavior of the natural DEJ and the dentin ceramic junction (DCJ) manufactured with a CAD-CAM system are compared. METHODS: The reference samples undergo no modification, while the experimental samples were drilled to receive a cemented feldspathic ceramic crown. Longitudinally cut samples were used to achieve a planar object observation and to look "inside" the tooth. A complete apparatus enabling the study of the compressive mechanical behavior of the involved tooth by a non-contact laser speckle interferometry (SI) was developed to allow nanometric displacements to be tracked during the compression test. RESULTS: It is observed that the DEJ acted as a critical zone accommodating the movement between dentin and enamel. A smooth transition occurs between dentin and enamel. In the modeled prosthetic, the same kind of accommodation effects also occurs, but with a steeper transition slope between dentin and ceramic. SIGNIFICANCE: On the natural tooth, the stress accommodation arises from a differential behavior between enamel and dentin from the DEJ. In the ceramic crown, the cemented dentin-ceramic junction should play this role. This study demonstrates the possible realization of prosthetic crown reconstructions approaching biomechanical behaviors.
OBJECTIVE: The dentin-enamel junction (DEJ) plays a crucial role in dental biomechanics; however, little is known about its structure and mechanical behavior. Nevertheless, natural teeth are a necessary model for prosthetic crowns. The mechanical behavior of the natural DEJ and the dentin ceramic junction (DCJ) manufactured with a CAD-CAM system are compared. METHODS: The reference samples undergo no modification, while the experimental samples were drilled to receive a cemented feldspathic ceramic crown. Longitudinally cut samples were used to achieve a planar object observation and to look "inside" the tooth. A complete apparatus enabling the study of the compressive mechanical behavior of the involved tooth by a non-contact laser speckle interferometry (SI) was developed to allow nanometric displacements to be tracked during the compression test. RESULTS: It is observed that the DEJ acted as a critical zone accommodating the movement between dentin and enamel. A smooth transition occurs between dentin and enamel. In the modeled prosthetic, the same kind of accommodation effects also occurs, but with a steeper transition slope between dentin and ceramic. SIGNIFICANCE: On the natural tooth, the stress accommodation arises from a differential behavior between enamel and dentin from the DEJ. In the ceramic crown, the cemented dentin-ceramic junction should play this role. This study demonstrates the possible realization of prosthetic crown reconstructions approaching biomechanical behaviors.
Authors: Michel Fages; Stephane Corn; Pierre Slangen; Jacques Raynal; Patrick Ienny; Kinga Turzo; Frederic Cuisinier; Jean-Cédric Durand Journal: J Mater Sci Mater Med Date: 2017-08-19 Impact factor: 3.896