Author(s): Thamer Yousif Marghalani
Purpose: This study compares the stress distribution in the structure of a loaded endodontically treated maxillary extracted canine restored with either custom-made zirconia (Cercon) or cast gold dowel and core. Materials and Methods: Standard treatments were implemented to prepare the gutta-percha-filled root canal and dowel space. The tooth along with the dowel and core fabricated pattern resin were prepared to receive an all-ceramic (Cercon) crown. An impression was made for the tooth preparation with the zirconia milled dowel and core in place to fabricate the Cercon crown using CAD/CAM. The restored canine was scanned, and from the scan two models were constructed with the surrounding ligament and bone. Three-dimensional finite element elastic analysis was then carried out for the stress distribution within the different regions of the two models due to a concentrated force of 100 N applied at the mid-lingual area. Analyses were made for three load angulations, vertical, buccolingual horizontal, and an in-between oblique force at 45o. Each region of the models was assumed isotropic and homogeneous. The two restored canines with zirconia and gold were compared in terms of the resulting maximum tensile, compressive, and Von Mises stresses. Results: Generally, there were no significant differences in the maximum stresses in most regions for both models. Von Mises stresses for zirconia dowel and core was 8.966 MPa and for cast gold dowel and core was 8.752 MPa. The maximum tensile stress for zirconia dowel and core was 9.326 MPa, and for cast gold dowel and core was 8.166 MPa. Conclusions: The present work validates the use of CAD/CAM zirconia material for ceramic dowel and cores. Clinical implications: CAD/CAM Zirconia can be used for a custom-made dowel and core in an esthetically demanding zone as an esthetic replacement for a metal cast dowel and core when restoring endodontically treated teeth.