Efficacy of build direction of 3D printed full coverage provisional restoration on the fracture resistance after aging

Abstract

To compare the efficiency of oblique and horizontal build orientations on the fracture resistance of full coverage provisional restoration fabricated by 3d printer. Materials and Methods: Typedont die of maxillary first molar was prepared for full coverage crowns. After tooth preparation, typodont was duplicated into thirty-two epoxy dies using a silicon base. Then randomly divided into two equal groups. Dies were scanned by an extraoral scanner digitally. Then software was used for the restoration design. Thirty-two crowns, divided into two groups and each group included 16 crowns, were put on a platform in the 3D printer software and rotated according to each build direction, 120° and 180° directions. The post cured is a LED light design for post-curing. Using A cementation loading device to cement all provisional crowns on their corresponding resin dies. Then, both groups were divided into three sub-groups, six samples nonaged, five samples were subjected to thermal cycle (1250 cycles, 5-55 ˚C), and five samples mechanical cycles (37,000 cycles, 50N). A USB digital microscope was used to assess the surface topography for samples in both groups. The samples were loaded to failure in newton (N) using a universal testing machine. To assess the failure mode pattern, fractured samples were examined using a digital microscope with a magnification of 35x. Result: Oblique group recorded statistically significant (p=0.044 < 0.05) higher mean value; (2122.16 N) than horizontal group subgroup; (1820.18 N) for non-aged groups. Regarding the effect of building direction on fracture load (oblique > horizontal), Regarding the effect of aging, non-aged > thermally aged > thermo-mechanical aged). The difference between groups regarding failure mode analysis was statistically non-significant. Conclusion: Oblique printed specimens have greater fracture resistance after aging than horizontally printed specimens. For 3D printing, an orientation of 120° is better.