Biomechanical In Vitro Study on the Stability of Patient-Specific CAD/CAM Mandibular Reconstruction Plates: A Comparison Between Selective Laser Melted, Milled, and Hand-Bent Plates

Study Design: An experimental in vitro study. Objective: Plate fractures are a recurrent problem in alloplastic mandibular reconstruction. Hypothetically it can be assumed that computer-aided design (CAD)/computer-aided manufacturing (CAM) reconstruction plates have a higher stability than conventional hand-bent plates. The aim of the study was to compare additive and subtractive fabricated CAD/CAM mandibular reconstruction plates as well as conventional plates with regard to their biomechanical properties. Methods: In a chewing simulator, plates of 2 conventional locking plate systems and 2 CAD/CAM-fabricated plate systems were compared. The plates were loaded in a fatigue test. The maximum number of cycles until plate fracture and the plate stiffness were compared. Results: While all conventional plates fractured at a maximum load between 150 and 210 N (Newton) after a number of cycles between 40 000 and 643 000, none of the CAD/CAM plates broke despite a nearly doubled load of 330 N and 2 million cycles. Both CAD/CAM systems proved to be significantly superior to the hand-bent plates. There was no difference between the 2 CAD/CAM systems. Conclusions: Concerning the risk of plate fracture, patient-specific CAD/CAM reconstruction plates appear to have a significant advantage over conventional hand-bent plates in alloplastic mandibular reconstruction.

Effect of Stress Distribution on Transverse and Longitudinal Framing in Cargo Ship using FEA Method

A cargo ship’s hull is made up of bent plates that are not stiffened. The hull can be strengthened by the structural member of the transverse or longitudinal framing system. Frames are strengths member that acts as integral parts of the ship girder when the ship exposed to the longitudinal and transverse stresses. One of the stresses is coming from the load by the container that the cargo ships carry. This research was conducted to analyse how the load does from the container affecting the total deformation and the stress distribution on the transverse framing system model. The analysis of model was using finite element analysis method. Finite element analysis is a numerical technique for solving engineering issues with complex loadings, geometries and material properties. The simulation results of equivalent (von-Mises) stress and total deformation will be compared with the Germanisher Lloyd rule. The result of total deformation and equivalent (von-Mises) stress must not exceed the value stated by Germanischer Lloyd rule. If the value of stress exceeds, it is considered a failure. All the results are not exceed the limit and is acceptable.