The work presented in this document is the method of modeling normal and worn gear teeth and their mechanical behavior. In this approach, the use of the SOLIDWORKS software was necessary to conduct this study. For the modeling of straight cylindrical gears before and after wear in SOLIDWORKS, we have adopted the method of guiding curves. For the study of a new composite material with a thermoplastic matrix, high density polyethylene reinforced with 40% birch fibers called HDPE 40, we have therefore integrated this new material into the library of materials available in SOLIDWORKS.A program to calculate the forces at each point of the profile as a function of the normalized position has been developed. Then five zones were chosen for the application of forces. For this purpose, small areas have been created in these areas in order to apply the forces. This allowed us to obtain the stresses and deformations.