Fracture analysis of hemispherical dental implant crowns composed of functionally graded transversely isotropic material under external pressure

Dental implants are artificial teeth surgically inserted into a person's jaw to restore their chewing ability or look. They support prosthetic teeth, such as crowns, bridges, and dentures. In this paper, the crown part of a dental implant system in the shape of a hemispherical shell composed of functionally graded transversely isotropic material is considered. The idea of transition theory has been employed to evaluate transitional and plastic stresses in the shell under external pressure, and the obtained results are used to compare the strength and compatibility of zirconia and titanium-based crowns. Resulting relations are substituted in the equilibrium equation to create a nonlinear differential equation that regulates this physical problem of the dental implant crown. For estimating transitional stresses and pressure in the shell, the transition function R in the form of radial stress Trr is considered, and the analytical method is applied to solve equations by taking the critical point P → ±∞ of the governing differential equation into consideration. The study examines a crown composed of FG transversely isotropic material more robust and biocompatible than homogenous transversely isotropic material. With the use of graphs and numerical computations, it is observed that functionally graded transversely isotropic material zirconia with k = 3 has the highest circumferential stresses and lowest radial stresses. Therefore, it can be concluded that zirconia dental implants, known as ceramic implants are more suitable than titanium dental implants due to their excellent aesthetic properties and biocompatibility.