We propose a new method of calculating adhesive strength of a novel bioactive nano-crystralline hydroxyapatite (HAp) coating of a dental implant by methods of Density Functional Theory (DFT) and Molecular Dynamics (MD) simulation. Hydroxyapatite is the material similar to the bone — that is why it is used in odontology to cover the implant to improve the process of osseointegration of the implant with the bone. It is also important to have a strong adhesive bond between the coating and the implant to avoid unpleasant situations dealing with the peeling of the coating. Our research focuses on understanding the strength of the bonds of interactions occurring during the process of spraying the dental implants, proposing factors that affect that strength, and ultimately looking at ways to improve the coating process. The goal of this work is to determine the strength of the interactions of the bio-nanocoating, hydroxyapatite, with titanium, which is the common material for the implant. Specifically the binding energy of different combinations of the constituents of the hydroxyapatite coating with titanium are calculated and ranked in order of intermolecular interactions. In the future, these components will be used to calculate the total binding energy of the HAp unit cell and the Ti (II) cation.

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One of the ways to improve and accelerate osseointegration of a surgical implant with bone is application of biocompatible coatings, in particular, hydroxyapatite (HAp). Since the cases of delamination of the coating take place in dental practice, it is very important to estimate the adhesive strength of HAp with the implant. A measure of the coating-to-substrate bond strength is the energy of this bond. In this research, quantum chemistry is used to calculate the binding energy of functional groups (anions) of hydroxyapatite and titanium 2+, which is a standard implant material. First, using Density Functional Theory with Becke three-parameter Lee-Yang-Parr hybrid exchange-correlation functional, the lowest potential energy surface is calculated. Then, by ab initio molecular dynamics, the reaction path, the reaction products, frequencies of oscillations, the activation energies and binding energies between various combinations of component anions of HAp and Ti(II) are calculated.

We consider delamination crack growth controlled by gas diffusion into crack. Initially, with small pressure, the crack can be considered as an ideal sink. However, as crack grows, the pressure becomes greater, and therefore the crack cannot be considered an ideal sink anymore. In this research for both ideal- and real-sink conditions, closed-form solutions for the dependence of the radius of the growing delamination on time are obtained.