PSI - Issue 23

Alla V. Balueva et al. / Procedia Structural Integrity 23 (2019) 173–178 Author name / Structural Integrity Procedia 00 (2019) 000 – 000

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1. Introduction

Nano-scale, bio-active coatings applied to bone prosthetics (Fig. 1) have gained much interest in the scientific community. It has been shown that such coatings improve the osseointegration process [e.g. Albrektsson and Johansson, 2001; Vladescu et al., 2016] resulting in faster healing times and lower failure rates for patients. Various calcium-phosphate compounds have been used successfully [e.g. Eliaz and Metoki, 2017; Le ó n and Jansen, 2009]. However, researchers have documented problems with the mechanical strength of CaP coatings as it adheres to the Titanium substrate [e.g., Misch et.al., 2008]. In our present research, we describe a mathematical model for measuring the binding energy between these compounds and the titanium surface [Balueva and Dashevskiy, 2017]. The molecular structure is described using the time- independent Schrödinger equation, which is then solved using Density Functional Theory [Elber and Karplus, 1990)] via the Kohn-Sham approximation method. Similar problems, but using different methods, have been considered in Grubova et. al., 2019. Nomenclature  The surface energy HA E Ground state energy of HAp Ti E Ground state energy of Titanium / HA Ti E Ground state energy of the product Titanium+HAp Ca 10 (PO 4 ) 6 (OH) 2 Hydroxyapatite (HAp) Ca 3 (PO 4 ) 2 Tricalcium Phosphate (TCP) Collectively speaking when it comes to phosphates, apatite is far from being rarely found across the planet. It is in fact present throughout [e.g., Hughes and Rakovan, 2002]. More central to the research conducted here, is the mineral hydroxyapatite (Fig. 2) that is considered. Hydroxyapatite, while little is still known about it, bears a fundamental focus that is determining the manner in which materials composed of it respond to their environment, specifically in the field of medicine [e.g., Ching et al., 2009]. This mineral plays a vital role in human ossified tissues, such as bone, tooth enamel, and dentine; hydroxyapatite in reality is located more in the enamel of the tooth rather than bone [e.g., Mostafa and Brown, 2007]. Not y et explicitly expressed, it is hydroxyapatite’s characteristics and its vast potential for scientific application in prosthetics that constitute the principal theme of this research. This review on the other hand comprises only of brief glimpses of other research performed by academia while nevertheless shedding light on questions revolving around the use of prosthetics implementing the usage of hydroxyapatite along with substrate metals like that of titanium [e.g., Wang et al., 1996].

Fig. 2. Hydroxyapatite unit cell (image from Cambridge Crystallographic Database)

Fig. 1. General view of a dental implant screwed into the jaw.

Moreover and as previously noted, hydroxyapatite (Fig. 2) is almost analogous to human bone, analogous to the extent that it has drawn the minds of medical scientists to substitute it in the place of bone tissue in surgical procedures, such as hip and tooth replacements [e.g., Mostafa and Brown, 2007; Pichugin et al., 2008]. It is tooth prosthetics, however, that function as the lead interest at the end of this review. Points considered are, for example, the behaviour of hydroxyapatite alone, its failures after being applied to substrates and tested, and including but not limited to a