Multifunctional Nanocomposites for Biotherapeutic Applications

Introduction

In the dentistry, the dental materials that are used nowadays are greatly challenged by the secondary disease, e.g., caries. After an initial dental treatment, this disease is one of the main reasons for failures in dental materials previously applied (Mjör, Moorhead, & J.E. Dahl, 2000; Sarrett, 2005; Bernardo, 2007). Thus, there is an increasing interest in the bioactivity of dental materials as materials that need to go beyond the mechanical and physical aspects aiming the tissue repair. The new composite materials are essential in direct tooth restoration, however, is fundamental that things like wear resistance, fracture toughness and compression, surface hardness, tensile and flexural strengths are known due demands of mastication in the oral environment (Loguercio, 2006; Sadeghi, Lynch, & Shahamat, 2010). While improvements in these areas are being accomplished there are several limitations that still found for modern materials (Sadeghi, Lynch, & Shahamat, 2010). The principal difficulties include the adapting the material to the internal surfaces of a prepared cavity, the creation of an effective marginal seal in the cavity tooth interface, material discolouration over time, secondary decay caused by material microleakage and post-operative sensitivity (Korkmaz, 2010; Sadeghi, & Lynch, 2009).

Nanoscience or molecular engineering is also known as nanotechnology is characterised as the creation of materials and functional structures with characteristic dimensions in the nano range (0.1-100 nm). In case of inorganic phases in an organic/inorganic composite in nanosized, they are called nanocomposites (Chen, 2010). Nanocomposites, nowadays, are one of the biggest contribution to restorative and aesthetic dentistry for the restoration of tooth structure. Nanocomposites are characterised by filler-particle sizes ≤ 100 nm and present advantages faced to the current microfilled and hybrid resin-based composites, due to their aesthetic and strength advantages, as well as, have better polish-ability properties which produce a smoother surface with better shade characteristics and their microhardness (Ogle, & Byles, 2014).

Biomaterials are successfully integrated into surrounding tissue and should match tissue's topography and their mechanical properties. Nowadays there are some evidence that the cellular response to a biomaterial may be enhanced in the synthetic polymer formulations by mimicking the surface roughness associated with the nano-structured extra-cellular matrix components of natural tissue (Li, & Webster, 2007; Liu, Slamovich, & Webster, 2007). Although the some of the benefits from nanotechnology are known, relatively few advantages have been described for biological applications, such as bone regeneration. Despite the bone itself is a nano-structured material composed of biological entities like proteins (such as, collagen type I) and hydroxyapatite crystals that have nanometer dimensions (Taton, 2001). Then, cells are naturally accustomed to interacting with nano-structured surface roughness in the body. Conventional materials (rough at the micron scale but are usually smooth at the nanoscale) provide nonbiologically inspired surface roughness values to cells. Thus, the use of nano-structured materials in bone tissue engineering (and all of the tissue engineering) represents a challenge and a paradigm shift (Balasundaram, & Webster, 2007).