“Effect of Hydroxyapatite Nanoparticles On Compressive strength and Flexural strength of Dental Composites Using Taguchi Method”

Several composite materials are being used in biomedical and dental field with their immense applications to repair and transform various organs in human body. Recent advances suggest that Hydroxyapatite is one of the most reliable and widely used inorganic composite in dentistry. Desirable applications of Hydroxyapatite are achieved by utilizing variety of hydroxyapatite and their composites. This study was conducted to evaluate the compressive & flexural strength. Cylindrical specimens (n=9) for compressive strength & rectangular shaped specimens (n=9) for flexural strength were made according to manufacturer’s recommendations. Dental composite is using quartz, silica, and alumina glass as filler for a long time. Taguchi optimization technique keeps the experimentation within limit giving valid product in the calculating of compressive and flexural strength optimization. The goal of the work is to detect the best combination of composite materials. Keywords: Hydroxyapatite, Compressive Strength, Flexural Strength, Taguchi’s optimization method.

Microstructure and Mechanical Properties of Inverse Nanocomposite Made from Polylactide and Hydroxyapatite Nanoparticles

Polymer nanocomposites have been extensively researched for a variety of applications, including medical osteoregenerative implants. However, no satisfactory solution has yet been found for regeneration of big, and so-called critical, bone losses. The requirement is to create a resorbable material which is characterised by optimum porosity, sufficient strength, and elastic modulus matching that of the bone, thus stimulating tissue regrowth. Inverse nanocomposites, where the ceramic content is larger than the polymer content, are a recent development. Due to their high ceramic content, they may offer the required properties for bone implants, currently not met by polymer nanocomposites with a small number of nanoparticles. This paper presents inverse nanocomposites composed of bioresorbable nano crystalline hydroxyapatite (HAP NPs) and polylactide (PLLA), produced by cryomilling and a warm isostatic pressing method. The following compositions were studied: 25%, 50%, and 75% of HAP NPs by volume. The mechanical properties and structure of these composites were examined. It was discovered that 50% volume content was optimal as far as compressive strength and porosity are concerned. The inverse nanocomposite with 50% nanoceramics volume displayed a compressive strength of 99 ± 4 MPa, a contact angle of 50°, and 25% porosity, which make this material a candidate for further studies as a bioresorbable bone implant.

Effects of Nanohydroxyapatite Incorporation into Glass Ionomer Cement (GIC)

Glass ionomer cement (GIC) or polyalkenoate cement is a water-based cement that is commonly used in clinical dentistry procedures as a restorative material. It exhibits great properties such as fluoride-ion release, good biocompatibility, ease of use and great osteoconductive properties. However, GIC’s low mechanical properties have become a major drawback, limiting the cement’s usage, especially in high stress-bearing areas. Nanohydroxyapatite, which is a biologically active phosphate ceramic, is added as a specific filler into glass ionomer cement to improve its properties. In this review, it is shown that incorporating hydroxyapatite nanoparticles (nHA) into GIC has been proven to exhibit better physical properties, such as increasing the compressive strength and fracture toughness. It has also been shown that the addition of nanohydroxyapatite into GIC reduces cytotoxicity and microleakage, whilst heightening its fluoride ion release and antibacterial properties. This review aims to provide a brief overview of the recent studies elucidating their recommendations which are linked to the benefits of incorporating hydroxyapatite nanoparticles into glass ionomer cement.

Synthesis of hybrid polyphenol/hydroxyapatite nanomaterials: adsorption vs. in situ incorporation

Plant-derived natural bioactive molecules are of great therapeutic potential but their application in nanomedicine has been so far scarcely studied. This work aimed at comparing two methodologies, i.e. adsorption and in situ incorporation, to prepare hybrid polyphenol/hydroxyapatite nanoparticles. Two flavonoids, baicalin and its aglycone derivative baicalein, and two phenolic acids derived from caffeic acid, rosmarinic and chlorogenic acids, were studied. Adsorption of these polyphenols on pre-formed hydroxyapatite nanoparticles did not modify particles size or shape and loading was less than 10 % (w/w). In contrast, presence of polyphenols during the synthesis of nanoparticles significantly impacted, and sometimes fully inhibited, hydroxyapatite formation, but recovered particles could exhibit higher loadings. Antioxidant properties of the polyphenols were preserved after adsorption but not when incorporated in situ. These results provide fruitful clues for the valorization of natural bioactive molecules in nanomedicine