Evaluation of hot‐pressed hydroxyapatite/poly‐L‐lactide composite biomaterial characteristics

Abstract

Hydroxyapatite/poly-L-lactide (HAp/PLLA) is a ceramic/polymer composite, whose application as a resorbable biomaterial for the substitution and repair of hard bone tissue is widely promising in orthopedic, oral, maxillofacial, and reconstructive surgery. Hot processing is a necessary step for obtaining HAp/PLLA composite blocks with mechanical properties similar to those of bones. In this article, the changes in structure and physicochemical properties of HAp/PLLA composite, hot pressed for different pressing times (5, 15, 30, 45, and 60 min), were studied. Because the morphology of HAp/PLLA composite biomaterial is very sensitive to this procedure, its surface microstructure was analyzed by scanning electron microscopy (SEM) coupled with an energy-dispersive X-ray (EDX) detector system. Structural changes occurring in the material, mostly changes in crystallinity of PLLA, were studied by wide-angle X-ray structural analyses (WAXS) and infrared (FTIR) spectroscopy. Using differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and gel permeation chromatography (GPC), the influence of hot pressing on the properties, crystallization kinetics, and decomposition of HAp/PLLA composite biomaterial was analyzed.

Biocomposites and hybrid biomaterials based on calcium orthophosphates

“…178 The mechanical properties of poly(α-hydroxyesters) could be substantially improved by the addition of calcium orthophosphates. 395,396 Shikinami and Okuno developed CDHA/PLLA modulus, while concurrently increasing the hydrophilicity of the polymeric substrate. In addition, an increase in apatite concentration was found to increase both the modulus and yield stress of the composite, which indicated good interfacial interactions between the biological apatite and PCL.…”

Calcium orthophosphate-based biocomposites and hybrid biomaterials

“…The mechanical properties of poly(a-hydroxyesters) could be substantially improved by the addition of calcium orthophosphates [326,327]. Shikinami and Okuno [137] developed CDHA/PLLA composites of very high mechanical properties; mini-screws and mini-plates made of these composites have been manufactured and tested [320].…”

“…As a result, quick setting and degradable biocomposite cements with a low-heat output and compressive strengths in the range of 1 to 12 MPa were prepared by varying the molecular weight of PPF, as well as the contents of the monomer, b-TCP, initiator, and porogen (NaCl) [453,454]. An acrylic cement with Sr-containing HA as a filler [110] and an injectable polydimethylsiloxane/HA cement [455] have been prepared as well.…”

Preparation and characterization of dense nanohydroxyapatite/PLLA composites

“…Material science teaches that final implant properties depend on numerous parameters: the most obvious are polymer characteristics (chemical composition, molecular weight, crystallinity [2,3]), and calcium phosphate characteristics (chemical and mineralogical composition, particle size distribution, aspect ratio, spatial distribution, particle/ polymer interaction, concentration…) [4][5][6][7][8][9]. Moreover, preparation conditions have a crucial effect on the final properties of the material [10]. The most popular bioresorbable composite bone substitutes are based on hydroxyapatite/poly-L-lactic acid mixtures (HA/PLLA), since the raw materials are already approved for human clinical use and their degradation products are easily metabolized.…”