The Impact of Nano-Crystal Hydroxyapatites on the Regeneration of Bone Defects

Calcium hydroxyapatite is a widely used material for replacing bone defects. However, the effectiveness of nano-crystalline calcium hydroxyapatite produced from eggshells in the replacement of bone defects has not been investigated yet. The study aimed to evaluate the effectiveness of using nano-crystalline calcium hydroxyapatite made from eggshell for the healing of bone defect of the femur in rats. Forty-eight (n=48) rats underwent a surgical procedure to simulate femoral defect. The animals were sub-divided into 4 groups (each with n=12) depending on the methods of bone defect replacement: I control group (CG) (without bone defect replacement); II intervention group (the bone defect was replaced by PRP (PRP); III intervention group (the bone defect was replaced by nano-crystalline hydroxyapatite obtained from eggshell) (HA) and IV interventional group (the bone defect was replaced by a combination of hydroxyapatite and PRP) (HA+PRP). The degree of effectiveness of studied methods was assessed using radiological (on the 14th day), histological (on the 61st day), and biomechanical analysis (on the 61st day). According to radiographic data, the CG group had the lowest level of bone regeneration after 14 days (4.2 ±1.7%). In the HA + PRP group, the level of bone regeneration was 22.1±7.1 %, which was higher in comparison with the rates of consolidation of bone defects in the HA group (20.7± 9.3) (p = 0.023). According to the histo-morphometry data, the rates of bone tissue regeneration in the PRP group (19.8 ±4.2%) were higher in comparison with the CG group (12.7 ± 7.3%), (p>0.05). In the HA+PRP group, bone regeneration rates (48.9±9.4 %) were significantly higher (p=0.001) than in the HA group (35.1±9.8%). According to the results of biomechanical assessment under the maximum stress (121.0722), the maximum bending deformation of the contralateral bone without defect was 0.028746, which was higher than the indicators of the HA+PRP group, where at the maximum stress (90.67979) the bending deformation was 0.024953 (p>0.05). Compared to CG, PRP, and HA, biomechanical bone strength was significantly higher in the HA + PRP group (p≤0.01). At the maximum stress (51.81391), the maximum bending strain in the CG group was 0.03869, which was lower than in the PRP group, where the maximum stress and bending strain were 59.45824 and 0.055171, respectively (p>0.05). However, the bone strength of the HA group was statistically significantly higher compared to the CG and PRP groups (p<0.01). The results demonstrated the effectiveness of the use of nanocrystalline calcium hydroxyapatite obtained from eggshell in the healing of a bone defect. The best results were observed in the group of the combined use of nano-crystalline calcium hydroxyapatite and PRP.

Synthesis and Characterization of Nano-sized Carbonated Calcium Hydroxyapatite (CHAp) from Rebon shrimp (Acetes erythraeus) as a Candidate for Dental Restoring Application

Carbonated calcium hydroxyapatite (CHAp) exhibits excellent biocompatibility with bone and teeth, making it an ideal candidate for orthopedic and dental application. However, the study of CHAp synthesis from natural material is still scarce. The purpose of this research is to synthesize and characterize of CHAp, using Rebon shrimp (Acetes erythraeus) as a calcium source. The synthesis was conducted by hydrothermal method with the variation of Ca/P ratios 1.61; 1.67; 1.73. The as-prepared CHAp was characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), and scanning electron microscopy-energy dispersive X-ray (SEM-EDX). The FT-IR results show that synthesized material exhibited characteristic CHAp band of hydroxide at 3448 and 1635 cm-1, carbonate at 872 and 1427 cm-1, and phosphate at 1049; 606; and 570 cm-1. The diffractogram pattern assigned the all observed peak of CHAp are in good agreement compared to CHAp database with the nano-scale size. It also observed that the high Ca/P ratio will decrease the crystallinity of CHAp. The as-prepared CHAp micrograph is agglomerates spherical form with size between 5-20 nm which build up from 18–26 nm crystallite particles. The result of this research confirmed that Rebon shrimp is the promising materials for calcium source in CHAp production.

High Resolution Ultrasound of Fillers and Their Implications in Aesthetic Medicine: A Study in Human Cadavers

The use of fillers for cosmetic or therapeutic purposes is very common and it’s increasing daily. Although it’s true that in most cases the results are as expected, the use of these substances is not free from the development of complications, even when it’s performed by highly trained medical physicians. On the other hand, these substances can be used indiscriminately by untrained personnel leading to a serious public health complication known as iatrogenic allogenosis, which leads to problems related to malpractice. Most of the time, professionals are consulted for a second opinion regarding the use of these substances, because use of these substances might be unknown due to the patients denying or forgetting the use of these. The presence of a previous unknown filler in aesthetic areas that require treatment may trigger severe or irreversible reactions, especially if non-absorbable fillers were injected. High resolution ultrasound is an extremely useful diagnostic tool for the identification of fillers. In this paper we will describe the ultrasound appearance of hyaluronic acid, calcium hydroxyapatite, liquid silicone, silicone oil, biopolymers, and Polymethylmethacrylate (PPMA) and then we compare it with it’s reported appearance in previous studies. The injection of the substances was carried out in human cadavers with the intention of gathering ultrasound images as similar to the imaging behavior of these substances in vivo. The obtained images can be used as precise references in the ultrasound evaluation, diagnosis, follow-up and behavior of the filler materials in the benefit of a comprehensive approach in the management of patients.

Calcium Hydroxyapatite: A Highly Stable and Selective Solid Catalyst for Glycerol Polymerization

Calcium-based catalysts are of high interest for glycerol polymerization due to their high catalytic activity and large availability. However, their poor stability under reaction conditions is an issue. In the present study, we investigated the stability and catalytic activity of Ca-hydroxyapatites (HAps) as one of the most abundant Ca-source in nature. A stochiometric, Ca-deficient and Ca-rich HAps were synthesized and tested as catalysts in the glycerol polymerization reaction. Deficient and stochiometric HAps exhibited a remarkable 100% selectivity to triglycerol at 15% of glycerol conversion at 245 °C after 8 h of reaction in the presence of 0.5 mol.% of catalyst. Moreover, under the same reaction conditions, Ca-rich HAp showed a high selectivity (88%) to di- and triglycerol at a glycerol conversion of 27%. Most importantly, these catalysts were unexpectedly stable towards leaching under the reaction conditions based on the ICP-OES results. However, based on the catalytic tests and characterization analysis performed by XRD, XPS, IR, TGA-DSC and ICP-OES, we found that HAps can be deactivated by the presence of the reaction products themselves, i.e., water and polymers.

Fillers and Vessels: The Story of Arterial Obstruction after Cosmetic Treatment

Most popular fillers in cosmetic medicine are hyaluronic acid based. These comprise over 90% of the market and come with the advantage to be soluble in case of complications. Other fillers are contained in the group of bio-stimulatory fillers. They exert a secondary volumizing effect by provoking a low-grade inflammatory response that produces extra collagen. Examples are calcium-hydroxyapatite and L-poly-lactid acid. Finally autologous fat is being used as a filling substance (lipofilling). The gravest complications with fillers are intravascular injections. In particular when injected in arteries fillers can block blood flow and lead to skin necrosis or vison loss in case the material occludes the Central Retinal Artery (CRAO). Two opposing theories about the nature of arterial occlusion exist. One based on Ian Taylor idea of choke anastomoses assume vasoconstriction induced by the filler, both of the primary offended artery and its anastomosing vasosomes. In this case resolving the hyaluronic acid filler with the enzyme hyaluronidase at the primary occluding location would suffice. This is done under ultrasound guidance. The other theory assumes displacement of parts of the filler to end arterioles. Then, the whole affected area has to be flooded with large dosages of hyaluronidase. Obstructions with fillers based on other materials cannot be resolved. It seems logical to prevent intra-arterial filler injection by duplex sonography detection of the course of arteries prior to injection. Ultrasound has additional advantages for cosmetic doctors such as recognizing remains of previously injected filler. It also can give feedback on a physician’s ability to inject filler in the correct subdermal location.

Calcium hydroxyapatite nanoparticles as a reinforcement filler in dental resin nanocomposite

The current study focuses on the fabrication of calcium hydroxyapatite (Ca10(PO4)6(OH)2) (HA) in a nanorange having whiskers- and cubic-shaped uniform particle morphology. The synthesized HA particles hold a promising feature as reinforcement fillers in dental acrylic resin composite. They increase the efficacy of reinforcement by length and aspect ratio, uniformity, and monodispersity. Therefore, the acrylic resin was reinforced with the as-synthesized monodispersed HA filler particles (0.2–1 Wt%). The presence of filler particles in the composite had a noticeable effect on the tribological and mechanical properties of the dental material. The morphological effect of HA particles on these properties was also investigated, revealing that cubic-shaped particles showed better results than whiskers. The as-fabricated composite (0.4 Wt%) of the cubic-shaped filler particles showed maximum hardness and improved antiwear/antifriction properties. Particle loading played its part in determining the optimum condition, whereas particle size also influenced the reinforcement efficiency. The current study revealed that particle morphology, particle size, uniformity, etc., of HA fillers, greatly influenced the tribological and mechanical properties of the acrylic resin-based nanocomposite. Improvement in the tribological properties of HA particle-reinforced acrylic resin composites (HA–acrylic resin) followed the trend as AR < CmC < WC < CC.

Calcium Hydroxyapatite: A Highly Stable and Selective Solid Catalyst for Glycerol Polymerization

Calcium-based catalysts are of a high interest for glycerol polymerization due to their high catalytic activity and large availability. However, their poor stability under reaction conditions is an issue. In the present study, we investigated the stability and catalytic activity of Ca-hydroxyapatites (HAps) as one of the most abundant Ca-source in nature. A stochiometric, a Ca-deficient and a Ca-rich HAps have been synthetized and tested as catalysts in the glycerol polymerization reaction. Deficient and stochiometric HAps exhibited a remarkable 100% selectivity to triglycerol at 15 % of glycerol conversion at 245 &deg;C after 8 h of reaction in the presence 0.5 mol.% of catalyst. Moreover, under the same reaction conditions, Ca-rich HAp showed a high selectivity (88 %) to di- and triglycerol at a glycerol conversion of 27 %. Most importantly, these catalysts were unexpectedly stable towards leaching under the reaction conditions based on the ICP-OES results. However, based on the catalytic tests and characterization analysis performed by XRD, XPS, IR, TGA-DSC and ICP-OES, we found that HAps can be deactivated by the presence of the reaction products themselves, i.e., water and polymers.

Rat skin inflammation markers change in response to calcium hydroxyapatite and hyaluronic acid administration

In the research, the level of some markers of skin inflammation in Wistar rats was examined after injection of calcium hydroxyapatite and hyaluronic acid drugs of various concentrations, where the nature, degree, extent of tissue damage and the general condition of the animals in general were close to humans’. Each drug was evaluated according to several indicators (MDA content, activity of neutrophil elastase, acid phosphatase, and catalase) to understand the measure of the adequacy of the body's response to the intensity of the stimulus. A biochemical analysis of the skin of laboratory rats after the injection of the studied drugs showed that the safest drugs contain nonstabilized 4% hyaluronic acid. Either in pure form or in a 1: 1 mixture with calcium hydroxyapatite at a concentration of 55.7%, since in 2 months after their injection in the skin of experimental animals, markers of inflammation (elastase, acid phosphatase and MDA levels), catalase and API activity were found at the normal level. The injection of drugs containing stabilized 2% hyaluronic acid and calcium hydroxyapatite 55.7%, as well as stabilized 2.6% hyaluronic acid and calcium hydroxyapatite at a concentration of 1% caused prolonged LPO activation, increased level of inflammation markers and decreased API. The injection of calcium hydroxyapatite drugs without hyaluronic acid, even at a 1: 1 dilution with saline, also caused prolonged LPO activation, an increased level of inflammation markers and a decreased API, and, in addition, revealed a significant increase in acid phosphatase activity, which is an indicator of the integrity of cell membranes. The obtained results made it possible to analyze the features of the molecular response and regulation of inflammation upon injection of calcium hydroxyapatite and hyaluronic acid drugs of different concentrations, which will help in prescribing of treatment.

Debridement, antibiotics, irrigation, and retention of the prosthesis with antibiotic-impregnated calcium hydroxyapatite in periprosthetic hip joint infection

Background We have developed antibiotic-impregnated calcium hydroxyapatite (CHA) as a novel antibiotic delivery system. Here, we assessed the clinical results of debridement, antibiotics, irrigation, and retention of the prosthesis (DAIR) with antibiotic-impregnated CHA for the treatment of prosthetic joint-associated infection (PJI) after total hip arthroplasty (THA). Methods Twelve patients (13 hips) treated with DAIR for PJI after THA at our institution between 1997 and 2017 were retrospectively evaluated. The study group included four men (five hips) and eight women, with an average age of 66.1 (range, 56–90) years. Four patients (five hips) had symptoms of infection within less than 3 weeks; however, eight patients had symptoms of infection over 3 weeks. All patients received DAIR with antibiotic-impregnated CHA in the surrounding bone. In one patient, the cup component revision was performed with one-stage re-implantation because of loosening, but the stem component was retained. In nine patients (10 hips), vancomycin hydrochloride was impregnated in the CHA. Results The average duration of follow-up was 8.3 (range, 2.9–18.6) years. No patients were lost to follow-up. Four patients included in this study died of other causes, with an average follow-up of 6.7 (range, 4.0–12.5) years. Intra-operative cultures were positive in 12 hips. Ten of 12 patients (11 of 13 hips) were successfully treated, and no signs of infection were observed at the latest follow-up. In two of 12 patients (two of 13 hips) for whom treatment failed, infection was successfully treated with two-stage re-implantation. Both patients had diabetes mellitus and symptoms of infection over 3 weeks. Eighty-five percent of patients were successfully treated by DAIR with antibiotic-impregnated CHA. No complications were observed with this antibiotic-impregnated CHA. Conclusions DAIR treatment with antibiotic-impregnated CHA produce a higher rate of success in patients with PJI after THA.