Coral--polyhydroxybutrate composite scaffold for tissue engineering: prefabrication properties

In this study the surface properties of two particulate coral and polyhydroxybutrate (PHB) were studied in order to characterize them prior to use in composite production. Coral powder and PHB particle were evaluated using scanning electron microscopy and confocal laser scanning microscopy, to measure surface porosity and pores size. The results showed that coral powder has multiple pleomorphic micropores cross each others give appearance of micro-interconnectivity. Some pore reached to 18 microm with an average porosity of 70%. PHB revealed multiple different size pores extended to the depth, with an average some times reach 25 microm and porosity 45%. These findings demonstrate that both coral and PHB have excellent pores size and porosity that facilitate bone in growth, vascular invasion and bone development. We believe that incorporation of coral powder into PHB will make an excellent composite scaffold for tissue engineering.

Chromosome aberration test for hydroxyapatite in sheep

The present study is aimed at finding the mutagenicity and cytotoxicity of dense form of synthetic hydroxyapatite (Source: School of Materials and Mineral Resources Engineering, Universiti Sains Malaysia) in the blood of sheep. The biomaterial was implanted in the tibia of Malin, an indigenous sheep breed of Malaysia. Blood was collected from the sheep before implantation of the biomaterial, cultured and a karyological study was made. Six weeks after implantation, blood was collected from the same animal, cultured and screened for chromosome aberrations. The mitotic indices and karyological analysis indicated that the implantation of synthetic hydroxyapatite (dense form) did not produce any cytotoxicity or chromosome aberrations in the blood of sheep.

Locally produced bovine bone sponge as a haemostatic agent

The aim of this study was to evaluate the morphological and biological properties of a locally produced "Bovine Bone Sponge" for use in dentistry. Bovine bone sponge was prepared from local calf bone. Endotoxin level and surface properties were investigated. The pore size and water uptake ability were measured and results were compared with the commercial haemostatic agent. The material was tested for its haemostatic property and its inhibition of alveolar bone resorption in a sheep model following dental extraction. Results revealed a significant difference in haemostatic effect, and a shorter bleeding time and a lower rate of alveolar bone resorption in bovine bone sponge compare to a commercial haemostatic agent.

An in vivo study of a locally-manufactured hydroxyapatite-based material as bone replacement material

Defects were created in the mandible of a rabbit model whereby the right side was implanted with hydroxyapatite (HA) while the left side was left empty to act as control. Both the implant and control sites were evaluated clinically and histologically at 4,12,20,22 weeks. Decalcified sections were studied under confocal laser scanning microscope. No reactive cells were evident microscopically in all sections. There was bone ingrowth as early as 4 weeks when viewed by the topographic method. Enhancement of osteoconduction was evident by the presence of abundant capillaries, perivascular tissue and osteoprogenitor cells of the host. At 22 weeks, the implanted defect showed mature bone formation filling almost the whole field. This study demonstrated that the dense HA exhibits excellent biocompatibility as noted by the complete absence of reactive cells. It also promotes osteoconduction.

In vivo chromosome aberration test for hydroxyapetite in mice

This study evaluates the cytotoxic and mutagenic effect of synthetic hydroxyapatite granules (source: School of Material and Mineral Resources Engineering, Universiti Sains Malaysia) in the bone marrow cells of mice. Mice are exposed to synthetic hydroxyapatite granules, the bone marrow cells are collected and observed for chromosome aberrations. No chromosome aberrations were noticed in the animals exposed to distilled water (negative control) and to the test substance, synthetic hydroxyapatite granules (treatment) groups. Chromosome aberrations were observed in the animals exposed to Mitomycin C (positive control group). There was no indication of cytotoxicity due to synthetic hydroxyapatite granules in the animals as revealed by the mitotic index. Hence, synthetic hydroxyapatite granules are considered non-mutagenic under the prevailing test conditions.

Mutagenicity of CORAGRAF and REKAGRAF in the Ames test

Mutagenicity of CORAGRAF (natural coral) and REKAGRAF (hydroxyapatite) was tested in Ames test with and without an external metabolic activation system (S9). The test revealed no mutagenic activity of both locally produced osseous substitutes.

Biocompatibility test of polyhydroxybutyrate on human cell line

The human fibroblast MRC-5 cells incubated with PHB granules (TM) added at a final concentration of 4 mg/ml showed a time-course pattern of survival. The percentages of dead cells obtained were at the rate of 3.8% after 7 days, respectively. When the MRC-5 cells grown in different material, using the test concentration of 4 mg/ml PCM, they were found to show a similar time-course increasing pattern of death as that obtained with PHB. However, the death was noted in the cells incubated for 7 days, the death rates obtained was 40.54% respectively.

Bone marrow mesenchymal stem cells differentiation and proliferation on the surface of coral implant

This study was designed to evaluate the ability of natural coral implant to provide an environment for marrow cells to differentiate into osteoblasts and function suitable for mineralized tissue formation. DNA content, alkaline phosptatase (ALP) activity, calcium (Ca) content and mineralized nodules, were measured at day 3, day 7 and day 14, in rat bone marrow stromal cells cultured with coral discs glass discs, while cells alone and coral disc alone were cultured as control. DNA content, ALP activity, Ca content measurements showed no difference between coral, glass and cells groups at 3 day which were higher than control (coral disc alone), but there were higher measurement at day 7 and 14 in the cell cultured on coral than on glass discs, control cells and control coral discs. Mineralized nodules formation (both in area and number) was more predominant on the coral surface than in control groups. These results showed that natural coral implant provided excellent and favorable situation for marrow cell to differentiate to osteoblasts, lead to large amount of mineralized tissue formation on coral surface. This in vitro result could explain the rapid bone bonding of coral in vivo.

Mechanical and thermal properties of hydroxyaptite filled poly (methyl methacrylate) heat processed denture base material

The aim of this study was to evaluate the effect of powder-to-liquid ratio on the glass transition temperature (Tg) and the tensile properties of denture base material prepared from poly (methyl methacrylate) (PMMA) and hydroxyapatite (HA) previously treated with 3-trimethoxysilylpropyl methacrylate (gamma-MPS). Specimens for mechanical testing were prepared by adding composites powder (PMMA, BPO and HA) to the monomer (MMA and EGDMA) followed by hand mixing as in dental laboratory description usage. The glass transition temperature was studied by using differential scanning calorimetry (DSC). It was observed that the tensile properties and the Tg were affected by the powder-to-liquid ratio. The mechanical characterization of the materials were performed by using single edge notch-tension (SEN-T) specimens; the fracture toughness was slightly higher in formulation which contained HA filler compared to commercial denture base material.