Papers by Author: Jintamai Suwanprateeb

Abstract: Resorability of 3D printed hydroxyapatite (3DP HA) in deionized water solution which was buffered with succinic acid-NaOH (pH 5.5) and Tris(hydroxymethyl aminomethane) (pH 7.4) for 1, 7, 14 and 28 days was carried out. Weight change and release of calcium (Ca) and phosphorus (P) were used to evaluate the sample resorption. It was found that the weight of samples soaking in both pH 5.5 and 7.4 solutions decreased with increasing soaking times, but the degree of decrease was greater at pH 5.5 than at pH 7.4. ICP-OES results showed that the release of Ca and P in both pH solutions increased with immersing times. The amount of Ca and P released at pH 5.5 was higher than at pH 7.4. Phase composition of the samples and the microstructure of the sample were characterized using XRD and SEM respectively. XRD analysis showed that hydroxyapatite (HA) and octacalcium phosphate (OCP) phases were found at the center of all samples, but the intensity of OCP peaks tended to decrease with increasing times. Only HA was found on the sample surface after immersion in both pH solutions at all soaking periods. After immersion, newly formed crystals were seen both at the center and/or on the surface of samples. These results suggested that pH could influence the resorption of the samples and also the formation of new calcium phosphate crystals.

Abstract: Synthetic polymers are widely used in biomedical applications due to their advantages compared to other materials including low cost and ease of processability, good corrosion resistance and high properties to weight ratio. Among several polymeric biomaterials, polyethylene is a biocompatible polymer which has a long history of being utilized in many biomedical applications ranging from simple components to advanced implants. Although dense polyethylene is known to be a bioinert material which does not interact with host tissue, polyethylene in its appropriate porous form has been shown to be able to integrate well with surrounding host tissues and could widen its uses as bioactive implants. Porous polyethylene structure which was fabricated by three dimensional printing (3DP) is demonstrated. Its manufacturing technique, properties and clinical applications as tissue integrated implants which permitted soft or hard tissue ingrowth in tissue regeneration and replacement is discussed.

Abstract: Granule characteristics and the agglomeration ability of 3D printed hydroxyapatite granules (3DP HA) when contacting water were compared to those of commercial bone graft granules based on hydroxyapatite/β-tricalcium phosphate/collagen mixture (Sunmax). Microstructure, phase composition, water absorption and granular agglomeration of the granules were characterized. SEM showed that the granule sizes of Sunmax were in the range of 0.8-1.5 mm whereas that of 3DP HA was relatively more uniform at about 1 mm. 3DP HA granules comprised the weaving of numerous minute crystals containing large pores and having high porosity while Sunmax granules were crushed granules and having low porosity. XRD analysis confirmed that Sunmax granules were biphasic hydroxyapatite and β-tricalcium phosphate while 3DP HA granules were monophasic hydroxyapatite. Sunmax granules exhibited greater agglomeration volume than that of 3DP HA granules. However, the water absorption of 3DP HA granules was greater than that of Sunmax granules. The greater agglomeration ability of Sunmax granules was likely due to the collagen constituent of the granules which could act as adhesive to bind granules together in addition to water capillary action. In contrast, 3DP HA granules formed the agglomeration by the water film due to the capillary action only so the efficiency was lower although the water absorption was greater.

Abstract: Hydroxyapatite (HA) is a well-known biocompatible material which is widely used in orthopedic and dental applications. Because its chemical structure is similar to the human bone so it is compatible to use as a based materials in drug delivery system for treatment of bone infection diseases. In this research we focused on fabrication of HA sphere shape by three dimension printing using calcium sulphate hemihydrate (CaSO₄·0.5H₂O) as a starting material, then the as-three dimension printed CaSO₄·0.5H₂O spheres were hydrothermally treated in 1M disodium hydrogenphosphate (Na₂HPO₄) at 100°C-180°C for 2-8 hr. The reaction was taken place and the conversion of CaSO₄·0.5H₂O was gradually changed to Ca₁₀(PO₄)₆(OH)₂. Phase analysis by X-ray diffraction indicated that monetite (CaHPO₄) was coexisted with HA when hydrothermally treated at pH 9 at low reaction temperature (<180°C). When the pH of 1M Na₂HPO₄ was adjusted to pH 11, 180°C for 6 hr, the as-three dimension printed calcium sulphate hemihydrate spheres were completely converted to HA spheres without any destruction of the sphere shape. This is confirmed that hydrothermal reaction could enhance the phase conversion of HA and the conversion time was four times faster than the normal conversion.

Abstract: Anti-tuberculosis drugs loaded three dimensionally printed hydroxyapatite (3D printed HA) were prepared and coated with polycaprolactone to study the effect of coating on compressive resistance, microstructure, drug content and releasing characteristics. Smooth coating layer was observed on the surfaces of all coated samples while the uncoated samples displayed rough and porous surfaces. Coated samples had greater compressive resistance than uncoated samples, but the total drug contents in coated samples were slightly lower than those of uncoated ones. Both coated and uncoated samples displayed burst release of drugs initially and followed by a small release afterward. Polycaprolactone coating greatly decrease the amount of burst release of rifampicin drug loaded samples, but slightly decrease in the case of isoniazid drug loaded samples. Higher solubility of isoniazid than rifampicin in release media was thought to be the cause of limited efficiency of coating as observed.

Abstract: Influence of bovine serum albumin (BSA) concentration, soaking times and soaking temperatures during biomimetic co-deposition process of three dimensionally printed hydroxyapatite (3D printed HA) on weight change, phase composition and microstructure were studied. At 23°C, weight change of all samples monotonically increased with increasing soaking time regardless of BSA concentration used while the weight change initially increased, but leveled off later with increasing soaking time when using solution temperature of 37°C. At 50°C, weight change initially increased for up to 4 h and remained constant for up to 16 h where the weight decreased afterward. This decrease could be related to the competition between the dissolution of 3D printed HA, the deposition of new calcium phosphate crystals and the incorporation of BSA during biomimetic process at high temperatures. From X-ray diffraction, no influence in BSA concentration, time and temperature on the phase composition was observed. Scanning electron microscopy revealed the deposition of new plate-like calcium phosphate crystals on all 3D printed HA. Hydroxyapatite and octacalcium phosphate were found to be the main phases of all biomimetically BSA.

Abstract: Factors influencing calcium phosphate deposition on three dimensional printed hydroxyapatite (3D printed HA) by biomimetic process including soaking times (2, 4 and 6 hrs), solution temperatures (23, 37 and 50 °C) and solution refreshment (refreshed and non-refreshed) were studied. It was found that the weight change of the samples increased with increasing soaking times at all temperatures regardless of solution refreshment. Using refreshed solution resulted in greater increase in weight change than using non-refreshed solution. In the case of solution temperature, two opposite trends were observed depending on the solution refreshment. Increasing solution temperatures in non-refreshed solution exhibited a decrease in the weight change whereas the increase in the weight change was observed when using refreshed solution. This could be related to the competition between the dissolution of 3D printed HA and the deposition of new calcium phosphate crystals during biomimetic process. Octacalcium phosphate and HA were found to be the main phases of biomimetically deposited 3D printed HA.

Abstract: In this study, an alveolar ridge preservation using novel hydroxyapatite granules which was fabricated by three dimensional printing technique in post-extraction socket was carried out and evaluated. Clinical, radiographic and histology were assessed prior to dental implant placement. Five volunteered patients who needed an extraction of anterior tooth and scheduled for implant replacement were enrolled in this pilot study. No sign of infection or local of systemic immune reaction to the three dimensional printed hydroxyapatite granules in all patients was noted. At 8 weeks post-surgery, the grafted area was observed to be completely filled with woven bone and the formation of new vessels was seen. In addition, the bone quality and quantity of the grafted site when placing the implant showed efficient implant stability (ISQ values ∼ 65) without the need of additional bone graft surgery. Overall results indicated that three dimensional printed hydroxyapatite granules could be potentially employed as bone grafting material for alveolar ridge preservation.

Abstract: The effects of drying air temperature and flow rate, spraying air flow rate and slurry feed rate were investigated on the morphology, size distribution, density and flowability of spray-dried hydroxyapatite granules. The granules were of good spherical shape and smooth surface, but low flowability. The granules of uniform size distribution were obtained at high spraying air flow rate and granules of small sizes were collected at high spraying and drying air flow rates, high slurry feed rate and low drying air temperature. Thus, by adjusting the spray drying conditions we can control the granule properties.

Abstract: Rifampicin drug was experimentally loaded into 3D printed porous hydroxyapatite using two types of solvents (methanol or N-methyl-2-pyrrolidone) and various solution impregnation techniques aiming to maximize the total drug content in the samples. All vacuum assisted impregnations gave greater rifampicin content in the sample than that of atmospheric immersion. For similar vacuum assisted impregnation technique, the use of methanol could produce greater amount of drug in the sample than using N-methyl-2-pyrrolidone. For each solvent, the loading technique which gave maximum drug content was different. 2_step vacuum loading technique could impregnate the greatest amount of drug in the hydroxyapatite sample when using methanol as a solvent while one step vacuum loading technique with 10 % solution level (1_step_10) gave the greatest amount of the impregnated drug when using N-methyl-2-pyrrolidone as a solvent. These differences were related to the evaporation rate of the solvent and the degree of concentrated drug on the surface of the samples.