Key Engineering Materials Vol. 829

Abstract: Calcium sulfate dihydrate (CSD) cement has been used as bone void filler and antibiotic carrier for many years. However, the main drawback of CSD cement is its brittleness that limits its handling property. Thus, the aim of this study is to fabricate granular CSD cement-gelatin-polycaprolactone (CSD-Gel-PCL) to improve handling property. To prepare CSD-Gel-PCL composite, granular CSD was prepared from calcium sulfate hemihydrate (CaSO₄.0.5H₂O; CSH) and distilled water with water/powder (W/P) ratio of 0.5. The CSD cement was crushed and sieved into 300-500 μm. The obtained granular CSD was then mixed with 3 wt.%, 5 wt.% and 7 wt.% gelatin solution which previously mixed with PCL (50 wt% PCL, 50 wt% gelatin), followed by freeze drying for 48 hours. The CSD granules were able to bind together after the addition of gelatin and PCL matrix. After freeze drying, the CSD granules were not easy to remove from the composite body. Scanning electron microscopy (SEM) analysis revealed that CSD granules were surrounded by polymer matrix in all 3 different specimens in which the higher gelatin concentration, the more the matrix found between the granules. Mechanical evaluation suggested that all of the specimens showed the same stress-strain curve pattern. The CSD-Gel-PCL composite with 7 wt% gelatin has the highest strength compared with the other specimens. Stress-strain curves indicated that combination of CSD granules, gelatin and PCL has produced bone filler with improved handling property.

Abstract: Calcium sulfate dihydrate (CSD) cement has been used as bone filler for decades. It is also used as antibiotics carrier to treat osteomyelitis. However, CSD cement alone when applied at bone defect has some limitation such as its brittleness. The brittleness limits its handling property. Thus, the aim of this study is to fabricate granular CSD cement-gelatin (CSD-Gel) that has good handling property to be used as bone void filler. To prepare CSD-Gel composite, granular CSD was prepared from calcium sulfate hemihydrate (CaSO₄.0.5H₂O; CSH) and distilled water with water/powder (W/P) ratio of 0.5. The CSD cement was crushed and sieved into 300-500 μm. The obtained granular CSD was then mixed with 3 wt.% and 7 wt.% gelatin solution, followed by freeze drying for 48 hours. The CSD granules were surrounded by gelatin matrix in all specimens. It was observed that more gelatin matrix found in the space between the granules in in the composite with 7 wt% gelatin compared with that in 3 wt% gelatin. Mechanical evaluation revealed that CSD-Gel 7% has significant higher compressive strength compared with that of CSD-Gel 3%.

Abstract: Calcium sulfate dihydrate (CSD) has been clinically used as bone filler for decades. CSD bone graft is cheap, biocompatible and can be transformed to other osteoconductive ceramics such as hydroxyapatite and carbonate apatite. In addition, porous ceramic bone grafts is desired clinically. Development of porous ceramics bone graft with simple and cost-effective method is preferred. Thus, in this study, porous CSD was developed. Porous CSD can be used both as bone filler or precursor for porous hydroxyapatite and carbonate apatite. Porous CSD was prepared by mixing calcium sulfate hemihydrate (CSH) containing sucrose granules with distilled water. After setting, the sucrose granules were removed by immersion in distilled water. Porous CSD was obtained after sucrose leaching. It was observed that more pore formed in the specimen with 50% sucrose granule compared with that of 25% sucrose granule. The sucrose was completely removed from the porous CSD evident from ATR-FTIR analysis. The diametral tensile strength of the porous CSD tend to decrease with the increase of sucrose granule. Finally, sucrose granule was feasible to be used as pore maker in preparation of porous CSD.

Abstract: Recently, ceramic material has become a main object of scientific interest especially in dental material. The advance of dental materials technology has led to use of zirconia-based ceramics for composite filler. In this study, composite filler has been synthesized from natural zircon sand through geopolymerization method. Composite prototype were made with different filler volume to evaluate mechanical properties including hardness number and diametral tensile strength. Samples divided into two groups with 50 wt% filler volume (group A) and 75 wt% filler volume (group B) which 3 samples for each group. The surface micro hardness of each group tested by Leco M-400-H1 vickers microhardness testing machine and for diametral tensile strength tested using universal testing machine (Lloyd) with crosshead speed of 1,0 ± 0,25 mm/min. The data were analyzed using independent sample t-test. The results showed that the average of hardness number on group A was 13,8 VHN while for group B was 24,1 VHN. The average of diametral tensile strength for group A was 20,461 MPa and 27,689 MPa for group B. Statistical result showed that the value (P<0,05). The conclusion, there is a signifficant difference on the result of hardness test between group A (50 wt% filler volume) and group B (75 wt% filler volume) and also on diametral tensile strength test.

Abstract: The widely use of dental composite triggers a lot of research to synthesize composite made from natural sources. One of the natural sources that could be used as a filler of composite is natural zircon sand from Indonesia. The physical properties of dental composite, such as Diametral Tensile Strength (DTS) and hardness could be affected by the filler of the composite. The aim of this research is to determine the value of diametral tensile strength and hardness of prototype composite with natural zircon sand-based filler by using geopolymerization method with various coupling agents. The procedures began from synthesizing Zirconia-Alumina-Silica filler from natural zircon sand using geopolymerization method with two different coupling agents, 3-mercapto propyltrimethoxysilane (3-MPTS) and 3-aminopropyltriethoxysilane (3-APTS), which then mixed with resin matrix to form composite resin, some of the samples were then subjected to a DTS test using Lloyd Universal Testing Machine (5.6 N initial load) until a crack/fracture was formed while some of them was subjected to a hardness test using Vickers Hardness Tester. The results showed the average DTS of dental composite using MPTS coupling agent was 13.78 MPa, while the average DTS of dental composite using APTS coupling agent was 8.90 MPa, and the average hardness result of dental composite coated by 3-MPTS was higher (20.68 VHN) than composite coated by 3-APTS (18.02 VHN). This difference could be affected by filler particle composition, filler surface area and also coupling agent variation. In conclusion, the tensile strength of the prototype resin composite sample group with the natural zircon sand filler using MPTS coupling agent was higher than the APTS coupling agent group.

Abstract: Composite fiber were already developed and looked promising in dentistry. PMMA, optically clear polymer, was combined with high mechanically properties ZrO₂-Al₂O₃-SiO₂ (ZAS) ceramic powder to improve the flexural strength value of dental post prototype. ZAS powder, with ratio 60:20:20, were first prepared via sol-gel technique. Afterwards, PMMA was dissolved in acetone then incorporate with ZAS powder 1% wt to gain ZAS-PMMA composite fiber via electrospinning method. Dental post prototype were fabricated into two groups, one group contain ZAS-PMMA composite fibers and one group contain neat BisGMA, as control, with amount of each groups samples was 10. As-prepared samples were tested by Universal Testing Machine (UTM) to evaluate the flexural strength values. Based on unpaired T-test analysis (p value < 0.05), the composite fiber post is significantly higher (48.17 %) than the neat BisGMA post. ZAS-PMMA composite fiber post was potential to be used as dental endodontic post in anterior.

Abstract: Dental composite is used to restore disease or fracture tooth structure and modify tooth shape as well as color in order to enhance the aesthetic properties. This restoration should possess sufficient strength and translucency at the same time. Diametral tensile strength and reflectance of dental composite were related to the selection of three main components; filler, coupling agent and resin matrix. Quarsi-experimental. This study was a follow-up study whereby the filler silica-zirconia-alumina system were synthesized by sol-gel technique with precursors composition ratio 70:20:10. The surface of subsequent filler were modified by 3-mercaptoppropyltrimethoxysilane (MPTMS) and aminopropyltrimethoxysilane (APTES) then becoming group A and B respectively. In order to prepared the dental composite, acetone was used to reduce the viscosity of Bisphenol A Glycidyl Methacrylate (BisGMA) thus enable introducing more content of filler into resin matrix. Phase of crystalline and particle morphology were identified by X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) consecutively. Universal Testing Machine (Lloyd) with crosshead speed 1mm/min was used to evaluate diametral tensile strength between two samples group. Dental composite contain filler-MPTMS coated were continuing tested to measure the reflectance values. Disc of each samples were prepared (n=3) with different thickness (1.5 mm and 3 mm) and same diameter (20 mm). Both diametral tensile strength and reflectance evaluation data were analysis by t-test unpaired. The result showed no statistically significant differences in diametral tensile strength between group A (47,6548 MPa) and B (41,4265 MPa). Reflectance evaluation also exhibited no statistically significant differences in dental composite contain filler-coated MPTMS with different thickness. Dental composite prototype based on diametral tensile strength and reflectance evaluation were potential to be used as alternative dental restoration.

Abstract: Spherical calcium-alginate gel beads containing HAIO, iron oxide (IO) nanoparticles embedded on hydroxapatite (HA), were prepared along with and poly (N-isopropylacrylamide) (PNIPAAM) or chitosan. These spheres, HAIO, HAIO-PNIPAAM and HAIO-chitosan spheres, were used as carriers of 5-fluorouracil (5-FU), one of the drugs for cancer chemical therapy, and the 5-FU release behavior in PBS solution was investigated at ambient and elevated temperatures using U-V spectrometry. The amount of the released 5-FU from the HAIO spheres was somewhat higher than that from HAIO-PNIPAAM and HAIO-chitosan spheres at ambient temperature. At elevated temperature, HAIO spheres showed an increase in quantity of released 5-FU. The amount of released 5-FU from HAIO-PNIPAAM spheres was almost the same, and that from HAIO-chitosan spheres was reduced compared to those at ambient temperature. These spheres, HAIO, HAIO-PNIPAAM and HAIO-chitosan spheres, show the similar swelling properties at elevated temperature. However, the combinations of Ca-alginate - PNIPAAM or Ca-alginate - chitosan may produce the different structures, which are core-shell network for HAIO-PNIPAAM spheres and or a polyelectrolyte complex for HAIO-chitosan spheres, leading to a different release behavior of 5-FU.

Abstract: Cellulose nanofiber-apatite nuclei composites were fabricated by mixing apatite nuclei with cellulose nanofiber slurry and air-drying. Then apatite-forming ability could be imparted to cellulose nanofiber-apatite nuclei composites. In order to investigate significance of mixed apatite nuclei, cellulose nanofiber-hydroxyapatite composites were fabricated by mixing commercially obtained stoichiometric hydroxyapatite particles with cellulose nanofiber slurry, and the bioactivity was evaluated by using simulated body fluid.

Abstract: Ti-12Ta-9Nb-6Zr-3V-O alloy, one of the shape-memory alloys with lower Young’s modulus in comparison with conventional titanium alloy, was treated with sulfuric acid to form roughened surface on the substrate. In order to impart hydroxyapatite formation ability to the Ti-12Ta-9Nb-6Zr-3V-O alloy, apatite nuclei (AN) were precipitated on the roughened surface using simulated body fluid (SBF) adjusted at higher pH than physiological condition. By this treatment, AN-precipitated Ti-12Ta-9Nb-6Zr-3V-O alloy was obtained. The AN-precipitated Ti-12Ta-9Nb-6Zr-3V-O alloy showed high hydroxyapatite formation ability in physiological SBF.