PURPOSE: The porosity of the bone cement is the most important cause of fatigue failure, the most common mode of failure of bone cement using widely in arthroplasty. It is important to evaluate the porosity of bone cement for improvement or development of bone cement, but the conventional 'stain, 'cut, and 'polish, manual method takes long time and efforts. So it is necessary to develop a new technique for evaluation of porosity of bone cement. We tried a technique using computer image analysis system to evaluate the porosity of bone cement specimen and assess efficacy of the method. Simultaneously we evaluated the relationship between the porosity of bone cement and fatigue failure. MATERIAL AND METHODS: We made 59, 2.5inch-length bone cement specimens(30 Simplex P, 29 Palacos R) using Simplex P and Palaces R which are widely using in clinical situation and checked radiogram using mammography film. After scanning the mammography film, we measured the porosity of the bone cement specimens using NIH(National Institute for Health) Image 1.6 version image analysis program. We also, measured the porosity of the bone cement specimens with conventional 'stain','cut' and 'polish' method, after then compared the results of two methods. Simultaneously, we evaluated the relationship between porosity & fatigue failure by loading 9.0, 10.0, 12.5 and 15.0 MPa load with frequency of 10Hz to the bone cement specimens under the physiologic condition. RESULTS: The coefficient of relation of simplex P and palaces R was 0.729 and 0.713 respectively, so there was high relationship between the image analysis system method and conventional one. It was easy and took shorter time to measure the porosity of bone cement specimens with image analysis system. There was high correlation between cement porosity and fatigue failure, regardless of level of load. CONCLUSION: It was very easy and fast to measure the porosity of the bone cement specimens with image analysis system and there was high correlation between cement porosity and fatigue failure.
Arthroplasty ; Fatigue ; Mammography ; Methylmethacrylate ; Porosity*

PURPOSE: This experiment examined the effects of anodization on commercially pure titanium implant fixtures. MATERIAL AND METHODS: The implant fixtures were anodized at three different voltage levels, producing three different levels of oxidation on the surface of the fixure. Implant were divided into four groups according to the level of oxidation. Group 1 consist of the control group of machined surface implants, Group 2 implants were treated by anodizing to 100 voltage, Group 3 implants were treated by anodizing oxidation to 200 voltage Group 4 implants were treated by anodizing oxidation to 350 voltage. Surface morphology was observed by Scanning Electron Microscope(SEM) and the surface roughness was measured using NanoScan E-1000(R). Implantation of the fixtures were performed using New Zealand white rabbits. Periotest(R) value(PTV), resonance frequency analysis(RFA), and removal torque were measured in 0, 2, 4, 8, 12 weeks after implantation. RESULTS: The results of the study were as follows: 1. Values for the measured surface roughness indicate statistically significant differences in Ra, Rq, and Rt values among group 1, 2, 3, and 4 at the top portion of the thread,(p<0.05) while values at the base of the threads indicated no significant difference in these values. 2. A direct correlation between the forming voltage, and surface roughness and irregularities were observed using scanning electron microscope. 3. No statistically significant differences were found between test groups regarding Periotest(R) values. 4. Analysis of the data produced by RFA, significant differences were found between group 1 and group 4 at 12 weeks after implantation.(p<0.05) CONCLUSIONS: In conclusion, no significant differences could be found among test groups up to a certain level of forming voltage threshold, beyond this forming voltage threshold, statistically significant differences occurred as the surface area of the oxide layer increased with the increase in surface porosity, resulting in enhanced bone response and osseointegration.
Osseointegration ; Porosity ; Rabbits ; Titanium ; Torque

STATEMENT OF PROBLEM: Despite of the recent development of the titanium casting system methods, the casting defects such as imperfect casting and internal porosity were frequently observed. PURPOSE: The purposes of this study were to compare and measure the castability, microhardness, and surface reaction between Grade 2 pure titanium and Ti-6Al-4V by casting these alloys from the different sprue design conditions. MATERIAL AND METHODS: Depending on the sprue designs and titanium alloys, 42 ready-made wax patterns were used. By analyzing the remodeling of the cast, internal porosity, microhardness, and titanium surface layer of SEM, there were several results we observed. RESULTS: 1. The measured castability of titanium were categorized in the ascending order: individual sprue group, runner bar group, and single group. This data are based on the statistically signigicant differences. 2. The castability of titanium has not showed the statistically significant differences among the alloys. However, CP-Ti groups were superior to Ti-6Al-4V groups by showing the noticeable castability. 3. The surface layers of the castings of all groups have showed 5 micrometer titanium oxide layers irrespective of sprue designs and titanium alloys. CONCLUSION: From the above study results, by fabricating the restorations from the centrifugal casting machine direct sprue designs revealed better castability. As we increased the number of sprues in the wax pattern, it revealed better castability. The castability of pure titanium rather than that of Ti-6Al-4V was remarkable. To fabricate the complex forms of the restorations, further researches on the efficient sprue designs and titanium alloys must be made.
Alloys ; Celiac Disease ; Investments* ; Porosity ; Titanium*

STATEMENT OF PROBLEM: The high melting temperature and chemical reactivity of titanium necessitates casting machines different from those used in conventional casting. Despite the new developments in Ti casting systems, inadequate mold filling and internal porosity are frequently observed casting defects. Therefore, the study on the fabrication technique including sprue design to solve these casting defects is still necessary. PURPOSE: The purpose of this study was to evaluate the effect of sprue design and cross sectional area of sprue on the internal porosity. MATERIALS AND METHODS: 30 simulated cast three units titanium crowns were prepared. 5 cast crowns for each with different sprue design(sinlge sprue, double sprue and plate sprue) of two cross sectional areas(small and large cross sectional areas) were fabricated. The sections of titanium castings were photographed in a microscope at x100 magnification to record internal porosities. RESULTS AND CONCLUSION: Within the limits of this study, the following conclusions were drawn: 1. There was a significantly lower in internal porosity of titanium castings for large cross sectional area of sprue group than the small group(P>.05). 2. There was no significant difference in internal porosity among sprue designs in similar cross sectional area of sprue(P>.05).
Celiac Disease* ; Crowns ; Freezing ; Fungi ; Porosity* ; Titanium*

To serve as carriers of cells and bioactive molecules, three-dimensional scaffolds play a key role in bone defect repair. The chemical component and microstructure of the scaffold can affect the mechanical properties and seed cells. A variety of fabrication techniques have been used in producing scaffolds, some made random porous structure, some created well-designed structure using rapid prototyping methods, and others prepared bio-derived materials as scaffolds. However, scaffolds may vary in their inner structure, mechanical properties and repairing efficiency as well because of different manufacturing methods. In this review, we overview the main achievements concerning the effects of material and microstructure on the mechanical performance, seed cells and defect repair of bone scaffolds.
Biocompatible Materials ; Bone and Bones ; Porosity ; Tissue Scaffolds

Cryogels are a type of hydrogel material which are fabricated by cryopolymerization at subzero temperature. Due to their unique macroporous structure, shape memory properties and injectability, cryogels have gained significant interest in the fields of tissue engineering for encouraging the repair and regeneration of injured tissues. In this review, the basic concepts relevant to cryogels are introduced, and then the fabrication principle, the process parameters and the unique properties of cryogel are discussed. Next, the latest advances of cryogels as three-dimensional scaffold for various tissue engineering applications are given. Finally, this review summarizes the current limitations of cryogels, and strategies to further improve their properties for tissue engineering. The purpose of this article is to provide a reference guide for the researchers in related fields.
Cryogels ; Porosity ; Tissue Engineering ; Tissue Scaffolds

A newly isolated white rot fungal strain KU-RNW027 was identified as Trametes polyzona, based on an analysis of its morphological characteristics and phylogenetic data. Aeration and fungal morphology were important factors which drove strain KU-RNW027 to secrete two different ligninolytic enzymes as manganese peroxidase (MnP) and laccase. Highest activities of MnP and laccase were obtained in a continuous shaking culture at 8 and 47 times higher, respectively, than under static conditions. Strain KU-RNW027 existed as pellets and free form mycelial clumps in submerged cultivation with the pellet form producing more enzymes. Fungal biomass increased with increasing amounts of pellet inoculum while pellet diameter decreased. Strain KU-RNW027 formed terminal chlamydospore-like structures in cultures inoculated with 0.05 g/L as optimal pellet inoculum which resulted in highest enzyme production. Enzyme production efficiency of T. polyzona KU-RNW027 depended on fungal pellet morphology as size, porosity, and formation of chlamydospore-like structures.
Biomass ; Laccase ; Manganese ; Peroxidase ; Porosity ; Trametes*

PURPOSE: To investigate change of CT attenuation of biliary stones in water soluble contrast media with time as well as the factors contributing to this change. MATERIALS AND METHODS: Thirty biliary stones were placed within cone-shaped plastic tubes, and as a control study, spiral CT scanning was performed 50 minutes after immersion in normal saline. The stones were rescanned at 5, 10, 20, 30, 45, 60, 90 and 120 minutes after immersion in water soluble contrast media. Mean CT attenuation value and volume of the stones were measured after three-dimensional reconstruction of images. Physical factors such as porosity[(wet weight - dry weight) / wetweight]x100, volume, and cholesterol as a chemical factor were measured. RESULTS: The pattern of change of CT attenuation was classified as one of three types. Fifteen stones (50%) were classified as type 1, in which attenuation increased with immersion time; in ten stones, this increase was rapid, particularly within the first 5 minutes. Twelve (40%) were classified as type 2, in which attenuation showed no significant change. Three stones showed no regular pattern, and these were classified as type 3. The mean porosity of type 1 (median; 32.7, mean+/-SD; 52.83+/-34.48) was greater than that of type 2 (median; 6.7, mean+/-SD; 30.58+/-48.25)(p<.05). The volume and cholesterol fraction of stones were not significantly different between type 1 and 2. CONCLUSION: In some biliary stones, CT attenuation value increases in water-soluble contrast media with time, and porosity is the most important factor in attenuation change.
Cholesterol ; Contrast Media* ; Immersion ; Plastics ; Porosity ; Tomography, Spiral Computed

Recently, many researches have been carried out on the production of artificial tissue using tissue engineering. However, studies on fat tissue are still insufficient. The purpose of this study was to examine that alginate sponge can be used as a three-dimensional scaffold for the culture of preadipocytes compared with fibroblasts, and that preadipocytes can differentiate into mature adipocytes in this sponge. The 3T3-L1 preadipocytes and the 3T3 fibroblasts were separately cultured in three-dimensional alginate sponge for 14 days. The morphology of cell and sponge, cell proliferation rate, and glycerol phosphate dehydrogenase activity were evaluated at the indicated periods. The results were as follows; 1. The alginate sponge showed a highly porous, well-interconnected pore structure and the sizes of pores were from 100 to 400micrometer. 2. The fibroblasts in sponge exhibited spindle shape with long irregular fibers on the 7th day and there was no oil-red O stained cell until 14 days. However, the preadipocytes in alginate sponge were round and some of cells transformed into mature fat cells which were stained with oil-red O after 14 days. 3. The proliferation rates of preadipocyte group were increased gradually during the culture period, but lower than those of fibroblast group(P< 0.05). 4. The glycerol phosphate dehydrogenase activities of preadipocyte group were significantly higher than those of fibroblast group during the culture period(P< 0.05), and the activities of 14 day-cultured preadipocytes were about 30 times higher than those of 7 day-cultured preadipocytes. The results suggest that alginate sponge, which has fixed shape and porosity, is adequate three-dimensional scaffolds for culture of fibroblast and preadipocyte. In addition, preadipocytes could be well proliferated and differentiated into adipocyte in the alginate sponge.
Adipocytes ; Cell Proliferation ; Fibroblasts ; Glycerol ; Oxidoreductases ; Porifera* ; Porosity ; Tissue Engineering

To demonstrate possible influences of general bone density on the mandible, histomorphometric analysis was carried out in mandibles and iliac bones and the correlation of the two bone densities was tested. Comparison of bony density in women and men over 60 years in the mandible was carried out too. Quantitative computed tomography (GCT) was taken in cross-section of mandibles at the same site where histomorphometric analysis was performed to evaluate the reliability of QCT. The analysis included 40 cadavers with no known disease affecting the bones. The subjects consisted of 15 females and 25 males with a mean age of 60.3 years. Spearman correlation analysis and Wilcoxon rank sum test was performed. The results were as follows. 1. There was statistically no correlation between the mandible and iliac bone in the walues of corrected cortical width (CCW), cortical porosity (POR) in cortex, and total bone volume(TBV), mean trabecular plate thickness (MTPT), mean trabecular plate density (MTPD), and mean trabecular plate separation (MTPS) in trabecular bone. 2. Comparison of women and men over 60 years, men had statistically higher bone density than women except for POR of buccal and lingual cortex, and MTPD of alveolar trabeculae in mandible. 3. There was statistically significant correlation between TBV of trabecular bone and CT NO., but not between POR and CT No. In mandible. According to the results above, there was no correlation between mandible and iliac bone density and between mandibular bony density and age. Further studies are required to support the results. A more noninvasive method to be able to measure the bone density of mandible should be developed and it is necessary to accumulate data on the normal values of bone density of mandible according to age and sex. Further study should be carried out about QCT to measure mandibular bony density using QCT.
Bone Density* ; Cadaver ; Female ; Humans ; Male ; Mandible* ; Porosity ; Reference Values