• 대한치과보철학회지
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• 제44권4호
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• pp.443-454
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• 2006

Purpose: This study aims to get the fundamental data which is necessary to the development direction of implant surface treatment hereafter, based on the understanding the surface structure and properties of titanium which is suitable for the absorption of initial tissue fluid by researching effects of additional surface treatments fir sandblasted with large git and acid-etched(SLA) titanium on surface micro-roughness, static wettability, fibronectin adsorption Materials and Method: In the Control groups, the commercial pure titanium disks which is 10mm in diameter and 2mm in thickness were treated with HCI after sandblasting with 50$\mu$m $Al_2O_3$. The experiment groups were made an experiment each by being treated with 1) 22.5% nitric acid according to SLA+ASTM F86 protocol, 2) SLA+30% peroxide, 3) SLA+NaOH, 4) SLA+ Oxalic acid, and 5) SLA+600$^{\circ}C$ heating. In each group, the value of Ra and RMS which are the gauges of surface roughness was measured, surface wettability was measured by analyzing with Sessile drop method, and fibronectin adsorption was measured with immunological assay. The significance of each group was verified by (SPSS, ver.10.0 SPSS Inc.) Kruskal-Wallis Test. (α=0.05) And the correlation significance between Surface micro-roughness and surface wettability. surface roughness and fibronectin adsorption, and surface wettability and fibronectin adsorption was tested by Spearman's correlation analysis. Result: All measure groups showed the significant differences in surface micro-roughness, surface wettability, and fibronectin adsorption. (p<0.05) There was no significance in correlation among the surface micro-roughness, surface wettability, and fibronectin adsorption. (p>0.05) Conclusion: Surface micro-roughness and surface wettability rarely affected the absorption of initial tissue fluid on the surface of titanium.

• Tribology and Lubricants
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• 제37권1호
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• pp.1-6
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• 2021

This paper presents the experimental results of hydrophobic surfaces developed using a stereolithography-based additive-manufacturing technique. The additive manufacturing technique can be used to manufacture objects with complex geometries from computer-aided design data. Several additive manufacturing methods, such as selective laser sintering, fused deposition modeling, stereolithography apparatus (SLA), and inkjet-based system, have been developed. The SLA is a form of three-dimensional printing technology used to create prototypes, patterns, and production parts in successive layers through photochemical processes. Light causes chemical monomers and oligomers to cross-link together to form objects composed of polymers. Moreover, this method is economical for fabricating surfaces with high output resolution and quality. Here, we fabricate various surfaces using different shapes using an SLA. The surfaces with micro-patterns are fabricated for 10 cases, including the biomimetic surface. The fabricated surfaces with various micro-patterns are evaluated for hydrophobicity performance based on the static contact angle. The contact angle is measured three times for each case, and the averaged value is used. The results indicate that the arrangements in a staggered structure have a larger contact angle than those in a line when the same micro-pattern is applied. Moreover, the mimetic surfaces exhibit more hydrophobic characteristics than those of artificial micro-patterns.

• The Journal of Advanced Prosthodontics
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• 제7권4호
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• pp.294-302
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• 2015

PURPOSE. The purpose of this study was to verify the clinical-feasibility of additive manufacturing by comparing the accuracy of four different manufacturing methods for metal coping: the conventional lost wax technique (CLWT); subtractive methods with wax blank milling (WBM); and two additive methods, multi jet modeling (MJM), and micro-stereolithography (Micro-SLA). MATERIALS AND METHODS. Thirty study models were created using an acrylic model with the maxillary upper right canine, first premolar, and first molar teeth. Based on the scan files from a non-contact blue light scanner (Identica; Medit Co. Ltd., Seoul, Korea), thirty cores were produced using the WBM, MJM, and Micro-SLA methods, respectively, and another thirty frameworks were produced using the CLWT method. To measure the marginal and internal gap, the silicone replica method was adopted, and the silicone images obtained were evaluated using a digital microscope (KH-7700; Hirox, Tokyo, Japan) at 140X magnification. Analyses were performed using two-way analysis of variance (ANOVA) and Tukey post hoc test (${\alpha}=.05$). RESULTS. The mean marginal gaps and internal gaps showed significant differences according to tooth type (P<.001 and P<.001, respectively) and manufacturing method (P<.037 and P<.001, respectively). Micro-SLA did not show any significant difference from CLWT regarding mean marginal gap compared to the WBM and MJM methods. CONCLUSION. The mean values of gaps resulting from the four different manufacturing methods were within a clinically allowable range, and, thus, the clinical use of additive manufacturing methods is acceptable as an alternative to the traditional lost wax-technique and subtractive manufacturing.

• 대한치과교정학회지
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• 제38권6호
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• pp.416-426
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• 2008

본 연구는 비글견에 식립된 sandblasted, large grit and acid-etched (SLA) 표면처리된 교정용 마이크로임플랜트와 평활면 마이크로임플랜트에 교정력을 가한 후 시간 경과에 따른 동요도와 골접촉률의 차이를 규명하기 위해 시행되었다. 비글 성견 네 마리를 이용하여 상, 하악 협측과 구개측 골에 대해 SLA 표면처리된 표면처리군 48개, 평활면의 비처리군 48개의 마이크로임 플랜트 96개를 식립하고 2주의 치유기간 후 교정력(150 - 200 g)을 지속적 으로 가했으며 식립 4주 후에 두 마리를 희생시키고, 12주 후에 나머지 2마리를 희생시켰다. 표면처리군과 비처리군 간의 마이크로 임플랜트의 동요도와 골과 임플랜트 간 접촉률을 조직학적인 측면에서 측정 비교하여 다음과 같은 결과를 얻었다. 상악 협측과 구개측에서는 표면처리군과 미처리군의 동요도에서 유의성 있는 차이가 없었으나 하악협측에서는 표면 처리군이 유의하게 안정적인 동요도를 보였다. 마이크로임플랜트와 인접골 간 접촉률은 상악 협측에서는 4주와 12주 모두 표면처리군과 미처리군 간에 유의 한 차이가 없었으나 하악 협측과 구개측의 경우 4주와 12주 모두 표면처리군이 비처리군에 비해 유의하게 높은 접촉률을 보였다. 표면처리군은 비처리군에 비해 임플랜트 주변에서 활발한 골개조가 관찰되었으며 모든 군에서 이물반응은 관찰되지 않았다. 본 연구를 통해 SLA 표면처리된 마이크로임플랜트는 평활면 마이크로임플랜트에 비하여 식립 초기에는 식립 부위에 따라 유의하게 높은 인접골 간 접촉률과 동요도의 안정성을 보임으로써 다양한 크기와 방향의 교정력의 적용이 가능할 것이라 생각한다.

• 한국정밀공학회지
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• 제30권3호
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• pp.340-348
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• 2013

In Projection Stereolithography Apparatus (PSLA), Digital Micromirror Device (DMD) and Liquid Crystal Display (LCD) are used as a beam pattern generator. The DMD shows high resolution, but it is mostly applied in micro stereolithography due to high cost and fabricable area. In LCD, the size of pattern beam is freely controlled due to various panel sizes. The LCD, however, has some limitations such as short life time by the high power light source, non-uniform light intensity of pattern beam and low transmittance of UV-light. To solve these problems in LCD-based PSLA, a Scanbeam-SLA with LCD of 19 inches and visible LED-array is developed. In this system, the light module works like a scanner for uniform illumination. The system configuration, working principle and fabrication examples are addressed in this study.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.503-507
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• 2002

Mask manufacturing is a high COC and COO process in developing of semiconductor devices, because of the mass production tool with high resolution. Direct writing has been thought to be one of the patterning method to cope with development or small-lot production of the device. This study focused on the development of the direct, mastless patterning process using stereolithography tool for the easy and convenient application to micro and miso scale products. Experiments are utilized by three dimensional CAD/CAM as a mask and photo-curable resin as a photo-resist in a conventional stereo-lithography apparatus. Results show that the resolution of the pattern was achieved about 300 micron because of complexity of SLA apparatus settings, inspite of 100 micro of inherent resolution. This paper concludes that photo resist and laser spot diameter should be adjusted to get finer patterns and the proposed method is significantly feasible to mastless and low cost patterning with micro and miso scale.

• Design & Manufacturing
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• 제16권3호
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• pp.58-65
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• 2022

Micro-fluidic chip has been fabricated by lithography process on silicon or glass wafer, casting using PDMS, injection molding of thermoplastics or 3D printing, etc. Among these processes, 3D printing can fabricate micro-fluidic chip directly from the design without master or template for fluidic channel fabricated previously. Due to this direct printing, 3D printing provides very fast and economical method for prototyping micro-fluidic chip comparing to conventional fabrication process such as lithography, PDMS casting or injection molding. Although 3D printing is now used more extensively due to this fast and cheap process done automatically by single printing machine, there are some issues on accuracy or surface characteristics, etc. The accuracy of the shape and size of the micro-channel is limited by the resolution of the printing and printing direction or layering direction in case of SLM type of 3D printing using UV curable resin. In this study, the printing direction and thickness of each printing layer are investigated to see the effect on the size, shape and surface of the micro-channel. A set of micro-channels with different size was designed and arrayed orthogonal. Micro-fluidic chips are 3D printed in different directions to the micro-channel, orthogonal, parallel, or skewed. The shape of the cross-section of the micro-channel and the surface of the micro-channel are photographed using optical microscopy. From a series of experiments, an optimal printing direction and process conditions are investigated for 3D printing of micro-fluidic chip.

• Journal of Periodontal and Implant Science
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• 제32권3호
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• pp.523-537
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• 2002

The present study was performed to evaluate the effect of tetracycline - HCl on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, SLA surface and $TiO_2blasted$ surface were used. Implant surface was rubbed with 5Omg/ml tetracycline - HCl solution for ${\frac}{1}{2}$ min., 1 min., $1{\frac}{1}{2}$ min., 2 min., and 3min. respectively in the test group and with no conditioning in the control group. Then, the specimens were processed for scanning electron microscopic observation. The following results were obtained. 1. In the pure titanium machined surfaces, the control specimen showed a more or less rough machined surface composed of alternating positive and negative lines corresponding to grooves and ridges. After treatment, machining line was more pronounced for the control specimens. but in general, test specimens were similar to control. 2. In the SLA surfaces, the control specimen showed that the macro roughness was achieved by large-grit sandblasting. subsequently, the acid-etching process crated the micro roughness, which thus was superimposed on the macro roughness. 3. In the SLA surfaces, irrespective of the application time of 50mg/ml tetracycline-HCl solution, in general, test specimens were similar to control. 4. In the $TiO_2blasted$ surfaces the control specimen showed the rough surface with small pits. The irregularity of the $TiO_2blasted$ surfaces with 50mg/ml tetracycline-HCl solution was lessened and the flattened areas were wider relative to the application time of tetracycline - HCl solution. In conclusion, pure titanium machined surfaces and SLA surfaces weren't changed irrespective of the application time of tetracycline-HCl solution. And the $TiO_2blasted$ surfaces conditioned with tetracycline - HCl solution began to be changed from $1{\frac}{1}{2}$ min. This results are expected to be applied to the regenerative procedures for peri-implantitis treatment.

• Journal of Periodontal and Implant Science
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• 제35권4호
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• pp.921-937
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• 2005

Mechanical and chemical methods are the two ways to treat the implant surfaces. By using mechanical method, it is difficult to eliminate bacteria and by-products from the rough implant surface and it can also cause the structural change to the implant surface. Therefore, chemical method is widely used in order to preserve and detoxicate the implant surface more effectively. The purpose of this study is to evaluate the effect of tetracylcline- HCl on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, SLA surface and $TiO_2blasted$ surface were used in this study. Implant surface was rubbed with sponge soaked in 50mg/ml tetracycline - HCl solution for $\frac{1}{2}$ min., 1min., $1\frac{1}{2}$ min., 2 min., and $2\frac{1}{2}min.$ respectively in the test group and with no treatment in the control group. The sponge was soaked in every 30 seconds. Then, the specimens were processed for scanning electron microscopic observation. Based upon the analysis of photographs by three dentists who are not related with this study, the results were obtained as follows; 1. In the pure titanium machined surfaces, the control specimen showed a more or less rough machined surface composed of alternating positive and negative lines corresponding to grooves and ridges. After treatment, machining line was more pronounced for the control specimens. but in general, test specimens were similar to control. 2. In the SLA surfaces, the control specimen showed that the macro roughness was achieved by large-grit sandblasting. Subsequently, the acid-etching process created the micro roughness, which thus was superimposed on the macro roughness. Irrespective of the application time of 50mg/ml tetracycline - HCl solution, in general, test specimens were similar to control. 3. In the $TiO_2blasted$ surfaces, the control specimen showed the rough surface With small pits. The irregularity of the $TiO_2blasted$ surfaces with 50mg/ml tetracycline - HCl solution was lessened and the flattened areas got wider after 1 minute.

• Journal of Periodontal and Implant Science
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• 제36권2호
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• pp.319-334
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• 2006

Mechanical and chemical methods are the two ways to treat the implant surfaces. By using mechanical method, it is difficult to eliminate bacteria and by-products from the rough implant surface and it can also cause the structural change to the implant surface. Therefore, chemical method is widely used in order to preserve and detoxicate the implant surface more effectively. The purpose of this study is to evaluate the effect of tetracylcline-hydrochloride(TC-HCI) on the change of implant surface microstructure according to application time. Implants with pure titanium machined surface, SLA surface and porous surface were used in this study. Implant surface was rubbed with sponge soaked in 50mg/ml TC-HCI solution for $\frac{1}{2}$ min., 1 min., $1\frac{1}{2}$ min., 2 min., and $2\frac{1}{2}$ min. respectively in the test group and with no treatment in the control group. Then, specimens were processed for scanning electron microscopic observation. 1. Both test and control group showed a few shallow grooves and ridges in pure titanium machined surface implants. There were not significant differences between two groups. 2. In the SLA surfaces, the control specimen showed that the macro roughness was achieved by large-grit sandblasting. Subsequently, the acid-etching process created the micro roughness, which thus was superimposed on the macro roughness. Irrespective of the application time of 50mg/ml TC-HCI solution, in general, test specimens were similar to control. 3. In the porous surfaces, the control specimen showed spherical particles of titanium alloy and its surface have a few shallow ridges. The roughness of surfaces conditioned with tetracycline-HCI was lessened and seen crater-like irregular surfaces relative to the application time. In conclusion, pure titanium machined surfaces and SLA surfaces weren't changed irrespective of the application time of tetracycline-HCI solution. But the porous surfaces conditioned with tetracycline-HCI solution began to be slightly changed from 2 min. This results are expected to be applied to the regenerative procedures for peri-implantitis treatment.