• 대한두개안면성형외과학회지
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• 제16권3호
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• pp.125-130
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• 2015

Background: Poly-L-lactide materials combined with hydroxyapatite (u-HA /PLLA) have been developed to overcome the drawbacks of absorbable materials, such as radiolucency and comparably less implant strength. This study was designed to evaluate the usefulness of u-HA/PLLA material in the repair of orbital medial wall defects. Methods: This study included 10 patients with pure medial wall blow-out fractures. The plain radiographs were taken preoperatively, immediately after, and 2 months after surgery. The computed tomography scans were performed preoperatively and 2 months after surgery. Patients were evaluated for ease of manipulation, implant immobility, rigidity and complications with radiologic studies. Results: None of the patients had postoperative complications, such as infection or enophthalmos. The u-HA/PLLA implants had adequate rigidity, durability, and stable position on follow-up radiographic studies. On average, implants were thawed 3.4 times and required 14 minutes of handling time. Conclusion: The u-HA/PLLA implants are safe and reliable for reconstruction of orbital medial wall in terms of rigidity, immobility, radiopacity, and cost-effectiveness. These thin yet rigid implants can be useful where wide periosteal dissection is difficult due to defect location or size. Since the u-HA/PLLA material is difficult to manipulate, these implants are not suitable for use in complex 3-dimensional defects.

• 대한두개안면성형외과학회지
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• 제21권2호
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• pp.99-105
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• 2020

Background: Due to the different handling properties of unsintered hydroxyapatite particles/poly-L-lactic acid (uHA/PLLA) and polycaprolactone (PCL), we compared the surgical outcomes and the postoperative implantation accuracy between uHA/PLLA and PCL meshes in orbital fracture repair. Methods: Patients undergoing orbital wall reconstruction with PCL and uHA/PLLA mesh, between 2017 and 2019, were investigated retrospectively. The anatomical accuracy of the implant in bony defect replacement and the functional outcomes such as diplopia, ocular motility, and enophthalmos were evaluated. Results: No restriction of eye movement was reported in any patient (n= 30 for each group), 6 months postoperatively. In the PCL group, no patient showed diplopia or enophthalmos, while the uHA/PLLA group showed two patients with diplopia and one with enophthalmos. Excellent anatomical accuracy of implants was observed in 27 and 22 patients of the PCL and uHA/PLLA groups, respectively. However, this study showed that there were neither any significant differences in the surgical outcomes like diplopia and enophthalmos nor any complications with the two well-known implants. Conclusion: PCL implants and uHA/PLLA implants are safe and have similar levels of complications and surgical outcomes in orbital wall reconstruction.

• 한국임상수의학회지
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• 제24권2호
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• pp.182-191
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• 2007

Bioabsorbable devices have been utilized and experimented in many aspects of orthopaedic surgery. Depending upon their constituent polymers, these materials can be tailored to provide sufficient rigidity to allow bone healing, retain mechanical strength for certain period of time, and then eventually begin to undergo degradation. The objective of this study was to estimate extent in which Poly-L-latic acid (PLLA) implants had bioabsorbability and biocompatibility with bone and soft tissue in dogs and also to develop bioabsorbable, biocompatible materials with the appropriate strength and degradation characteristics to allow for regular clinical use for treating orthopedic problems in humans as well as animals. Eighteen dogs were used as experimental animals and were inserted two types of PLLA implants. PLLA rods were inserted into subcutaneous tissue of back or the abdomen wall. And the rods were tested for material properties including viscosity, molecular weight, melting point, melting temperature, crystallinity, flexural strength, and flexural modulus over time. PLLA screws were inserted through cortical bone into bone marrow in the femur of the dogs and stainless steel screw was inserted in the same femur. Radiographs were taken after surgery to observe locations of screw. Histological variations including cortical bone response, muscular response, bone marrow response were analyzed over the time for 62weeks. The physical properties of PLLA rods had delicate balances between mechanical, thermal and viscoelastic factors. PLLA screws did not induce any harmful effects and clinical complications on bone and soft tissue for degradation period. These results suggest that PLLA implants could be suitable for clinical use.

• 접착 및 계면
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• 제4권1호
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• pp.18-27
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• 2003

Micromechanical 시험법과 표면 젖음성 측정을 이용하여 플라즈마 처리된 생분해성 poly(p-dioxanone) (PPDO) 섬유강화 poly(L-lactide) (PLLA) 복합재료의 계면물성과 미세파괴 분해메카니즘을 연구하였다. PPDO 섬유강화 PLLA 복합재료는 장기간의 사용기간 동안 우수한 기계적 물성을 제공할 수 있다. PPDO 섬유와 PLLA 기지재료의 분해정도는 열분석과 광학적인 관찰을 통해서 확인하였다. PPDO 섬유와 PLLA 기지재료 사이의 계면전단강도와 접착일은 플라즈마 처리 시간이 60초 일때 가장 컸으며, 접착일과 polar 표면자유에너지는 계면전단강도와 비례하였다. 초기상태의 PPDO 섬유는 연성파단 형상이 나타났으나, 분해시간이 진행됨에 따라 분자량 감소로 인해 점차적으로 취성 파단 형상으로 변하였다. 계면물성과 미세파괴 분해메카니즘은 분해가 진행됨에 따라 변하기 때문에 섬유강화 생분해성 복합재료의 성능을 조절하는데 중요한 요인들이다.

• 접착 및 계면
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• 제3권2호
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• pp.17-29
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• 2002

Micromechanical 시험법과 표면 젖음성 측정을 이용한 implant용 생분해성 복합재료의 계면물성과 미세파괴 분해 메카니즘을 연구하였다. 분해시간이 경과함에 따라서 poly(ester-amide) (PEA)와 생활성 유리섬유의 인장강도와 탄성률 그리고 신율은 점차적으로 감소하는 경향을 보인 반면, chitosan 섬유는 거의 변화가 없었다. 생활성 유리섬유와 poly-L-lactide(PLLA) 사이의 계면전단강도는 PEA나 chitosan 섬유 시스템의 경우보다 더 큰 값을 보였으나, 계면전단강도 감소 속도는 가장 빨랐고 chitosan 섬유의 경우가 가장 느린 결과를 보였다. 접착일 ($W_a$)은 생활성 유리섬유와 PLLA 사이에서 가장 높은 값을 나타냈으며, 이러한 표면 젖음성 결과는 계면전단강도 결과와 잘 일치하였다. 계면물성과 미세파괴 분해 메카니즘은 생분해성 복합재료의 성능을 조절할 수 있는 가장 중요한 요인들이다.

• Composites Research
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• 제14권4호
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• pp.15-26
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• 2001

Implant용 bioabsorbable 복합재료의 계면물성과 미세파괴분해 메카니즘을 micromechanical 시험법과 음향방출을 이용하여 평가하였다. Poly(ester-amide)와 bioactive 유리섬유의 인장 강도와 탄성률 그리고 연신율은 분해시간에 따라 점차적으로 감소하는 경향을 보인 반면, chitosan 섬유는 분해시간 내에서 거의 변화가 없었다. Dual matrix composite 시험법을 이용하여 측정된 bioactive 유리섬유와 poly(L-lactide) 사이의 계면전단강도는 chitosan이나 poly(ester-amide) 섬유의 경우 보다 큰 값을 보였다. 그리고 계면전단강도 감소는 bioactive 유리섬유 강화 poly(L-lactide) 복합재료에서 가장 빨랐으며, chitosan 섬유의 경우가 상대적으로 가장 느린 경향을 보였다. Poly(ester-amide) 섬유의 분해시간에 따른 음향방출 진폭과 에너지는 점차로 감소하였고, 음향방출 진폭의 분포 역시 점차 좁아짐을 보여주었다. Bioactive 유리섬유에서 인장파단에 의한 음향방출 진폭과 에너지는 압축파단의 경우 보다 크게 나타났으며, 또한, 인장 및 압축시험 모두에서 초기상태가 분해 후 보다 더 큰 값을 보였다. 본 연구에서 평가한 계면물성과 미세파괴분해 메카니즘은 생흡수성 복합재료의 성능을 조절할 수 있는 중요한 요소가 될 것이다.

• Journal of Periodontal and Implant Science
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• 제28권4호
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• pp.601-611
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• 1998

Ion irradiation is a very promising tool to modify the chemical structure and physical properities of polymers. This study was aimed to evaluate the cellular adhesion to ion beam-irradiated surface of biodegradable poly-l-lactide(PLLA) membrane. The PLLA membrane samples were irradiated by using 35 KeV $Ar^+$ to fluence of $5{\times}10^{13}$, $5{\times}10^{14}$ and $5{\times}10^{15}\;ion/cm^2$. Water contact angles to control and each dose of ion beam-irradiated PLLA membranes were measured. Cultured fetal rat calvarial osteoblasts were seeded onto control and each dose of ion beam-irradiated PLLA membranes and cultured. After 24 hours, each PLLA membranes onto which osteoblasts attached were examined by scanning electron microscopy(SEM). Osteoblasts were removed from each PLLA membrane and then, the vitality and the number of cells were calibrated. Alkaline phosphatase of detached cells from each PLLA membranes were measured. Ion beam-irradiated PLLA membranes showed no significantly morphological change from control PLLA membranes. In the measurement of water contact angle to each membrane, the dose range of ion beam employed in this study reduced significantly contact angles. Among them, $5{\times}10^{14}\;ion/cm^2$ showed the least contact angle. The vitalities of osteoblastes detached from each membranes were confirmed by flow cytometer and well attached cells with their own morphology onto each membranes were observed by SEM. A very strong improvement of the cell adhesion and proliferation was observed for ion beam-irradiated surfaces of PLLA membranes. $5{\times}10^{15}\;ion/cm^2$ exhibited the most strong effect also in cellular adherence. ALPase activities also tended to increase in ion beam-irradiated membranes but statistical differences were not found. These results suggested that ion beam irradiation is an effective tool to improve the adhesion and spreading behaviour of the cells onto the biodegradable PLLA membranes for the promotion of membrane-tissue integration.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2001년도 춘계학술발표대회 논문집
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• pp.263-267
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• 2001

The changes of interfacial properties and microfailure degradation mechanisms of bioabsorbable composites with hydrolysis were investigated using micromechanical test and acoustic emission (AE). As hydrolysis time increased, the tensile strength, the modulus and the elongation of PEA and bioactive glass fibers decreased, whereas those of chitosan fiber changed little. Interfacial shear strength (IFSS) of bioactive glass fiber/poly-L-lactide (PLLA) composite was significantly higher than that two other systems. The decreasing rate of IFSS was the fastest in bioactive glass fiber/PLLA composite, whereas that of chitosan fiber/PLLA composite was the slowest. With increasing hydrolysis time, distribution of AE amplitude was narrow, and AE energy decreased gradually.

• Journal of Periodontal and Implant Science
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• 제31권2호
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• pp.299-315
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• 2001

Application of membranes for guided tissue regeneration(GTR) have been confined to the subgingival barrier functions; however, many studies have provided evidence that some drugs, including tetracycline, initially can promote the growth of periodontal ligament or alveolar bone in peridontal therapy. Osseous regeneration in periodontal defects is increased by local administration of tetracycline due to its anti-collagenolytic effect, which enhances bone-forming ability via osteoblast cell chemotaxis and reduced bone resorption. The aim of this study was to evaluate effects of tetracycline loaded poly-L-lactide(PLLA) barrier membranes for guided bone regenerative potential. Tetracycline was incorporated into the PLLA membrane with the ratio 10% to PLLA by weight. Ability to guided bone regeneration of the membranes were tested by measuring new bone in the tibial defects($7{\times}10{\times}5\;mm^3$) of the beagle dog for 4,5, and 6 weeks. In control, drug-unloaded PLLA membranes were used in same size of defect. In histologic finding of the defect area, a few inflammatory cells were observed in both groups. These membrane were not perforated by connective tissue and maintained their mechanical integrity for the barrier function for 4-6 weeks. New bone formation was greater in defects covered by tetracycline-loaded membrane than in defects covered by drug- unloaded membranes. In bone regeneration guiding potential test, tetracycline-loaded membrane was more effective than drug- unloaded membranes(p<0.05). These results suggest that tetracycline-loaded PLLA membranes potentially enhance guided bone regenerative efficacy and might be a useful barrier for GTR in periodontal treatment.

• 한국임상수의학회:학술대회논문집
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• 한국임상수의학회 2007년도 춘계학술대회
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• pp.98-98
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• 2007