• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제41권5호
• /
• pp.265-269
• /
• 2015

The purpose of this study was to investigate implant-supported restoration as a technique for restoring missing teeth in patients with aplastic anemia. Recurrent bleeding from wound sites leads to persistent release of iron in the tissue. Excessive iron in tissue is related to clinical findings, including fibrosis, poor wound healing, and high level of angiogenesis, which are possible etiological factors of reduced osseointegration. A 44-year-old female patient with aplastic anemia was treated with multiple endosseous implants throughout the mandible and in the posterior region of the maxilla. After 14 implants were placed, radiological and clinical parameters were assessed during the follow-up period. Marginal bone did not change significantly during the follow-up period. The fine trabecular bone in intimate contact and enclosing the implant fixture was sufficient for successful osseointegration. None of the 14 implants were associated with compilations during the seven-year experimental period. This study suggests that dental implant procedures are a safe and reliable treatment option for restoration of missing dentition in patients with aplastic anemia.

• 대한의용생체공학회:의공학회지
• /
• 제29권3호
• /
• pp.212-221
• /
• 2008

The total hip replacement (THR) has been used as the most effective way to restore the function of damaged hip joint. However, various factors have caused some side effects after the THR. Unfortunately, the success of the THR have been decided only by the proficiency of surgeons so far. Hence, It is necessary to find the way to minimize the side effect caused by those factors. The purpose of this study was to suggest the definite data, which can be used to design and choose the optimal hip implant. Using finite element analysis (FEA), the biomechanical condition of bone cement was evaluated. Stress patterns were analyzed in three conditions: cement mantle, procimal femur and stem-cement contact surface. Additionally, micro-motion was analyzed in the stem-cement contact surface. The 3-D femur model was reconstructed from 2-D computerized tomography (CT) images. Raw CT images were preprocessed by image processing technique (i.e. edge detection). In this study, automated edge detection system was created by MATLAB coding for effective and rapid image processing. The 3-D femur model was reconstructed based on anatomical parameters. The stem shape was designed using that parameters. The analysis of the finite element models was performed with the variation of parameters. The biomechanical influence of each parameter was analyzed and derived optimal parameters. Moreover, the results of FE A using commercial stem model (Zimmer's V erSys) were similar to the results of stem model that was used in this study. Through the study, the improved designs and optimal factors for clinical application were suggested. We expect that the results can suggest solutions to minimize various side effects.

• 대한치과보철학회지
• /
• 제53권2호
• /
• pp.120-127
• /
• 2015

목적: 4종의 임플란트 나사산이 골유착 중간과정과 완료 이후 단계에서 보이는 응력분산 특성을 평가하고자 한다. 재료 및 방법: 실린더형 몸체(외경 4.1 mm 길이 10 mm)에 이전연구에서 식립 특성이 우수하게 평가되었던 V-자형 나사산과 다른 3종(buttress형, reverse buttress형, square형)의 나사산을 가진 4종의 임플란트가 악골에 매식된 복합체 모델을 CAD 프로그램으로 제작하였다. 지대주 상부에 100 N의 힘을 임플란트 장축과 30도 방향으로 부하하고 인접골 응력분포를 유한요소 해석하였다. 응력분산 특성이 골유착 진척 상태에 따라 달라질 수 있다는 가정하에 임플란트/골 계면을 골유착 미숙단계와 골유착 완료단계의 두 가지로 구분하여 분석하였다. 골유착 미숙단계는 임플란트/골 계면을 비선형 contact 조건(마찰계수 0.3)으로 모사하였고, 골유착이 완료된 단계에 대해서는 계면이 충분히 결합된 것으로 간주하여 접합(bonding) 조건을 부여하였다. 결과: 골유착 정도에 따라 임플란트의 응력분산 특성이 달라졌다. 골유착 미숙단계에서는 골응력과 나사산에 따른 응력 특성의 차이도 상대적으로 컸고 골유착 완료단계에서는 골응력의 절대값과 나사산간 차이가 모두 감소하였으며, V-자형 나사산의 응력분산 특성은 골유착 미숙 및 완료단계에서 모두 4종 나사산의 중간 정도였다. 이로부터 나사산 디자인의 차이는 임플란트 식립후 골유착이 진행되는 과정까지 영향을 미치며, 일단 골유착이 완료되면 나사산의 영향은 급격히 감소할 것임을 추론할 수 있었다. 결론: V-자형 나사산의 응력분산 특성은 골유착이 이루어지는 단계와 완료된 이후 단계 전기간 동안 4종 나사산의 중간 정도였다.

• 대한치과교정학회지
• /
• 제44권5호
• /
• pp.246-253
• /
• 2014

Objective: To evaluate the bioactivity, and the biomechanical and bone-regenerative properties of Ti6Al4V miniscrews subjected to anodization, cyclic precalcification, and heat treatment (APH treatment) and their potential clinical use. Methods: The surfaces of Ti6Al4V alloys were modified by APH treatment. Bioactivity was assessed after immersion in simulated body fluid for 3 days. The hydrophilicity and the roughness of APH-treated surfaces were compared with those of untreated (UT) and anodized and heat-treated (AH) samples. For in vivo tests, 32 miniscrews (16 UT and 16 APH) were inserted into 16 Wistar rats, one UT and one APH-treated miniscrew in either tibia. The miniscrews were extracted after 3 and 6 weeks and their osseointegration (n = 8 for each time point and group) was investigated by surface and histological analyses and removal torque measurements. Results: APH treatment formed a dense surface array of nanotubular TiO2 layer covered with a compact apatite-like film. APH-treated samples showed better bioactivity and biocompatibility compared with UT and AH samples. In vivo, APH-treated miniscrews showed higher removal torque and bone-to-implant contact than did UT miniscrews, after both 3 and 6 weeks (p < 0.05). Also, early deposition of densely mineralized bone around APH-treated miniscrews was observed, implying good bonding to the treated surface. Conclusions: APH treatment enhanced the bioactivity, and the biomechanical and bone regenerative properties of the Ti6Al4V alloy miniscrews. The enhanced initial stability afforded should be valuable in orthodontic applications.

• 구강회복응용과학지
• /
• 제29권3호
• /
• pp.259-271
• /
• 2013

임플란트 고정체-지대주 결합구조체의 형태에 따른 교합부하의 반응이 다양하여 본 연구에서는 하중위치 및 결합구조체 접촉 비율에 따라 3단 계단형 결합구조체와 경사형에서 어떠한 차이가 있는 지를 3차원 유한요소분석을 시행하였다. 2종의 임플란트-지대주 결합 구조체에 연결된 상부 치관을 제작하여 각 치관에 설정된 하중위치에 200 N의 하중을 부여하였다. 임플란트 중심 부위에서 하중조건이 멀어질수록 피질골정에 가해지는 응력이 증가되기에 하중조건은 응력발생에 영향을 미치는 주요 요소이며 다음으로 결합구조형태에도 영향을 받았다. 또한 수직 하중에 비해 빗금 경사 하중이 부여된 경우 계단형은 경사형에 비해 유리한 응력 분포를 보였다. 그리고 지대주 결합구조체가 고정체의 내벽에 대해 접촉이 많아 질수록 골질에 대한 응력분산이 유리한 것으로 나타났다. 결론적으로 고정체 폭경에서 벗어난 빗김 수직 및 경사 하중은 결합구조체의 종류와 관계없이 피질골정에 응력을 집중시키므로 저작기능시 교합접촉면을 고정체의 폭경 내에 위치하도록 하는 것이 생체역학적으로 바람직 할 것으로 사료되었다.

• Journal of Periodontal and Implant Science
• /
• 제51권5호
• /
• pp.352-363
• /
• 2021

Purpose: Some systemic conditions, especially diabetes mellitus (DM), adversely affect dental implant success. This study aimed to investigate the effects of ibuprofen-loaded TiO₂ nanotube (ILTN) dental implants in alloxan-induced diabetic rabbits. Methods: Twenty-six New Zealand white rabbits were treated with alloxan monohydrate to induce DM. At 2 weeks following DM induction, 3 types of implants (sandblasted, large-grit, and acid-etched [SLA], ILTN, and machined) were placed into the proximal tibia in the 10 rabbits that survived following DM induction. Each type of implant was fitted randomly in 1 of the holes (round-robin method). The animals were administered alizarin (at 3 weeks) and calcein (at 6 weeks) as fluorescent bone markers, and were sacrificed at 8 weeks for radiographic and histomorphometric analyses. Results: TiO₂ nanotube arrays of ~70 nm in diameter and ~17 ㎛ in thickness were obtained, and ibuprofen was loaded into the TiO₂ nanotube arrays. A total of 26 rabbits were treated with alloxan monohydrate and only 10 rabbits survived. The 10 surviving rabbits showed a blood glucose level of 300 mg/dL or higher, and the implants were placed in these diabetic rabbits. The implant stability quotient (ISQ) and bone-to-implant contact (BIC) values were significantly higher in the ILTN group (ISQ: 61.8, BIC: 41.3%) and SLA group (ISQ: 62.6, BIC: 46.3%) than in the machined group (ISQ: 53.4, BIC: 20.2%), but the difference in the BIC percentage between the SLA and ILTN groups was not statistically significant (P=0.628). However, the bone area percentage was significantly higher in the ILTN group (78.0%) than in the SLA group (52.1%; P=0.000). Conclusions: The: ILTN dental implants showed better stability (ISQ) and BIC than the machined implants; however, these values were similar to the commercially used SLA implants in the 2-week diabetic rabbit model.

• Maxillofacial Plastic and Reconstructive Surgery
• /
• 제30권2호
• /
• pp.150-157
• /
• 2008

This study evaluated the influence of smooth and brushite-coated implant surfaces in dogs. The first through fourth mandibular premolars were extracted from eight young adult dogs. Twelve weeks after extraction. implantation was performed at the extraction sites. In total, 40 implant fixtures were implanted in the dog mandibles. Twenty machined implants served as controls and twenty brushite-coated surfaces served as tests. Dogs were sacrificed 2 and 4 weeks after implantation. The hemi-mandibles were obtained and processed histologically to obtain non-decalcified sections. Longitudinal sections of each implant were made and analyzed using light microscopy. The overall implant success rate was 83.3%. Histomorphometrically. the experimental group had a better percentage of bone-implant contact than the control group (p<0.05) and there was a significant difference between the 2- and 4-week groups after implantation (p<0.05) Our results suggest that the implant surface morphology influences the increase in peri-implant osteogenesis in the early period of peri-implant healing.

• 대한치과보철학회지
• /
• 제41권3호
• /
• pp.300-318
• /
• 2003

Statement of problem: The success of implants depends on intimate and direct contact of implant material on bone tissue and on functional relationship with soft tissue contact. Creation and maintenance of osseointegration depend on the understanding of the tissue's healing, repairing, and remodeling capacity and these capacities rely on cellular behavior. Altering the surface properties can modify cellular responses such as cell adhesion, cell motility, bone deposition, Therefore, various implant surface treatment methods are being developed for the improved bone cell responses. Purpose: The purpose of this study was to evaluate the responses of osteoblast-like cells to surface-modified titanium. Materials and Methods: The experiment was composed of four groups. Group 1 represented the electropolished surface. Group 2 surfaces were machined surface. Group 3 and Group 4 were anodized surfaces. Group 3 had low roughness and Group 4 had high roughness. Physicochemical properties and microstructures of the discs were examined and the responses of osteoblast-like cells to the discs were investigated. The microtopography was observed by SEM. The roughness was measured by three-dimension roughness measuring system. The microstructure was analyzed by XRD, AES. To evaluate cell responses to modified titanium surfaces, osteoblasts isolated from calvaria of neonatal rat were cultured. Cell count, morphology, total protein measurement and alkaline phosphatase activities of the cultures were examined. Results and Conclusion: The results were as follows 1. The four groups showed specific microtopography respectively. Anodized group showed grain structure with micropores. 2. Surface roughness values were, from the lowest to the highest, electropolished group, machined group, low roughness anodized group, and high roughness anodized group. 3. Highly roughened anodized group was found to have increased surface oxide thickness and surface crystallinity. 4. The morphology of cells, flattened or spherical, were different from each other. In the electropolished group and machined group, the cells were almost flattened. In two anodized groups, some cells were spherical and other cells were flattened. And the 14 day culture cells of all of the groups were nearly flattened due to confluency. 5. The number of attached cells was highest in low roughness anodized group. And the machined group had significantly lower cell count than any other groups(P<.05). 6. Total protein contents showed no difference among groups. 7. The level of alkaline phosphatase activities was higher in the anodized groups than electropolished and machined groups(P<.05).

• 대한치과보철학회지
• /
• 제48권2호
• /
• pp.122-127
• /
• 2010

연구목적: 본 연구는 machined 임플란트와 골유도능이 있는 calcium phosphate를 electron-beam deposition으로 coating처리한 임플란트의 골/임플란트 접촉률을 조직형태계측학적으로 비교하는 것이다. 연구 재료 및 방법:여섯 마리의 수컷 New Zealand white rabbit과직경3.3 mm, 길이 5 mm의 임플란트 24개를 준비하였다. Machined 임플란트 (대조군)와 calcium phosphate coated 임플란트(실험군)를 좌, 우 경골에 2개씩 총 4개를 식립하고 임플란트 주위에 부하가 가해지지 않도록 하여 3주, 6주의 치유기간을 두었다. 식립 3주와 6주후, 각각 3마리의 토끼를 희생하여 조직시편을 제작하였다. 제작된 시편을 광학현미경 하에서 골/임플란트 접촉률 (BIC ratio)을 계산하고 paired t-test로 두 군을 비교하였다. 결과:골/임플란트 접촉률은 임플란트 식립 3주후, 대조군에서 평균과 표준편차는$44.1{\pm}16.5%$ 이었고 실험군은 $70.8{\pm}18.9%$로 실험군이 통계적으로 유의하게 높았다 (P= 0.0264). 6주후의경우, machined 임플란트는 $78.6{\pm}15.1%$, calcium phosphate coated 임플란트는 $79.0{\pm}26.0%$로 두 군 간 통계적으로 유의한 차이는 없었다. 결론: Calcium phosphate coated 임플란트는 machined 티타늄 임플란트에 비해 빠른 초기 골반응을 나타냈다. 그러므로, 임상적으로 calcium phosphate coated 임플란트를 사용했을 때, 수술 후 치유 기간을 단축하여 조기 부하가 가능할 것으로 사료된다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
• /
• 제37권4호
• /
• pp.301-311
• /
• 2011

Introduction: This study examined the effect of the application of low intensity pulsed ultrasound on bone healing after an injection of adipose tissue-derived stem cells (ADSCs) during the implantation of a titanium implant in the tibia of diabetes-induced rats. Materials and Methods: Twelve Sprague-Dawely rats were used. After inducing diabetes, the ADSCs were injected into the hole for the implant. Customized screw type implants, 2.0 mm in diameter and 3.5 mm in length, were implanted in both the tibia of the diabetes-induced rats. After implantation, LIPUS was applied with parameters of 3 MHz, 40 mW/$cm^2$, and 10 minutes for 7 days to the left tibiae (experimental group) of the diabetesinduced rats. The right tibiae in each rat were used in the control group. At 1, 2 and 4 week rats were sacrificed, and the bone tissues of both tibia were harvested. The bone tissues of the three rats in each week were used for bone-to-implant contact (BIC) and bone area (BA) analyses and the bone tissues of one rat were used to make sagittal serial sections. Results: In histomorphometric analyses, the BIC in the experimental and control group were respectively, $39.00{\pm}18.17%$ and $42.87{\pm}9.27%$ at 1 week, $43.74{\pm}6.83%$ and $32.27{\pm}6.00%$ at 2 weeks, and $32.62{\pm}11.02%$ and $47.10{\pm}9.77%$ at 4 weeks. The BA in experimental and control group were respectively, $37.28{\pm}3.68%$ and $31.90{\pm}2.84%$ at 1 week, $20.62{\pm}2.47%$ and $15.64{\pm}2.69%$ at 2 weeks, and $11.37{\pm}4.54%$ and $17.69{\pm}8.77%$ at 4 weeks. In immunohistochemistry analyses, Osteoprotegerin expression was strong at 1 and 2 weeks in the experimental group than the control group. Receptor activator of nuclear factor kB ligand expression showed similar staining at each week in the experimental and control group. Conclusion: These results suggest that the application of low intensity pulsed ultrasound after an injection of adipose tissue-derived stem cells during the implantation of titanium implants in the tibia of diabetes-induced rats provided some positive effect on bone regeneration at the early stage after implantation. On the other hand, this method is unable to increase the level of osseointegration and bone regeneration of the implant in an uncontrolled diabetic patient.