• Elastomers and Composites
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• 제50권2호
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• pp.119-125
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• 2015

Because of their low surface free energy and absence of polar groups at the surface, polyolefins are substrates whose wetting and adhesion are very difficult. Free radical grafting of monomers to backbone polymer is one of the most attractive ways for the chemical modification of polymers. Synthesis of graft copolymer through graft polymerizations of PE and/or PP with phthalic anhydride (PhAn) was made and FTIR spectra of the graft polymer were the examined. And also the effects of phthalic anhydride content on the grafting ratio, thermal properties and contact angle of the graft polymer were examined.

• 구강회복응용과학지
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• 제29권1호
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• pp.23-36
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• 2013

이 연구의 목적은 상악동 골증대술과 동반된 이식된 골의 3차원적인 형태를 평가하고 골이식 재료 및 임플란트의 종류, 수술 방법과 골흡수 정도 사이의 관계를 평가하는 것이다. 임플란트 식립을 위한 상악동 골증대술을 시행받은 환자들의 차트를 후향적으로 검토하였고 골이식재의 부피 및 부위의 방사선학적 분석을 시행하였다. 임플란트 식립 6개월 후 잔존 골 이식재의 비율로 측정된 부피 재생은 이식 재료의 형태 및 수술 방법과 연관성이 있었다. 원광대학교 산본 치과병원에서 15명의 환자에서 상악동 골이식술과 동반하여 53개의 임플란트가 식립되었다. 임플란트 식립 6개월 후 촬영된 컴퓨터 단층촬영에서 $Puros^{(R)}$ 와 다른 여러 가지 골이식재를 혼용한 그룹에비해 $Puros^{(R)}$ 이식재를 단독으로 사용한 그룹에서 더 높은 골흡수 정도를 보였다 (P<0.05). 그리고 수술 방법에 따른 골흡수 정도는 통계학적으로 유의성있는 차이를 보였다 (P<0.05). 골이식과 동시에 임플란트를 식립한 그룹에 비해 지연된 임플란트 식립을 시행한 그룹에서 더 높은 골이식재의 부피 변화율을 보였다. 후향적 자료 분석을 통해 $Puros^{(R)}$ 와 다른 여러 가지 골이식재를 혼용한 그룹에 비해 $Puros^{(R)}$ 이식재를 단독으로 사용한 그룹에서 더높은 골흡수 정도를 보였다. 또한 골이식과 동시에 임플란트를 식립한 그룹에서 지연 식립한 그룹보다 더 낮은 흡수율을 보여주었다.

• Journal of Korean Neurosurgical Society
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• 제62권4호
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• pp.450-457
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• 2019

Objective : Anterior cervical discectomy and fusion (ACDF) is commonly used surgical procedure for cervical degenerative disease. Among the various intervertebral spacers, the use of allografts is increasing due to its advantages such as no harvest site complications and low rate of subsidence. Although subsidence is a rare complication, graft collapse is often observed in the follow-up period. Graft collapse is defined as a significant graft height loss without subsidence, which can lead to clinical deterioration due to foraminal re-stenosis or segmental kyphosis. However, studies about the collapse of allografts are very limited. In this study, we evaluated risk factors associated with graft collapse. Methods : We retrospectively reviewed 33 patients who underwent two level ACDF with anterior plating using allogenous bone graft from January 2013 to June 2017. Various factors related to cervical sagittal alignment were measured preoperatively (PRE), postoperatively (POST), and last follow-up. The collapse was defined as the ratio of decrement from POST disc height to follow-up disc height. We also defined significant collapses as disc heights that were decreased by 30% or more after surgery. The intraoperative distraction was defined as the ratio of increment from PRE disc height to POST disc height. Results : The subsidence rate was 4.5% and graft collapse rate was 28.8%. The pseudarthrosis rate was 16.7% and there was no association between pseudarthrosis and graft collapse. Among the collapse-related risk factors, pre-operative segmental angle (p=0.047) and intra-operative distraction (p=0.003) were significantly related to allograft collapse. The cut-off value of intraoperative distraction ${\geq}37.3%$ was significantly associated with collapse (p=0.009; odds ratio, 4.622; 95% confidence interval, 1.470-14.531). The average time of events were as follows: collapse, $5.8{\pm}5.7months$; subsidence, $0.99{\pm}0.50months$; and instrument failure, $9.13{\pm}0.50months$. Conclusion : We experienced a higher frequency rate of collapse than subsidence in ACDF using an allograft. Of the various preoperative factors, intra-operative distraction was the most predictable factor of the allograft collapse. This was especially true when the intraoperative distraction was more than 37%, in which case the occurrence of graft collapse increased 4.6 times. We also found that instrument failure occurs only after the allograft collapse.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제36권5호
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• pp.224-229
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• 2014

The maxillary posterior area is the most challenging site for the dental implant. Although the sinus graft is a predictable and successful technique for rehabilitation of atrophic and pneumatized posterior maxilla, when there is severe destruction of alveolar bone, a very long crown length remains challenging after successful dental implants installation with sinus graft. We performed vertical augmentation of the maxillary posterior alveolar ridge using the allogenic block bone graft with a simultaneous sinus graft using allogenic and heterogenic bone chips. After about six months, we installed the dental implant. After this procedure, we achieved a more favorable crown-implant fixture ratio and better results clinically and biomechanically. This is a preliminary report of vertical augmentation of maxillary posterior alveolar ridge using allogenic block bone graft and simultaneous maxillary sinus graft. Further research requires longer observation and more patients.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제30권1호
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• pp.108-113
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• 2008

It would be desirable to regenerate bone vertically in a predictable way; such a technique would allow for more favorable implant - crown ratio and better esthetics for implant placement. Traditionally, several techniques has been proposed for this purpose including GBR with particulated bone and block bone graft using mandible or illium however, the efficacy of these techniques has not been firmly established because they have some week points or complications each other that it is difficult to draw firm conclusion for superiority. In recent years, We have treated 11-cases of vertical deficiency of alveolar bone using thin block and chip bone graft technique and the postoperative results showed good prognosis with few complications. So we report the results of its treatment and cases with review of literature.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제36권4호
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• pp.146-153
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• 2014

Purpose: This study compares and evaluates the efficacy of graft materials after maxillary sinus bone grafts with autogenous tooth bone graft material (AutoBT), demineralized freeze-dried bone allograft (DFDBA) and deproteinized bovine bone mineral (DBBM). Methods: The study involved 30 sinuses in 26 patients who visited the Division of Oral and Maxillofacial Surgery, Department of Dentistry in Ajou University Hospital and received either AutoBT, DFDBA or DBBM with sinus elevation using the lateral window technique. Sinus graft height was measured before, immediately after, and six months after bone graft with panoramic radiography and the height changes of the sinus floor was compared according to the graft materials. Results: After six months, the decrease ratio of graft heights were 13.57% for AutoBT group, 14.30% for DFDBA group, and 11.92% for DBBM group. There was no statistically significant difference. Conclusion: The new maxillary sinus floor formed by the upper border of bone graft material, can repneumatize after the maxillary sinus elevation. Thus, long-term stability of sinus graft height represents an important factor for implant success. We found that the three graft materials for sinus elevation do not differ significantly and all three graft materials showed excellent resistance to maxillary sinus repneumatization. However, due to the special circumstances of the maxillary sinus and small sample, the actual difference between the three graft materials may not have been detectable. Therefore further study needs to be conducted for more reliable study results.

• Elastomers and Composites
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• 제58권3호
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• pp.128-135
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• 2023

To improve the adhesive strength of natural rubber (NR) for a seismic isolation damper, citraconic acid-g-NR (CCA-g-NR) was synthesized via the melt grafting of citraconic acid (CCA) onto NR using an azobisisnomerobutyronitrile (AIBN) initiator. Subsequently, the influence of CCA and AIBN concentrations on the graft ratio G/R (%) and graft efficiency G/E (%) of the CCA-g-NR was investigated. The optimum CCA and AIBN concentrations required to achieve the desired G/R (3.49%) and G/E (49.8%) were found to be 7 phr and 0.13 phr, respectively. Additionally, we studied the influence of CCA-g-NR concentration on the mechanical properties (tensile strength, elongation at break, and modulus at 300%), adhesive strength, and cure characteristics of the rubber compound in the seismic isolation damper. As the concentration of CCA-g-NR increased, the elongation at break and adhesive strength of the compound increased, whereas its tensile strength and modulus at 300% decreased. Moreover, as the concentration increased, the maximum torque decreased and the scorch time was delayed to obtain an optimal vulcanization time.

• Elastomers and Composites
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• 제52권3호
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• pp.194-200
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• 2017

After the grafting of methacrylic acid (MA) to ethylene propylene diene monomer (EPDM), a new peak at $1704cm^{-1}$ corresponding to the carboxylic acid group was observed in the infrared (IR) spectrum. This characteristic MA molecule peak grew larger as the MA contents were increased. After casting films were prepared from pure EPDM and MA-grafted EPDM, differential scanning calorimeter (DSC) measurements were made the pure EPDM exhibited a melting point of approximately $45^{\circ}C$ while that of the MA-grafted EPDM was $135{\sim}140^{\circ}C$. As the graft ratio of MA increased, the absorbed heat capacity increased at temperatures near $135{\sim}140^{\circ}C$, indicating that an increased amount of MA reacted. Furthermore, owing to the addition of crystalline MA, it is expected that strength of the elastomer will improve as the graft ratio increases, as a result of the increased number of hard segments.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제36권3호
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• pp.116-123
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• 2014

Purpose: The purpose of this study was to evaluate risks for wound dehiscence after guided bone regeneration (GBR) in dental implant surgery. Methods: Patients who received dental implant therapy with GBR procedure at Seoul National University Bundang Hospital (Seongnam, Korea) from June 2004 to May 2007 were included. The clinical outcome of interest was complications related to dental implant surgery. The factors influencing wound dehiscence, classified into patient-related factors, surgery-related factors and material-related factors, were evaluated. Results: One hundred and fifteen cases (202 implants) were included in this study. Wound dehiscence (19.1%) was considered a major complication. The risk of wound dehiscence was higher in males than in females (odds ratio=4.279, P =0.014). In the main graft, the allogenic group had the lowest risk of wound dehiscence (odds ratio=0.106, P =0.006). Though the external connection group had a higher risk of wound dehiscence than the internal connection group (odds ratio=2.381), the difference was not significant (P =0.100). Conclusion: In this study, male gender and main graft have the highest risk of wound dehiscence. To reduce wound dehiscence after GBR, instructions on postoperative care with supplementary procedure for the protection of the wound dehiscence is recommended, especially to male patients. A main graft with a gel base can reduce the risk of wound dehiscence.

• 한국의류학회지
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• 제7권1호
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• pp.11-16
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• 1983

Variance of whiteness after graft copolymerization of acrylonitrile, methylmethacrylate and acrylamide onto bleached cellulose using Ce(IV) salt as initiators and the effect of homopolymer on the grafted fibers by photo-irradiation were studied. Also, the development of Yellowing were determined after carbon-arc radiation in a Fade-o-meter. The results were as follows: (1) Variation of whiteness of grafted cellulose fibers were influenced by graft-ratio, Inorganic-Organic Balance (IOB) of functional group in used monomers and adhering homopolymers on the grafed fibers. (2) Yellowing was not affected by the concentration of Ceric Ammonium Nitrate directly during reaction (eg. 0.008>0.006>0.014 M).