• Journal of Periodontal and Implant Science
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• v.23 no.3
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• pp.411-421
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• 1993

The purpose of this study was to assess the effect of polycaprolactone strip with minocycline on the periodontal pocket in humans and the various clinical parameters in rapidly progressive periodontitis. Nine patients with rapidly progressive periodontitis were selected for the study. They had not taken antibiotics for 6 months and had no history of dental treatment for 6 months before the study. They were in good general health. By the split-mouth method, patients received a supragingival scaling, experimental group (9sites) were subjected to subgingival placement of polycaprolactone strips(1 strip) containg 30% minocyclne and control group (9 site) were subjected to subgingival placement of not polycaprolactone strips(1 strip) containing 30 A Minocycline. Strips were replaced with freshly filled ones at 1 week and 2 week. All strips were removed from pockets at 3 week Clinical examination (plaque index, gingival index, probing pocket depth) and distribution on the bacteria morphology of subgingival plaque were monitored on baseline (0 week), 1, week, 2 week, 4 week and 8 week. The result were as follows : 1. Plaque index in experimental group was not significantly reduced during all weeks(P<0.05), but slightly reduced at 2, 4 and 8 weeks and that in control group was not significantly reduced during monitoring period. 2. Probing pocket depth was significantly reduced at 2, 4 and 8 weeks(P<0.05) in experimental group, but that in control group was not siginificantly changed during monitoring period. 3. Gingival index was significantly improved at 2, 4 and 8 weeks(P<0.05) in experimental group but that in control group was not significantly changed. 4. Percentage of cocci was significantly increased at 2, 4 and 8 weeks in experimental group but that in control group was not significantly changed. 5. Percentage of non-motile rods in both group were not significantly changed when compared with those of baseline(0 week) (P<0.05). 6. Percentage of motile rods was siginificantly reduced at 1, 2 and 4 weeks in experimental group (p<0.05) but that in control group was not significantly changed. 7. Percentage of spirochetes was siginificantly reduced during all weeks(P<0.05) but that in control group was not significantly changed. The result showed that polycaprolactone containing 30% minocycline effect the clinical index and bacterial morphotype.

• Journal of Periodontal and Implant Science
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• v.28 no.3
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• pp.389-401
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• 1998

In this study, 21 patients diagnosed as adult periodontitis were divided into 4 groups. One quadrant with an average of 6mm deep pocket depth was chosen from each individual - Group A inserted tetra-cycline fiber after removing supragingival calculus while group RP had calculus removal and root planning alone. Group RP+A received combination of these treatments while group C received none. Plaque index, bleeding on probing, pocket depth, attachment level, and distribution of subgingival plaque were compared and evaluated among these groups at periods of first visit, 4th week and 8th week. The results were as follows ; 1. Plaque index and bleeding on probing improved after treatment and no significant difference was found between the groups. 2. When comparing the change in pocket depth between the groups, the use of tetracycline fiber showed significant reducton in pocket depth comparable to root planing. Combined therapy of tetracycline fiber and root planing showed synergistic effect in pocket depth reduction. 3. When comparing the change in attachment level between the groups, the use of tetracycline fiber showed significant increase in clinical attachment level comparable to root planing, but no synergistic effect was found in the combined therapy. 4. When comparing the change in the motile bacteria ratio between the groups, group RP and group RP+A showed significant decrease compared with control group. 5. There were no severe adverse effects from using tetracycline fiber, except for a few patient who experienced mild discomfort. In summary, the use of local adminstration of tetracycline fiber in adjunction to mechenical treatment can be effective for adult periodontitis.

• Journal of Periodontal and Implant Science
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• v.35 no.2
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• pp.299-310
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• 2005

The severe form of chronic periodontitis(CP) has been reported to be strongly associated with the presence of allele 2 of composite IL-1B(+3954) and IL-1A(+4845) genetic polymorphisms(genotype positive). However, other studies have reported conflicting findings. These might have resulted from differences in ethnic background and disease entities. The aim of this study was to determine the distribution of IL-1A(+4845), IL-1B(+3954), IL-1B(-511), and IL-1 RN(VNTR) genetic polymorphisms in children as a future Korean population. The study population consisted of 92 children from the Dept. of Pediatric Dentistry, Chonnam National University Hospital. Genomic DNA was obtained from buccal swab. The IL-1A(+4845), IL-1B(+3954), and IL-1B(-511) genes were genotyped by amplifying the polymorphic region using multiplex polymerase chain reaction(PCR), followed by restriction enzyme digestion and gel electrophoresis. IL-1 RN(VNTR) polymorphism were then evaluated by PCR amplification and fragment size analysis in agarose gel. The allele 2 frequency was 41.3%, 4.3%, 47.8%, and 9.9% for IL-1A(+4845), IL-1B(+3954), IL-1B(-511), and IL-1 RN respectively. The frequency of genotype with allele 2 carriage for IL-1A(+4845), IL-1B(+3954), IL-1B(-511), and IL-1 RN was 77.1%, 7.6%, 63.0%, and 15.2% respectively. The allele 2 frequency in IL-1B(+3954) was significantly higher in female than in male population(p<0.05). The negative association was shown between the presence of allele 2 in IL-1B(-511) and in IL-1B(+3954), and the carriage rate of IL-1B(+3954) allele 2 tended to lower in IL-1B(-511) allele 2(P=0.056). Only 7.3% of children carried the composite genotype of IL-1A(+4845) and IL-1B(+3954). These results suggest that the polymorphism of IL-1B(+3954) and the positive composite genotype was relatively rare in Korean population.

• Journal of Biomedical Engineering Research
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• v.20 no.1
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• pp.37-44
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• 1999

Because of bone resorption, wear of ultra-high molecular weight polyethylene(UHMWPE) in total knee arthroplasty has been recognized as a major factor in long-term failure of knee implant. The surface damage and the following harmful wear debris of UHMWPE is largely related to contact stress. Most of the previous studies focused on the contact condition only at the articulating surface of UHMWPE. Recently, contact stress at the metal-backing interface has been implicated as one of major factors in UHMWPE wear. Therefore, the purpose of the is study is to investigate the effect of the contact stress for different thickness, conformity friction coefficient, and flexion degree of the UHMWPE component in total knee system, considering the contact conditions at both interfaces. In this study, a two-dimensional non-linear plane strain finite element model was developed. The results showed that the maximum value of von-Mises stress occurred below the articulating surface and the contact stress was lower for the more conforming models. All-polyethylene component showed lower stress distribution than the metal-backed component. With increased friction coefficient on the tibiofemoral contact surface, the maximum shear stress increased about twofold.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.155.2-155.2
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• 2013

Strain-relaxed SiGe layer on Si substrate has numerous potential applications for electronic and opto- electronic devices. SiGe layer must have a high degree of strain relaxation and a low dislocation density. Conventionally, strain-relaxed SiGe on Si has been manufactured using compositionally graded buffers, in which very thick SiGe buffers of several micrometers are grown on a Si substrate with Ge composition increasing from the Si substrate to the surface. In this study, a new plasma process, i.e., the combination of PIII&D and HiPIMS, was adopted to implant Ge ions into Si wafer for direct formation of SiGe layer on Si substrate. Due to the high peak power density applied the Ge sputtering target during HiPIMS operation, a large fraction of sputtered Ge atoms is ionized. If the negative high voltage pulse applied to the sample stage in PIII&D system is synchronized with the pulsed Ge plasma, the ion implantation of Ge ions can be successfully accomplished. The PIII&D system for Ge ion implantation on Si (100) substrate was equipped with 3'-magnetron sputtering guns with Ge and Si target, which were operated with a HiPIMS pulsed-DC power supply. The sample stage with Si substrate was pulse-biased using a separate hard-tube pulser. During the implantation operation, HiPIMS pulse and substrate's negative bias pulse were synchronized at the same frequency of 50 Hz. The pulse voltage applied to the Ge sputtering target was -1200 V and the pulse width was 80 usec. While operating the Ge sputtering gun in HiPIMS mode, a pulse bias of -50 kV was applied to the Si substrate. The pulse width was 50 usec with a 30 usec delay time with respect to the HiPIMS pulse. Ge ion implantation process was performed for 30 min. to achieve approximately 20 % of Ge concentration in Si substrate. Right after Ge ion implantation, ~50 nm thick Si capping layer was deposited to prevent oxidation during subsequent RTA process at $1000^{\circ}C$ in N2 environment. The Ge-implanted Si samples were analyzed using Auger electron spectroscopy, High-resolution X-ray diffractometer, Raman spectroscopy, and Transmission electron microscopy to investigate the depth distribution, the degree of strain relaxation, and the crystalline structure, respectively. The analysis results showed that a strain-relaxed SiGe layer of ~100 nm thickness could be effectively formed on Si substrate by direct Ge ion implantation using the newly-developed PIII&D process for non-gaseous elements.

• Journal of Periodontal and Implant Science
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• v.28 no.4
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• pp.645-660
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• 1998

The purpose of this study was to make and ascertain a decision making process on the base of patient-oriented utilitarianism in the treatment of patients of chronic adult periodontitis. Fifty subjects were chosen in Yonsei Dental hospital and the other fifty were chosen in Severance dental hospital according to the selection criteria. Fifty four patients agreed in this study. NS group(N=32) was treated with scaling and root planing without any surgical intervention, the other S group(N=22) done with flap operation. During the active treatment and healing time, all patients of both groups were educated about the importance of oral hygiene and controlled every visit to the hospital. When periodontal treatment needed according to the diagnostic results, some patients were subjected to professional tooth cleaning and scaling once every 3 months according to an individually designed oral hygienic protocol. Probing depth was recorded on baseline and 18 months after treatments. A questionnaire composed of 6 kinds(hygienic easiness, hypersensitivity, post treatment comfort, complication, functional comfort, compliance) of questions was delivered to each patient to obtain the subjective evaluation regarding the results of therapy. The decision tree for the treatment of adult periodontal disease was made on the result of 2 kinds of periodontal treatment and patient's ubjective evaluation. The optimal path was calculated by using the success rate of the results as the probability and utility according to relative value and the economic value in the insurance system. The success rate to achieve the diagnostic goal of periodontal treatment as the remaining pocket depth less than 3mm and without BOP was $0.83{\pm}0.12$ by non surgical treatment and $0.82{\pm}0.14$ by surgical treatment without any statistically significant difference. The moderate success rate of more than 4mm probing pocket depth were 0.17 together. The utilities of non-surgical treatment results were 100 for a result with less than 3mm probing pocket depth, 80 for the other results with more than 4mm probing pocket depth, 0 for the extraction. Those of surgical treatment results were the same except 75 for the results with more than 4mm. The pooling results of subjective evaluation by using a questionnaire were 60% for satisfaction level and 40% for no satisfaction level in the patient group receiving nonsurgical treatment and 33% and 67% in the other group receiving surgical treatment. The utilities for 4 satisfaction levels were 100, 75, 60, 50 on the base of that the patient would express the satisfaction level with normal distribution. The optimal path of periodontal treatment was rolled back by timing the utility on terminal node and the success rate, the distributed ratio of patient's satisfaction level. Both results of the calculation was non surgical treatment. Therefore, it can be said that non-surgical treatment may be the optimal path for this decision tree of treatment protocol if the goal of the periodontal treatment is to achieve the remaining probing pocket depth of less than 3mm for adult chronic periodontitis and if the utilitarian philosophy to maximise the expected utility for the patients is advocated.