• Journal of Periodontal and Implant Science
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• 제38권1호
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• pp.103-108
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• 2008

Purpose: Studies reported controversial results about prognosis of root resection with 0%-38% failure rate. The purpose of this study is to consider clinical efficacy of root resection. Materials and Methods: This study reported three cases of root resection which were performed on different sites. In first case, lower right first molar showed pus discharge and 7 mm of probing pocket depth. It was diagnosed as fracture of mesial root. Hemisection of mesial root was performed. In second case, upper right first molar showed severe bone loss on disto-buccal root and 7 mm of probing pocket. Resection of disto-buccal root was performed In third case, lower left second molar showed severe bone loss on distal root including apex and 15mm of probing pocket depth. Hemisection of distal root was performed. Result: In these three cases of root resection, compromised molars were treated successfully and conserved. Conclusion: Root resection is a successful procedure treating compromised multi-rooted teeth and conserving teeth when proper case selection is performed.

• 한국임상보건과학회지
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• 제8권2호
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• pp.1436-1443
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• 2020

Purpose: The purpose of this study was to differences in the expression rate of Porphyromonas gingivalis according to smoking status, smoking amount and period of smoking. Methods: At the time of investigation, 30 smokers and non-smokers were recruited among patients with periodontitis with a probing pocket depth(PPD) of 4 mm or more. General information was collected using a self-questionnaire, and the average value was used by a dentist to measure the probing pocket depth of three times each for the first or second molar. Plaque collection and analysis were performed by collecting only subgingival plaque using a conventional method, and the expression rate of P. gingivalis was confirmed using polymerase chain reaction (PCR). For statistical analysis, the SPSS Ver 25.0 program was used. Results: Smoking did not have a significant effect on the expression of P. gingivalis, but it did affect the expression of more type II genotypes (p<0.05). In addition, smokers had more slight periodontal pocket, and the amount and duration of smoking did not affect the expression of P. gingivalis. Conclusions: In the future, it is necessary to reinforce the group of smokers and non-smokers with healthy oral conditions, and to investigate the quantitative difference in the expression rate and genotype of P. gingivalis over time of harmful substances in smoking.

• 한국기계가공학회지
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• 제1권1호
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• pp.38-47
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• 2002

Machining quality has been improved with the development of cutting tools. However, it is difficult to obtain a high degree of quality in machining a deep pocket with a long end mill, since machining accuracy is mainly dependent on the stiffness of the cutting tool and tool holder. To improve machining quality in machining a deep pocket using an end mill, the performance by cutting condition compare with others. Owing to this problem, it is necessary to select suitable tool and holder in the deep pocket machining. In this study, the hydraulic holder for the high speed machining is introduced and the performance of that is compared with others according to cutting conditions. The cutting parameters involved were; slenderness ratio in the range of 3 to 6 (L/D), radial depth of cut from 0.01 to 0.05 mm. Cutting force and surface roughness, precision of form were observed during the experiment to investigate cutting state.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 한국자동제어학술회의논문집(국내학술편); 포항공과대학교, 포항; 24-26 Oct. 1996
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• pp.848-851
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• 1996

Based on the minimum cutting time criteria, the tool path generation algorithm of a pocket machining is developed as a form of a built-in cycle for the WOP(workshop oriented programming) of a CNC controller. Based on the given CAD database and tool information, an optimal cutting depth and geometric properties can be generated, then six different tool paths will be generated internally and automatically. Finally, the G code which commands tool movements is generated for CNC machining.

• Journal of Periodontal and Implant Science
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• 제31권4호
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• pp.737-747
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• 2001

Regeneration of Periodontium with PRP does not only improve regeneration rate and density of bone but have a possibility to estimate faster healing process for soft tissue. And also, synthetic bone and xenogenic bone graft are effective on regeneration of periodontium. The purpose of this study is to evaluate the effectiveness of synthetic bone ($Biogran^{(R)}$) and xenogenic bone ($BBP^{(R)}$) grafts with the PRP technique on regeneration of periodontium. 52 Generally healthy Pt. who had pocket depth 5mm at any of 6 surfaces of the teeth were in the study at Dept. of Perio. in Dankook Dental Hospital. Open Flap was treated for 18 infra-bony pockets as control group, $Biogran^{(R)}$ with PRP was inserted for 25 infrabony pockets as first test group, and $BBP^{(R)}$ with PRP was inserted for 22 infrabony pockets as 2nd test group. Then evaluation was made after 3 and 6 months 1. 6 months after surgery, each difference of average probing pocket depth was $2.61{\pm}0.23$ for control, $3.40{\pm}0.30$ for 1st test, and $3.45{\pm}0.37$ for 2nd test group. 2. 6 months after surgery, each difference of clinical probing attachment level was $1.39{\pm}0.12$ for control, $2.88{\pm}0,24$ for 1st, and $2.86{\pm}0,27$ for 2nd test group. 3. 6 months after surgery, each difference of Maximal probing attachment level was $1.11{\pm}0.16$ for control, $3.28{\pm}0.30$ for 1st, and $3.27{\pm}0.35$ for 2nd test group. 4. There were significant differences for clinical change of each three group which were between average probing pocket depth and clinical attachment level of 3,6 months and minimal and maximal attachment level after 6 months 5. There were significant differences for average probing pocket depth which were only at control group and 2nd test group between 1 and 6months. For clinical attachment level and minimal and maximal proving attachment level, there was a significant difference after 6month of surgery. 6. There was no significant difference between two test groups for average probing depth, clinical attachment level, and minima1 and maximal probing attachment level. As the result, PRP with bone graft is very effective for regeneration of periodontium and there is no difference between xenogenic bone and synthetic bone.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2001년도 춘계학술대회 논문집
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• pp.1060-1063
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• 2001

The mechanical etching technique has recently been developed to a powder blasting technique for various materials, capable of producing micro structures larger than 100$\mu$m. This paper describes the performance of powder blasting technique in micro-pocketing of stainless steel and the effect of the number of nozzle scanning and the nozzle height on the depth and width of pockets. Experimental results showed that increasing the no. of nozzle scanning and decreasing the nozzle height resulted in the increase of depth and width in pockets. Increase of width results from wear of mask film.

• 한국정밀공학회지
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• 제19권1호
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• pp.219-226
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• 2002

The mechanical etching technique has recently been developed to a powder blasting technique for various materials, capable of producing micro structures larger than 100$\mu$ m. This paper describes the performance of powder blasting technique in micro-pocketing of stainless steel and the effect of the number of nozzle scanning and the nozzle height on the depth and width of pockets. Experimental results showed that increasing the no. of nozzle scanning and decreasing the nozzle height resulted in the increase of depth and width in pockets. Increase of width results from wear of mask film.

• Journal of Periodontal and Implant Science
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• 제28권2호
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• pp.371-376
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• 1998

This study presents an evaluation of the effectiveness of nonsurgical subgingival scaling and root planing related to initial pocket depth, type of teeth, and individual root surfaces. A total of 110 teeth designated for periodontal surgery in 67 patients with marginal periodontitis were selected and received thorough scaling and root planing with standard rigid Gracey curettes. After a healing period of 4 to 8 weeks, residual calculus was assessed at the time of periodontal surgery following the reflection of mucoperiosteal flap. The results demonstrated a high correlation between the percentage of residual calculus and initial pocket depth. It was further noted that tooth type and involved root surface also influenced the rate of calculus remnant. The results of this study suggest that complete removal of subgingival calculus utilizing conventional instrumentation via closed approach is rare.

• Journal of Periodontal and Implant Science
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• 제28권4호
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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.

• Journal of Periodontal and Implant Science
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• 제17권1호
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• pp.105.2-105.2
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• 1987