• 대한치과보철학회지
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• 제34권1호
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• pp.70-84
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• 1996

This paper reports marginal bone loss around osseointegrated implants after loading in partially edentulous patients in dental hospital, Yonsei University. Two types of implants($Br{\aa}nemark^{TM},\;IMZ^{TM}$) were used. Through the digital measurement on periapical radiograph around 37 implants in human subjects, marginal bone loss was observed for 24 months after delivery of prostheses. The results were as follows; 1. According to experimental periods marginal bone loss in total implants was 1.775 mm at 12 months, 1.921 mm at 24 months after delivery of prostheses(p<0.05). 2. Marginal bone loss in the $Br{\aa}nemark$ implants was 1.831 mm at 12 months, 1.833 mm at 24 months after delivery of prostheses(p<0.05). 3. Marginal bone loss in the IMZ implants was 1.578 mm at 12 months, 2.907 mm at 23 months after delivery of prostheses(p<0.05). 4. During the first year after loading, the IMZ implants showed less marginal bone loss than the $Br{\aa}nemark$ implants but, during the next the $Br{\aa}nemark$ implants showed less than the IMZ implants(p>0.05). These results indicate that marginal bone loss around osseointegrated implants occurs within the first 12 months after delivery of prostheses and stabilizes thereafter, so it is necessary to be careful of using dental implants for the first year after delivery of prostheses.

• 대한치과보철학회지
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• 제33권2호
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• pp.198-209
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• 1995

In order to evaluate the fitness and the degree of rounding of porcelain margins in collarless metal cermic restorations, collarless metal ceramic restorations were fabricated with shoulder margins of 90 and 120 degress, each consisting of ten specimens, on master dies through the direct lift technique. And ten metal ceramic restorations with a shoulder 90 degrees were fabricated. All specimens were embedded in resin and sectioned longitudinally. The sections were observed under a stereomicroscope and photographed(${\times}$200). The labial marginal gap between the die and the porcelain margin were measured with a scale. The space between the porcelain margin and the die, that is formed from marginal rounding and cementation were calculated with a computer coordinating area curvimeter. The following results were obtained. 1. There was no statistical difference between the fitness of porcelain margin of collarless metal ceramic restorations and marginal fitness of metal ceramic restoration. 2. There was no statistical difference between a shoulder of 90 and 120 degrees in the fitness of porcelain margin of collarless metal ceramic resorations. 3. Collarless metal ceramic restorations with a shoulder of 90 degrees and 120 degrees showed significantly more labial marginal rounding than metal ceramic restorations. 4. There was no statistical difference between a shoulder of 90 and 120 degrees in rounding of porcelain margin of collarless metal ceramic restorations. According to the results, rounding of porcelain margins can be observed in collarless metal ceramic restorations. Thus, there is a need for improvement in dental materials and techniques to minimize this problem, Furthermore, care should be exercised during the clinical procedure.

• 대한교통학회지
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• 제25권6호
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• pp.209-230
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• 2007

이 논문은 혼잡현상을 갖는 교통체계의 사회비용함수를 사회비용 최소화문제로부터 도출하여 분석하였다. 이 논문은 이 분야의 기존 연구에서 다루지 않았던 다음의 두 가지를 중점적으로 분석하였다. 하나는 이용자들의 시간가치가 다를 경우에 비용함수의 구조가 어떻게 달라지는지를 검토하는 것이고, 다른 하나는 사회비용함수를 구성하는 공급자 비용함수의 구조를 파악하는 것이었다. 분석의 결과는 다음과 같이 요약될 수 있다. 첫째, 한계사회비용은 특정한 시간가치를 가진 고객이 소비한 시간가치비용과 추가 고객의 처리에 수반되는 시스템 전체의 서비스시간 증가에 따른 한계혼잡비용으로 구성된다. 둘째, 한계혼잡비용은 공급자의 보상한계비용과 같은 바, 후자는 공급자가 추가의 고객을 가장 경제적으로 처리함에 필요한 용량의 변경에 의한 서비스시간의 변화 양에 대한 이용자 전체의 시간가치를 보상해준다는 전제아래서의 공급자 한계비용을 지칭한다. 셋째, 보상한계비용은 서비스시간함수가 산출과 용량에 대해 동차함수일 경우 한계용량비용에 시스템 이용률의 역수를 곱한 값과 같다.

• 대한치과보철학회지
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• 제39권6호
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• pp.641-658
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• 2001

All-ceramic restorations have become an attractive alternative to porcelain-fused-to-metal crowns. In-Ceram, and more recently IPS Empress 2 were introduced as a new all-ceramic system for single crowns and 3-unit fixed partial dentures. But their strength and marginal fit are still an important issue. This study evaluated the fracture resistance and marginal fit of three systems of 3 unit all-ceramic bridge fabricated on prepared maxillary anterior resin teeth in vitro. The 3 all-ceramic bridge systems were: (1) a glass-infiltrated, sintered alumina system (In-Ceram) fabricated conventionally, (2) the same system with copy-milled alumina cores (copy-milled In-Ceram), (3) a heat pressed, lithium disilicate reinforced glass-ceramic system (IPS Empress 2). Ten bridges of each system with standardized design of framework were fabricated. All specimens of each system were compressed at $55^{\circ}$ at the palatal surface of pontic until catastrophic fracture occurred. Another seven bridges of each system were fabricated with standard method. All of the bridge-die complexes were embedded in epoxy resin and sectioned buccolingually and mesiodistally. The absolute marginal discrepancy was measured with stereomicroscope at ${\times}50$ power. The following results were obtained: 1. There was no significant difference in the fracture strength among the 3 systems studied. 2. The Weibull modulus of copy-milled In-Ceram was higher than that of In-Ceram and IPS Empress 2 bridges. 3. Copy-milled In-Ceram($112{\mu}m$) exhibited significantly greater marginal discrepancy than In Ceram ($97{\mu}m$), and IPS Empress 2 ($94{\mu}m$) at P=0.05. 4. The lingual surfaces of the ceramic crowns showed smaller marginal discrepancies than mesial and distal points. There was no significant difference between teeth (incisor, canine) at P=0.05. 5. All-ceramic bridges of three systems appeared to exhibit sufficient initial strength and accept able marginal fit values to allow clinical application.

• 대한치과기공학회지
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• 제34권2호
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• pp.105-111
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• 2012

Purpose: The purpose this study was to evaluate the marginal fitness of metal copings fabricated using rapid prototyping method and to compare the fitness with copings by conventional method. Then clinical availability of fixed dental prostheses (FDPs) fabricated using rapid prototyping method shall be confirmed based on marginal fitness. Methods: Ten same cases of3 unit FDPs epoxy models (abutment teeth 14 and 16) were manufactured. Each of ten epoxy models were scanned by 3shape D-700 scanner to be designed by experienced technician, and photopolymer 3 unit FDPs were fabricated using rapid prototyping methodand fabricated using Lost wax technique (LW) with same models. Marginal fitness of 3 unit FDPs were measured by silicone replica technique. T-test of independent sample for statistical analysis was executed with SPSS 12.0K for Windows. (${\alpha}$=.05) Results: Significantly higher mean (SD) marginal fitness (P<.000) were observed in the RP group $(95.9(18.0){\mu}m$ compared to the conventionally LW group $(80.1(13.8){\mu}m$. Conclusion: Marginal fitness of LW group showed excellent rather than RP group. However marginal fitness of 3 unit FDPs fabricated by RP method did not get out of clinical allowance value range significantly to allow clinical application.

• 한국콘텐츠학회논문지
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• 제16권1호
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• pp.151-157
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• 2016

구강인기방법과 지르코니아 블록 종류에 따른 지르코니아 코핑의 변연적합도 변화를 관찰하기 위해 2종의 고무인상재와 1종의 구강스캐너를 사용한 구강인기방법과 3종의 지르코니아 블록을 사용하여 지르코니아 코핑을 10개씩 제작하여 표면 거칠기와 변연적합도를 측정하였다. 표면 거칠기는 LUXEN Smile($2.3{\pm}0.9{\mu}m$) 블록이 가장 우수하였다. 그리고 협측 변연간격은 HL시편($26.5{\pm}2.1{\mu}m$), 설측 변연간격은 HL시편($27.2{\pm}2.1{\mu}m$), 근심 변연간격은 HJ시편($29.6{\pm}4.0{\mu}m$), 원심 변연간격은 HJ시편($29.0{\pm}3.0{\mu}m$)이 가장 낮게 나타났으며, 통계학적으로 유의차가 있었다(p<0.05). 이 결과, 구강인기방법과 지르코니아 블록 종류가 변연적합도에 영향을 준 것으로 나타났으며, 변연간격은 모든 군에서 임상적 허용 범위 내에 속했다.

• Maxillofacial Plastic and Reconstructive Surgery
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• 제34권6호
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• pp.440-448
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• 2012

Purpose: The purpose of this study was to evaluate marginal bone loss of the alveolar crest on implants with or without guided bone regeneration and variables that have influenced. Methods: The clinical evaluation were performed for survival rate and marginal bone loss of 161 endosseous implants installed with guided bone regeneration (GBR) in 83 patients from September 2009 to October 2010 in relation to sex and age of patients, position of implant, implant system, length and diameter of implant. Study group (n=42) implant with GBR procedure, control group (n=41) implant without GBR technique. Simultaneous GBR approach using resorbable membranes combined with autogenous bone graft or freeze-dried bone allograft or combination. Radiographic examinations were conducted at healing abutment connection and latest visit. Marginal bone level was measured. Results: Mean marginal bone loss was 0.73 mm in study group, 0.63 mm in control group. Implants in maxillary anterior area (1.21 mm) were statistically significant in study group (P<0.05), maxillary posterior area (0.81 mm) in control group (P<0.05). Mean marginal bone loss 1.47 mm for implants with diameter 3.4 mm, 0.83 mm for implants of control group with diameter 4.0 mm (P<0.05). Some graft materials showed an increased marginal bone loss but no statistically significant influence of sex, implant type or length. Conclusion: According to these findings, this study demonstrated the amount of marginal bone loss around implant has maintained a relative stable during follow-up periods. We conclude that implants with GBR had similar survival rate and crestal bone level compared with implants in native bone.

• 대한치과보철학회지
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• 제45권6호
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• pp.760-768
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• 2007

Statement of problem. Conventional denture treatment for totally edentulous patients is associated with a variety of functional and psychosocial problems. The placement of implants in the anterior region of the maxilla and mandible and the fabrication of an implant-retained overdenture might solve these problems. Purpose. This study compared the marginal bone loss around the implant and evaluated the implant survival rate and complications in patients treated with overdentures retained by implants for 2 years. Material and methods. Patients who had received implant-retained overdentures using a Dolder bar at Samsung Medical Center from January 1999 to June 2005 and had participated in the annual recall programs for two years were selected for this study. A total of 18 patients and 56 $Br{\aa}ne-mark\;system^{(R)}$ implants were used, and their data were reviewed. Evaluations of the survival rate, bone quality, marginal bone loss, and complications were performed. The data on the Dolder bar length and clip length were measured. The change in marginal bone loss and the correlation between the marginal bone loss and bar length, clip length, or bone quality were investigated. Results. Implants placed in this study showed a 100% survival rate. The average annual bone loss was 1.12mm in the first year and 0.27mm in the second year in the maxilla, and 0.58mm in the first year and 0.22mm in the second year in the mandible. The marginal bone loss in the maxilla showed no significant association with those in the mandible. (P>.05). There was no significant difference in marginal bone loss around implants between the first and second year. (P>.05) There was no statistically significant relationship (P>.05) between the marginal bone loss and bone quality, clip length, or Dolder bar length. The Dolder bar length showed a high correlation with the clip length. (P<.05) Various complications were noted. Conclusion. These results confirmed the favorable outcome for patients treated with implant-retained overdentures.

• 대한치과기공학회지
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• 제38권4호
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• pp.255-262
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• 2016

Purpose: This study examined the effect of wettability of gypsum materials and rubber impression material on the marginal fitness of zirconia copings. Methods: Three commercially available gypsum materials(Fugirock EP, Snow Rock, Tuff Rock) and three zirconia blocks(iJAM Emerald, LUXEN Smile block, ICE Zirkon transluzent) were studied. The zirconia copings were fabricated by using dental CAD/CAM system. Contact angles on the impression materials were measured with contact angle measuring device. Silicone replica method was used to measure the marginal fitness and cutting was performed on the bucco-lingual and mesio-distal sides. It were observed with a stereomicroscope at °ø40 magnification. The data were statistically analyzed with One-way ANOVA. Results: Mean values of contact angles were $58.3{\pm}0.7^{\circ}$ for Tuff Rock, $77.5{\pm}0.5^{\circ}$ for Fugirock EP and $87.8{\pm}0.5^{\circ}$ for Snow Rock and the difference between them was statistically significant(p<0.05). The smallest values of marginal fitness for the JF groups were $30.7{\pm}3.0{\mu}m$ for bucco-lingual direction, $29.3{\pm}3.0{\mu}m$ for mesio-distal direction. One-way ANOVA showed statistically significant difference between groups for marginal fitness(p<0.05). Conclusion: Tuff rock gypsum material had superior wettability to others. The mean marginal fitness of the Tuff rock gypsum material group were significantly better than other groups. Thus they can be also expected to show clinically satisfactory marginal fitness.

• Restorative Dentistry and Endodontics
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• 제18권1호
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• pp.55-72
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• 1993

The aim of this study was to compare the marginal leakage of class II light curing composite resin restoration according to filling methods. With using acid etching technique and dentin bonding agent, various methods were suggested to eliminate or reduce the marginal leakage. In this study, class II cavities were prepared in 100 extracted human premolars with cementum margin(1mm below the CEJ) and the teeth were randomly assigned to 5 groups of 20 teeth each. The teeth in group 1, 2, 3 and 4 were restored by direct filling methods using P-50 and Clearfil Photoposterior of 10 teeth each, but the method of insertion of the restorative materials varied with each group. And the teeth in group 5 were restored by inlay method using Kulzer Inlay and CR Inlay. Filling methods are as follows : Group 1 : The composite resin was inserted in one layer in the proximal box and one layer in the occlusal portion. Group 2 : Insertion was in two equally thick horizontal layers in the proximal box. Group 3 : Insertion was in two diagonally placed layers in the proximal box. Group 4 : The composite resin was inserted in the same way as in group 3 except that a glass ionomer liner was first placed on the axial wall and gingival floor. Group 5 : The teeth were restored by Inlay technique using dure cure resin cement. All the teeth were thermocycled, stained with 1 % methylene blue solution, sectioned mesiodistally, and scored for marginal leakage. To compare the marginal leakage, ANOVA and T-test were used in analysis. The following results were obtained : 1. In direct filling methods, there was no significant difference in marginal leakage at both occlusal and cervical margins. 2. In all groups, occlusal margin showed significantly less leakage than cervical margin. 3. In group using glass ionomer liner, there was no significant reduction of marginal leakage at the cervical margin. 4. The group restored by inlay method showed significantly less marginal leakage than groups restored by direct filling methods at both occlusal and gingival margins. 5. There was no significant difference in each group according to filling materials.