• The Journal of Advanced Prosthodontics
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• 제6권5호
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• pp.346-350
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• 2014

PURPOSE. Impact forces in implant supported FDP (fixed dental prosthesis) are higher than that of tooth supported FDPs and the compositions used in frameworks also has a paramount role for biomechanical reasons. The aim of this study was to evaluate the flexural strength of two different zirconia frameworks. MATERIALS AND METHODS. Two implant abutments with 3.8 mm and 4.5 mm platform were used as premolar and molar. They were mounted vertically in an acrylic resin block. A model with steel retainers and removable abutments was fabricated by milling machine; and 10 FDP frameworks were fabricated for each Biodenta and Cercon systems. All samples were thermo-cycled for 2000 times in $5-55^{\circ}C$ temperature and embedded in $37^{\circ}C$ artificial saliva for one week. The flexural test was done by a rod with 2 mm ending diameter which was applied to the multi-electromechanical machine. The force was inserted until observing fracture. The collected data were analyzed with SPSS software ver.15, using Weibull modulus and independent t-test with the level of significance at ${\alpha}=.05$. RESULTS. The mean load bearing capacity values were higher in Biodenta but with no significant differences (P>.05). The Biodenta frameworks showed higher load bearing capacity ($F_0=1700$) than Cercon frameworks ($F_0=1520$) but the reliability (m) was higher in Cercon (m=7.5). CONCLUSION. There was no significant difference between flexural strengths of both zirconia based framework systems; and both Biodenta and Cercon systems are capable to withstand biting force (even parafunctions) in posterior implant-supported bridges with no significant differences.

• 대한치과보철학회지
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• 제25권1호
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• pp.17-40
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• 1987

The purpose of this study was to clarify the effect of clasp design on abutment tooth adjacent to a distal extension base under the influence by the location of functional loading. The RPI clasp, the Akers clasp and the combination clasp were selected for evaluation. Tests were performed at 10Kg, 20Kg, 30Kg loads on the buccal, central, lingual, mesial and distal positions of loading platform of each mandibular distal extension partial denture. The laser reflexion method was used for three dimensional measurement of abutment movement, which is possible to measure precisely without contact. The movement in the mesiodistal(X), buccolingual(Y), and occlusoapical(Z) directions and the rotational movement(R) were measured, and in addition, the total movement (SV) as expressed by the three dimensional summation vector independent of direction was calculated. The data were analyzed using Student t-test, p<.05. The following results were obtained from this study; 1. Clasp design did not generally affect the direction of abutment tooth movement except the movement in an undesirable occlusal direction in case of the Akers clasp and the combination clasp. 2. The greater the load on the prosthesis, the greater was the abutment tooth movement, and the direction of abutment tooth movement was affected by positional loading. 3. Each prosthesis was dislodged from the test base under the small amount of load in the distal load position, and the buccal loading showed the greatest abutment tooth movement under the maximum load. 4. RPI clasp was evaluated as the most favorable design.

• 대한치과보철학회지
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• 제36권2호
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• pp.336-354
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• 1998

Traditionally, many kinds of mechanical bonding techniques were used for bonding resins to the surface of the metal alloys. If there is a seperation between resin and metal junction by stress accumulation and temperature change of oral cavity, the cracks or crazing may occur, accompanied by failure of resin bonding to metal. This study was designed to compare the shear bond strength of the type IV gold alloy and Cr-Co alloy surfaces treated with various methods and thermocycling. Universal Instron (Model 1000) and scanning electron microscope (JEOL, Japan) was used to record the shear bond strength of 5 groups. Forty specimens were made for each group ; group 1 was treated with sandblasting only, group 2 was coated with V-primer after sandblasting, group 3 was coated with Metal primer, group 4 wase coated with MR Bond and group 5 was coated with silane. After treated with various methods, thermocycling was done for half of the each group. The surfaces of failed pattern were observed with SEM. The results were as follows : 1. Shear bond strength of the group 1 was lower than that of another groups in type IV gold alloys and bond strength of the group 1, 2 were lower than that of group 3, 4, 5 in Cr-Co alloys. 2. Shear bond strength of the gold alloy with resin was higher than that of Cr-Co alloy when specimens were coated with V-primer. 3. Shear bond strength of the Co-Cr alloys with resin was higher than that of gold alloys when specimens were coated with Metal primer. 4. The bond strength of all specimens did not decreased significantly after thermocycling. 5. Adhesive failures were found in group 1 and Cr-Co alloy in group 2, but adhesive and cohesive failures were found in another groups.

• 대한치과보철학회지
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• 제39권1호
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• pp.14-24
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• 2001

The purpose of this study was to compare the fracture strengths and the fracture patterns of several hybrid-ceramic crowns and metal-ceramic crown. Ten crowns were constructed for each group according to the manufacturer's instruction. Removable template of silicone rubber impression material was used for standardization of each crowns. Each crown was cemented on a metal die with hybrid glass ionomer cement. All crowns cemented were stored in distilled water, $36^{\circ}C$ for 24 hours prior to loading in an universal testing machine. The load was directed at 130 degrees the long axis of metal die. The fracture strengths were measured and the fracture patterns were observed. The following results were obtained from this study 1. The mean fracture strengths of $Artglass^{(R)}$, $Sculpture^{(R)}$ and $Targis^{(R)}$ were $57.5{\pm}9.5Kgf,\;62.7{\pm}12.2Kgf$ and $60.2{\pm}10.1Kgf$ respectively. There was no significant difference among each hybrid ceramic crown group. 2. The toad required to fracture hybrid-ceramic crowns was significantly smaller than metal-ceramic crowns($131.7{\pm}22.0Kgf$). 3. In the metal-ceramic crowns, labial porcelain detached partially from porcelain-metal junction of proximal side by load. 4. Hybrid-ceramic crowns showed a simple fracture pattern that fracture line began at the loading area and extended through proximal surface, perpendicular to the margin. The crown was separated into two parts of labial side and lingual side. Above results revealed that three kinds of the hybrid-ceramic crowns used in this study must have careful application in clinical use since the strength of hybrid-ceramic crown was lower(about 1/2) than that of metal-ceramic crown.

• 구강회복응용과학지
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• 제31권3호
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• pp.262-272
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• 2015

구치부 교합지지 상실과 비정상적 악간 관계는 교합 부조화로 이어지며 다양한 병적 징후를 동반한다. 저작, 심미 및 발음 기능을 회복하기 위해 교합고경과 교합평면 재설정에 따른 완전구강회복이 필요하게 된다. 본 증례는 75세의 여성으로 교합지지 상실과 불균일한 교합평면 및 II 급 부정교합을 가지고 있었다. 안모를 관찰하고 악간관계를 평가한 결과 상하악의 최대교두간접촉위가 상실되면서 수직교합고경이 감소된 것으로 진단되었다. 상악 국소의치와 하악 고정성보철물로 상실된 교합수직고경을 회복하고 조화로운 교합평면을 형성하였다. 수직고경 거상량은 7.5 mm로 하였고, 임시보철물을 이용하여 8 주간 경과 관찰 후 최종 보철물을 제작하였으며 저작효율과 심미성은 개선되었다.

• The Journal of Advanced Prosthodontics
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• 제12권6호
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• pp.376-382
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• 2020

PURPOSE. To determine the shear bond strengths of different denture base resins to different types of prefabricated teeth (acrylic, nanohybrid composite, and cross-linked) and denture teeth produced by computer-aided design/computer-aided manufacturing (CAD/CAM) technology. MATERIALS AND METHODS. Prefabricated teeth and CAD/CAM (milled) denture teeth were divided into 10 groups and bonded to different denture base materials. Groups 1-3 comprised of different types of prefabricated teeth and cold-polymerized denture base resin; groups 4-6 comprised of different types of prefabricated teeth and heat-polymerized denture base resin; groups 7-9 comprised of different types of prefabricated teeth and CAD/CAM (milled) denture base resin; and group 10 comprised of milled denture teeth produced by CAD/CAM technology and CAD/CAM (milled) denture base resin. A universal testing machine was used to evaluate the shear bond strength for all specimens. One-way ANOVA and Tukey post-hoc test were used for analyzing the data (α=.05). RESULTS. The shear bond strengths of different groups ranged from 3.37 ± 2.14 MPa to 18.10 ± 2.68 MPa. Statistical analysis showed significant differences among the tested groups (P<.0001). Among different polymerization methods, the lowest values were determined in cold-polymerized resin.There was no significant difference between the shear bond strength values of heat-polymerized and CAD/CAM (milled) denture base resins. CONCLUSION. Different combinations of materials for removable denture base and denture teeth can affect their bond strength. Cold-polymerized resin should be avoided for attaching prefabricated teeth to a denture base. CAD/CAM (milled) and heat-polymerized denture base resins bonded to different types of prefabricated teeth show similar shear bond strength values.

• The Journal of Advanced Prosthodontics
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• 제13권1호
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• pp.36-45
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• 2021

Purpose. To investigate the fracture resistance of monolithic CAD-CAM all-ceramic surveyed crowns with two different occlusal rest seat designs. Materials and Methods. Two maxillary first premolar were prepared for all-ceramic surveyed crowns with wide (2/3rd of buccolingual width of an unprepared tooth) or narrow (1/3rd of buccolingual width of an unprepared tooth) disto-occlusal rest seat (ORS) designs. Eighty monolithic CAD-CAM all-ceramic surveyed crowns were prepared and divided into 4 groups - Group CR, Composite resin material as a control; Group LDS, Lithium disilicate based material; Group ZIPS, zirconia-material (IPS ZirCAD); and Group ZLHT, zirconia- material (CeramillZolidht+). Crowns were cemented on an epoxy resin die with adhesive resin cement. The fracture resistance of crowns was tested with the universal machine. Univariate regression analysis was used. Results. The mean ± standard deviation of maximum failure force values varied from 3476.10 ± 285.97 N for the narrow ORS subgroup of group ZIPS to 687.89 ± 167.63 N for the wide ORS subgroup of group CR. The mean ± standard deviation of maximum force was 1075 ± 77.0 N for group CR, 1309.3 ± 283.9 N for group LDS, 3476.1 ± 285.97 N for group ZIPS, and 2666.7 ± 228.21 N for group ZLHT, with narrow occlusal rest seat design. The results of the intergroup comparison showed significant differences in fracture strength with various material groups and occlusal rest seat designs (P<.001). Conclusion. The zirconia-based all-ceramic surveyed crowns fractured at more than double the load of Lithium disilicate based crowns. The crowns with narrow base occlusal rest seat design had statistically significantly higher fracture resistance than surveyed crowns with wide occlusal rest seat design. The use of narrow occlusal rest seat design in CAD-CAM all ceramic surveyed crowns provides higher fracture resistance, and therefore narrow occlusal rest design can be used for providing esthetics with high strength.

• 대한치과보철학회지
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• 제51권2호
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• pp.82-89
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• 2013

연구 목적: 본 연구는 양극산화 임플란트에 골형성단백질과 혈관내피세포성장인자를 코팅한 임플란트를 토끼의 경골에 식립하여 골과 임플란트 계면의 골유착 향상의 가능성을 평가하고자 시행하였다. 연구 재료 및 방법: 6마리의 토끼 양측 경골에 코팅을 하지 않은 양극 산화 임플란트(대조군)와 골형성단백질과 혈관내피세포성장인자를 코팅한 임플란트(실험군)을 각각 한쪽에 2개씩 식립하였다, 토끼는 2주, 8주에 각각 3마리씩 희생하였고 전체 식립된 임플란트는 24개이었다. 각 시기별, 그룹별 임플란트 수는 각각 6개씩이었다. 임플란트안정지수(resonance frequency analysis (RFA)), 회전 제거력(Removable torque measurement (RTQ))을 희생 시기에 측정하였다. 독립표본 t-test (SPSS Ver. 15.0, Chicago, USA)을 이용하여 2주, 8주에서 대조군과 실험군의 차이를 비교 분석하고, 유의수준95%에서 통계적으로 검정하였다. 결과:대조군과 실험군 모두 8주에서 우수한 골유착을 보였다. 특히 실험군에서 8주에 ISQ, RTQ 값 모두 대조군과 비교하여 우수한 값을 나타내었다 (P<.05). 하지만 2주에서는 두군 사이에 통계적 유의성을 보이지 않았다(P>.05). 결론: 골형성 단백질과 혈관내피세포성장인자를 임플란트 표면에 코팅하여 식립하는 것은 치유의 후반기에 골유착을 증대하는 것으로 사료된다.

• 대한치과보철학회지
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• 제55권2호
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• pp.156-163
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• 2017

1급 지적장애는 일상 생활과 사회 생활의 적응이 현저하게 곤란하여 일생 동안 타인의 보호가 필요한 사람으로 보통 불량한 구강환경을 가지며 치아 우식, 치근단 염증 및 다수의 치아 결손을 보여 적절한 보철적 회복을 필요로 한다. 다수의 치아가 결손된 지적장애 환자의 경우 가철성 보철물의 안정, 유지와 관리가 어렵기 때문에 고정성 보철이 필요하며 임플란트 치료가 유일한 방법이다. 본 증례는 1급 지적장애인 45세 남성환자로 불량한 구강환경으로 인해 대부분의 치아가 상실되어 저작기능 회복을 위해 내원하였으며 임플란트 및 생체친화적이고 강한 강도의 단일 구조 지르코니아를 이용한 고정성 보철물로 최종 수복하였다. 이상의 치료과정 결과 심미적, 기능적으로 만족할 만한 결과를 얻을 수 있었기에 보고하는 바이다.

• 대한치과보철학회지
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• 제54권2호
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• pp.140-145
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• 2016

심한 치아 마모는 치질의 손상, 교합면의 부조화, 기능적, 심미적 문제들을 야기할 수 있다. 치아의 마모로 인해 나타나는 수직 고경의 감소는 악골의 보상성 성장과 치아의 맹출로 어느 정도 상쇄될 수 있지만 심미적 보철물을 제작하는 데 필요한 공간과 보철물의 유지 등을 얻기 위해서는 수직 고경의 거상이 필요할 수 있다. 본 증례의 환자는 44세 남자 환자로 다수 치아에 마모를 가지고 있고 심미적인 치아를 원한다는 주소로 본원에 내원하였다. 수복을 위한 악간 공간이 부족하여 진단 왁스업을 토대로 전치부 기준 3 mm의 수직고경 거상을 결정하고, 가철성 교합 안정 장치와 임시수복물을 적정 기간 사용하여 환자의 적응도를 평가하였다. 적절한 적응을 확인한 후 단일 구조 지르코니아를 이용한 고정성 보철물로 전악 수복하였고 비기능적 습관으로부터 보철물과 주위 조직을 보호하기 위해 연질의 교합안정장치를 장착하게 하였다. 이상과 같은 치료 과정을 통해 수직 고경 거상을 동반한 보철 수복을 실시하였고 적절한 심미적, 기능적 결과를 얻었기에 이를 보고하고자 한다.