• 대한치과기공학회지
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• 제38권3호
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• pp.111-117
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• 2016

Purpose: The present study was performed to investigate the effect of abutment inclined angle on the marginal fit of zirconia all-ceramic crown. Methods: The Ti abutments with 3 different inclined angle($2^{\circ}$, $4^{\circ}$ and $6^{\circ}$) were fabricated. The zirconia copings were fabricated for each abutment by using dental CAD/CAM system. The manufactured zirconia copings were duplicated through silicone replica technique, and a replicated specimen was sectioned in the center of bucco-lingual and mesio-distal axial to measure the marginal fit by using a stereo microscope. The results were analyzed using a one-way ANOVA with SPSS 22.0 for Windows(${\alpha}=0.05$). Results: On the bucco-lingual axial, marginal fit was the RL3($41.5{\pm}3.4{\mu}m$), RL2($44.3{\pm}4.3{\mu}m$) and RL1($47.5{\pm}5.7{\mu}m$), respectively. On the mesio-distal axial, marginal fit was the RL3($41.1{\pm}3.7{\mu}m$), RL2($45.7{\pm}5.3{\mu}m$) and RL1($46.2{\pm}4.5{\mu}m$), respectively. One-way ANOVA showed statistically significant difference between groups for marginal fit(p<0.05). Conclusion: For marginal fit of the abutments inclined angle, RL3 specimen was superior. The abutment inclined angle had influence on marginal fit of the zirconia copings. The marginal fit of each group were within clinically acceptable range.

• The Journal of Advanced Prosthodontics
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• 제5권2호
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• pp.198-203
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• 2013

PURPOSE. The purpose of this study was to investigate the effect of resin cements and primer on the retentive force of zirconia copings bonded to zirconia abutments with insufficient retention. MATERIALS AND METHODS. Zirconia blocks (Lava, 3M ESPE, St. Paul, MN, USA) were obtained and forty sets of zirconia abutments and copings were fabricated using CAD/CAM technology. They were grouped into 4 categories as follows, depending on the types of resin cements used, and whether the primer is applied or not:Panavia F2.0 (P), Panavia F2.0 using Primer (PRIME Plus, Bisco Inc, Schaumburg, IL, USA) (PZ), Superbond C&B (S), and Superbond C&B using Primer (SZ). For each of the groups, the cementation was conducted. The specimens were kept in sterilized water ($37^{\circ}C$) for 24 hours. Retentive forces were tested and measured, and a statistical analysis was carried out. The nature of failure was recorded. RESULTS. The means and standard deviations of retentive force in Newton for each group were $265.15{\pm}35.04$ N (P), $318.21{\pm}22.24$ N (PZ), $445.13{\pm}78.54$ N (S) and $508.21{\pm}79.48$ N (SZ). Superbond C&B groups (S & SZ) showed significantly higher retentive force than Panavia F2.0 groups (P & PZ). In Panavia F2.0 groups, the use of primer was found to contribute to the increase of retentive force. On the other hand, in Superbond C&B groups, the use of primer did not influence the retention forces. Adhesive failure was observed in all groups. CONCLUSION. This study suggests that cementation of the zirconia abutments and zirconia copings with Superbond C&B have a higher retentive force than Panavia F2.0. When using Panavia F2.0, the use of primer increases the retentive force.

• The Journal of Advanced Prosthodontics
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• 제4권3호
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• pp.162-169
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• 2012

PURPOSE. Fracture of the veneering material of zirconia restorations frequently occurs in clinical situations. The purpose of this in vitro study was to compare the fracture strengths of zirconia crowns veneered with various ceramic materials by various techniques. MATERIALS AND METHODS. A 1.2 mm, $360^{\circ}$ chamfer preparation and occlusal reduction of 2 mm were performed on a first mandibular molar, and 45 model dies were fabricated in a titanium alloy by CAD/CAM system. Forty-five zirconia copings were fabricated and divided into three groups. In the first group (LT) zirconia copings were veneered with feldspathic porcelain by the layering technique. In the second group (HT) the glass ceramic was heat-pressed on the zirconia coping, and for the third group (ST) a CAD/CAM-fabricated high-strength anatomically shaped veneering cap was sintered onto the zirconia coping. All crowns were cemented onto their titanium dies with Rely $X^{TM}$ Unicem (3M ESPE) and loaded with a universal testing machine (Instron 5583) until failure. The mean fracture values were compared by an one-way ANOVA and a multiple comparison post-hoc test (${\alpha}$= 0.05). Scanning electron microscope was used to investigate the fractured interface. RESULTS. Mean fracture load and standard deviation was $4263.8{\pm}1110.8$ N for Group LT, $5070.8{\pm}1016.4$ for Group HT and $6242.0{\pm}1759.5$ N for Group ST. The values of Group ST were significantly higher than those of the other groups. CONCLUSION. Zirconia crowns veneered with CAD/CAM generated glass ceramics by the sintering technique are superior to those veneered with feldspathic porcelain by the layering technique or veneered with glass ceramics by the heat-pressing technique in terms of fracture strength.

• 대한치과보철학회지
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• 제47권4호
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• pp.406-415
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• 2009

연구목적: 본 연구는 유색 및 백색 지르코니아 세라믹으로 제작된 코핑의 디자인에 따른 지르코니아 세라믹 코핑의 파절 하중과 변연 적합성을 평가한 것으로 그 결과를 임상에 응용하는데 도움을 주고자 하였다. 연구재료 및 방법: CAD/CAM system (Everset, KAVO Dental GmbH, Biberach, Germany)을 이용하여, 80개의 상악 제1 소구치 세라믹 코핑을 제작하되, 1그룹은 전체적으로 균일하게 0.3 mm로, 2그룹은 협면 0.3 mm 설면 0.6 mm, 3그룹은 전체 0.6 mm 균일하게, 4그룹은 협면 0.6 mm 설면 1.0 mm로 디자인하고, 유색 (I) 및 백색 (II) 지르코니아 코핑을 각 그룹당 10개가 되게 하였다. 소성직후와 조정 후 코핑의 변연 적합성을 Video Microscope System (sv-35, Sometech, Seoul, Korea)를 이용하여 100배율로 관찰하였고, 금속 주 모형에 코핑을 강화형 글래스아이오노머 시멘트로 합착 후 Universal Testing Machine (Instron 4467, Norwood, MA, USA)을 이용하여 파절 하중을 측정하여, one-way ANOVA test 를 시행하여 결과를 분석하였다. 결과: 1. CAD/CAM 지르코니아 코핑의 파절 하중은 1그룹, 2와 3그룹, 그리고 4그룹간에 유의성있는 차이를 보였으며 I4, II4의 파절 하중값이 가장 컸다. 2. 코핑의 디자인이 같고 색이 다른 그룹간의 비교에서는 전 그룹 모두 파절 하중값의 유의성은 없었다. 3. 소성 직후 변연 오차 측정값은 I2그룹을 제외한 전 그룹에서 협측 측정점에서 변연오차가 가장 큰 경향을 보였다. 4. 소성 직후 변연 오차 측정값은 I 그룹 지르코니아 그룹에서 그룹별 전체적인 변연적합도를 보았을 때 그룹간에 유의한 차이는 없었다 (P>.05). 5. 소성직후 변연 오차 측정값은 백색 지르코니아 그룹에서 그룹별 전체적인 변연 적합도를 보았을때 II1그룹의 변연 오차가 가장 컸다 (P<.05). 6. 소성직후 변연오차 측정값은 디자인이 같은 그룹의 유색, 백색 비교에서, I1와 II1그룹을 제외한 나머지 그룹에서 백색 지르코니아의 변연 적합도가 더 좋았다 (P<.05). 7. 내면 조정 후에는 색상화 및 지르코니아 코어 디자인에 따른 전 그룹간 변연 적합도의 차이는 없었다 (P>.05). 결론: 지르코니아 코핑 디자인과 색상화에 따른 변연 적합성은 소성 직후에는 다소 차이가 있었으나 내면 조정을 하면 임상 사용에는 무리가 없을 것으로 판단되었고, 파절강도 강화를 위해 코핑의 두께는 가급적 두꺼워야 하나, 가시면 (순면, 협면)의 심미성(반투명성)을 고려할 경우 가시면을 0.3 mm로 얇게 해도 파절 강도에 큰 영향을 주지 않는 것으로 사료되었다.

• The Journal of Advanced Prosthodontics
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• 제7권5호
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• pp.368-374
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• 2015

PURPOSE. The aim of the study was to evaluate the effect of abutment shade, ceramic thickness, and coping type on the final shade of zirconia all-ceramic restorations. MATERIALS AND METHODS. Three different types of disk-shaped zirconia coping specimens (Lava, Cercon, Zirkonzahn: ${\phi}10mm{\times}0.4mm$) were fabricated and veneered with IPS e.max Press Ceram (shade A2), for total thicknesses of 1 and 1.5 mm. A total of sixty zirconia restoration specimens were divided into six groups based on their coping types and thicknesses. The abutment specimens (${\phi}10mm{\times}7mm$) were prepared with gold alloy, base metal (nickel-chromium) alloy, and four different shades (A1, A2, A3, A4) of composite resins. The average $L^*$, $a^*$, $b^*$ values of the zirconia specimens on the six abutment specimens were measured with a dental colorimeter, and the statistical significance in the effects of three variables was analyzed by using repeated measures analysis of variance (${\alpha}$=.05).The average shade difference (${\Delta}E$) values of the zirconia specimens between the A2 composite resin abutment and other abutments were also evaluated. RESULTS. The effects of zirconia specimen thickness (P<.001), abutment shade (P<.001), and type of zirconia copings (P<.003) on the final shade of the zirconia restorations were significant. The average ${\Delta}E$ value of Lava specimens (1 mm) between the A2 composite resin and gold alloy abutments was higher (close to the acceptability threshold of 5.5 ${\Delta}E$) than th ose between the A2 composite resin and other abutments. CONCLUSION. This in-vitro study demonstrated that abutment shade, ceramic thickness, and coping type affected the resulting shade of zirconia restorations.

• The Journal of Advanced Prosthodontics
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• 제9권3호
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• pp.152-158
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• 2017

PURPOSE. The purpose of this study was to evaluate the influence of different coping thicknesses and veneer ceramic cooling rates on the failure load of zirconia-ceramic crowns. MATERIALS AND METHODS. Zirconia copings of two different thicknesses (0.5 mm or 1.5 mm; n=20 each) were fabricated from scanning 40 identical abutment models using a dental computer-aided design and computer-aided manufacturing system. Zirconia-ceramic crowns were completed by veneering feldspathic ceramics under different cooling rates (conventional or slow, n=20 each), resulting in 4 different groups (CONV05, SLOW05, CONV15, SLOW15; n=10 per group). Each crown was cemented on the abutment. 300,000 cycles of a 50-N load and thermocycling were applied on the crown, and then, a monotonic load was applied on each crown until failure. The mean failure loads were evaluated with two-way analysis of variance (P=.05). RESULTS. No cohesive or adhesive failure was observed after fatigue loading with thermocycling. Among the 4 groups, SLOW15 group (slow cooling and 1.5 mm chipping thickness) resulted in a significantly greater mean failure load than the other groups (P<.001). Coping fractures were only observed in SLOW15 group. CONCLUSION. The failure load of zirconia-ceramic crowns was significantly influenced by cooling rate as well as coping thickness. Under conventional cooling conditions, the mean failure load was not influenced by the coping thickness; however, under slow cooling conditions, the mean failure load was significantly influenced by the coping thickness.

• 대한치과기공학회지
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• 제37권4호
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• pp.243-250
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• 2015

Purpose: The aim of this study was to investigate the shear bond strength between various commercial zirconia coping and veneering ceramic, and to observe the failure mode. Methods: For each zirconia block (iJAM Emerald, LUXEN Smile block, ICE Zirkon transluzent), 10 rectangular specimens were layered with Cercon ceram kiss, IPS e.max ceram, ICE Zirkon ceramic according to recommended by the manufacturer. The shear bond strength tests of the veneering porcelain to zirconia were carried out until fracture by a universal testing machine. After the shear bond tests, failure modes were characterized visually, under a stereomicroscope, such as adhesive, cohesive, or mixed. Data were analyzed with One-way ANOVA followed by Scheffe's tests. Results: The shear bond strength ($mean{\pm}SD$) of zirconia-veneer ceramic were JC group $13.9{\pm}3.6MPa$; JE group $17.7{\pm}2.4MPa$; JI group $15.1{\pm}2.5MPa$; LC group $9.5{\pm}1.5MPa$; LE group $16.2{\pm}2.3MPa$; LI group $12.6{\pm}0.8MPa$; ZC group $16.0{\pm}2.3MPa$; ZE group $18.5{\pm}3.4MPa$; and ZI group $15.3{\pm}3.2MPa$. The One-way ANOVA showed a significant difference between groups (p<0.05). The failure mode in most experimental groups was mixed failure, except for the LC group, which showed adhesive failure, and JE group, LE group and ZE group showed cohesive failure. Conclusion: For IPS e.max ceram, the shear bond strength value was highest for all kinds of zirconia blocks. For ICE Zirkon transluzent, the shear bond strength value was highest for all kinds of veneering ceramics. Most of experimental group interfaces revealed mixed failure mode.

• The Journal of Advanced Prosthodontics
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• 제7권3호
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• pp.233-239
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• 2015

PURPOSE. This study aimed to evaluate the fit of zirconia ceramics before and after veneering, using 3 different veneering processes (layering, press-over, and CAD-on techniques). MATERIALS AND METHODS. Thirty standardized zirconia CAD/CAM frameworks were constructed and divided into three groups of 10 each. The first group was veneered using the traditional layering technique. Press-over and CAD-on techniques were used to veneer second and third groups. The marginal gap of specimens was measured before and after veneering process at 18 sites on the master die using a digital microscope. Paired t-test was used to evaluate mean marginal gap changes. One-way ANOVA and post hoc tests were also employed for comparison among 3 groups (${\alpha}$=.05). RESULTS. Marginal gap of 3 groups was increased after porcelain veneering. The mean marginal gap values after veneering in the layering group ($63.06{\mu}m$) was higher than press-over ($50.64{\mu}m$) and CAD-on ($51.50{\mu}m$) veneered groups (P<.001). CONCLUSION. Three veneering methods altered the marginal fit of zirconia copings. Conventional layering technique increased the marginal gap of zirconia framework more than pressing and CADon techniques. All ceramic crowns made through three different veneering methods revealed clinically acceptable marginal fit.

• The Journal of Advanced Prosthodontics
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• 제2권2호
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• pp.33-38
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• 2010

PURPOSE. Marginal fit is a very important factor considering the restoration's long-term success. However, adding porcelain to copings can cause distortion and lead to an inadequate fit which exposes more luting material to the oral environment and causes secondary caries. The purpose of this study was to compare the marginal fit of 2 different all-ceramic crown systems before and after porcelain veneering. This study was also intended to verify the marginal fit of crowns originated from green machining of partially sintered blocks of zirconia (Lava CAD/CAM system) and that of crowns obtained through machining of fully sintered blocks of zirconia (Digident CAD/CAM system). MATERIALS AND METHODS. 20 crowns were made per each system and the marginal fit was evaluated through a light microscope with image processing (Accura 2000) at 50 points that were randomly selected. Each crown was measured twice: the first measurement was done after obtaining a 0.5 mm coping and the second measurement was done after porcelain veneering. The means and standard deviations were calculated and statistical inferences among the 2 groups were made using independent t-test and within the same group through paired t-test. RESULTS. The means and standard deviations of the marginal fit were $61.52{\pm}2.88{\mu}m$ for the Digident CAD/CAM zirconia ceramic crowns before porcelain veneering and $83.15{\pm}3.51{\mu}m$ after porcelain veneering. Lava CAD/CAM zirconia ceramic crowns showed means and standard deviations of $62.22{\pm}1.78{\mu}m$ before porcelain veneering and $82.03{\pm}1.85{\mu}m$ after porcelain veneering. Both groups showed significant differences when analyzing the marginal gaps before and after porcelain veneering within each group. However, no significant differences were found when comparing the marginal gaps of each group before porcelain veneering and after porcelain veneering as well. CONCLUSION. The 2 all-ceramic crown systems showed marginal gaps that were within a reported clinically acceptable range of marginal discrepancy.

• 대한치과보철학회지
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• 제48권3호
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• pp.194-201
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• 2010

연구 목적: 본 연구는 지르코니아 코핑의 다양한 디자인과 시멘트 종류에 따른 지르코니아 도재관의 파절 저항성과 변연 적합도를 평가하고자 하였다. 연구 재료 및 방법: CAD/CAM system (Everest, KAVO Dental GmbH, Biberach, Germany)을 이용하여, 다양한 두께를 가진 지르코니아 코핑을 디자인하고 제작하였다. 80개의 코핑을 디자인에 따라 20개씩 4개의 그룹으로 분류하였으며, 각 그룹은 다시 시멘트 종류에 따라 시편을 10개씩 나누어 2개의 소그룹으로 분류하였다. Group I은 전체적으로 균일하게 0.3 mm로, group II는 협면과 협측 교합면은 0.3 mm, 설면과 설측 교합면을 0.6 mm, group III은전체0.6 mm 균일하게, Group IV는 협면과 협측 교합면은 0.6 mm 설면과 설측 교합면을 1.0 mm로 디자인 하였다. Putty index를 이용해 같은 크기와 형태의 지르코니아 도재관을 축성 후, 완성하였다. 미세 경도측정기의 현미경 (Matsuzawa, MXT-70, Japan)으로 도재관의 변연 적합도를 측정하였고, 만능시험기 (Z020, Zwick, Germany)를 이용하여 cross-head speed를 1 mm/min로 도재관이 파절될 때까지 수직 하중을 가해 파절 저항성을 측정하였다. One-way ANOVA와 two-way ANOVA 를 이용해 그 결과를 비교 분석 하였으며, 사후 검정으로 Duncan's multiple range test ($\alpha$=0.05)를 사용하였다. 결과:1. 코핑 디자인에 따른 변연적합성은 유의한 차이가 있었다 (P<.05). 2. 임시합착제 (Cavitec$^{(R)}$)로 합착한 군에서 코핑 디자인에 따른 지르코니아 도재관의 파절강도는 유의한 차이가 있었다 (P<.05). 3. 영구접착제 (Panavia-$F^{(R)}$)로 접착한 군에서 코핑 디자인에 따른 지르코니아 도재관의 파절강도는 통계학적인 유의차가 없었다 (P>.05). 4. 시멘트의 종류에 따른 동일한 디자인사이에서의 파절강도는 group I과 group II에서 Panavia-F 접착군이 Cavitec$^{(R)}$ 접착군보다 통계학적으로 유의성 있게 높았다 (P<.05). 5. 도재관의 파절 양상은 지르코니아 코핑의 디자인에 따른 차이는 없었으며, 시멘트의 종류에 따라 Cavitec$^{(R)}$ 접착군에서는 시편이 완전 분리되는 전부 파절, Panavia-$F^{(R)}$ 접착군에서는 전장 도재층에서만 파절되는 부분파절이 주로 나타났다. 결론: 제한된 결과이기는 하나 심미성을 위해 가시면을 얇게 하고 강도를 위해 비가시면의 지르코니아 코핑을 두껍게 하는, 즉 기능에 따라 두께를 달리 하는 세라믹 하부구조 디자인이 임상에서 선택적으로 활용될 수 있을 것으로 사료되었다.