• The Journal of Advanced Prosthodontics
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• 제7권4호
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• pp.271-277
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• 2015

PURPOSE. This study was to evaluate the marginal fit of two CAD-CAM anatomic contour zirconia crown systems compared to lithium disilicate glass-ceramic crowns. MATERIALS AND METHODS. Shoulder and deep chamfer margin were formed on each acrylic resin tooth model of a maxillary first premolar. Two CAD-CAM systems (Prettau$^{(R)}$Zirconia and ZENOSTAR$^{(R)}$ZR translucent) and lithium disilicate glass ceramic (IPS e.max$^{(R)}$press) crowns were made (n=16). Each crown was bonded to stone dies with resin cement (Rely X Unicem). Marginal gap and absolute marginal discrepancy of crowns were measured using a light microscope equipped with a digital camera (Leica DFC295) magnified by a factor of 100. Two-way analysis of variance (ANOVA) and post-hoc Tukey's HSD test were conducted to analyze the significance of crown marginal fit regarding the finish line configuration and the fabrication system. RESULTS. The mean marginal gap of lithium disilicate glass ceramic crowns (IPS e.max$^{(R)}$press) was significantly lower than that of the CAD-CAM anatomic contour zirconia crown system (Prettau$^{(R)}$Zirconia) (P<.05). Both fabrication systems and finish line configurations significantly influenced the absolute marginal discrepancy (P<.05). CONCLUSION. The lithium disilicate glass ceramic crown (IPS e.max$^{(R)}$press) had significantly smaller marginal gap than the CAD-CAM anatomic contour zirconia crown system (Prettau$^{(R)}$Zirconia). In terms of absolute marginal discrepancy, the CAD-CAM anatomic contour zirconia crown system (ZENOSTAR$^{(R)}$ZR translucent) had under-extended margin, whereas the CAD-CAM anatomic contour zirconia crown system (Prettau$^{(R)}$Zirconia) and lithium disilicate glass ceramic crowns (IPS e.max$^{(R)}$press) had overextended margins.

• The Journal of Advanced Prosthodontics
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• 제8권1호
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• pp.43-52
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• 2016

PURPOSE. This study was conducted to evaluate the effects of full-coverage all-ceramic zirconia, lithium disilicate glass-ceramic, leucite glass-ceramic, or stainless steel crowns on antagonistic primary tooth wear. MATERIALS AND METHODS. There were four study groups: the stainless steel (Steel) group, the leucite glass-ceramic (Leucite) group, the lithium disilicate glass-ceramic (Lithium) group, and the monolithic zirconia (Zirconia) group. Ten flat crown specimens were prepared per group; opposing teeth were prepared using primary canines. A wear test was conducted over 100,000 chewing cycles using a dual-axis chewing simulator and a 50 N masticating force, and wear losses of antagonistic teeth and restorative materials were calculated using a three-dimensional profiling system and an electronic scale, respectively. Statistical significance was determined using One-way ANOVA and Tukey's test (P<.05). RESULTS. The Leucite group ($2.670{\pm}1.471mm^3$) showed the greatest amount of antagonist tooth wear, followed by in decreasing order by the Lithium ($2.042{\pm}0.696mm^3$), Zirconia ($1.426{\pm}0.477mm^3$), and Steel groups ($0.397{\pm}0.192mm^3$). Mean volume losses in the Leucite and Lithium groups were significantly greater than in the Steel group (P<.05). No significant difference was observed between mean volume losses in the Zirconia and Steel groups (P>.05). CONCLUSION. Leucite glass-ceramic and lithium disilicate glass-ceramic cause more primary tooth wear than stainless steel or zirconia.

• The Journal of Advanced Prosthodontics
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• 제10권4호
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• pp.300-307
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• 2018

PURPOSE. To investigate the fatigue and fracture resistance of computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic molar crowns on dental implants and human teeth. MATERIALS AND METHODS. Molar crowns (n=48; n=8/group) were fabricated of a lithium-disilicate-strengthened lithium aluminosilicate glass ceramic (N). Surfaces were polished (P) or glazed (G). Crowns were tested on human teeth (T) and implant-abutment analogues (I) simulating a chairside (C, crown bonded to abutment) or labside (L, screw channel) procedure for implant groups. Polished/glazed lithium disilicate (E) crowns (n=16) served as reference. Combined thermal cycling and mechanical loading (TC: $3000{\times}5^{\circ}C/3000{\times}55^{\circ}C$; ML: $1.2{\time}10^6$ cycles, 50 N) with antagonistic human molars (groups T) and steatite spheres (groups I) was performed under a chewing simulator. TCML crowns were then analyzed for failures (optical microscopy, SEM) and fracture force was determined. Data were statistically analyzed (Kolmogorow-Smirnov, one-way-ANOVA, post-hoc Bonferroni, ${\alpha}=.05$). RESULTS. All crowns survived TCML and showed small traces of wear. In human teeth groups, fracture forces of N crowns varied between $1214{\pm}293N$ (NPT) and $1324{\pm}498N$ (NGT), differing significantly ($P{\leq}.003$) from the polished reference EPT ($2044{\pm}302N$). Fracture forces in implant groups varied between $934{\pm}154N$ (NGI_L) and $1782{\pm}153N$ (NPI_C), providing higher values for the respective chairside crowns. Differences between polishing and glazing were not significant ($P{\geq}.066$) between crowns of identical materials and abutment support. CONCLUSION. Fracture resistance was influenced by the ceramic material, and partly by the tooth or implant situation and the clinical procedure (chairside/labside). Type of surface finish (polishing/glazing) had no significant influence. Clinical survival of the new glass ceramic may be comparable to lithium disilicate.

• 대한심미치과학회지
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• 제23권2호
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• pp.86-94
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• 2014

In recent years, perhaps the biggest driver in new material development is the desire to improve crown and bridge esthetics compared to the traditional PFM or all-metal restorations. As such, zirconia, leucite-containing glass ceramic and lithium disilicate glass ceramic have become prominent in the dental practice. Each material type performs differently regarding strength, toughness, ease of machining and the final preparation of the material prior to placement. For example, glass ceramic are typically weaker materials which limits its use to single-unit restorations. On the other hand, zirconia has a high fracture toughness which enables multi-unit restorations. This material requires a long sintering procedure which excludes its use for fast chair side production. Developed hybrid material of CAD/CAM is contained nano ceramic elements. This new material, called a Resin Nano Ceramic is unique in durability and function. The material is not a resin or composite. It is also not a pure ceramic. The material is a mixture of both and consists of ceramic. Like a composite, the material is not brittle and is fracture resistant. Like a glass ceramic, the material has excellent polish retention for lasting esthetics. The material is easily machined chair side or in a dental lab, polishes quickly to an esthetic finish and if necessary, can be useful restoratives.

• The Journal of Advanced Prosthodontics
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• 제15권1호
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• pp.44-54
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• 2023

PURPOSE. To assess the clinical performance of monolithic CAD-CAM lithium disilicate glass-ceramic (LDGC) crowns and metal-ceramic (MC) crowns provided by predoctoral students. This study also assessed the effects of patient and provider-related factors on their clinical performance as well as patient preference for these types of crowns. MATERIALS AND METHODS. Twenty-five patients who received 50 crowns (25 LDGC CAD-CAM and 25 MC) provided by predoctoral students were retrospectively examined. LDGC CAD-CAM crowns were milled in-house using the CEREC Bluecam system and cemented with either RelyX Unicem or Calibra Esthetic resin cements. MC crowns were cemented with RelyX Unicem cement. Clinical assessment of the crowns and the supporting periodontal structures were performed following the modified California Dental Association (CDA) criteria. Patients' preference was recorded using a visual analog scale (VAS). The results were statistically analyzed using log-rank test, Pearson Chi-squared test and Kaplan-Meier survival analysis. RESULTS. Twelve complications were observed in the MC crown group (9-esthetic, 2-technical and 1-biological). In comparison, 2 complications in the LDGC CAD-CAM crown group were observed (1-technical and 1-esthetic). The 6-year cumulative survival rates for MC crowns and LDGC CAD-CAM were 90.8% and 96%, respectively, whereas the success rates were 83.4% and 96%, respectively. Overall, patients preferred the esthetic outcomes of LDGC CAD-CAM crowns over MC crowns. CONCLUSION. The high survival and success rates, low number of complications, and the high level of patients' acceptance of monolithic LDGC CAD-CAM crowns lend them well as predictable and viable alternatives to the "gold standard" MC crowns.

• 대한치과의사협회지
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• 제56권3호
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• pp.159-166
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• 2018

지르코니아 강화 리튬 실리케이트 세라믹 재료는, 현재 널리 사용되고 있는 e.max(리튬디실리케이트 세라믹) 재료에 비하여 더 개선된 강도를 지니고 있다. 단일 크라운의 수복에 사용될 수 있으며, 1.5mm 의 두께를 확보하는 것이 예지성 있는 치료를 위해 매우 중요하다. Celtra Duo의 경우 열처리를 수행하는 것이 강도나 마모 저항성 측면에서 도움이 될 것이다. 접착을 위해서는 불산의 처리가 도움이 되며, 너무 짧은 시간의 불산은 접착 강도의 개선에 도움을 주지 못할 수 있으므로 충분한 시간의 불산 처리가 필요하다. 지르코니아 강화 리튬 실리케이트 세라믹 재료는 실험실 연구가 지속적으로 수행되고 출판되고 있지만, 아직 신뢰할만한 임상연구는 매우 부족한 실정이다. 추가적인 임상연구를 통해 과학적인 근거를 마련하는 것이 매우 중요한 부분이 될 것이다.

• 대한치과의사협회지
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• 제58권7호
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• pp.435-442
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• 2020

치과의사가 수복재료를 선택하고 환자에게 추천할 때는 수복할 치아 위치, 결손 정도, 환자의 심미적 요구도, 저작력, 나이, 경제적 여건 등 여러 가지의 요인을 고려한다. 그렇지만, 수복재료를 선택할 때의 일차적인 기준은 구강 내에서 기능 시 작용하는 교합력을 최우선으로 고려해야 한다. 미국 국립보건원(NIH) 지원으로 조사된 연구 결과에 의하면, 전치부 수복재료로서는 리튬 디실리케이트계 글라스-세라믹이 54%, layered zirconia가 17%, 루사이트 강화 글라스-세라믹이 13% 순을 보여, 전치부 수복재료로서 리튬 디실리케이트계 글라스-세라믹이 가장 많이 사용었다. 또한 구치부 수복재료로서는 단일구조 지르코니아가 32%, 금속-세라믹이 31%, 리튬 디실리케이트계 글라스-세라믹이 21% 순을 나타냈다. 세라믹 수복 재료의 특성을 살펴보면, 단일구조 지르코니아는 강도는 높지만 명도가 높고 저온열화로 인한 강도 저하가 일어날 수 있다. layered zirconia는 심미성은 우수하지만 강도가 낮은 비니어 세라믹의 칩핑과 박리가 문제가 되고 있다. 리튬 디실리케이트계 글라스-세라믹은 심미성은 우수하지만 지르코니아에 비해 강도가 낮으므로 구치부에 적용 시 파절이 일어날 위험성이 있다. 루사이트계 글라스-세라믹은 심미성은 우수하지만 기본적으로 강도가 낮기 때문에 전치부에 한정하여 적용한다. 세라믹 크라운이 구치부 교합력에 저항하기 위해서는 350 MPa 이상의 굴곡강도를 가져야 한다. 리튬 디실리케이트계 글라스-세라믹은 광투과성이 양호한 심미성이 있는 재료이므로 비니어 없이 전치부에 적용할 수 있고, 굴곡강도가 400 MPa 이상이므로 구치부 교합력에 저항할 수 있고, HF에 의한 산부식과 실란(silane) 처리가 가능하므로 레진과 강한 결합력을 얻을 수 있고, 또한 포세린에 비해 대합치의 마모가 적다. 이러한 점들을 고려하면 리튬 디실리케이트계 글라스-세라믹 재료는 전구치부의 단일치 수복에 적합한 성질을 갖고 있음을 알수 있다. 그렇지만 그의 임상 응용이 더욱 증가하기 위해서는 이들 재료에 대한 보다 많은 연구와 이해가 필요하리라고 생각된다.