Vaswani Priya L, Sanyal Pronob K, Gosavi Siddharth Y, Kore Abhijeet R
Postgraduate Student, Department of Prosthodontics and Crown and Bridge, School of Dental Sciences, Krishna Institute of Medical Sciences Deemed University , Satara, Maharashtra, India .
Professor and Head, Department of Prosthodontics and Crown and Bridge, School of Dental Sciences, Krishna Institute of Medical Sciences Deemed University , Satara, Maharashtra, India .
J Clin Diagn Res. 2017 Jan;11(1):ZC01-ZC05. doi: 10.7860/JCDR/2017/21370.9131. Epub 2017 Jan 1.
Limited published information is available about the influence of preparatory designs and die materials on marginal accuracy of porcelain fused to metal copings using recently developed die materials.
To detect the influence of margin geometries and dimensional accuracy of contemporary die materials on vertical marginal gaps in Porcelain fused to metal coping using a Stereomicroscope (three dimensional analysis).
Two chrome cobalt alloy models of mandibular first molars prepared to have shoulder and deep chamfer finish lines were CAD-CAM milled. Elastomeric impressions of these models were made in a custom tray, poured in Type IV Gypsum(n=10) and Resin modified Gypsum(n=10) and also packed with Epoxy resin (n=10) as a die material to form a total of 60 samples, 30 in each group (shoulder and deep chamfer). Wax patterns were fabricated, invested and castings in ceramic alloy were obtained in traditional manner. These copings were later analyzed on CAD/CAM models using stereomicroscope.
Both the designs did not exhibit significant difference (p<0.05). Whereas, the three die materials exhibited significant difference (p<0.05) by Two way ANOVA test and Tukey's multiple Post Hoc test. Results from this study showed that vertical marginal gaps for copings fabricated on resin modified gypsum as a die material were within the clinically acceptable range.
Margin geometries both shoulder and deep chamfer have equal influence on vertical marginal gaps in metal ceramic restorations. Copings fabricated on Epoxy resin dies exhibited highest value of vertical marginal discrepancy, where as least value was determined for copings constructed on dies fabricated from resin modified gypsum.
关于预备设计和铸模材料对使用最新开发的铸模材料的烤瓷熔附金属冠边缘精度的影响，公开信息有限。
使用体视显微镜（三维分析）检测当代铸模材料的边缘几何形状和尺寸精度对烤瓷熔附金属冠垂直边缘间隙的影响。
制作两个下颌第一磨牙的铬钴合金模型，预备出肩台和深斜面边缘线，采用计算机辅助设计与制造（CAD-CAM）铣削。在定制托盘里对这些模型制取弹性印模，分别灌注IV型石膏（n = 10）、树脂改性石膏（n = 10），并使用环氧树脂（n = 10）作为铸模材料进行包埋，共形成60个样本，每组30个（肩台和深斜面）。制作蜡型，包埋并以传统方式获得陶瓷合金铸件。随后使用体视显微镜在CAD/CAM模型上对这些冠进行分析。
两种设计均未显示出显著差异（p < 0.05）。而通过双向方差分析和Tukey多重事后检验，三种铸模材料显示出显著差异（p < 0.05）。本研究结果表明，以树脂改性石膏作为铸模材料制作的冠的垂直边缘间隙在临床可接受范围内。
肩台和深斜面这两种边缘几何形状对金属陶瓷修复体的垂直边缘间隙有同等影响。在环氧树脂铸模上制作的冠显示出最高的垂直边缘差异值，而在树脂改性石膏制作的铸模上构建的冠确定为最低值。
