Aditya Priyam, Madhav V N V, Bhide S V, Aditya Amita
Sinhgad Dental College & Hospital, Pune, India.
J Indian Prosthodont Soc. 2012 Sep;12(3):143-8. doi: 10.1007/s13191-012-0119-8. Epub 2012 May 11.
An increase in the marginal discrepancy is seen after cementation with a luting agent and provision of cement space with a die-spacer is the most preferred method to avoid it. Recommended thickness of die-spacer is 25-40 μm. Smaller die-spacer thickness was consistently found at the axio-occlusal line angles as compared to the other surfaces which has been postulated to that the spacer paint tends to flow away from the sharp line angles and cusp tips as a result of increased surface tension. The absence of adequate relief spaces in these areas impedes the flow of cement beyond the occlusal portion of the casting, which would result in incomplete seating because of hydraulic pressure. Fifty stone dies were duplicated from a steel die and were divided into five groups of sample size 10, where the die-spacer was selectively placed. Measurements were taken at four points, 90° apart from each other with the help of optical microscope. Later all the castings were cemented using Glass Inomer cement as a luting agent, under a 10 kg static load and measurements were recorded. Statistical analysis showed samples with no spacer had the maximum pre and post cementation gap while the least discrepancy was seen in group with additional layer of die-spacer painted over the axio-occlusal line angle. The results were highly significant which clearly indicated the superiority of this group over others. Within limitations of the study, it can be said that application of additional layer of die-spacer at the axio-occlusal line angle will help in decreasing the post cementation marginal discrepancy in full cast metal crowns.
用粘结剂粘结后，边缘差异会增加，而用代型间隙剂提供粘结剂空间是避免这种情况的最优选方法。推荐的代型间隙剂厚度为25 - 40μm。与其他表面相比，在轴 - 牙合线角处始终发现代型间隙剂厚度较小，据推测这是因为间隙剂涂料由于表面张力增加而倾向于从尖锐的线角和牙尖处流走。这些区域缺乏足够的缓冲空间会阻碍粘结剂流到铸件的牙合面部分之外，这会由于液压导致就位不完全。从一个钢代型复制了50个石膏代型，并将其分成五组，每组样本量为10，代型间隙剂被选择性地放置。借助光学显微镜在彼此相隔90°的四个点进行测量。之后，所有铸件在10kg静载下用玻璃离子水门汀作为粘结剂进行粘结，并记录测量结果。统计分析表明，没有间隙剂的样本在粘结前和粘结后的间隙最大，而在轴 - 牙合线角处涂有额外一层代型间隙剂的组中差异最小。结果具有高度显著性，清楚地表明了该组相对于其他组的优越性。在该研究的局限性范围内，可以说在轴 - 牙合线角处应用额外一层代型间隙剂将有助于减少全冠铸造修复体粘结后的边缘差异。
