Duma Virgil-Florin, Sinescu Cosmin, Bradu Adrian, Podoleanu Adrian
3OM Optomechatronics Group, Faculty of Engineering, Aurel Vlaicu University of Arad, 77 Revolutiei Ave., 310130 Arad, Romania.
Doctoral School, Polytechnic University of Timisoara, 1 Mihai Viteazu Ave., 300222 Timisoara, Romania.
Materials (Basel). 2019 Mar 21;12(6):947. doi: 10.3390/ma12060947.
Dental prostheses are sintered in ovens that sometimes suffer from a loss of calibration. This can lead to variations of the sintering temperature outside the range recommended by the manufacturer. Stress and even fractures in dental ceramics may occur, and this leads to the necessity to rebuild the dental construct. The aim of this work is to monitor the quality of sintering processes using an established biomedical imaging technique-optical coherence tomography (OCT). Conventional current procedures imply the fabrication of supplemental samples that add to the expenses and are only evaluated visually. To our knowledge, we were the first to propose the use of OCT, a non-destructive method that brings objectivity for such assessments, focusing, in a previous study, on metal ceramic dental prostheses. Here, a different material, pressed ceramics, is considered, while we propose a quantitative assessment of the results-using reflectivity profiles of en-face (i.e., constant-depth) OCT images of sintered samples. The results for both the pressed ceramics and metal ceramics prostheses are discussed by obtaining the analytic functions of their reflectivity profiles. A multi-parametric analysis demonstrates the best parameter to characterize the loss of calibration of dental ovens. Rules-of-thumb are extracted; producing dental prostheses with defects can thus be avoided.
牙科修复体在烤炉中烧结，而这些烤炉有时会出现校准偏差。这可能导致烧结温度在制造商推荐范围之外发生变化。牙科陶瓷可能会出现应力甚至断裂，这就使得必须重新制作牙科修复体。这项工作的目的是使用一种成熟的生物医学成像技术——光学相干断层扫描（OCT）来监测烧结过程的质量。传统的现行程序需要制作补充样品，这增加了成本，而且仅通过目视进行评估。据我们所知，我们是第一个提出使用OCT的，这是一种无损方法，为这类评估带来了客观性，在之前的一项研究中，重点关注金属陶瓷牙科修复体。在这里，我们考虑了一种不同的材料——压制陶瓷，同时我们提出对结果进行定量评估——使用烧结样品的正面（即恒定深度）OCT图像的反射率剖面。通过获得压制陶瓷和金属陶瓷修复体反射率剖面的解析函数，对两者的结果进行了讨论。多参数分析确定了表征牙科烤炉校准偏差的最佳参数。由此得出了经验法则，从而可以避免生产出有缺陷的牙科修复体。
