Department of Reconstructive Sciences, University of Connecticut Health Center, 263 Farmington Avenue, Farmington, CT 06030-1615, USA.
J Dent. 2010 Dec;38(12):995-1000. doi: 10.1016/j.jdent.2010.08.015. Epub 2010 Aug 27.
Internal three-dimensional (3D) "fit" of prostheses to prepared teeth is likely more important clinically than "fit" judged only at the level of the margin (i.e. marginal "opening"). This work evaluates two techniques for quantitatively defining 3D "fit", both using pre-cementation space impressions: X-ray microcomputed tomography (micro-CT) and quantitative optical analysis. Both techniques are of interest for comparison of CAD/CAM system capabilities and for documenting "fit" as part of clinical studies.
Pre-cementation space impressions were taken of a single zirconia coping on its die using a low viscosity poly(vinyl siloxane) impression material. Calibration specimens of this material were fabricated between the measuring platens of a micrometre. Both calibration curves and pre-cementation space impression data sets were obtained by examination using micro-CT and quantitative optical analysis. Regression analysis was used to compare calibration curves with calibration sets.
Micro-CT calibration data showed tighter 95% confidence intervals and was able to measure over a wider thickness range than for the optical technique. Regions of interest (e.g., lingual, cervical) were more easily analysed with optical image analysis and this technique was more suitable for extremely thin impression walls (<10-15μm). Specimen preparation is easier for micro-CT and segmentation parameters appeared to capture dimensions accurately.
Both micro-CT and the optical method can be used to quantify the thickness of pre-cementation space impressions. Each has advantages and limitations but either technique has the potential for use as part of clinical studies or CAD/CAM protocol optimization.
与仅在边缘（即边际“开口”）水平评估的“拟合”相比，假体对预备牙的内部三维（3D）“拟合”在临床上可能更为重要。本研究评估了两种定量定义 3D“拟合”的技术，均使用预粘固间隙印模：X 射线微计算机断层扫描（micro-CT）和定量光学分析。这两种技术都可以用于比较 CAD/CAM 系统的能力，并记录“拟合”作为临床研究的一部分。
使用低粘度聚（乙烯基硅氧烷）印模材料对其模具上的单个氧化锆修复体进行预粘固间隙印模。该材料的校准样本在千分尺的测量台之间制造。微 CT 和定量光学分析的检查均可获得校准曲线和预粘固间隙印模数据集。回归分析用于比较校准曲线和校准集。
micro-CT 校准数据显示更紧密的 95%置信区间，并且能够测量比光学技术更宽的厚度范围。用光学生物分析更容易分析感兴趣区域（例如，舌侧，颈侧），并且该技术更适合极薄的印模壁（<10-15μm）。micro-CT 更易于进行样本制备，并且分割参数似乎可以准确捕获尺寸。
micro-CT 和光学方法均可用于量化预粘固间隙印模的厚度。每种方法都有其优点和局限性，但任何一种技术都有可能作为临床研究或 CAD/CAM 方案优化的一部分使用。
