Loetzerich Jan Markus, Raith Stefan, Reich Sven
Graduate student, Department of Prosthodontics and Biomaterials, Centre of Implantology, University Hospital RWTH Aachen, Aachen, Germany.
Research Assistant, Department of Prosthodontics and Biomaterials, Centre of Implantology, University Hospital RWTH Aachen, Aachen, Germany.
J Prosthet Dent. 2025 Jul;134(1):160-166. doi: 10.1016/j.prosdent.2023.09.004. Epub 2023 Oct 17.
Internal fit is an important aspect of indirect restorations, but methods for the 3-dimensional (3D) measurement of absolute marginal and intaglio fit are sparse.
The purpose of this in vitro study was to evaluate an innovative 3D measurement method (AIXFit) based on intraoral scanning data for analyzing the fit of dental restorations.
For the evaluation of AIXFit, 12 monolithic zirconia crowns were fabricated on typodont preparations. The fit was measured digitally with the AIXFit system and compared with the results obtained from an established 2-dimensional (2D) sectional procedure. To compare the values of both methods at identical locations, a common reference system was developed, with each die fixed in a gypsum stand with reference points. Using an intraoral scanner (True Definition), each die with its reference points and the intaglio surface of the finished crown were digitalized as standard tessellation language files. The AIXFit software program, with a specially developed best-fit algorithm, was used to match the intaglio surface of the crown with the surface of the preparation. The virtual cement gap was calculated over the entire surface and returned values for x≥0 µm. A 2D comparison method involved adhesively fixing the crown to the die and sectioning it into 4 parts with a diamond band saw. The thickness of the cement gap was determined under a light microscope at ×100 magnification at 5 defined measuring points per quarter, so that a total of 240 measurements were available for comparison. A software program (Blender Foundation) was used to superimpose the data from the AIXFit system with the data from the 2D method and to compare the cement gaps at the same locations. The agreement between these methods was verified using paired t tests and determine correlation coefficients (α=.05).
The mean ±standard deviation difference between the AIXFit and 2D methods was 6.7 ±29 µm). Two 1-sided tests showed statistical equivalence between the methods of measurement when considering an interval between -20 and +20 µm. The correlation coefficients showed a positive association for both methods (r=.931).
The AIXFit software program appeared to be accurate for the digital measurement of internal fit when using the True Definition scanner. It enabled a cast-free workflow and allowed the analysis of the entire intaglio surface.
内部适合性是间接修复体的一个重要方面，但用于绝对边缘和内表面适合性的三维（3D）测量方法很少。
本体外研究的目的是评估一种基于口内扫描数据的创新3D测量方法（AIXFit），用于分析牙齿修复体的适合性。
为了评估AIXFit，在模型牙制备上制作了12个整体式氧化锆全冠。使用AIXFit系统对适合性进行数字测量，并与从既定的二维（2D）切片程序获得的结果进行比较。为了比较两种方法在相同位置的值，开发了一个通用参考系统，每个代型固定在带有参考点的石膏支架中。使用口内扫描仪（True Definition），将每个带有参考点的代型和完成全冠的内表面数字化为标准镶嵌语言文件。AIXFit软件程序采用专门开发的最佳拟合算法，用于使全冠的内表面与制备表面匹配。在整个表面上计算虚拟粘结剂间隙，并返回x≥0 µm的值。二维比较方法包括将全冠粘结固定在代型上，并用金刚石带锯将其切成4部分。在光学显微镜下，以100倍放大倍数在每四分之一的5个定义测量点处确定粘结剂间隙的厚度，因此总共可获得240次测量结果用于比较。使用一个软件程序（Blender Foundation）将AIXFit系统的数据与二维方法的数据叠加，并比较相同位置的粘结剂间隙。使用配对t检验验证这些方法之间的一致性，并确定相关系数（α = 0.05）。
AIXFit和二维方法之间的平均±标准差差异为6.7±29 µm。两个单侧检验表明，在考虑-20至+20 µm的区间时，测量方法之间具有统计学等效性。相关系数表明两种方法呈正相关（r = 0.931）。
当使用True Definition扫描仪时，AIXFit软件程序对于内部适合性的数字测量似乎是准确的。它实现了无模型工作流程，并允许对内表面进行整体分析。
