Department of Dental Materials and Prosthesis, School of Dentistry of Ribeirão Preto, University of São Paulo, São Paulo, Brazil.
Nuclear Instrumentation Laboratory, COPPE, Federal University of Rio de Janeiro, Rio de Janeiro, Brazil.
J Esthet Restor Dent. 2020 Jun;32(4):403-409. doi: 10.1111/jerd.12574. Epub 2020 Feb 24.
Evaluate the effects of the scanning techniques and the crystallization in the internal and marginal adaptation of milled lithium disilicate crowns by two techniques computer microtomography analysis.
Sixteen polyurethane teeth prepared for a complete crown were divided into two groups according to the scanner method (n = 8): indirect (IND), dental stone models were scanned with laser-surface scanner, and direct (DIR), digital typodont creates with an intraoral scanner. Internal and marginal gap were evaluated by micro-computed tomography (microCT). The replica technique (RT) was applied for analysis of total volume (TV) and marginal volume (MV) gap in microCT. The data showed normal distribution (Shapiro-Wilk test). One-way ANOVA (scanner techniques) with repeated measures (crystallization) was performed. Multiple comparisons were performed with Bonferroni adjustment (α = .05).
The axial gap showed a significant difference between the times (P = .017) for lower values after crystallization. The vertical marginal gap presented a significant difference in times for higher value after crystallization (P = .001). The marginal horizontal gap IND was greater than DIR after crystallization (P = .001) and IND before lower than after crystallization. For TV was not significant difference and MV in DIR was reduction (P = .002) after crystallization.
Crystallization changes the relationship between the crown and tooth, reducing internal gap and preventing the adequate fit in indirect and direct scanning.
The measure gap under technological methodology is useful for adjust clinical parameters prosthetic in the CAD/CAM and the applicability of the new possibilities of analysis.
通过两种计算机微断层扫描分析技术评估铣削二硅酸锂瓷冠内部和边缘适应性的扫描技术和结晶效果。
根据扫描仪方法（n = 8）将 16 个准备用于全冠的聚氨酯牙分为两组：间接（IND），用激光表面扫描仪扫描牙石模型，直接（DIR），用口内扫描仪在数字模型牙上创建。通过微计算机断层扫描（microCT）评估内部和边缘间隙。复制技术（RT）用于分析 microCT 中的总容积（TV）和边缘容积（MV）间隙。数据显示正态分布（Shapiro-Wilk 检验）。采用单因素方差分析（扫描仪技术）和重复测量（结晶）。采用 Bonferroni 调整（α =.05）进行多重比较。
轴向间隙在结晶后较低值之间存在显著差异（P =.017）。结晶后，垂直边缘间隙的较高值存在显著差异（P =.001）。结晶后，IND 的边缘水平间隙大于 DIR（P =.001），结晶前的 IND 小于结晶后。对于 TV 没有显著差异，结晶后 DIR 的 MV 减少（P =.002）。
结晶改变了冠与牙之间的关系，减少了内部间隙，并防止了间接和直接扫描的适当贴合。
在 CAD/CAM 中，技术方法下的间隙测量对调整临床参数和分析新的可能性具有应用价值。
