Zhang Zutai, Tamaki Yukimichi, Hotta Yasuhiro, Miyazaki Takashi
Department of Oral Biomaterials & Technology, Showa University School of Dentistry, 1-5-8 Hatanodai, Tokyo, Japan.
Dent Mater. 2006 Jul;22(7):681-7. doi: 10.1016/j.dental.2005.06.008. Epub 2005 Dec 15.
For titanium casting, most commercial investments for titanium recommend casting at a low mold temperature to reduce oxidation. However, the thermal expansion values of the molds at low casting temperatures may be insufficient. The purpose of the current study was to investigate the possibility of obtaining accurate titanium crown casts using wax pattern fabricated by a CAD/CAM system with a non-expanded mold.
Three types of experimental magnesia-based investments (A, B and C) were made and their properties were evaluated for dental use. Two kinds of wax patterns for full-coverage coping crowns (S-0: cement space of 0 microm; S-20: cement space of 20 microm) were fabricated using a commercial CAD/CAM system. A traditional method (TM) using inlay wax was performed for comparison. The investment for titanium casting was decided from the fundamental data of experimental investments. Titanium crowns were replaced on the stone die and the thickness of the cement layer was evaluated.
There were no significant differences for the setting time and setting expansion among the experimental investments, but the aluminous cement content played a role in hardening and contracting the mold. The fit of the titanium crowns differed significantly between the TM and the CAD/CAM system. The ranges of thickness obtained from the TM, S-0 and S-20 were 20.78-357.88 microm, 25.12-107.46 microm and 17.84-58.92 microm, respectively.
High quality titanium crown casting was obtained using a combination of wax patterns fabricated by a CAD/CAM system and a non-expanded MgO-based investment.
对于钛铸造，大多数用于钛的商业包埋材料建议在低铸模温度下铸造以减少氧化。然而，在低铸造温度下铸模的热膨胀值可能不足。本研究的目的是探讨使用由CAD/CAM系统制作的蜡型和非膨胀铸模获得精确钛冠铸件的可能性。
制作了三种实验性氧化镁基包埋材料（A、B和C），并对其牙科应用性能进行了评估。使用商用CAD/CAM系统制作了两种全冠修复体蜡型（S-0：粘结剂间隙为0微米；S-20：粘结剂间隙为20微米）。采用传统的嵌体蜡方法（TM）进行比较。根据实验性包埋材料的基础数据确定钛铸造用包埋材料。将钛冠放置在石膏模型上，并评估粘结剂层的厚度。
实验性包埋材料在凝固时间和凝固膨胀方面无显著差异，但铝酸盐水泥含量对铸模的硬化和收缩有影响。TM和CAD/CAM系统制作的钛冠适合性有显著差异。TM、S-0和S-20获得的厚度范围分别为20.78 - 357.88微米、25.12 - 107.46微米和17.84 - 58.92微米。
通过结合使用CAD/CAM系统制作的蜡型和非膨胀氧化镁基包埋材料，获得了高质量的钛冠铸件。
