过熔铸技术作为一体式多单位固定局部义齿支架的替代方法。

de Oliveira Correa Giovani, Henriques Guilherme Elias Pessanha, Mesquita Marcelo Ferraz, Sobrinho Lourenco Correr

Department of Restorative Dentistry, Piracicaba School of Dentistry, State University of Campinas, UNICAMP, Sao Paulo, Brazil.

J Prosthet Dent. 2006 Mar;95(3):243-8. doi: 10.1016/j.prosdent.2006.01.001.

STATEMENT OF PROBLEM

Soldering has been suggested to achieve acceptable fit of multi-unit fixed partial denture (FPD) frameworks of 3 or more elements. However, distortion of the entire framework may occur.

PURPOSE

The purpose of this study was to evaluate marginal fit in 1-piece-casting FPD frameworks comparing 2 casting techniques: the conventional technique (CT) and the over-refractory technique (ORT). The techniques were evaluated on castings made from commercially pure titanium (CP Ti; Tritan), titanium-aluminum-vanadium (Ti-6Al-4V), and nickel-chromium (Ni-Cr; VeraBond II) alloys.

MATERIAL AND METHODS

A metal master cast including 3 preparations was created to simulate a 5-unit FPD. The metal cast was duplicated in vinyl polysiloxane for fabrication of 60 working casts. For the CT, 0.7-mm-thick patterns were waxed on the casts using an electrical wax-dipping unit. Patterns were removed from the preparations before investing. For the ORT, the silicone impressions were poured with an investment material (Rematitan for CP Ti and Ti-6Al-4V, and Talladium for Ni-Cr). The patterns were waxed on the refractory casts, and the assembly was invested. Both CT and ORT (n = 10), CP Ti, and Ti-6Al-4V frameworks were cast using an arc-melting titanium vacuum-casting machine. The Ni-Cr frameworks were cast using an automated centrifugal-casting machine. The mean marginal discrepancies of the frameworks were measured at the mesial, distal, buccal, and lingual interfaces. Marginal gap measurements were recorded 3 times for each surface to the nearest 0.5 microm using a traveling microscope (x50). The data were analyzed with 2-way analysis of variance, followed by the Tukey HSD test (alpha=.05).

RESULTS

Marginal discrepancies for the ORT specimens (82.8 +/- 1.7 microm for CP Ti; 64.4 +/- 1.3 microm for Ti-6Al-4V; and 77.2 +/- 1.5 microm for Ni-Cr) were significantly lower than those obtained for the CT specimens (106.3 +/- 2.6 microm for CP Ti; 75.7 +/- 0.8 microm for Ti-6Al-4V; 101.9 +/- 1.7 microm for Ni-Cr) (P < .05). For both techniques, marginal discrepancies were significantly different among the alloys evaluated, presenting the following order from greatest to least marginal discrepancy: CP Ti, Ni-Cr alloy, and Ti-6Al-4V (P < .05).

CONCLUSION

The ORT for multi-unit FPD frameworks demonstrated significantly lower marginal discrepancies than the CT.

问题陈述

有人提出使用焊接来使包含3个或更多部件的多单位固定局部义齿（FPD）框架达到可接受的贴合度。然而，整个框架可能会发生变形。

目的

本研究的目的是评估采用两种铸造技术的一体式铸造FPD框架的边缘贴合度，这两种技术分别是传统技术（CT）和过耐火技术（ORT）。在由商业纯钛（CP Ti；Tritan）、钛铝钒（Ti - 6Al - 4V）和镍铬（Ni - Cr；VeraBond II）合金制成的铸件上对这些技术进行评估。

材料与方法

制作一个包含3个预备体的金属主模型，以模拟一个5单位的FPD。用乙烯基聚硅氧烷复制该金属模型，以制作60个工作模型。对于CT，使用电动浸蜡装置在模型上蜡制0.7毫米厚的铸型。在包埋前将铸型从预备体上取下。对于ORT，用包埋材料（CP Ti和Ti - 6Al - 4V用Rematitan，Ni - Cr用Talladium）灌注硅橡胶印模。在耐火模型上蜡制铸型，然后将组件进行包埋。CT和ORT（n = 10）的CP Ti和Ti - 6Al - 4V框架均使用电弧熔化钛真空铸造机铸造。Ni - Cr框架使用自动离心铸造机铸造。在近中、远中、颊侧和舌侧界面测量框架的平均边缘差异。使用移动显微镜（x50）对每个表面的边缘间隙测量记录3次，精确到最接近的0.5微米。数据采用双向方差分析，随后进行Tukey HSD检验（α = 0.05）。

结果

ORT标本的边缘差异（CP Ti为82.8±1.7微米；Ti - 6Al - 4V为64.4±1.3微米；Ni - Cr为77.2±1.5微米）显著低于CT标本（CP Ti为106.3±2.6微米；Ti - 6Al - 4V为75.7±0.8微米；Ni - Cr为101.9±1.7微米）（P < .05）。对于这两种技术，在评估的合金中边缘差异显著不同，从最大到最小边缘差异的顺序如下：CP Ti、Ni - Cr合金和Ti - 6Al - 4V（P < .05）。