Northeast S E, Van Noort R, Johnson A, Winstanley R B, White G E
Department of Restorative Dentistry, University of Sheffield, Western Bank.
Br Dent J. 1992 Mar 7;172(5):198-204. doi: 10.1038/sj.bdj.4807820.
The quality of construction of fixed bridge prostheses directly affects their long-term survival. The cost, alloy composition and marginal fit of bridges made by 30 commercial dental laboratories is assessed. Duplicate models of a three unit bridge preparation were sent to 30 different laboratories, as if required for a patient receiving treatment under the General Dental Service. Material was sent via general dental practitioners, requesting metal-ceramic bridges made from 45% Au alloy, precious metal or non-precious metal. Proximal contacts were overbuilt at 65% of sites and pontic tissue contacts were excessive in all but one bridge. Eight laboratories did not use alloys corresponding to the request made. The mean marginal gaps of non-precious metal bridges (145 microns) were significantly greater than those for 45% gold alloy (106 microns). Marginal fit was poor and a number of factors have been observed, with other postulated, which may have contributed to this problem.
固定桥修复体的制作质量直接影响其长期存留率。对30家商业牙科实验室制作的桥体的成本、合金成分及边缘适合性进行了评估。将一个三单位桥体预备的复制模型寄给30家不同的实验室，就如同为接受普通牙科治疗服务的患者所需那样。材料通过普通牙科医生寄出，要求制作由45%金合金、贵金属或非贵金属制成的金属烤瓷桥。在65%的部位邻面接触过度修复，除了一个桥体外，所有桥体的桥体组织接触均过多。8家实验室未使用与要求相符的合金。非贵金属桥体的平均边缘间隙（145微米）显著大于45%金合金桥体（106微米）。边缘适合性较差，已观察到一些因素，还有一些因素被推测可能导致了这一问题。
