摘要
目的 :比较激光焊接和整铸的多单位非贵金属烤瓷合金固定桥精度 ,探讨激光焊接是否能改进多单位固定桥精度 ,为临床应用提供依据。方法 :分别制作整铸和激光焊接 4单位CW PA烤瓷合金固定桥 ,分别就位于金属模具 ,观察就位情况、测试边缘间隙、外形尺寸即近远中桥长线距变化。结果 :①整铸桥由于铸造变形而不能完全就位 ;②焊接桥的边缘间隙是 74μm ,符合临床适合性标准 ,近远中桥长线距比整铸桥明显接近于金属模具 (P <0 0 5 )。结论 :激光焊接能提高多单位固定桥精度 ,激光焊接是一种很有希望的焊接方法。
Objective: To assess whether laser welded bridge be fit for the clinical usage, this study compares the accuracy of laser welded multi unit bridges with one piece casted bridges.Methods: A precise stainless mold which was 20 mm length composed of two abutments (one premolar and one molar) and one pontic (two missed teeth) was made. 5 wax patterns of four unit FPD frameworks in one piece casting based on the mold were made. After that, they were invested with inner (Bellavest) and outer investment (phosphate and gypsum). Then they were casted with CW PA (Ni Cr Nb) alloys. The other 5 wax patterns of four unit FPD frameworks were invested and casted in two halves. Each couple of frameworks were ultra sonic washed in distilled water and inserted to the standard metal FPD mold accurately. Laser welding machine (DL 2002) was used to weld each couple of frameworks at 305V, 20ms. Both groups of specimens were tested on their mesiodistal span dimensions and the diameters of alloy crowns. Then they were inserted to their original stainless mold, where the marginal fitness was examined. Results: ①The one piece casted fixed multi unit bridge couldn′t be inserted to abutments completely because of distortion, while the laser welded bridge could be inserted to abutments completely. The average marginal opening of laser welded bridges was about 74 μm and conformed to clinical standard of fitness. ②Mesiodistal dimensions of one piece casted bridges at the inner, bottom and top margins were 19 5600±0 3877 mm, 41 2206±0 4140 mm, 41 0598±0 3379 mm respectively; while those of laser welded bridges were 20 2950±0 1191 mm, 41 9625±0 0788 mm, 42 0584±0 1089 mm, which were obviously close to metal abutments (P<0 05). ③The alloy crowns′ diameters of one piece casted bridges were examined as following, the premolar: ΦIJ=9 8386±0 0567 mm, ΦLK=9 9596±0 0548 mm, the molar: ΦEF=11 7948±0 0252 mm, ΦHG=11 9412±0 0763 mm; The alloy crowns′ diameters of laser bridges were as following, the premolar: ΦIJ=9 7927±0 0636 mm, ΦLK=9 9438±0 0726 mm, the molar: ΦEF=11 8287±0 0863 mm, ΦHG=11 8893±0 1049 mm. There was no significant difference between the two groups (P<0 05). Conclusion: Laser welding greatly improve the fitness of multi unit fixed bridges.
出处
《华西口腔医学杂志》
CAS
CSCD
北大核心
2000年第2期112-115,共4页
West China Journal of Stomatology
