Siadat Hakimeh, Alikhasi Marzieh, Mirfazaelian Ali, Zade Mohsen Mohammad Ali
Department of Prosthodontics and Implant, Department of Dental Research, School of Dentistry, Medical Sciences/University of Tehran, Tehran, Iran.
Implant Dent. 2008 Sep;17(3):299-308. doi: 10.1097/ID.0b013e318183621d.
Despite careful attention to waxing, investing, and casting, marginal discrepancies are inevitable. Vertical and horizontal discrepancies can result in crestal bone resorption, peri-implantitis, and loss of osseointegration.
The aim of this study was to evaluate marginal gap and overhang in 3 casting techniques for implant framework fabrication.
A total of 24 frameworks, 8 each with the Burn-out Cap (ITI; Straumann) (group BC), with Impression Cap (ITI; Straumann) (group IC), and with conventional wax-up technique (group WX) were fabricated. All specimens were waxed on the analog abutments and cast with Type IV gold alloy. All castings were fixed on the analog abutments with cyanoacrylate and embedded in acrylic resin. Specimens were sectioned and prepared for scanning electron microscope evaluation. Frameworks were analyzed for vertical and horizontal discrepancies with x200 magnification (scanning electron microscopy). Data were analyzed statistically by multivariate analysis and the post hoc tests (alpha = 0.05).
The vertical discrepancy measurements for the 3 groups showed mean values of 53.74 +/- 11.0 mum, 63.6 +/- 13.2 mum, and 50.1 +/- 17.3 mum, respectively. The interfacial gap differences were not statistically significant in all groups (P > 0.05). Waxing the frameworks with impression caps significantly increased the horizontal discrepancy at the interfaces (P < 0.001).
Within the limitations of this experiment, it was demonstrated that the vertical discrepancy of the frameworks made with the 3 techniques were comparable in lack of accuracy with each other. Although conventional waxing produced the least horizontal discrepancy, the difference with burn-out cap group was not statistically different.
尽管在熔模制作、包埋和铸造过程中十分小心，但边缘差异仍不可避免。垂直和水平差异可导致牙槽嵴骨吸收、种植体周围炎以及骨结合丧失。
本研究旨在评估三种用于制作种植体支架的铸造技术的边缘间隙和悬突情况。
共制作24个支架，其中8个采用 burnout帽（ITI；士卓曼）（BC组），8个采用印模帽（ITI；士卓曼）（IC组），8个采用传统熔模技术（WX组）。所有标本均在模拟基台上制作熔模，并用IV型金合金铸造。所有铸件用氰基丙烯酸酯固定在模拟基台上，并嵌入丙烯酸树脂中。将标本切片并准备用于扫描电子显微镜评估。在200倍放大率下（扫描电子显微镜）分析支架的垂直和水平差异。数据通过多变量分析和事后检验进行统计学分析（α = 0.05）。
三组的垂直差异测量平均值分别为53.74±11.0μm、63.6±13.2μm和50.1±17.3μm。所有组的界面间隙差异无统计学意义（P>0.05）。用印模帽制作支架显著增加了界面处的水平差异（P<0.001）。
在本实验的局限性内，结果表明用这三种技术制作的支架在垂直差异方面缺乏准确性，彼此相当。虽然传统熔模制作产生的水平差异最小，但与burnout帽组的差异无统计学意义。
