Surface analysis and corrosion resistance of different stainless steel orthodontic brackets in artificial saliva

The purpose of this study was to investigate the variation in corrosion resistance of commercial stainless steel (SS) brackets with different brands and types for the same application, using the electrochemical technique. The linear polarization test was used to evaluate the corrosion resistance, in terms of polarization resistance (Rp), of as-received commercial SS brackets in acidic artificial saliva. A two-way analysis of variance was used to analyze the Rp with the factors of brand and type. A scanning electron microscope and an atomic force microscope were used to analyze the surface morphology and roughness, respectively. The X-ray photoelectron spectroscopy was used to identify the chemical composition of the passive film on SS brackets. Results showed that different brands of SS brackets had a statistically significant difference in Rp (P < .0001), whereas there was no statistical difference between the bracket types ("Roth" and standard) (P = .27). Different surface topography, including surface roughness and defect, was present among the tested SS brackets. The same passive film structure, containing Cr2O3/Fe2O3 with small amounts of NiO, was observed on all SS brackets. The surface topography of the commercial SS brackets with identical surface passive film structure did not correspond with the difference in corrosion resistance.     

少汗型外胚层发育不全1例

本文报道1例外胚层发育不全病例,并分析外胚层发育不全的临床表现、发病原因及遗传方面的影响因素等.     

舌大小二维超声成像测量分析方法的建立及其评价

目的：建立一种舌大小测量分析方法，为舌大小在错He发病中的作用研究奠定基础。方法：采用B超超声像方法取舌正中纵断面和横切面图像，选取代表舌大小的参数进行测量，从而分析舌大小。结果：通过对测量结果的可重复性和准确性检验。认为这一测量方法是准确可行的，结论：建立的舌大濒分析方法可以作为研究手段使用。     

上颌尖牙唇向错位34例临床矫治

为了对上颌尖牙唇向错位进行正确的矫治设计,作者根据错位的病因、X线头影测量结果,对34例上颌尖牙唇向错位病例,分别采用前牙片段方丝辅弓法,改良Richett's弓法,推磨牙向后法,拔除第2乳磨牙法,拔除第一双尖牙法,取得满意结果。作者认为在矫治上颌尖牙唇向错位时,应充分利用潜在间隙,根据X线头影测量结果及错位形成原因进行综合分析,选用最佳方法进行矫治。