氟对镍钛弓丝色泽的影响

目的研究氟对镍钛弓丝色泽的影响。方法将4种镍钛弓丝（IMD、SL、TP、YY）各40个样本,分为4个小组。其中1个为对照组,放入人工唾液中不作处理;3个为实验组,分别放入含有不同浓度氟离子（0.05%、0.10%、0.15%）的氟化人工唾液中进行处理,每天处理3次（早、中、晚）,每次3 min,然后去离子水冲洗样本,去除残留的氟化物溶液后放回人工唾液试管中。28 d后取出样本,观察表面色泽变化和微观形态。结果随着氟离子浓度的增加,弓丝色泽的改变呈持续加重的趋势（P<0.05）。氟离子浓度相同的条件下,IMD与YY色泽改变的差异无统计学意义,SL与TP的差异也无统计学意义（P>0.05）,但IMD和YY的色泽改变均明显高于SL和TP（P<0.01）。结论镍钛弓丝的表面色泽变化随着氟离子浓度的上升而加重。不同品牌的镍钛弓丝在同一氟环境下色泽改变的情况不完全相同。     

4种镍钛正畸弓丝钛离子析出量的体外实验研究

目的:通过测试在人工唾液中4种品牌镍钛正畸弓丝钛离子的析出量,以了解其耐腐蚀性。方法:选择临床常用的4种品牌的镍钛正畸弓丝,分别为3M、SL、TP、SMT,调配人工唾液,并将人工唾液的pH值分别调节为4.0及6.75,减取的正畸弓丝两端较直的部分(每段2 cm)放入EP树脂管中,加入已调节好pH值的人工唾液1 mL,保存置37 ℃电子恒温箱,在1、7、28 d时分别取出弓丝样本后测试试管中钛离子的析出量,进行统计学分析。结果:第1天时4种品牌镍钛正畸弓丝钛离子的析出量最大,7、28 d时钛离子的析出量平均后,均要少于弓丝浸泡第1天时的析出量,不同品牌间钛离子的析出量的差别不具有统计学意义。结论:4种品牌的镍钛正畸弓丝具有良好的抗腐蚀性,但是酸性环境可以加速镍钛正畸弓丝中钛离子的析出量影响镍钛正畸弓丝的抗腐蚀性。     

自制美学镍钛涂层弓丝的耐腐蚀性研究

目的：研究美学镍钛涂层弓丝的耐腐蚀性能。方法：将美学涂层镍钛弓丝与未涂层镍钛弓丝浸泡于人工唾液中,37℃恒温,采用恒电位法测定阳极极化曲线,浸泡实验测定析出镍、铬离子浓度。结果：涂层弓丝的腐蚀电流显著降低,涂层弓丝析出相对低水平的金属离子。结论：美学涂层可降低弓丝合金的腐蚀倾向,提高其耐腐蚀性能。     

氟化物对正畸镍钛丝疲劳性能影响的研究

目的：研究氟化物对正畸镍钛圆丝疲劳性能的影响。方法：选用4种不同品牌的镍钛圆丝,分别用人工唾液和含氟人工唾液浸泡1周后,进行动态力学实验,分析其疲劳性能的差异,扫描电镜观察实验前、后镍钛丝的表面和断面结构差异。结果：4种镍钛丝的疲劳性能差异均无统计学意义（P>0.05）,在两种液体中浸泡后表面都可见到点蚀现象的发生。结论：氟化物会使正畸镍钛丝发生腐蚀现象,但并不会影响其疲劳性能。     

正畸合金丝在人工唾液中腐蚀行为的电化学研究

目的：运用电化学方法研究常用正畸合金丝的耐腐蚀性能。方法：采用经典三电极体系的电化学方法,在人工唾液中检测常用正畸不锈钢弓丝、镍钛丝、β-钛丝及钴铬丝的自然腐蚀电位和腐蚀电流密度,从而研究其自身腐蚀行为。结果：在人工唾液中,4种弓丝的的自然腐蚀电位顺序为SS＞CoCr＞β-Ti＞NiTi;腐蚀电流密度顺序为NiTi＞β-Ti＞CoCr＞SS。结论：在人工唾液中,常用正畸合金丝自身均会发生电化学腐蚀,产生相应的腐蚀电流。     

氟化物涂膜后唾液氟浓度的变化

目的 观察并比较使用氟化物涂膜及氟化钠溶液后，唾液中氟离子浓度的变化。方法 选取20例5岁儿童。随机分为氟化钠涂膜组和氟化钠溶液组，每组10例。使用氟化物前及使用后0．25h、0．5h、lh、2h、6h、12h、24h分别留取非刺激性全唾液，唾液离心后用氟离子选择电极法测定唾液中的氟离子浓度。结果 使用氟化钠涂膜后0．25h、0．5h、lh、2h、6h，唾液中氟离子浓度高于用氟前；使用后0．5—6h，唾液中氟离子浓度高于使用氟化钠溶液组。结论 氟化钠涂膜与氟化钠溶液相比。能延长氟化物和牙釉质接触的时间和浓度。     

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目的    评价3种正畸用镍钛形状记忆合金弓丝的细胞毒性。方法    于2009年11月至2010年3月,在中国医科大学口腔医学院选择正畸临床常用的3种品牌镍钛形状记忆合金弓丝（A：Masel牌美国产热激活型镍钛牙齿矫形丝;B：Smart牌国产热激活型镍钛牙齿矫形丝;C：有研亿金牌国产镍钛丝）,制作试件各若干枚,长度0.5 cm。将其依次分为3份,一份处理后直接提取浸提液;另外两份处理后置于人工唾液中浸泡,分别于4周和8周后取出提取浸提液。选择L-929细胞系作为细胞毒性的实验对象,用倒置相差显微镜观察L-929细胞在合金丝浸提液中的生长情况,通过四甲基偶氮唑盐微量酶反应比色法（MTT 法）得出细胞在培养24 h和48 h的吸光度（OD）值以及细胞相对增殖率（RGR）,对3种品牌镍钛形状记忆合金弓丝做出细胞毒性评价。结果    在人工唾液浸泡后,3种品牌镍钛形状记忆合金弓丝的细胞毒性均随浸泡时间延长而逐渐增加（P < 0.05）;在相同的浸泡时间下,A弓丝的细胞毒性最小,C弓丝的细胞毒性最大;3种镍钛形状记忆合金弓丝细胞毒性均在正常范围之内。结论    （1）人工唾液环境增加了镍钛形状记忆合金丝的细胞毒性,并随着浸泡时间的增加细胞毒性加大。（2）不同品牌、不同浸泡时间,正畸用镍钛弓丝细胞毒性不同。     

儿童使用APF凝胶和氟化泡沫氟的作用量及摄入量比较

目的检测中国儿童氟化泡沫使用量、滞留量并与含氟凝胶比较。方法研究对象为成都市、小学1年级学生（年龄6～7岁）105人，55人使用氟化泡沫、50人使用含氟凝胶。将含氟凝胶或泡沫放置在已称重的托盘后再称总重，按常规操作程序应用于实验对象。使用后收集唾液、托盘及盘中剩余药物。取出托盘2min及10min后，用事前称重塑料试管继续收集唾液2min。实验室检测采用盲法，使用氟离子电极检测样本氟浓度并计算回收的总氟量。结果6～7岁儿童平均使用0．52±0．10g的氟化泡沫和2．61±0．43g含氟凝胶。滞留的氟量氟化泡沫为1．76±0．72mg，含氟凝胶为6．75±4．56mg。氟化泡沫的用量为含氟凝胶重量的19．92％，吸收量为含氟凝胶的26．07％。结论　氟化泡沫有明显减少病人氟使用量的优点。     

模拟口腔环境下温控型镍钛弓丝力学性能的实验研究

目的研究温控型镍钛弓丝在不同温度人工唾液环境下的力学性能变化,为临床合理、有效地使用温控型镍钛弓丝提供参考。方法利用Instron万能材料力学实验机在25、33、37、60 ℃人工唾液中对4种温控型镍钛弓丝进行改良部分牙弓托槽弯曲实验。将4种温控型镍钛弓丝加载挠曲至3 mm后卸载,绘制弓丝卸载的载荷-挠曲曲线,计算卸载至2.5 mm与0.5 mm之间的卸载刚度,结果采用单因素方差分析法进行统计分析。结果随着温度的升高,4种弓丝的卸载力值均有不同程度的升高;同种弓丝的卸载刚度在25、33、37 ℃时十分接近,而在60 ℃时卸载刚度均有明显增大。结论在本实验条件下,4种温控型镍钛弓丝表现出不同的力学性能,但均表现出临床所需的超弹性与形状记忆效应,也均表现出明显的温度敏感性。     

不同氟化物对人工羟基磷灰石摄氟量的影响

目的：探讨复合氟化物制剂（Co-F)及其组成成分中的氟化锌对牙齿无机质的影响。方法：将羟基磷灰石浸入各种氟化物溶液中，经过1、10d作用后，测定羟基磷灰石摄取氟量。应用与Co-F溶液相同氟浓度的氟化钠溶液作为对照。结果：发现浸入氟化锌溶液的羟基磷灰石摄取氟量最高。X线衍射分析有磷酸锌及氟化钙生成。浸入对照组氟化钠溶液的羟基磷灰石摄取氟量明显低于浸入Co-F溶液的羟基磷灰石摄取氟量。浸入Co-F溶液的羟基磷灰石1d及10d期间摄取氟量与浸入氟化锌溶液的羟基磷灰石摄取氟量相比较，没有显著性差异。结论：在羟基磷灰石摄取氟方面，复合氟化物制剂中氟化锌组分有重要的作用。     

Effect of fluoride prophylactic agents on the mechanical properties of nickel-titanium-based orthodontic wires

BACKGROUND: Titanium-based alloys have high corrosion resistance because they form a thin, stable oxide layer. Nevertheless, fluoride prophylactic agents can cause corrosion and associated discoloration of titanium-based orthodontic wires. The purpose of this investigation was to study the effects of fluoride prophylactic agents on the mechanical properties of nickel-titanium (Ni-Ti) and copper-nickel-titanium (Cu-Ni-Ti) orthodontic archwires. METHODS: Preformed rectangular Ni-Ti and Cu-Ni-Ti wires were immersed in either an acidulated fluoride agent, a neutral fluoride agent, or distilled water (control) for 1.5 hours at 37 degrees C. After immersion, the loading and unloading elastic modulus and yield strength of the wires were measured with a 3-point bend test in a water bath at 37 degrees C, in accordance with the criteria in the current American National Standard/American Dental Association Specification No. 32 for Orthodontic Wires (2000). Scanning electron microscopy was also used to characterize the effects of the fluoride treatment on the wire topography. RESULTS: Unloading mechanical properties of Ni-Ti orthodontic wires were significantly decreased after exposure to both fluoride agents (1-way analysis of variance [ANOVA] and Dunnett's post hoc, alpha =.05); however, Cu-Ni-Ti wire mechanical properties were not significantly affected by either fluoride agent (1-way ANOVA, alpha =.05). Corrosive changes in surface topography were observed for both wires, with Cu-Ni-Ti appearing to be more severely affected. CONCLUSIONS: The results suggest that using topical fluoride agents with Ni-Ti wire could decrease the functional unloading mechanical properties of the wire and contribute to prolonged orthodontic treatment.     

Effect of Fluoride Prophylactic Agents on the Surface Topography of NiTi and CuNiTi Wires

Aim: The aim of this study was to see the effect of topical fluoride on surface texture on nickel-titanium and copper-nickel-titanium orthodontic archwires. Materials and methods: Preformed rectangular NiTi and CuNiTi wires were immersed in in fluoride solution and artificial saliva (control) for 90 minutes at 37°C. after immersion optical microscope was used to see the fluoride effect on the wire topography. Results: The acidulated fluoride agents appeared to cause greater corrosive effects as compared to the neutral fluoride agents. Conclusion: The result suggest that using topical fluoride agents leads to corrosion of surface topography indirectly affecting the mechanical properties of the wire that will lead to prolonged orthodontic treatment. Clinical significance: The use of topical fluoride agents has to be limited in patients with prolonged orthodontic treatment as it causes the corrosion of the NiTi and CuNiTi wires. Keywords: NiTi, CuNiTi, Fluoride agents, Optical microscope. How to cite this article: Mane PN, Pawar R, Ganiger C, Phaphe S. Effect of Fluoride Prophylactic Agents on the Surface Topography of NiTi and CuNiTi wires. J Contemp Dent Pract 2012;13(3):285-288. Source of support: Nil Conflict of interest: None declared.     

Effect of chlorhexidine-containing prophylactic agent on the surface characterization and frictional resistance between orthodontic brackets and archwires: an in vitro study

Background

The purpose of this study was to assess the surface characterization and frictional resistance between stainless steel brackets and two types of orthodontic wires made of stainless steel and nickel-titanium alloys after immersion in a chlorhexidine-containing prophylactic agent.

Methods

Stainless steel orthodontic brackets with either stainless steel (SS) or heat-activated nickel-titanium (Ni-Ti) wires were immersed in a 0.2% chlorhexidine and an artificial saliva environment for 1.5 h. The frictional force was measured on a universal testing machine with a crosshead speed of 10 mm/min over a 5-mm of archwire. The surface morphology of bracket slots and surface roughness of archwires after immersion in chlorhexidine were also characterized using a scanning electron microscope (SEM) and an atomic force microscope (AFM), respectively.

Results

There was no significant difference in the frictional resistance values between SS and Ni-Ti wires immersed in either chlorhexidine or artificial saliva. The frictional resistance values for the SS and Ni-Ti wires immersed in 0.2% chlorhexidine solution were not significantly different from that inartificial saliva. No significant difference in the average surface roughness for both wires before (as-received) and after immersion in either chlorhexidine or artificial saliva was observed.

Conclusions

One-and-half-hour immersion in 0.2% chlorhexidine mouthrinse did not have significant influence on the archwires surface roughness or the frictional resistance between stainless steel orthodontic brackets and archwires made of SS and Ni-Ti. Based on these results, chlorhexidine-containing mouthrinses may be prescribed as non-destructive prophylactic agents on materials evaluated in the present study for orthodontic patients.     

氟离子对2种牙科用钛合金耐腐蚀性的影响

目的在模拟口腔环境下,探讨氟离子对Ti-12Zr合金和Ti-6Al-4V合金耐腐蚀性的影响。方法2种钛合金在含有不同浓度NaF（0%、0.05%、0.1%、0.2%）的酸性人工唾液（pH=4.0）电解池中测得极化曲线;然后将试件浸泡于恒温的实验溶液中,扫描电镜（SEM）下观察各组试件的表面形貌。结果2种钛合金在酸性人工唾液中的自腐蚀电位、极化电阻随着NaF浓度的升高而减小,自腐蚀电流密度随着NaF浓度的升高而增大;且当NaF浓度高于0.1%时2种钛合金的自腐蚀电位、极化电阻以及自腐蚀电流密度的变化明显（P＜0.05）;同时,扫描电镜结果显示当NaF浓度高于0.1%时2种钛合金表面开始发生严重的腐蚀;Ti-12Zr合金在NaF浓度为0.2%酸性人工唾液中的极化电阻明显高于Ti-6Al-4V合金（P＜0.05）。结论氟离子可降低Ti-12Zr合金及Ti-6Al-4V合金的耐腐蚀性,且在NaF浓度高于0.1%时更为明显。     

Corrosion behavior of shape memory, superelastic, and nonsuperelastic nickel-titanium-based orthodontic wires at various temperatures.

OBJECTIVE: Nickel-titanium orthodontic wires have various temperature-dependent phases. The purpose of this study was to investigate temperature-dependent corrosion characteristics of shape memory, superelastic, and nonsuperelastic orthodontic wires. METHODS: Four orthodontic wires were investigated: 27 and 40 degrees C copper Ni-Ti (superelastic and shape memory, respectively), superelastic Ni-Ti, and nonsuperelastic Nitinol Classic. Differential scanning calorimetry (DSC) was used to confirm phase/temperature behavior of the wires. Sectioned halves of as-received archwires were assessed electrochemically in artificial saliva at 5, 24, 37, and 45 degrees C. Open circuit potential (OCP) was monitored for 2h followed by polarization resistance and cyclic polarization tests. RESULTS: DSC results showed Nitinol was primarily martensitic-stable whereas NiTi, 27 degrees C CuNiTi, and 40 degrees C CuNiTi possessed austenite-finish temperatures of approximately 19, 21, and 38 degrees C. The OCP of the CuNiTi wires was significantly greater than NiTi and Nitinol but no apparent trend in values was apparent with regard to temperature or phases present. Corrosion current density (i(corr)) increased with temperature for all wires, but not all were equally influenced. The two lowest austenite-finish temperature wires (27 degrees C CuNiTi and NiTi) approximately tripled in i(corr) from 37 to 45 degrees C. Greater incidence of pitting was observed in the CuNiTi wires. SIGNIFICANCE: This study showed the corrosion rate of various nickel-titanium wires increase with temperature and different phases present may influence corrosion rate trends.     

SLM钴铬合金在含氟人工唾液中的电化学耐腐蚀性能研究

目的通过电化学阻抗谱方法研究选择性激光熔覆（Selective laser melting,SLM）技术制作的钴铬合金在含氟人工唾液中的耐腐蚀性能。方法运用SLM技术和传统铸造（CAST）技术,使用相同成分的钴铬合金,分别制作40个直径10mm×3mm厚度的圆柱形试件。在p H值为2.5和5.0,含氟浓度为0.00%、0.05%、0.1%和0.2%的人工唾液中,利用电化学阻抗谱检测2种加工方法制作的钴铬合金的耐腐蚀性能。结果当p H=5.0时,Na F 0.1%环境下SLM组和CAST组Rp值分别为3.49±0.44和1.59±0.88;Na F 0.2%环境下SLM组和CAST组Rp值分别为5.30±3.29和1.71±1.10。当p H=2.5时,Na F0.00%环境下SLM组和CAST组Rp值分别为6.40±0.26和2.05±0.35;Na F0.05%环境下SLM组和CAST组Rp值分别为5.67±0.25和1.15±0.83;Na F0.1%环境下SLM组和CAST组Rp值分别为4.74±0.50和0.24±0.10;Na F0.2%环境下SLM组和CAST组Rp值分别为4.76±0.97和0.30±0.09。在以上各实验条件下,SLM组和CAST组之间的表面氧化层电阻Rp值差异均具有统计学意义（P〈0.05）。结论 SLM技术制作的钴铬合金耐腐蚀性能优于铸造组。