氮掺杂纳米TiO_2抗菌剂的体外细胞毒性研究

目的：通过对高可见光活性氮掺杂纳米二氧化钛（纳米N-TiO2）抗菌剂体外细胞毒性的测定,初步评价纳米N-TiO2抗菌剂的生物安全性。方法：采用含不同浓度纳米N-TiO2抗菌剂的培养液培养人牙周膜成纤维细胞,另设空白对照组和阳性对照组。在显微镜下观察细胞形态及数量,MTT法测定各组细胞培养1、3和5d的吸光度值,并计算细胞的相对增值率,从而判断细胞毒性的级别。结果：各观察期,实验组的人牙周膜成纤维细胞生长良好,形态正常,表现出较高的细胞增值率,1d为109.67±8.5、3d为109.99±7.0、5d为102.53±6.4;与空白对照组比较差异无统计学意义;实验组的吸光度值在各个时间段与空白对照组比较差异均无统计学意义（P〉0.05）,且随培养时间的延长,吸光度值增大。结论：纳米N-TiO2抗菌剂实验期内无细胞毒性,生物安全性较好。     

光源距离对6种LED固化灯光强度衰减的影响

目的:评估6种LED固化灯光照射强度随光源距离的增加出现衰减的程度。方法:选择6种LED光固化灯:配置标准光导棒的Bluephase、Bluephase C8和Elipar S10,配置聚光透镜的Ascent PX,配置涡轮光导棒的Demi和Ti-Lite GT-1500。使用光强测量仪在距光源0、1、2、3、4、5 mm测量光固化灯的光照射强度,每一距离测量10次,并计算光强度平均值及相应的光强度衰减率。结果:6种固化灯初始光强度分别为859 m W/cm2(Bluephase C8)、1 121 m W/cm2(Bluephase)、1 133 m W/cm2(Elipar S10)、1 300 m W/cm2(Ascent PX)、1 497 m W/cm2(Demi)和1 192 m W/cm2(Ti-Lite)。除Ascent PX的1~3 mm光源距离外,光源距离每增加1 mm,6种固化灯的光照射强度均出现显著降低(P<0.05)。距离光源5 mm时,只有Bluephase、Elipar S10和Ascent PX的光强度超过了400 m W/cm2,光强度衰减率分别为56.7%、58.7%、53.8%,明显低于Bluephase C8(66%)、Demi(78.8%)和Ti-Lite(>72.2%)。结论:临床中应尽可能选用高强度LED固化灯并延长照射时间以弥补光源距离增加所造成的光强度衰减,建议选择配置标准光导棒或聚光透镜的高强度LED光固化灯。     

牙钻手机机械清洗与手工清洗的效果评价

目的 比较牙钻手机机械清洗与手工清洗的效果。方法 将污染程度相同的牙钻手机80支随机分成两组,每组40只,一组采用全自动清洗机清洗,另一组采用手工清洗,两组均按标准流程操作,清洗后采用ATP生物荧光法检测清洗效果。结果 ATP生物荧光检测相对发光单位（RLU）平均值分别为：机械清洗组为9,手工清洗组为41,两组均低于生产厂家提供的RLU≤45的推荐值,两组差异有统计学意义（P＜0.05）。结论 机械清洗的效果优于手工清洗,建议消毒供应中心采用机械清洗法清洗牙钻手机,确保清洗质量。     

牙科修复用CuO掺杂纳米二氧化钛的制备与表征

目的 通过氧化铜掺杂,制备改性氧化铜纳米二氧化钛光催化剂,检测氧化铜掺杂对CuO/TiO₂复合光催化剂吸收光谱的影响,为研制口腔临床修复功能性材料提供依据。方法 采用共沉淀法制备CuO/TiO₂（CuO掺杂纳米二氧化钛）,通过X射线衍射仪（XRD）、扫描电镜（SEM）和紫外-可见光吸收光谱（UV-vis谱）对其形态、结构、组成和性质进行表征。结果 成功制备了CuO/TiO₂复合光催化剂,不同CuO掺杂比的TiO₂的形貌基本不变,CuO掺杂使CuO/TiO₂吸收光谱发生红移,增加了可见光的吸收边界,提高可见光响应。结论 掺杂CuO后的光催化剂有效地提高其可见光响应能力,减少了空穴和电子复合,提高了可见光响应的性能。本研究对解决口腔临床修复对抗菌抑菌自洁特性材料的需求具有参考意义。     

QLF法研究一种含氟涂料对离体牛牙釉质的抗酸性效果

目的：采用定量光导荧光系统观察含氟涂料对牛牙釉质的抗酸性效果。方法：20个新鲜拔除的牛前牙,于每个标本唇面建立4个2mm×2mm开窗,随机分为4组,分别用含氟涂料、含氟牙膏、1%氟化钠溶液、去离子水处理,然后浸泡在脱矿液中,分别于处理的第1,2,4,8d,采用QLF法检测各组标本的荧光损失量△F（%）和病变面积△P（mm2）,计算△Q（%,mm2）,并再次处理。结果：用含氟涂料处理的牛牙釉质龋标本,再矿化面积最多、△Q降低最大,且与其他处理组有显著差异（P〈0.05）。结论：同其它方法相比,含氟涂料有利于增进离体牛牙釉质的抗酸性。     

载银纳米二氧化钛在口腔材料中抗菌性的研究

复杂的口腔微生态环境中存在多种致病性细菌、真菌等,可引起一系列口腔感染性疾病,如釉质脱矿、龋病、义齿性口炎和种植体周围炎等。传统抗菌方法大多未能达到预期的抗菌效果。载银纳米二氧化钛是一种新型复合型纳米无机抗菌剂,可有效杀灭口腔细菌并分解细菌内毒素,无明显耐药性,被广泛应用于口腔材料的抗菌性能研究中。本文就载银纳米二氧化钛的抗菌机制、生物相容性及安全性、在口腔材料中抗菌性能的研究现状进行综述。     

Comparative bond strength of brackets cured using a pulsed xenon curing light with 2 different light-guide sizes.

Light curing of composite resin material beneath orthodontic brackets is common in clinical orthodontics. Experiences with composite resins and high-intensity lights indicate some advantages to staged curing of the composite. In this study, the shear/peel bond strength of orthodontic brackets bonded to bovine enamel and cured with a pulsed xenon plasma arc light was compared with that of bonds cured with a conventional tungsten-quartz-halogen light and a nonpulsed xenon plasma arc light. The pulsed light provided less light energy than the nonpulsed lights. A small and a larger light-guide tip were used with the pulsed xenon plasma arc light. Three different orthodontic composite resin adhesives were tested with each light. The pulsed xenon plasma arc light resulted in either the same or decreased shear/peel bond strength when compared with the nonpulsed lights. There appeared to be no advantage to the use of a pulsed xenon plasma arc light in bonding orthodontic brackets. Results from using either a small or a large light-guide tip varied with the adhesive tested.     

Polymerization efficiency of LED curing lights

ABSTRACT: Purpose: The purpose of this study was to compare the curing efficiency of three commercially available light‐emitting diode (LED)‐based curing lights with that of a quartz tungsten halogen (QTH) curing light by means of hardness testing. In addition, the power density (intensity) and spectral emission of each LED light was compared with the QTH curing light in both the 380‐to 520‐nm and the 450‐ to 500‐nm spectral ranges. Materials and Methods: A polytetrafluoroethylene mold 2 mm high and 8 mm in diameter was used to prepare five depth‐of‐cure test specimens for each combination of exposure duration, composite type (Silux Plus [microfill], Z‐100 [hybrid]), and curing light (ZAP Dual Curing? Light, LumaCure?, VersaLux?, Optilux 401?). After 24 hours, Knoop hardness measurements were made for each side of the specimen, means were calculated, and a bottom/top Knoop hardness (B/T KH) percentage was determined. A value of at least 80% was used to indicate satisfactory polymerization. A linear regression of B/T KH percentage versus exposure duration was performed, and the resulting equation was used to predict the exposure duration required to produce a B/T KH percentage of 80% for the test conditions. The power densities (power/unit area) of the LED curing lights and the QTH curing light (Optilux 401?) were measured 1 mm from the target using a laboratory‐grade, laser power meter in both the full visible light spectrum range (380–780 nm) and the spectral range (between 450 and 500 nm), using a combination of long‐ and short‐wave edge filters. Results: The emission spectra of the LED lights more closely mirrored the absorption spectrum of the commonly used photoinitiator camphorquinone. Specifically, 95% of the emission spectrum of the VersaLux, 87% of the LumaCure, 84% of the ZAP LED, and 78% of the ZAP combination LED and QTH fell between 450 and 500 nm. In contrast, only 56% of the emission spectrum of the Optilux 401? halogen lamp fell within this range. However, the power density between 450 and 500 nm was at least four times greater for the halogen lamp than for the purely LED lights. As I a result, the LED‐based curing lights required from 39 to 61 seconds to cure a 2‐mm thick hybrid I resin composite and between 83 and 131 seconds to adequately cure a microfill resin composite. By I comparison, the QTH light required only 21 and 42 seconds to cure the hybrid and microfill resin I composites, respectively.     

Thermal emission and curing efficiency of LED and halogen curing lights

The purpose of this study was to compare the thermal emission and curing efficiency of LED (LEDemetron 1, SDS/Kerr) and QTH (VIP, BISCO) curing lights at maximum output and similar power, power density and energy density using the same light guide. Also, another LED curing light (Allegro, Den-Mat) and the QTH light at reduced power density were tested for comparison. Increase in temperature from the tips of the light guides was measured at 0 and 5 mm in air (23 degrees C) using a temperature probe (Fluke Corp). Pulpal temperature increase was measured using a digital thermometer (Omega Co) and a K-type thermocouple placed on the central pulpal roof of human molars with a Class I occlusal preparation. Measurements were made over 90 seconds with an initial light activation of 40 seconds. To test curing efficiency, resin composites (Z100, A110, 3M/ESPE) were placed in a 2-mm deep and 8-mm wide plastic mold and cured with the LED and QTH curing lights at 1- and 5-mm curing distances. Knoop Hardness Numbers (KHN) were determiped on the top and bottom surfaces (Leco). Bottom hardness values were expressed as a percentage of maximum top hardness. No significant differences were found in maximum thermal emission or KHN ratios between the LED (LEDemetron 1) and the QTH (VIP) at maximum output and similar energy densities (ANOVA/Tukey's; alpha=0.05).     

纳米TiO2陶瓷涂层托槽耐磨性研究

目的：对自行研制的纳米TiO2陶瓷涂层直丝托槽耐磨性进行测试,并与国产普通金属直丝托槽进行比较。方法：选取纳米TiO2陶瓷涂层直丝托槽与国产普通金属直丝托槽各5付,测试比较弓丝拉伸前后托槽表面光洁度、托槽-弓丝摩擦力,评估托槽耐磨性。结果：纳米TiO2陶瓷涂层直丝托槽较国产普通金属直丝托槽耐磨性好,弓丝拉伸前后托槽表面光洁度、托槽-弓丝摩擦力无明显改变。结论：纳米TiO2陶瓷涂层直丝托槽具有良好耐磨性,可以满足口腔正畸临床需要。     

纯钛种植体表面纳米Ti02生物活性涂层的构建

目的:在纯钛表面构建纳米TiO2涂层并探索最佳的工艺条件.方法:采用溶胶凝胶法在纯钛表面构建纳米级TiO2涂层,用x线衍射和扫描电镜表征其晶体结构、表面形貌以及厚度,筛选出最佳的热处理温度和涂层厚度;用体外成骨细胞培养评价其生物活性.结果:热处理温度为500℃的单层TiO2涂层具有良好的晶体结构和均匀的纳米级表面形貌,与钛基底结合牢固.体外成骨细胞培养显示其具有良好的生物活性.结论:本实验构建的TiO2涂层具有良好的性能,为后续复合性梯度功能涂层的设计和组装打下了基础.     

Limited reciprocity in curing efficiency of bulk-fill resin-composites

ObjectiveThe aim of the study was to identify experimental limits of the general reciprocity hypothesis that the same photo-cure outcomes will result from applying essentially constant energy densities, despite reciprocal variations in the irradiance and irradiation time-period, for a representative set of bulk fill (BF) and non-BF resin composites.MethodsSix BF and two non-BF resin-composites were selected. The unset pastes were inserted into white acetal molds (5 mm id) with (n = 6) depths (1, 2, 3, 4, 5 and 6 mm). Three light curing units (LCUs) of increasing radiant emittance capability: 1200, 2000 and 3200 mW/cm² were used. Composite specimen groups (n = 3, per depth, per LCU) were irradiated on the upper surface only. For each specific composite, the irradiation times for each LCU were reduced reciprocally, as the LCU irradiance increased, to deliver a constant energy density (J/cm²) to that composite. However, the required energy density for a given composite differed in accordance with each composite manufacturer recommendations. After storing for 24 h at 37 °C, light transmission measurements were made through each specimen and re-expressed as Apparent Absorbance (A′). Vickers hardness (H_V) measurements (n = 10) were made on both top and bottom surfaces, for each specimen, and H_V versus “depth” profile plots created. From the top-surface data, a Depth-of-Cure parameter could be derived. Data were statistically evaluated for differences between top and bottom H_V values and for other predefined variables of interest.ResultsIrradiation with the LCU of 1200 mW/cm² generally gave the highest H_V/depth for most materials tested compared to the other curing lights with higher power output, regardless of top and bottom measurements (p < 0.001). However, this difference was material-dependent. With one BF composite, 1200 and 2000 mW/cm² irradiance did not show a significant difference between top and bottom H_V. Composites with higher translucency showed reduced differences in top/bottom H_V than more opaque composites.SignificanceReciprocity was found to be limited with most materials examined, such that irradiance periods of 10 s, gave generally better H_V outcomes than by using LCUs of superior radiant emittance while reciprocally reducing irradiance time to maintain constant dose of energy density.     

纳米陶瓷涂层托槽的研制

目的:研制纳米陶瓷涂层托槽,并对托槽涂层结构表面性能进行初步研究。方法:合成尺度均一的具有光化学活性的锐钛矿型纳米态二氧化钛靶材,采用电子束物理气相沉积技术在国产金属直丝托槽表面沉积纳米二氧化钛薄膜。使用X射线衍射法和电镜观察涂层的表面性状。结果:研制生产出纳米二氧化钛陶瓷涂层托槽,托槽表面沉积二氧化钛薄膜厚度约 5~8μm。二氧化钛晶粒尺寸均一,分布均匀,表面光洁度高。结论:托槽表面纳米二氧化钛镀膜对托槽槽沟尺寸几乎无影响,且具有良好表面性状及光化学活性,可以满足口腔正畸临床需要。     

硅橡胶中纳米二氧化钛对白色念珠菌生长影响的初探

目的 通过研究纳米二氧化钛对硅橡胶体外抗白色念珠菌性能的影响,探讨用纳米二氧化钛改善硅橡胶抗白色念珠菌性能的可靠性.方法 硅橡胶中加入质量分数分别为0.5%、1.0%、1.5%、2.0%的纳米二氧化钛抗菌剂,分别记为A、B、C、D组,对照组硅橡胶不加纳米二氧化钛,采用薄膜密着法在光照和无光照条件下测定各组硅橡胶对白色念珠菌的抗菌作用.结果 光照条件下,A、B、C、D组菌落数[分别为(439.0±21.9)CFU、(289.3±7.8)CFU、(173.0±7.6)CFU、(86.7±3.9)CFU]与对照组[(597.3±5.5)CFU]的差异均有统计学意义(P<0.05);非光照条件下,A、B、C、D组菌落数[分别为(543.7±22.8)CFU、(478.0±17.0)CFU、(422.7±21.8)CFU、(283.0±12.1)CFU]与对照组[(611.3±10.0)CFU]的差异均有统计学意义(P<0.05).D组抗菌性能最好,无光照条件下,抑菌率为53.7%;光照条件下,抑菌率可达85.9%.结论 添加了纳米二氧化钛抗菌剂的硅橡胶在光照和无光照条件下均能抑制白色念珠菌生长,随着纳米二氧化钛质量分数的增加,硅橡胶抑菌效果增强.纳米二氧化钛质量分数相同时,光照下硅橡胶的抑菌性比无光照强.