能量恒定时不同光密度对不同颜色纳米树脂硬度的影响

目的：在2种能量水平下采用3种光密度固化2种纳米复合树脂试片,通过检测比较其硬度值评价不同光密度及不同颜色对纳米树脂固化程度的影响。方法：设定12J及16J两个能量水平,用3盏光固化灯,光密度分别为400mW／cm2、800mW／cm2和1000mW／cm2,固化2种纳米树脂,颜色为A1、A2、A3、A3．5。将固化试片浸泡在蒸馏水中,避光37℃保存24h,测量试片表面和底面的维氏硬度值。结果：所有实验组的底面硬度均能达到有效的硬度百分率。16J的试片底面维氏硬度显著高于12J。采用800mW／cm。光密度固化效果较好,底面硬度随着树脂颜色加深而减小。结论：复合树脂固化的总能量恒定的观点不成立。在相同能量下,光密度800mw／cm。的光固化灯及较浅颜色的树脂可获得更高的转化率。能量为16J的固化效果优于12J,但在本实验条件下都能够满足临床需要。     

固化灯及照射距离对纳米树脂显微硬度的影响

目的观察在不同照射距离下,不同固化模式对复合树脂表面显微硬度的影响。方法将复合树脂制备成直径4mm,厚2mm的圆片状实验模块,根据照射距离（2mm、5mm、10mm）与固化模式（430mw／cm^2卤素灯40秒与860mw／cm^2二极管固化灯20秒）分成6组,每组6个,共36个。固化后用硬度计测定每个树脂块顶面与底面的韦氏硬度值。统计分析各组间显微硬度值的差别。结果随照射距离增大,树脂块显微硬度显著降低（p〈0．01）;各组树脂块顶面显微硬度值均高于底面（p〈0．01）;在2mm与5mm照射距离下,不同固化方式对树脂块表面硬度无显著影响（p〉0．05）;在10mm照射距离下,二极管固化灯组底面的显微硬度显著高于卤素灯组（p〈0．01）。结论远距离照射下,要使深层复合树脂充分固化应选择高功率的固化模式。     

卤素和LED光固化灯照射复合树脂的机械强度比较

目的探讨3M2500型卤素光固化灯和3M FreeLight型LED光固化灯对光固化复合树脂机械强度及固化深度的影响。方法用WD-5A型电子拉力试验机、DUH-W201S型动态超显微硬度计2种仪器,通过测试比较卤素光固化灯和LED光固化灯照射Tetric ceram HB(Vivadent)A2色光固化复合树脂后其挠曲强度、压缩强度、表面硬度、固化深度的差异,从而比较3M2500型卤素光固化灯和3M FreeLight型LED光固化灯的性能。结果卤素光固化灯照射Tetric ceram HB复合树脂40s,LED光固化灯照射Tetric ceram HB10s,前者固化深度平均可达3.98mm,后者固化深度平均可达2.136mm,两者均可完全固化2mm,LED光固化灯固化树脂深度低于卤素光固化灯;表面硬度DHT115平均值分别为73.292MPa和39.668MPa,统计学分析95%水平有差别(P<0.05),LED灯对应的树脂硬度低于卤素灯;压缩强度平均值分别为242.1MPa和287.7MPa,统计学分析95%水平无明显差别(P>0.05);挠曲强度平均值分别为88.9MPa和97.0MPa,统计学分析95%水平无明显差别(P>0.05)。结论LED灯照射Tetric ceram HB复合树脂10s能达到卤素灯照射Tetric ceram HB复合树脂40s的聚合水平,适合于口腔临床应用。     

不同温度及不同光固化灯对光固化复合树脂硬度的影响

目的:探讨不同温度处理后的光固化复合树脂用卤素光固化灯和第2代LED光固化灯照射后复合树脂硬度的差别.方法:设5℃(冷藏)、23℃(常温)、40℃(加热)3种不同温度处理光固化复合树脂Clearfil AP-X.再分别用卤素光固化灯Translux CL和LED灯Elipar FreeLight2照射,采用显微维氏硬度计测量树脂试件表面和底部的硬度.结果采用SPSS 17.0软件包进行方差分析.结果:40℃加热处理后的树脂试件表面和底部的硬度值均较其他2种温度处理后的树脂硬度值增高(P＜0.01).3种温度处理后.LED灯照射树脂试件表面和底部硬度值比卤素灯照射后的硬度值高(P＜0.01).结论:树脂试件使用前预加热处理,可以增强树脂的硬度;第2代LED灯的固化效率优于卤素灯.     

两种新型光固化灯与传统卤素灯照射复合树脂固化效果的比较

目的 探讨新型光固化灯Starlight S型LED光固化灯、DNX-TW-518型等离子弧光灯与传统的卤素光固化灯对Z100(3M,America)光固化复合树脂的固化深度和表面硬度的影响.方法 根据ISO 4049:2000标准.分别用两种新型光固化灯与传统卤素灯在标准条件下照射同一种复合树脂.检测其各自的固化深度和硬度.测试结果用SPSS软件进行方差分析和Dunnett-t检验,α=0.05.结果 卤素先固化灯照射Z100复合树脂40s组的平均固化深度可达3.760mm.高于LED光固化灯照射10s组的平均固化深彪.285mm(P<0.05);略高于LED光固化灯照射208组的平均固化深度3.693mm,但两者之同比较差别无统计学意义(P>0.05).等离子弧光灯照射3s组、5s组的平均固化深度分剐为1.984mm、2.575mm,均小于卤素灯照射40s组(P<0.05).而等离子孤光灯照射10s组的平均固化深度为4.387mm.高于卤素灯照射40s组(P灯20S组(55.309±4.472)GPa(P0.05).结论 不同光固化灯照射光敏复合树脂在相同条件下的固化深度和表面硬度不同.两种新型光固化灯田化复合树脂的潜力与卤素灯相似甚至有些方面胜于卤素灯.适合于口腔临床应用.     

流动性复合树脂核材料在短时超高光强照射下的聚合效果

目的:评估流动性双重固化复合树脂核材料在短时超高强度照射下的聚合效果.方法:将双重固化流动性复合树脂核材料(regular dentine,Para core)注满单端开口的长方体形不透光硅橡胶模具中,将光固化灯紧贴开口端,以1000 mW/cm2持续照射10、20 s或以3200 mW/cm2持续照射3、6s.试件避光保存1h后取出,测量试件纵断面距照射光源1～10 mm间,以1 mm为间隔共10个深度的努氏显微硬度以判断聚合效果.试件继续避光保存24 h后,重复上述测量.采用SPSS 16.0软件包对数据进行统计学分析.结果:除3200 mW/cm2、3s光照射条件无法引发光固化反应外,在其余光照射条件下,试件在光影响深度内的硬度值在光照后24 h都显著高于单纯化学固化产生的硬度值,但光照射对试件的影响深度有限.在试件的光影响深度内,随着光照射时间的延长,试件的硬度值得到显著提高;而试件在3200 mW/cm2、6 s和1000 mW/em2、20 s条件下光照射后24 h的硬度值无显著差异.结论:3200 mW/cm2光强度照射时间必须延长到6s,才能保证引发流动性复合树脂核材料的光固化反应,并获得合适的聚合效果.     

瓷块厚度及透光性对树脂水门汀固化硬度的影响

目的 研究瓷块的厚度和透光性对不同类型树脂水门汀固化硬度的影响,为临床的全瓷粘接提供参考。方法 选择三种树脂水门汀Choice2,Duolink,RelyX Ultimate Clicker,分别通过不同厚度(0.5 mm、1.0 mm、1.5 mm、2.0 mm)的高透(HT)和低透(LT)的IPS e.max Presss瓷块,用800 mw/cm²高强度LED灯进行光照固化。三种树脂水门汀透过盖玻片照射的试件作为对照组。在固化后30 min和24 h通过显微硬度仪测量固化后树脂的表面努氏硬度值。评价瓷块厚度和透光性对树脂水门汀固化硬度的影响。结果 Choice 2固化后的努氏硬度值在各个厚度及透光度下与对照组相比均显著降低。Duolink和RelyX Ultimate固化后的努氏硬度值在HT瓷块厚度达到2.0mm时,实验组与对照组相比显著降低。在LT瓷块中,当厚度达到1.5 mm时,实验组硬度值即显著降低。结论 当IPS e.max Presss低透瓷块达到1.5 mm厚度,高透瓷块达到2.0 mm厚度时,树脂水门汀的固化硬度会显著降低,从...     

光固化灯功率密度的影响因素分析

目的 分析复合树脂充填治疗中可能影响复合树脂固化的光固化灯的使用因素,为临床选择合适的光固化灯提供参考.方法 调查杭州市两家口腔专科医院104盏临床使用的光固化灯的功率密度及相关信息;对其中3盏不同功率密度的光固化灯(分别为1、2、3号灯)以不同距离和角度照射及光固化灯使用不同防护套前、后功率密度的变化进行对比分析.结果 104盏光固化灯的功率密度范围为0 ～ 1180 mW/cm2,平均值为(519.7±294.5) mW/cm2.随着光固化灯光导棒照射距离和角度的增加,辐射仪感应窗测得的功率密度值降低,当照射距离增加至8 mm时,1、2、3号灯的功率密度值分别从(1133.7±17.6)、(895.3±7.4)、(401.3±6.0) mW/cm2下降为(545.7±25.1)、(448.0±22.7)、(200.0±7.5) mW/cm2,均为初始功率密度值的50％;加大照射角度至60°,1、2、3号灯的功率密度值分别下降为(269.0±3.0)、(265.3±26.8)和(129.7±4.7) mW/cm2,三者差异有统计学意义(P＜0.05).光固化灯头使用防护套后,功率密度为初始密度的80.2％ ～ 100％,防护套使用前、后的功率密度值差异有统计学意义(P＜0.05).结论 进行树脂充填治疗时应考虑以上临床影响因素,选择功率密度在600 mW/cm2以上的光固化灯,才能更好地满足光固化树脂充分固化的要求.     

颜色及光照射条件对复合树脂核材料聚合的影响

目的:评估材料颜色和光照射条件对流动性双重固化复合树脂核材料聚合的影响.方法:将双重固化流动性复合树脂核材料(牙本质色和白色,Para Core)注满单端开口的长方体不透光硅橡胶模具中,将光固化灯紧贴开口端以1000 mW/cm2持续照射20 s或以3 200 mW/cm2持续照射6 s获得4组试件(n=5).试件避光保存1h后,测量试件纵断面距光源1、2、3mm深度的努氏显微硬度.试件继续避光保存24 h后,重复上述测量.采用单因素方差分析对数据进行统计学分析.结果:4组试件随测量深度的增加试件的硬度值显著降低.光照后24 h,牙本质色试件每个测量深度的硬度值在1 000 mW/cm2×20 s和3 200 mW/cm2×6 s条件间无显著差异,但白色试件每个测量深度的1 000 mW/cm2×20 s的硬度值要显著高于3 200 mW/cm2 × 6 s的硬度值.结论:不同颜色的复合树脂核材料需要选择合适的光照射条件来获得最佳的聚合效果.     

2种光固化灯固化对3种不同复合树脂聚合收缩的影响

目的:比较2种光固化灯对3种复合树脂聚合收缩的影响。方法:相移投影栅形貌测量仪测量Z100、Z250、AP-X等3种复合树脂在卤素灯和发光二极管固化灯开始固化后50s及开始固化后400s的树脂聚合收缩量。使用SPSS12.0软件包对QTH及LED固化组聚合收缩量进行单因素方差分析。结果:在开始固化后50s和400s,QTH固化灯和LED固化灯固化Z100、Z250树脂产生的聚合收缩量有显著差异,QTH固化灯固化Z100、Z250树脂产生的聚合收缩量显著大于LED固化灯(P<0.05),QTH和LED固化灯固化AP-X树脂产生的聚合收缩量则无统计学差异(P>0.05)。结论:LED及QTH固化灯固化Z100、Z250树脂产生的聚合收缩影响有显著差异(P<0.05),LED及QTH固化灯固化AP-X产生的聚合收缩无显著差异(P>0.05)。     

Curing efficiency of three different curing modes at different distances for four composites

This study investigated the influence of the different curing distances with three polymerization modes in terms of the surface microhardness of four resin composites as a function of energy density. A hybrid resin composite and flowable composite from each of two manufacturers were evaluated. The specimens were polymerized with one of two light-curing units: 1) Mini LED AutoFocus (1500 mW/cm2) with a fast curing mode, for which two polymerization regimens were used: a) one AutoFocus function cycle and b) two AutoFocus function cycles, and 2) LEDemetron I (950 mW/cm2) with a 20-second curing time. Polymerization was performed with the curing tip at a distance of 0 mm, 3.0 mm, 6.0 mm, and 9.0 mm from the top surface of the specimen, and the power density of each light source was measured with a spectrophotometer. All specimens were stored in distilled water in a light-proof container at 37°C for 24 hours, and their top and bottom surface Knoop hardness numbers were determined. Microhardness data were submitted to two-way analysis of variance and multiple comparisons with a Tukey test. All statistical analyses were performed at a significance level of 0.05. Though the curing lights tested exhibited a decrease in power density with distance, the rate and extent of power density loss were not the same. The polymerization mode and curing tip distance had a significant effect on the composite microhardness. There was also a significant interaction among polymerization mode, curing tip distance, and microhardness. The curing ability of the three polymerization modes was ranked in terms of the hardness percent values: the LEDemetron I > two cycles of the Mini LED AutoFocus > one cycle of the Mini LED AutoFocus.     

Evaluation of a dual peak third generation LED curing light

This study compared 3 light-emitting diode curing lights (UltraLume 5, FreeLight 2, LEDemetron I) with a quartz-tungsten-halogen light (Optilux 401) to determine which was the better at photopolymerizing 5 resin composites. The composites were 2 mm thick and were irradiated for the manufacturers' recommended curing times at distances of 2 mm and 8 mm from the light guide. The Knoop hardness at each of 22 points over a 10-mm diameter footprint at the top and bottom of the composites was used to compare the lights. The 4 curing lights and irradiation distances did not have the same effect on all the composites (P < .001). It was concluded that overall the UltraLume 5 dual peak third generation LED curing light was able to polymerize these 5 resin composites as well as or better than the other curing lights.     

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.     

Hardness of a bleaching-shade resin composite polymerized with different light-curing sources

The microhardness of a bleaching-shade resin composite polymerized with different light-curing units was evaluated. Composite samples (3M ESPE Filtek Supreme) were applied to brass rings (2 mm in thickness, 5 mm in diameter). Three commercial LED lights were used to polymerize the specimens and the results were compared to those of a conventional halogen light. The light sources used in the present study were: Demetron Optilux 401 (QTH), 3M ESPE Elipar FreeLight (LED 1); Kerr L.E. Demetron I (LED 2), and ColtoluxLED lights (LED 3). The microhardness of the top and bottom surfaces was assessed with a digital Vickers hardness-measuring instrument, under load. At the bottom surface, no significant difference among the light sources was observed (two-way ANOVA). At the top surface, the QTH light source presented significantly higher hardness values compared to the values observed when LED 1 and LED 3 were used. There were no significant differences between the QTH and LED 2 light sources. Significantly higher hardness values were also found at the top surface when compared to the values observed at the bottom surface. The power density of the polymerization light sources seemed to be responsible for the observed resin composite hardness, not their irradiance.     

Variation of depth of cure and intensity with distance using LED curing lights.

OBJECTIVES: The purpose of the study was to determine the correlation between intensity of light-emitting diode (LED) and tungsten-halogen light sources, and depth of cure of a resin composite at different distances. METHODS: Four LED curing lights (Flashlite 1001, Freelight 2, Smartlite IQ and Ultralume 5) and one tungsten halogen (Optilux 501, with 8 and 11 mm tips) were evaluated. Intensity was measured according a modified ISO Standard 10650 at distances of 0, 2, 4, 6, 8, 10 mm between the light tip and detector. Depth of cure (DOC) of TPH Spectrum shade A2 was measured according to the international standard ISO 4049 at the same distances. RESULTS: For all lights, intensity decreased as distance increased. The authors documented a logarithmic correlation between intensity and distance for all lights except the Smartlite IQ, Ultralume 5 and the Optilux 501 with the 11 mm tip, which showed a linear relationship between intensity and distance. All lights demonstrated a logarithmic correlation between intensity and DOC, and a linear correlation between DOC and distance. Smartlite IQ and Optilux 501 (11 mm tip) also had the least reduction in intensity and DOC at 10 mm. SIGNIFICANCE: Clinicians often an experience difficulty placing the light tip close to the resin surface when curing resin composites. While both intensity and DOC decrease with increasing distance, the relationship between these factors and distance may not be similar for all lights and may depend on the characteristics of individual lights.     

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).     

Cure width potential for MOD resin composite molar restorations

OBJECTIVES: To investigate the capability of modern light-curing units exhibiting differences in emission spectra and light source exit window dimensions, for "one-shot" full-width curing of extensive (molar MOD) resin composite restorations. METHOD: Specimens of Tetric (TT), Tetric Ceram HB (TC), Tetric Evoceram (TE) and Tetric Ceram Bleach (TB) resin composites containing varying ratios of Lucirin (TPO) and/or camphorquinone (CQ) photoinitiators were packed into a bar-shaped mould (12 mm length x 2 mm width x 2 mm thickness). Each product was irradiated using a halogen (Optilux 401; QTH), a conventional LED (LEDemetron; LED) and two so-called "third generation" oval-footprint LED light-curing units (LCUs) of the same model. The latter featured bimodal emission spectra (blue and ultraviolet diodes) with either high (unmodified output) and approximately 50% (modified output) blue light intensity (UltraLume-5; ULs, ULm, respectively). Vickers hardness number was obtained across the lateral extent of the bar at 1mm increments from the centre point on both upper and lower surfaces of the specimens. RESULTS: Significant linear relationships (R(2)=0.71-0.98) for each distance from the central position of all LCUs were identified between measured light intensity and corresponding upper and lower surface hardness values for each product (P<0.05). No significant differences (P>0.05) were recorded in total upper surface hardness of TC or TE cured with LED (68.7+/-3.2 and 70.5+/-2.5) or ULm (56.8+/-2.0 and 57.7+/-2.0). However, upper surface hardness of TT (CQ only) cured with ULm was significantly decreased (P<0.05) compared with other LCUs. When the ratio of hardness at the edge to central positions of the bar-shaped specimens for either surface was calculated, no significant difference (P>0.05) was identified for TB (containing TPO and decreased CQ) cured with either ULs or ULm (P>0.05) and was significantly increased (P<0.05) when cured with ULs compared with LED and QTH. SIGNIFICANCE: Variability in light intensity across the curing-tip face, spectral output of dental light-curing units and differences in product photoinitiator chemistry all influence curing efficiency significantly across the width of extensive resin composite geometries.     

Influence of curing tip distance on resin composite Knoop hardness number,using three different light curing units

This in vitro study evaluated the influence of curing tip distance on the Knoop Hardness Number (KHN) of a resin composite when using three different light curing units: (1) a halogen light (XL 1500 curing unit-3M), (2) a "softstart-polymerization" (Elipar Trilight curing in an exponential mode-ESPE) and (3) a PAC (Apolo 95E curing unit-DMD). The resin composite, Filtek Z250 (3M), was cured by these curing units at three light-tip distances from the resin composite: 0 mm, 6 mm and 12 mm. The resin composite specimens were flattened to their middle portion and submitted to 18 KHN measurements perspecimen. The results showed that for the Elipar Trilight unit, the hardness of the resin composite decreased as the light tip distance increased. The XL 1500 unit presented a significant decrease in hardness as the depth of cure of the resin composite increased. Apolo 95E caused a decrease in the resin composite hardness values when the depth of cure and light tip distance increased.     

INFLUENCE OF THE DISTANCE OF THE CURING LIGHT SOURCE AND COMPOSITE SHADE ON HARDNESS OF TWO COMPOSITES

This study evaluated the influence of curing tip distance, shade and filler particle size on Vickers microhardness (VHN) of composite resins. Two composites were tested: Filtek Z250 microhybrid (3M ESPE; shades A1 and A3.5) and Filtek Supreme nanofilled (3M ESPE; shades A1B and A3.5B). For each resin, 42 specimens (5 mm in diameter and 2 mm height) were prepared being 21 for each shade. The specimens were exposed using a 20-second exposure to a quartz-tungsten-halogen light source with an irradiance of approximately 560 mW/cm², at the following distances: 0 mm (surface contact), 6 mm and 12 mm from composite surface. Effectiveness of cure of different resins, shades and curing distances was determined by measuring the top and bottom hardness (VHN) of specimens using a digital microhardness tester (load: 50 g; dwell time: 45 seconds) 24 hours following curing. The hardness ratio was calculated by dividing VHN of the bottom surface by VHN of top surface. Three-way ANOVA and Tukey''s post-hoc test (p<0.05) revealed statistically significant differences for all analyzed factors. As for top hardness, as microhardness ratio (bottom/top), the factors shade, distance and composite filler particle size exerted influence on resin curing. Lighter shade composites (A1 and A1B) showed higher hardness values. At 6 and 12 mm curing tip distances, hardness was lower when compared to 0 mm. The microhybrid composite resin presented higheer hardness, being its microhardness ratio satisfactory only at 0 mm for both shades and at 6 mm for the lighter shade. The nanofilled composite resin did not present satisfactory microhardness at the bottom while the microhybrid composite resin had higher hardness than the nanofilled. Composite''s curing tip distance and shade can influence hardness.