Er:YAG激光照射牙科全瓷材料后的光透射率和温度变化分析

目的 评估牙科全瓷材料的光学特性和激光穿透全瓷材料后温度变化之间的关系,为临床提供依据和指导。方法 选择两种光学特性不同的全瓷样品（Zenostar T、X-CERA TT）制成不同厚度的方块。用分光光度计测量两种样品在不同厚度下的光透射率;将Er：YAG激光设定波长为2 940 nm,频率为15 Hz,脉宽为330 us,光斑直径为1 mm,照射全瓷瓷块样品5 s,用热电偶温度计测量激光穿透样品前后的温度,计算其温度变化情况。结果 两种材料的光透射率都随着样品厚度的增加而下降,同等厚度的瓷块在200 ～ 780 nm波长光源照射下,Zenostar T与X-CERA TT的光透射率不存在明显差异;在780 ～ 2 500 nm波长光源,X-CERA TT样品的光透射率高于Zenostar T样品。Er：YAG激光能量从50 mJ逐级增加,至250 mJ,温度测量结果显示：Zenostar T和X-CERA TT全瓷样品测试温度分别升高5.01 ～ 56.5℃和3.67 ～ 34.4℃。在1 ～ 1.5 mm样品厚度区间内,随着Er：YAG激光照射能量增加后,Zenostar T样品的温度升高幅度均高于X-CERA TT样品（P< 0.05）;样品为2 ～ 2.5 mm厚度时,Zenostar T和X-CERA TT样品的温度变化幅度之间没有统计学差异（P> 0.05）。所有样品的光透射率及温度测试的结果均符合指数分布,但是两者之间不存在指数相关性。结论 Er：YAG激光穿透牙科全瓷材料后的温度变化与该材料光学透射性之间不存在明显相关性。     

Er:YAG激光在拆除全瓷修复体中应用的研究进展

全瓷修复体因兼具美观性及高强度在口腔修复中被广泛应用。玻璃陶瓷及氧化锆全瓷材料是临床中应用最为广泛的两种全瓷材料。然而,当全瓷修复体因边缘微渗漏、继发龋等问题需要拆除时,其高强度和高粘接强度极大地增加了拆除难度。近年来,临床医师开始尝试使用Er:YAG激光拆除全瓷修复体。研究表明,Er:YAG激光可以安全高效地应用于玻璃陶瓷修复体的拆除,对于较薄的氧化锆修复体也能发挥作用。全瓷修复体材质及厚度、水门汀类型、激光功率等多种因素均可以影响Er:YAG激光的作用时间。然而,目前研究局限于病例报道及体外研究,缺乏系统的临床研究。Er:YAG激光拆除全瓷修复体的具体作用机制以及激光频率、粘接剂类型、基牙对拆除速度的影响有待进一步研究。     

Er:YAG激光预处理对牙本质-全瓷粘结剪切强度影响的体外研究

目的研究Er:YAG激光预处理牙本质对牙本质与全瓷粘结剪切强度的影响,以期为Er:YAG激光在临床的应用提供参考。方法选择新鲜拔除的完整第三磨牙80颗,根据表面处理方法不同随机分为5组,每组颊面标记为ABCDE,舌面标记为abcde。A/a:Er:YAG激光光照+Optibond Versa/Adper Easy One组;B/b:Er:YAG激光光照+35%磷酸酸蚀+Optibond Solo Plus/Adper Single Bond 2组;C/c:Er:YAG光照能量密度15.73 J/cm~2/31.46 J/cm~2组;D/d:Optibond Versa/Adper Easy One粘结剂组;E/e:35%磷酸酸蚀+Optibond Solo Plus/Adper Single Bond 2组。计算机设计制作牙制作直径3 mm厚2 mm IPS e.max PressⅡ瓷块,常规粘结后制作剪切试件并测剪切粘结强度,电子显微镜下观察断裂类型。SPSS20.0统计学分析软件分别对实验数据进行单因素方差分析和χ~2检验,对实验数据进行两两比较。结果 Er:YAG激光光照与全酸蚀粘结剂联合组剪切强度(23.01±4.41/25.37±3.96)MPa,显著高于其他组,差异有统计学意义(P<0.05)。结论不同厂家的全酸蚀粘结剂联合Er:YAG激光预处理牙面均能够有效提高牙本质与全瓷的粘接强度。     

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目的评价Er:YAG激光照射对牙本质与瓷块间粘接强度的影响。方法选取2010年9月至2011年9月山西医科大学口腔医院颌面外科因正畸拔除的完整无龋坏、无隐裂的前磨牙30颗,分别制备3mm×3mm的牙本质面,随机分为以下3组:Er:YAG激光组、酸蚀组、酸蚀+Er:YAG激光组,每组10个样本。通过扫描电镜观察各组样本的表面形态,并检测牙本质与瓷块间的粘接强度。结果酸蚀+Er:YAG激光组粘接强度值最高,与酸蚀组和Er:YAG激光组相比较,差异有统计学意义(P<0.01),而酸蚀组与Er:YAG激光组间差异无统计学意义(P>0.05)。结论酸蚀联合Er:YAG激光照射能够增强牙本质与瓷块间的粘接强度,是牙体组织粘接前有效的表面处理方式。     

厚度与颜色影响IPS e.max和In-Ceram全瓷修复体色彩再现效果的实验研究

目的：研究IPS e.max和VITA In-Ceram氧化铝2种全瓷材料不同瓷层厚度与颜色对修复体色彩再现的影响,探索全瓷修复体的混色规律,为全瓷修复的临床比色、配色等提供实验依据。方法：2种全瓷材料各以A1、A2、A3为目标颜色制作不同厚度的圆形试件：IPS e.max铸瓷（0.6mm、0.9mm、1.2mm、1.5mm）;VITA In-Ce-ram切削氧化铝（核冠/饰瓷：0.5/1.2mm、0.7/1.0mm、0.9/0.8mm）,同一厚度同一颜色各制作直径为15mm的圆盘形试件7个,共计147个。使用Crystaleye分光光度比色仪对试件的颜色进行测量,测量结果以CIE＊a＊b＊格式表示。结果：2种全瓷材料黑白背景下的色差值（△E和△L）均受到厚度和颜色的影响,其差别有统计学意义（P〈0.05）。结论：在有限的临床修复空间中,全瓷材料的颜色改变、厚度的微小差别以及体瓷和饰瓷之间的厚度变化将影响修复体最终的颜色和透明性。     

Er:YAG激光治疗牙体牙髓病的研究进展

Er:YAG激光是一种新型牙体硬组织激光,可以高效地切割牙体并且不会对牙髓造成热损伤。临床上Er:YAG激光可用于去龋备洞及粘结修复前的牙面蚀刻。另外,Er:YAG激光在根管预备以及盖髓术、牙髓切断术中也有着良好的应用前景。     

不同脉冲宽度Er: YAG激光激活根管荡洗的研究

目的:探究Er:YAG激光的不同脉冲宽度模式对激光在前牙单根管树脂模型内形成的空泡动力及热沉积效应的影响。方法:示波器精确测定Er:YAG激光不同脉冲宽度模式的脉冲波形。在单根管树脂模型中,应用Er:YAG激光不同脉冲宽度模式进行激光激活荡洗.高速摄像机对激活荡洗形成的空泡进行摄录,并对图像进行分析,计算空泡直径、空泡体积、膨胀周期、塌缩周期和总周期。热电偶测量根管模型内髓腔液体温度变化,SPSS 19.0进行统计分析。结果:Er:YAG激光呈现驰豫振荡的固体激光特性。不同脉冲宽度模式下,首个脉冲峰宽度存在显著差异,空泡直径、空泡体积、塌缩周期和振荡周期随脉宽的增大而减小(P<0.05),髓腔液体温度随脉宽增大而增加(P<0.05)。结论:Er:YAG激光激活荡洗过程中,脉宽越窄,激光输出的首个脉冲峰宽度越小,空泡体积越大,髓腔内液体升温越低。窄脉宽Er:YAG激光模式可能更有利于激光激活荡洗。     

不同参数激光处理根管对纤维桩粘结强度影响的实验研究

目的:研究不同参数Er:YAG激光处理根管壁牙本质对纤维桩粘结强度的影响,为激光临床应用提供参考。方法:收集60颗人类上颌中切牙,根据不同处理方法随机分为5组;空白对照组;3 W-50 μs Er:YAG激光组;3 W-100 μs Er:YAG 激光组;4.5 W-50 μs Er:YAG激光组;4.5 W-100 μs Er:YAG激光组,每组12颗。离体牙根管预备,充填,桩道预备后,Bisco树脂加强型纤维桩通过RelyX^TM Unicem粘结树脂水门汀粘固于根管内。流水状态下慢速锯将纤维桩外周平行片切,再垂直粘结面片于试件1 mm、4 mm、7 mm处切成三段1.0 mm×1.0 mm的长方形柱状试件,进行微拉伸强度测试。不同根管处理方法与牙根不同区域微拉伸强度均数采用两因素方差分析(α=0.05)。电镜下进行断裂类型分析,组件不同类型断裂率采用χ²检验(α=0.05)。 结果:3 W10-100 μs Er:YAG组拉伸强度值最高(5.55±0.97) MPa,与对照组(4.06±1.22) MPa相比较差异有显著性(P＜0.05) 。根管上部和中部粘结强度高于根管下部,差异有显著性(P＜0.05)。结论:Er:YAG激光处理牙本质表面对其与纤维桩粘结强度的影响与激光功率大小和脉冲持续时间有关,3 W-100 μs Er:YAG激光处理表面可以显著增强纤维桩与根管牙本质的粘结强度。     

Er∶YAG激光对牙本质与瓷块间粘接强度影响研究

目的 评价Er∶YAG激光照射对牙本质与瓷块间粘接强度的影响.方法 选取2010年9月至2011年9月山西医科大学口腔医院颌面外科因正畸拔除的完整无龋坏、无隐裂的前磨牙30颗,分别制备3 mm ×3 mm的牙本质面,随机分为以下3组:Er∶YAG激光组、酸蚀组、酸蚀+Er∶YAG激光组,每组10个样本.通过扫描电镜观察各组样本的表面形态,并检测牙本质与瓷块间的粘接强度.结果 酸蚀+Er∶YAG激光组粘接强度值最高,与酸蚀组和Er∶YAG激光组相比较,差异有统计学意义(P＜0.01),而酸蚀组与Er∶YAG激光组间差异无统计学意义(P＞0.05).结论 酸蚀联合Er∶YAG激光照射能够增强牙本质与瓷块间的粘接强度,是牙体组织粘接前有效的表面处理方式.     

点阵Er:YAG激光照射兔口腔黏膜后的组织学变化

目的: 研究点阵Er:YAG激光照射口腔黏膜后的组织学变化。方法: 使用Er:YAG激光照射家兔口腔黏膜,应用H-E、Masson、弹性纤维染色方法,评估照射后1、2、4周黏膜上皮厚度、固有层胶原纤维和弹性纤维含量。采用SPSS19.0软件包对实验结果进行统计学分析。结果: 点阵Er:YAG照射后,黏膜损伤区仅限黏膜上皮内,3~7 d后完全愈合,不遗留色素及瘢痕,黏膜上皮厚度显著增加（P<0.05）,固有层胶原纤维、弹性纤维含量显著增加（P<0.05）。点阵Er:YAG激光照射家兔口腔黏膜损伤小、愈合快,黏膜上皮重构,黏膜固有层胶原变性、收缩。结论: 点阵Er:YAG激光照射口腔黏膜后,胶原纤维及弹性纤维增生、重组,黏膜收紧,弹性增加。     

Compositional analysis of root cementum and dentin after Er:YAG laser irradiation compared with CO2 lased and intact roots using Fourier transformed infrared spectroscopy

The present study examines the dental root after Er:YAG laser irradiation, compared with CO2 lased and non-treated surfaces, using Fourier Transformed Infrared (FTIR) spectroscopy. Freshly extracted human teeth were irradiated by Er:YAG laser at an energy output of 40 mJ/pulse, 10 Hz (0.4 watts), with or without water coolant, and by CO2 laser at an energy output of 0.5 watts in continuous wave mode without coolant. The surfaces were chalky and smooth after irradiation by Er:YAG laser with water coolant, were charred and irregular after irradiation by Er:YAG laser without water coolant, and were completely carbonized after CO2 laser irradiation. The FTIR profiles from samples of the surfaces that were irradiated by Er:YAG laser with water coolant were similar to those from non-treated samples, except for a slight decrease on the OH and amide bands, which are mainly related to organic components. This decrease was observed to be extreme after CO2 laser irradiation and moderate after Er:YAG laser irradiation without coolant. The formation of new bands showing toxic substances was observed to a large extent after CO2 laser irradiation and to a smaller extent after Er:YAG laser irradiation without water coolant. In contrast, no such bands were detected after Er:YAG laser irradiation with water coolant. The present results show that these laser treatments selectively ablated more organic components than inorganic components and that Er:YAG laser irradiation with water coolant did not cause major compositional changes or chemically deleterious changes in either root cementum or dentin.     

Er:YAG激光照射后釉质结构和成分变化的研究

目的:观察Er:YAG激光不同能量和照射时间对釉质表面形态和成分的影响。方法:处理后的104个釉质样本随机抽取8个为C组(空白对照组),剩余部分随机分为A(照射10 s)和B(照射20 s)两大实验组,其中每一大组再随机分为6个小组,分别用Er:YAG激光以1～6 W不同能量进行照射。照射后体视显微镜测量A、B两组凹坑的直径和深度,能量色散型X射线荧光光谱(EDX)测定3组的Ca、P含量和其比值的变化。结果:1～6 W不同能量照射20 s(B组)的凹坑直径和深度均明显大于照射10 s(A组)各能量组,差异均有统计学意义(P<0.05);A、B两组实验组的Ca、P含量均明显高于空白对照组,差异有统计学意义(P<0.05);空白组和两实验组的Ca/P比值差均无统计学差异(P>0.05)。结论:在Er:YAG激光一定能量的照射下,釉质的结构和成分均会产生一定的变化。     

Effect of Er:YAG laser on adhesion of root canal sealers

This in vitro study evaluated the effect of Er:YAG laser on adhesion to human dentin of Grossman, Endomethasone, N-Rickert, and Sealer 26 root canal sealers. The crowns of 40 human molars were cut on the occlusal side until a flat dentin surface was obtained. The teeth were divided into two groups: group 1, no laser application; and group 2, irradiation with Er:YAG laser (KaVo Key Laser 2; 11 mm focal distance, perpendicular to the dentin surface, 4 Hz frequency, 200 mJ energy, 62 J total energy and 313 pulses, 1-min application time, and 2.25 W power). Five samples were tested for each sealer and each group. An Instron universal testing machine was used for the adhesion test. Sealer 26 showed the best adhesion both with and without laser application (p < 0.01). Grossman and N-Rickert sealers had intermediate values, and Endomethasone had the worst adhesion. Application of Er:YAG laser did not alter the adhesion of Grossman, N-Rickert, or Endomethasone sealers. However, laser application increased the adhesion of Sealer 26. The epoxy resin-based root canal sealer (Sealer 26) adhered better to dentin prepared with and without Er:YAG laser than the zinc oxide/eugenol-based sealers (Endomethasone, N-Rickert, and Grossman).     

Effect of low-level Er:YAG laser irradiation on cultured human gingival fibroblasts

BACKGROUND: Low-level laser irradiation has been reported to enhance wound healing. Activation of gingival fibroblasts (GF) has a potential for early wound healing in periodontal treatment. The present study aimed to investigate the direct effect of low-level Er:YAG laser irradiation on gingival fibroblasts proliferation in order to clarify the laser effect on healing. METHODS: Cultured human gingival fibroblasts (hGF) were exposed to low-power, pulsed Er:YAG laser irradiation with different energy densities ranging from 1.68 to 5.0 J/cm(2). The cultures were analyzed by means of trypan blue staining and counted under a light microscope. The effect of Er:YAG laser on hGF was also evaluated using a transmission electron microscope (TEM). RESULTS: Cultures irradiated with Er:YAG laser presented faster cell growth when compared with untreated controls. This difference was statistically significant. Transmission electron microscopy revealed rough endoplasmic reticulum, prominent Golgi complexes, and mitochondria after laser irradiation. CONCLUSIONS: Our results showed that the low-level Er:YAG laser irradiation stimulates the proliferation of cultured gingival fibroblasts. The optimal stimulative energy density was found to be 3.37 J/cm(2). This result suggests that Er:YAG laser irradiation may be of therapeutic benefit for wound healing.     

Er：YAG激光照射离体牙釉质后表面形态和髓腔温度的观察

目的观察不同能量和时间作用下Er：YAG激光照射人离体牙釉质后表面形态和髓腔温度的变化。方法临床收集24颗离体牙,制备成96个实验样本,按不同处理方法分为A、B两组,分别照射10、20 s,每组再分为6个亚组,选择超短脉冲20 Hz,分别采用1、2、3、4、5、6 W的能量对每个亚组样本的釉质进行照射,用数字式温度计记录髓腔温度的变化,扫描电子显微镜（SEM）下观察样本釉质形态的变化。结果随着照射时间的延长和能量的增加,髓腔温度有上升的趋势;SEM观察A、B两组的釉质形态均有改变,但两组均未发现熔融和碳化现象。结论在Er：YAG激光一定能量的照射下,釉质的形态和髓腔温度产生一定的变化,但是未出现熔融和碳化现象,为临床龋齿的治疗提供了依据。     

Effect of Er:YAG laser and EDTAC on the adhesiveness to dentine of different sealers containing calcium hydroxide

AIM: To evaluate the effect of 15% EDTAC solution and Er:YAG laser irradiation on the adhesiveness to dentine of root canal sealers containing calcium hydroxide. METHODOLOGY: The crowns of 60 maxillary human molars were ground until dentine was exposed. The teeth were divided into three groups of 20 teeth: group I, the dentine surface received no treatment; group II, 15% EDTAC solution was applied to the dentine; group III, the dentine received Er:YAG laser application (11 mm focal distance with perpendicular incidence to dentine surface; 4 Hz frequency; 200 mJ energy; 2.25 W potency; 62 J total energy; 1 min application time). Aluminium cylinders filled with the sealers, Sealer 26, Apexit, Sealapex and CRCS, were then applied to the treated surfaces. Adhesiveness was measured with a universal testing machine, with traction results given in MegaPascals (MPa). These results were submitted to anova tests. RESULTS: Statistical analysis showed significant differences (P < 0.01) amongst adhesiveness values of the sealers and treatments tested. Thus, sealers could be ranked in decreasing adhesiveness values: Sealer 26, CRCS, Apexit, Sealapex. Er:YAG laser irradiation and EDTAC solution application increased adhesiveness values only for Sealer 26 and Apexit. Laser irradiation was superior to EDTAC application only for Sealer 26 adhesiveness values. CONCLUSIONS: Er:YAG laser is as efficient as EDTAC solution in increasing adhesiveness of root canal sealers containing calcium hydroxide to human dentine.     

Scanning electron microscopy and Fourier transformed infrared spectroscopy analysis of bone removal using Er:YAG and CO2 lasers

BACKGROUND: A thorough analysis of laser-ablated bone tissue is required before applying the technique to osseous surgery. In this study, we examine the morphological features and chemical composition of the bone surface after Er:YAG and CO2 lasers ablation. METHODS: Six Wistar rats were used. An Er:YAG laser was used for ablation at an output energy of 100 mJ/pulse and a pulse rate of 10 Hz (1 W). Continuous CO2 laser irradiation was performed at an output energy of 1 W. Sites drilled using a conventional micromotor were used as controls. Analysis using scanning electron microscopy (SEM) and Fourier transformed infrared (FTIR) spectroscopy was performed. RESULTS: Er:YAG laser ablation produced a groove with similar dimensions to that produced by bur drilling, whereas the CO2 laser produced only a charred line with minimal tissue removal. SEM observations revealed that the groove produced by the Er:YAG laser had well-defined edges and a smear layer-free surface with a characteristically rough appearance and with entrapped fibrin-like tissue. The melting and carbonization produced by the CO2 laser were not observed on sites irradiated by the Er:YAG laser. FTIR spectroscopy revealed that the chemical composition of the bone surface after Er:YAG laser ablation was much the same as that following bur drilling. The production of toxic substances that occurred after CO2 laser irradiation was not observed following Er:YAG laser irradiation or bur drilling. CONCLUSION: These results suggest that the use of Er:YAG laser ablation may become an alternative method for oral and periodontal osseous surgery.     

Scanning electron microscope comparative surface evaluation of glazed-lithium disilicate ceramics under different irradiation settings of Nd:YAG and Er:YAG lasers

Objective:To evaluate the surface of glazed lithium disilicate dental ceramics after irradiation under different irradiation settings of Nd:YAG and Er:YAG lasers using a scanning electron microscope (SEM).Materials and Methods:Three glazed-press lithium disilicate ceramic discs were treated with HF, Er:YAG, and Nd:YAG, respectively. The laser-setting variables tested were laser mode, repetition rate (Hz), power (W), time of exposure (seconds), and laser energy (mJ). Sixteen different variable settings were tested for each laser type, and all the samples were analyzed by SEM at 500× and 1000× magnification.Results:Surface analysis of the HF-treated sample showed a typical surface texture with a homogenously rough pattern and exposed ceramic crystals. Er:YAG showed no effect on the surface under any irradiation setting. The surface of Nd:YAG-irradiated samples showed cracking, melting, and resolidifying of the ceramic glaze. These changes became more pronounced as the power increased. At the highest power setting (2.25 W), craters on the surface with large areas of melted or resolidified glaze surrounded by globules were visible. However, there was little to no exposure of ceramic crystals or visible regular surface roughening.Conclusions:Neither Er:YAG nor Nd:YAG dental lasers exhibited adequate surface modification for bonding of orthodontic brackets on glazed lithium disilicate ceramics compared with the control treated with 9.5% HF.     

Temperature rise during Er:YAG and Nd:YAP laser ablation of dentin

This in vitro study compared temperature rises during cavity preparation with an Er:YAG laser, Nd:YAP laser, and a high-speed handpiece. Eighteen teeth were sectioned longitudinally and divided into six groups: group 1 was treated with a carbide bur on a high-speed dental handpiece; group 2 was treated with an Er:YAG laser with an energy of 140 mJ, a pulse repetition rate of 4 Hz; and group 3 was treated with an Nd:YAP laser with an energy of 240 mJ, a pulse repetition rate of 10 Hz. In these groups no water cooling was used. Groups 4 to 6 were treated in the same way, but with water spray. Temperature increases were measured at different dentin thicknesses by a microthermocouple attached to the inner side of the pulp chamber. Water cooling was essential to reduce temperature effects in all groups. Nd:YAP laser induced significantly higher temperature rises than Er:YAG or handpiece. Temperature response to the Er:YAG laser and the handpiece seemed to be similar.