脉冲Nd：YAG激光照射对牙本质通透性的影响

应用牙本质通透性测定装置，定量测定脉冲Ｎｄ：ＹＡＧ激光在不同参数条件下照射后对牙本质通透性的影响。结果表明：在４个不同的激光参数条件下，激光照射后牙本质通透性均较照射前呈显著性下降，其中以每秒１５个脉冲０．７５Ｗ的２．０ｍｉｎ组和每秒１５个脉冲１．００Ｗ的２．０ｍｉｎ组下降最为明显，与每秒１５个脉冲０．７５Ｗ的１．５ｍｉｎ组之间呈显著性差异（ＦＫＰＦＦ＜０．０５）。提示脉冲Ｎｄ：ＹＡＧ激光在一定参数条件下照射，可熔融和封闭牙本质小管，是治疗牙齿敏感症的有效手段之一     

Effects of Nd: YAG laser irradiation on the root canal wall dentin of human teeth: a SEM study

The purpose of this study was to observe the morphological and histological changes on the root canal walls after Nd:YAG laser application. Twenty vital, recently extracted single-rooted human teeth were used for this study. Root canals were cleaned and shaped by a conventional step-back technique--by means of k files up to a 20 k-file type at working length--and subsequently shaped by Ni-Ti root-canal rotary instrumentation up to 30/06 and irrigated with 2.5% hypochlorite solution. Ten teeth (control group) were left unlased, while the other ten teeth were irradiated with Nd:YAG laser by means of a 320 microns fibre inserted in the root canal at 1 mm from the apex with a power of 1.5 Watt and a frequency of 15 pps for five seconds in retraction with rotating movements. The control specimen showed debris and smear layer on the root canal surface obscuring the dentin tubules. The root canal walls irradiated with Nd:YAG laser showed a clear glazed surface, some open dentinal tubules and some surface craters with cracks. Such results confirm that smear layer and debris are removable with Nd:YAG laser, however clearing all root canal walls is still difficult and, if the energy level and duration of application are inadequate, a certain degree of thermal damage and morphological changes in dentin structure are observable.     

Nd: YAG laser irradiation in root canal disinfection

Abstract The purpose of this study was to assess the efficacy of Nd:YAG laser irradiation in disinfecting the root canal system. Seventy-five teeth were uniformly instrumented and sterilized, and their root canals were infected for 60 min with an overnight culture of Enterococcus faecalis in Tryptic Soy Broth. The teeth were divided into 6 groups: 1 - non-infected controls; 2 - infected controls; 3 - infected, laser treated; 4 - infected, laser dummy (dye only); 5 - infected, laser dummy (dye and air-water spray); 6 - infected, NaOCl-treated (reference group). After treatment, the root canals were dried and dentinal shavings removed for a post-treatment culture. Quantitative analysis of bacteria surviving the various treatments were performed, and the bacterial counts for each group were compared. SEM analysis of teeth split longitudinally was used to illustrate the effect of treatment on the smear layer and on surface bacteria. Nd:YAG laser irradiation (group 3) significantly reduced the number of bacteria while NaOCl irrigation (group 6) effectively disinfected the canals.     

Nd: YAG激光对牙根面结构及变异链球菌黏附的影响

目的 研究不同功率的水冷Nd: YAG激光照射治疗对牙根面结构及变异链球菌黏附的影响。方法 将因重度慢性牙周炎拔除的离体牙分为4组,均进行手工刮治和根面平整,制备牙根片,激光1、2、3组分别用功率为4、6、8 W的水冷Nd: YAG激光照射处理60 s,对照组不作处理。用扫描电子显微镜（SEM）观察各组根片的表面结构。将变异链球菌接种于各组牙根片表面并进行培养,计数各组根片表面细菌的黏附量（CFU·mL-1）;同时用SEM观察对照组及激光2组根面的细菌黏附情况。结果 SEM观察根片表面结构,激光组较对照组牙根表面的玷污层、碎屑及菌斑样物质附着减少,但裂隙增多。3个激光组牙根表面的细菌黏附量均少于对照组（P<0.05）,而不同功率的激光组之间的差异无统计学意义（P>0.05）。SEM观察细菌黏附情况,激光2组表面的细菌黏附量明显少于对照组。结论 与单纯刮治相比,刮治后进行水冷Nd: YAG激光治疗能清除牙根表面的玷污层、碎屑及菌斑样物质,并能减少变异链球菌的黏附,但激光会导致牙根表面出现裂隙。本实验中,6 W为激光最佳功率,既能较好地去除牙根表面的玷污层和碎屑等,又能较好地控制激光对根面的热损害程度。     

Temperature elevation on the root surface during Nd:YAG laser irradiation in the root canal.

Nd:YAG lasers have been suggested as a potential tool in endodontic therapy because of their sterilizing and sealing effects on the dentinal tubules. However, the generation of heat in the root canal by laser irradiation may produce potentially harmful effects on adjacent tissues. The purpose of this study was to evaluate the temperature elevation on the root surface when Nd:YAG laser was irradiated in the root canal. The apical third area of 90 single-rooted teeth were irradiated with normal pulsed Nd:YAG laser (50, 80, 100, 150, and 200 mJ/pulse; 20, 25, and 30 pulses/s). The temperature elevation was measured and recorded on the root surface simultaneously. The temperature elevation did not exceed 10 degrees C only when the laser energy output was below 100 mJ/pulse and under 20 pulses/s.     

Pulpal space pressure and temperature changes from Nd:YAG laser irradiation of dentin

Objectives. To investigate pulpal space pressure and temperature after application of Nd:YAG laser, and high-speed diamond bur on dentin surface.

Methods. One and 3 W Nd:YAG laser and high-speed diamond bur were used to remove dentine from twenty extracted premolars. The pulp chambers were monitored for pressure and temperature changes with a pressure transducer and thermocouple, respectively.

Results. Regardless of the remaining dentin thickness (RDT), laser irradiation and high-speed diamond bur use generated an increase in pulpal space pressure and temperature (ANOVA and Fisher's LSD tests, P<0.001). Pressure and temperature increased with an increase in laser power. Three-Watt laser irradiation caused greater changes than 1 W (1.75 kPa and 1.31 °C, 0.53 kPa and 0.34 °C, respectively). Both pulpal space pressure (P<0.001) and temperature (P<0.005) increased as the RDT decreased.

Conclusions. Laser irradiation and the use of a high-speed diamond bur generated an increase in pulpal space pressure and temperature. Pulpal space pressure and temperature increased with an increase in energy density of laser and a decrease in RDT.     

Nd:YAG激光对不同水门汀与牙本质间边缘微渗漏的影响

目的:评价Nd:YAG激光对不同水门汀与牙本质之间边缘微渗漏的影响。方法:选用人离体磨牙48颗,间接法制作树脂嵌体,随机分为激光组和对照组,激光组使用80 mJ、10 Hz脉冲Nd:YAG激光照射后,分别用6种水门汀粘结树脂嵌体。全部试件放在37℃生理盐水中7 d,并冷热循环300次后,放置于0.5%的品红溶液中染色24 h,沿嵌体长轴纵剖后在根管显微镜下观察微渗漏情况,采用SPSS 17.0软件包对数据进行统计学处理。结果:6组牙本质经Nd:YAG激光照射后微渗漏程度均有降低趋势,且前2种水门汀有统计学差异(P<0.05)。另外,树脂水门汀与牙本质之间的微渗漏程度比水基水门汀低。结论:80 mJ、10 Hz脉冲Nd:YAG激光照射牙本质壁,可提高洞壁的密合度,减少微渗漏。     

脉冲Nd:YAG激光根管内照射对狗牙尖周组织的影响

目的：观察脉冲Ｎｄ：ＹＡＧ激光根管内照射对狗牙尖周组织的影响。方法;组织学切片法和超薄切片法。结果;２．１Ｗ,１４０ｍＪ,１５Ｈｚ的脉冲;Ｎｄ：ＹＡＧ激光根管内照射２５ｓ,对尖周组织产生了明显的损伤,并延缓了尖周病变的愈合。１．２Ｗ,８０ｍＪ,１５Ｈｚ的脉冲Ｎｄ;ＹＡＧ激光根管内照射２５ｓ,对尖周组织产生的损伤明显轻于传统根管治疗,有利于尖周病变的愈合。     

Effect of Nd:YAG laser irradiation on shear bond strength of glass-lonomer luting cement to dentin surface

PURPOSE: The purposes of this study were to evaluate the shear bond strength of luting glass-ionomer cement to a dentin surface treated by pulsed Nd:YAG laser irradiation, and to prove the hypothesis that the bond strength of glass-ionomer luting cement to dentin is favorably altered after Nd:YAG laser irradiation. MATERIALS AND METHODS: Sixty-four extracted human molars with an exposed flat dentin surface were divided into four groups (n = 16). After painting black ink on their surfaces, the teeth of groups 1, 2, and 3 were irradiated by an Nd:YAG laser at 1.064-microm wavelength at 1, 2, and 3 W, respectively; group 4 was untreated and served as a control. Some specimens of each group were used for morphologic and atomic analytic study, and the others were used for shear bond testing. The shear bond test was performed after cylindric titanium specimens were cemented with glass-ionomer cement on a circular dentin area and specimens were immersed in distilled water. The tested specimens were also morphologically investigated. RESULTS: Shear bond strength of group 3 was significantly higher than that of the control group. Morphologic observation of the cement-dentin interface showed good adaptation of the luting cement to laser-treated dentin. Analysis of atomic contents on the dentin surface showed a significant increase of calcium:phosphorus ratio after laser irradiation. CONCLUSION: The dentin surface was modified morphologically and chemically, and the shear bond strength of glass-ionomer luting cement to dentin was increased by Nd:YAG laser irradiation at 3 W.     

Treatment of dentin hypersensitivity by Nd:YAG laser

BACKGROUND, AIMS: Promising results using Nd:YAG laser against dentin hypersensitivity have been reported. The aim of this double-blind, controlled, split-mouth designed clinical trial was to assess the effect of a single Nd:YAG laser application on alleviating hypersensitivity. METHODS/RESULTS: Seventeen subjects participated in the study. Each of them had two teeth treated; one with the laser activated and one with nonactivated (placebo), for 2 min The assessment of pain was performed by a VAS, after an air blast at baseline immediately after treatment, at 1 week, 4 weeks and 16 weeks. Mean values of VAS for test and control teeth were compared by paired t-test (alpha = 0.05). The results showed mean baseline VAS values of 6.59 (+/- 1.65) and 6.14(+/- 1.95) for test and control teeth, respectively. Immediately after treatment, these values decreased to 4.09(+/- 2.28) and 3.89(+/- 2.11), respectively. After 1 week, 4 weeks and 16 weeks the mean values for test and control teeth were 3.85 +/- 2.36, 4.03 +/- 1.95, 3.60 +/- 2.66, and 4.44 +/- 2.56, 3.41 +/- 2.30, 3.42 +/- 2.30, respectively. There were no statistically significant differences between test and control at any time. However, both groups improved significantly (P < 0.05) from baseline to immediately after application, and at 1 week, 4 weeks and 16 weeks, respectively. The changes that occurred between immediately after application and 1 week, 4 weeks and 16 weeks, respectively, were not statistically significant. CONCLUSION: It is concluded that the effect of treatment of hypersensitive teeth with Nd:YAG laser is not different from placebo. The observed effects seem to last for at least 16 weeks.     

Nd:YAG激光去除根管内充填材料效果的研究

目的通过测定根管内充填材料的清除率和根管外壁温度的变化,评价不同功率Nd:YAG激光去除根管内充填材料的效果。方法选取临床拔除的40颗单根管离体上颌中切牙,常规镍钛锉根管预备、热牙胶充填根管后,随机均分为A、B、C实验组和D对照组,分别采用1.0,1.5,2.0 W的Nd:YAG激光及Protaper D3再治疗锉去除根管内充填材料,同时测量根管外壁的温度变化。各样本在处理前后分别采用mimics软件将口腔颌面锥形束CT(CBCT)的扫描数据进行处理,计算出实验前根管内充填材料体积、处理后剩余充填材料体积及根管充填材料清除率。结果 A、B、C、D四组根管充填材料清除率分别为80.49%、89.82%、78.09%、21.09%,除A组与C组比较无统计学差异外,其他组间两两比较均有统计学差异(P<0.05);A、B、C、D四组根管外壁温度升高均值分别为5.28、6.48、7.73、0.80℃,A、B、C组均与D组有统计学差异(P<0.05)。结论Nd:YAG激光能够有效去除根管内充填材料,参数设置为频率20 Hz,功率1.5 W,SP模式的Nd:YAG激光根管充填材料清除率高,根管外壁温度较再治疗锉明显升高,但在牙周可耐受范围以内。     

脉冲Nd:YAG激光照射对髓腔温度的影响

目的 :通过离体牙实验 ,研究脉冲Nd :YAG激光照射牙面引起的牙髓腔内温度的变化 ,探讨激光脱敏的安全性和可行性。方法 :采用Nd :YAG激光机以 5J ,10J ,15J ,2 0J四种累积能量分别照射 1.5mm×2 .0mm大小的牙本质区域 ,测定相应牙髓腔内温度的变化。结果 :牙髓腔内的温度随激光能量的增加而升高 ,当能量密度在 5 5 .6J/cm2 — 111J/cm2 时 ,牙髓腔内的温度升高不会超过 5— 10℃。牙本质厚度与温度缺乏相关性 ,存在个体差异。结论 :5 5 .6J/cm2 — 111J/cm2 能量密度为本型激光脱敏的安全阈值。牙合面脱敏的能量密度比颈部略高 ,可达到 16 6 .7J/cm2 。     

Nd:YAG 激光与根面平整对牙龈成纤维细胞在根面附着的影响

目的 :为探讨Nd :YAG激光照射对牙周病患牙根面的生物相容性影响。方法 :应用体外细胞培养技术 ,观察激光照射等处理根面的不同方式对人牙龈成纤维细胞 (Humangingivalfibroblast,HGF)附着的影响。结果 :Nd :YAG激光照射 根面平整组 ,成纤维细胞接种 2 4h后的附着量明显高于单纯Nd :YAG激光照射组和单纯根面平整组 (P<0 .0 5 )。而单纯激光照射组 (80mj/mm2 )和单纯根面平整组细胞附着量又明显大于未处理组 (P <0 .0 5 )。结论 :用一定能量密度的Nd :YAG激光照射与根面平整术联合应用可提高HGF在患牙根面上的附着量。     

超声波预备根管与Nd：YAG激光照射后根管牙本质的SEM研究

目的：评价超声预备根管及Ｎｄ：ＹＡＧ 激光照射根管壁后,根管内壁的清洁度和管壁牙本质微结构的变化。方法：１２ 个离体成人上前牙分为４ 组制备根管：手用器械、超声根管治疗仪、手用器械＋ Ｎｄ：ＹＡＧ 激光照射、超声波＋ Ｎｄ：ＹＡＧ 激光照射,扫描电镜下观察并照像记录。结果：手用扩锉预备的根管内壁有涂层污染和病理组织残留;超声波预备后根管内壁清洁、涂层消除,牙本质小管口开放;手用器械或超声制备后辅以适当能量激光照射的管内壁牙本质小管口封闭,管间牙本质熔融,并形成空泡状结晶。结论：超声波预备根管可达到理想的清洁效果,但牙本质小管口开放易造成根管术后渗漏。而Ｎｄ：ＹＡＧ 激光照射有利于封闭牙本质小管口,减少根尖孔渗漏,还具有封闭根管内壁死腔的作用。     

Molecular analysis of Er:YAG laser irradiation on dentin

The aim of this study was to evaluate by dispersive Raman spectroscopy the mineral and organic components of human dentin before and after laser irradiation and acid etching. The occlusal enamel of six non-carious human third molars was removed providing 6 dentin discs, which were divided in four quadrants each of them receiving a different surface treatment: etching with a 37% phosphoric acid gel (control); irradiation by Er:YAG laser (KaVo Key Laser II) with 80 mJ, 3 Hz, 30 s (group I); 120 mJ, 3 Hz, 30 s (group II); and 180 mJ, 3 Hz, 30 s (group III). The Raman spectra of normal (untreated) and treated dentin were analyzed and the mineral and the organic component were evaluated. Results were submitted to statistical analysis by ANOVA and Tukey's test at 5% significance level. The minerals and organic content were less affected in the control group and group I (p>0.05). Group II presented more reduction in mineral content (p<0.01) whereas in group III the inorganic (p<0.05) and organic (p<0.01) content were more affected. Dispersive Raman spectroscopy provided valid information of dentin chemical constituents with non-chemical sampling preparation.     

Nd:YAG laser irradiation effect on apical intracanal dentin - a microleakage and SEM evaluation

The purpose of this in vitro study was to evaluate the effect of neodymium:yttrium-aluminum-garnet (Nd:YAG) laser irradiation on intracanal dentin surface by SEM analysis and its interference in the apical seal of filled canals. After endodontic treatment procedures, 34 maxillary human incisors were randomly assigned to 2 groups. In the negative control group (n=17), no additional treatment was performed and teeth were filled with vertically condensed gutta-percha; in the laser-treated group (n=17), the root canals were irradiated with Nd:YAG laser (1.5 W, 100 mJ, 15 Hz) before filling as described for the control group. Two specimens of each group were prepared for SEM analysis to evaluate the presence and extent of morphological changes and removal of debris; the other specimens were immersed in 0.5% methylene blue dye (pH 7.2) for 24 h for evaluation of the linear dye leakage at the apical third. SEM analysis of the laser-treated group showed dentin fusion and resolidification without smear layer or debris. The Student's t-test showed that the laser-treated group had significantly less leakage in apical third than the control group. Within the limitations of this study, it may be concluded that the morphological changes on the apical intraradicular dentin surface caused by Nd:YAG laser resulted in less linear dye apical leakage.     

Evaluation of root canal dentin after Nd:YAG laser irradiation and treatment with five different irrigation solutions: a preliminary study

This study evaluated in vitro any changes in the morphology and mineral content of root canal dentin after treatments with Nd:YAG laser irradiation and 5 different irrigation solutions. The groups of extracted single-rooted human teeth were exposed to sterile saline solution, 5.25% NaOCl, 3% H2O2, 15% ethylenediaminetetraacetic acid, 2% chlorhexidine gluconate, and Nd:YAG laser irradiation. All prepared teeth were bisected longitudinally; half of each tooth was used for wavelength dispersive x-ray fluorescence spectrometry analysis to assess the mineral content. The other half was studied by using scanning electron microscopy to analyze the surface of the dentin. The results showed that the calcium level and calcium/phosphorus ratio decreased significantly with the NaOCl irrigation solutions (p < .05), suggesting the presence of changes at molecular level. Significant differences among the test groups were also observed in the scanning electron microscopy evaluation (p < .05). The lowest scores for root cleaning were obtained by using ethylenediaminetetraacetic acid followed by Nd:YAG laser treatment.     

Nd：YAG激光照射感染根管的扫描电镜观察

以不同能量的Ｎｄ：ＹＡＧ激光照射牙齿感染根管，与常规机械预备相比较，通过扫描电镜（ＳＥＭ）观察根管内壁的形态学变化。结果表明：激光能量在１５Ｈｚ、６０ｍＪ即可引起管壁牙本质熔融，结合冲洗可有效去除玷污层；随着能量增加，牙本质小管可部分封闭，但不能完全闭合。提示Ｎｄ：ＹＡＧ激光在根管治疗术中具有应用前景     

Nd：YAG激光照射釉质,牙本质和牙骨质的形态变化

应用不同能量的脉冲Ｎｄ：ＹＡＧ激光照射釉质、牙本质和牙骨质表面，用ＳＥＭ观察其形态变化。结果表明：这些组织的表面产生许多密集、形态和边缘不规则的凹窝结构，深度１５～４０μｍ不等，但３种组织表面形态的改变和程度各不相同。分析讨论了粗糙的表面对复合树脂粘结的潜在意义，并提出合适的激光能量参数     

Effects of Nd: YAG laser, air-abrasion and acid-etching on human enamel and dentin

The effects of the Nd:YAG laser, air-abrasion and acid-etching systems on mineral content and surface morphology of cut dentin and enamel were examined in 10 extracted human teeth. Enamel specimens were lased for two seconds at a fluence of 0.75 J and a frequency of 15 Hz, air-abraded for two seconds with 50 micron Al-oxide and etched for 60 seconds with 37% ortho-phosphoric acid. Dentinal specimens were subjected to the same procedure for half the time. Untreated areas of the same specimens served as the control. Morphologically, the lased dentin showed an apparently melted surface with partial obstruction of the dentin tubules, as well as cracks along the lased surface. Air-abrasion created very irregular surfaces on enamel and dentin. Dentin tubules were observed on the acid-etched dentin samples but not the air-abraded surfaces. The Nd:YAG laser created the most surface irregularity on both enamel and dentin. Laser treatment appeared to alter the chemical structure and surface morphology of the dentin and enamel.