脉冲Nd：YAG激光照射对牙本质通透性的影响

本实验用不同能量参数的脉冲Ｎｄ：ＹＡＧ激光；分别照射牙本质窝洞底产啊，电镜观察和测定牙本擀通透性，研究激光对牙本质的作用，初步探讨了Ｎｄ：ＹＡＧ激光脱敏的机制，结果显示：０．６Ｗ（４０ｍＪ，１５Ｈｚ）组的牙本质通透性与对照组无统计差异，０．９Ｗ（６０ｍＪ，１５Ｈｚ）和１．２Ｗ（８０ｍＪ，１５Ｈｚ）组的牙本质通透性明显增加，ＳＥＭ示所有激光组牙本质融熔，牙本质小管口模糊不清，洞底小管口部分被融熔物质     

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     

脉冲Nd：YAG激光用于狗牙活髓切断术的实验研究

目的：观察脉冲Ｎｄ∶ＹＡＧ激光照射狗牙活髓切断术后断面的牙髓组织愈合情况。方法：动物分成３组，每组５个牙。一组对照，一组切髓后激光照射断面，条件４０Ｈｚ、６０ｍＪ（２．４Ｗ），另一组切髓后激光照射断面，条件为４０Ｈｚ、４０ｍＪ（１．６Ｗ）。各组均用盖髓剂盖髓。分别于３、１５、４５ｄ处死动物，组织切片光镜观察。结果：能量参数为４０Ｈｚ、６０ｍＪ（２．４Ｗ）、照射时间５ｓ的Ｎｄ∶ＹＡＧ激光对切髓术后牙髓组织具有良好的促进愈合作用，牙髓炎性反应小、牙本质桥形成良好。而能量参数为４０Ｈｚ、４０ｍＪ（１．６Ｗ）、照射时间１０ｓ的激光照射断髓面，对牙髓组织则产生不可逆转的损伤作用。结论：一定能量的Ｎｄ∶ＹＡＧ激光对切髓术有促进愈合作用。激光对牙髓组织的损伤程度更多取决于激光照射时间，而非输出功率。应用脉冲Ｎｄ∶ＹＡＧ激光切髓时，应严格控制照射时间     

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     

脉冲Nd:YAG激光影响复合树脂修补烤瓷粘接强度实验研究

目的：评价激光进行瓷面处理对复合树脂修补烤瓷的粘接效果。方法：分别用８％氢氟酸及３组能量参数的脉冲Ｎｄ：ＹＡＧ激光（１５Ｈｚ、４０ｍＪ、０．６Ｗ;１５Ｈｚ、６０ｍＪ、０．９Ｗ;１５Ｈｚ、８０ｍＪ、１．２Ｗ）对烤瓷牙粘接表面进行照射,照射时间均为１ｍｉｎ,涂硅烷液及活化剂后,粘接复合树脂。应用电子万能试验机测试复合树脂－烤瓷的抗剪切粘接强度。采用扫描电镜观察瓷处理面的形貌特征。结果：激光０．６Ｗ组、０．９Ｗ组、１．２Ｗ组及酸蚀组的抗剪切粘接强度分别为８．６１、１４．０７、１１．２２及１３．４７ＭＰａ,激光０．６Ｗ组明显低于酸蚀组,两者具有统计学差异,而０．９Ｗ组及１．２Ｗ组与酸蚀组则无显著性差异。扫描电镜显示经激光处理的瓷面粗糙不平,呈浅凹状及火山口状结构。结论：在适当能量参数下,脉冲Ｎｄ：ＹＡＧ激光可代替酸蚀进     

重症牙本质过敏牙Nd：YAG激光照射后的SEM观察

用脉冲Ｎｄ：ＹＡＧ牙科激光照射３个新鲜离体的重症牙本质过敏牙３０ｍＪ、８０ｍＪ，脉冲数１０／ｓ，１ｍｉｎ，并涂布２％甲紫液。ＳＥＭ显示：照射３０ｍＪ者，牙本质小管口部分或完全封闭，表面密度明显提高，出现＂弹坑＂样结构；照射８０ｍＪ者，牙本质小管口模糊，出现不规则均质化物质；涂布２％甲紫液照射３０ｍＪ区的大部分牙本质小管口封闭，表面密度提高，出现均质化物质和＂弹坑＂样结构，所有的照射区都未发现微裂。提示：牙本质小管口的封闭和牙本质表面的溶融是牙本质过敏症激光脱敏的形态学变化。２％甲紫液可作为该激光的光敏剂使用。     

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。     

Nd：YAG激光清除龋坏牙本质的作用：扫描电镜研究

清除龋坏牙本质是Ｎｄ：ＹＡＧ激光在口腔科的重要应用之一。本研究目的的评价Ｎｄ：ＹＡＧ激光应用于清除龋坏牙本质的效果以及对龋坏下正常牙本质形态改变的应用。实验用Ｎｄ：ＹＡＧ激光照射处理离体牙牙本本质浅龋区,然后对实验区作扫描电镜观察。结果发现：激光参数在１５ｐｐｓ,６０ｍＪ／ｐ时,牙本质表面龋坏组织基本清除干净,牙本质小管口缩小,管间牙本质粗糙。     

钕钇铝──石榴石激光对牙本质表面形态影响的扫描电镜观察

对２０例离体无龋恒牙牙本质表面作钕钇铝——石榴石（Ｎｄ：ＹＡＧ）激光照射，在扫描电镜（ＳＥＭ）下观察照射后牙本质的表面形态变化。结果表明：Ｎｄ：ＹＡＧ激光照射可使牙本质表面粗糙模糊，牙本质小管口形态破坏，并且随着照射时间增长，或照射功率加强，牙本质表面的这种改变增大，提示：Ｎｄ：ＹＡＧ激光对牙本质表面结构有累加性熔作用。     

Nd：YAG激光处理与磷酸酸蚀牙本质后抗剪切粘结强度的比较研究

应用４组能量参数不同的Ｎｄ：ＹＡＧ激光处理及磷酸酸蚀牙本质表面后，分别与光固化复合树脂粘结，比较各激光处理组与酸蚀组之间抗剪切粘结强度的差别。结果表明：激光处理组的抗剪切粘结强度高于酸蚀组，其中，４０ｍＪ１５ｐｐｓ激光处理组的抗剪切粘结强度明显高于酸蚀组（Ｐ〈０．０１），并高于其它激光处理组（Ｐ〉０．０５）。讨论了Ｎｄ：ＹＡＧ激光对牙本质表面的作用，及其与光固化复合树脂良好粘结机理和其临床应用的安     

Permeability of dentine after Nd:YAG laser treatment: an in vitro study

summary The purpose of this investigation was to determine the effects of Nd:YAG laser treatment on the permeability of dentine. Forty dentine discs were prepared by horizontal sectioning through the middle coronal third of freshly extracted non-carious third molars. After the removal of the pulp the discs were finished with 600 grit and divided into three test groups and one control group (n = 10). For the test groups three different laser power settings were chosen: test group A: 3 × 60 sec, 60 mJ; test group B: 3 × 60 sec, 90 mJ; test group C: 3 × 60 sec, 120 mJ. No laser treatment was performed on the control group. In a two-chamber system the filtration rate of dentine tubules from an exactly defined area of the specimens was measured using a radioactive Ringer solution under a pressure of 30 cm H2O. Permeability measurements were carried out three times prior to lasing, three times immediately following laser treatment and six times after the application of phosphoric acid. Analysis of variance showed a significant influence of the Nd:YAG laser treatment on the permeability of dentine (P < 0.001). The mean quotient of non-treated control vs. lased dentine was 2.19 ± 0.86 for the 60 mJ beam, 1.49 ± 0.88 for the 90 mJ beam, and 204 ± 2.17 for the 120 mJ beam. Etching the lased surfaces had a statistically significant influence on the permeability of the dentine only in the 60 mJ group ( P < 0.001). The data show that the Nd:YAG laser treatment often increases the permeability of smear layer covered dentine but moderates the increase of permeability after etching the surface with phosphoric acid.     

Nd：YAG激光照射对牙本质表面微观特征影响的实验研究

目的：研究不同剂量Nd：YAG激光照射后,牙本质小管封闭深度及不同深度内钙磷比值的变化,得出Nd：YAG激光治疗牙本质过敏症的最佳参数。方法：酸蚀法建立牙本质敏感模型,应用不同参数的Nd：YAG激光照射样本,A组（0 mj,0 Hz,对照组）;B组（30 mj,5 Hz）;C组（30 mj,10 Hz）;D组（50 mj,5 Hz）;E组（50 mj,10 Hz）。照射完成后将样本纵剖,扫描电镜观察照射前后样本牙本质小管封闭深度并用X?线能谱分析不同深度处样本钙磷比值变化。结果：扫描电镜见B组牙本质小管表面封闭,近表面处小管直径比对照组变小。 C、D两组牙本质小管熔融达一定厚度,且牙本质结构完整。 E组牙本质熔融厚度达25μm,但熔融区中有微孔产生。 X线能谱分析各组样本5μm、20μm深处的钙磷比值,差异无统计学意义。结论：Nd：YAG激光牙本质脱敏的较为理想参数为（30 mj,10 Hz）和（50 mj,5 Hz）。     

Ex vivo study of the adhesion of an epoxy-based sealer to human dentine submitted to irradiation with Er : YAG and Nd : YAG lasers

AIM: To evaluate the adhesion of an epoxy-based sealer to human dentine submitted to irradiation with Er : YAG or Nd : YAG laser at various parameters. METHODOLOGY: Ninety maxillary canine teeth were sectioned transversely at the cemento-enamel junction and at the root tip to leave an 8-mm-long cylinder. The tooth specimen was centred in a metallic ring (16 mm diameter and 8 mm height) and embedded in acrylic resin. The root canals were prepared using a low-speed handpiece and a conical diamond bur, which was attached to a paralleling device. This bur was lowered to a depth previously determined by a silicone stop. Specimens were divided into nine groups: group I, dentine was treated with 2 mL of 17% EDTAC for 5 min. Groups II-V were irradiated with Er : YAG laser at the following parameters: group II - 8 Hz and 200 mJ input (120 mJ output); group III - 8 Hz and 400 mJ input (240 mJ output); group IV - 16 Hz and 200 mJ input (120 mJ output); group V - 16 Hz and 400 mJ input (240 mJ output). Groups VI-IX were irradiated with Nd : YAG laser at the following parameters: group VI - 10 Hz and 1 W input (0.4 W output); group VII - 10 Hz and 2 W input (0.8 W output); group VIII - 15 Hz and 1 W input (0.4 W output); group IX - 15 Hz and 2 W input (0.8 W output). The root canals were filled with an epoxy-based root canal sealer and submitted to a push-out test. RESULTS: Statistical analysis showed significant differences (P < 0.01) between Er : YAG and Nd : YAG laser treatments at the higher frequencies compared with 17% EDTAC. Greater adhesion values were obtained for groups IV and V (Er : YAG laser) and groups VIII and IX (Nd : YAG laser), which were statistically different from groups II and III (Er : YAG laser) and groups VI and VII (Nd : YAG laser). Treatment with only 17% EDTAC had the lowest adhesion values. CONCLUSIONS: An increase in frequency, independent of power settings, of the lasers used in this study increased adhesion of an epoxy-based root canal sealer.     

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.     

脉冲Nd:YAG激光辅助极固宁脱敏剂治疗老年牙本质过敏症的临床研究

目的：研究脉冲Nd：YAG激光辅助极固宁脱敏剂治疗老年牙本质过敏症的临床效果。方法：实验组用脉冲Nd：YAG激光1W（30mJ／cm^2、15Hz）照射120sec后，涂擦极固宁脱敏剂3次;对照组强采用极固宁脱敏剂3次。结果：实验组即刻、3个月及6个月有效率分别为87．29％、81．36％和75．42％，对照组的有效率为79．09％、63．64％和52．73％。即刻两组差异无屁著性（P〉0．05），而3个月、6个月差异有显著性（P〈0．01）。结论：脉冲Nd：YAG激光辅助极固宁脱敏荆治疗老年牙本质过敏症是一种高效、作用持久、使用安全的方法。     

The sealing ability of an epoxy resin root canal sealer after Nd:YAG laser irradiation of the root canal

AIM: To evaluate ex vivo the effect of Nd:YAG laser irradiation with and without black ink on instrumented root canal walls, and the degree of both coronal and apical microleakage of filled root canals. METHODOLOGY: Seventy-two single-rooted teeth were instrumented up to a size 40 K-file, and then divided into six groups of 10 teeth: groups 1 and 4 remained unlased and acted as control groups, groups 2 and 5 were treated with a Nd:YAG laser (Fidelis Plus, Herzele, Belgium), groups 3 and 6 were treated with a laser and black ink; the remaining 12 teeth served as positive and negative controls. The laser was operated at 1.5 W, 15 Hz, four times for 5 s with a 20-s interval. Groups 4-6 were filled using cold lateral condensation of gutta-percha and AH26. After storage in water for 48 h at 37 degrees C, through-and-through leakage (L in microL day-1) was measured for 48 h under a pressure of 1.2 atm using a fluid transport model and recorded as L=0 (L1), 010 (L3). After the assessment of leakage with the fluid transport model, the teeth were immersed in rhodamine B solution for 48 h at 37 degrees C. Apical and coronal dye leakage was scored after longitudinal splitting of these teeth. All teeth of groups 1-3 were split longitudinally and observed under SEM for evaluation of remaining smear layer. RESULTS: Through-and-through leakage was only observed in the group lased with black ink (two samples-L2). Apical and coronal dye leakage was observed in all groups; there were no statistically significant differences amongst the three experimental groups. The through-and-through leakage, measured with the fluid transport model in two teeth of group 6, was confirmed in the dye leakage test (rhodamine B dye was observed along the total length of the root filling). There was evidence of melted and ablated root canal dentine in the laser-treated groups. These findings were more obvious in root canals lased in association with black ink. All apical foramina in the lased group remained patent. CONCLUSIONS: Nd:YAG laser irradiation with black ink increased the amount of melted and ablated dentine areas compared with that without black ink. Nd:YAG lasing in association with black ink did not result in a reduction of either coronal or apical microleakage in root filled teeth.     

The combined occluding effect of sodium fluoride varnish and Nd:YAG laser irradiation on human dentinal tubules.

Various methods and materials used in the treatment of dentin hypersensitivity are thought to achieve a therapeutic benefit by tubule occlusion. The aim of the present study was to evaluate the combined occluding effect of sodium fluoride varnish and Nd:YAG laser irradiation on human dentinal tubules. Thirty-six dentin specimens with exposed dentinal tubule orifices were used in this study. The samples were randomly divided into four groups. Groups A, B, and C were varnished by sodium fluoride, whereas group D served as a control. Then, group C was lased by 30 mJ of Nd:YAG laser, 10 pulses/s for 2 min by light painting. Three hours later, groups B and C were brushed by an electrical toothbrush for 30 min. Under SEM observation, the control group showed numerous exposed dentinal tubule orifices, and the sodium fluoride varnished specimens showed closure of exposed dentinal tubule orifices. After electrical toothbrushing, most of the sodium fluoride varnish was brushed away, except in the specimens that were irradiated by Nd:YAG laser. Over 90% of the dentinal tubule orifices were occluded by sodium fluoride varnish combined with Nd:YAG laser irradiation.     

激光和脱敏剂治疗牙本质敏感症的临床疗效对比

目的对比Nd：YAG激光和Gluma脱敏剂治疗牙本质敏感症的临床疗效。方法 20例牙本质敏感症患者,两例对称的同名患牙分别随机分到激光组和Gluma组。激光组选用的参数为120 mJ,5 Hz,照射时间1 min,Gluma组药物涂擦时间为2 min。记录患者在治疗后即刻、术后1周、术后1个月对探针和气流刺激的视觉模拟评分（visual analogue scale,VAS）。结果术后即刻激光组、Gluma组VAS分别为4.05±0.95、4.75±1.33（P〉0.05）,术后1周激光组、Gluma组VAS分别为3.10±0.91、3.70±1.03（P〉0.05）,提示短期内激光和Gluma对牙本质敏感症的疗效无差异。术后1个月激光组、Gluma组的VAS分别为2.35±0.75、3.20±0.83（P〈0.01）,提示随着时间延长,激光照射可以显著缓解患者的牙本质敏感症状。结论 Nd：YAG激光（120 mJ,5 Hz）照射1 min与脱敏剂Gluma涂擦2 min相比,脱敏效果1周内两者无差异,术后1个月疗效以激光为优。