Nd:YAG连续激光治疗颌面深部海绵状血管畸形的相关实验研究——Nd:YAG连续激光照射致兔面神经热效应的肌电研究

目的　观察不同剂量参数下Nd:YAG激光照射家兔面神经所致形态及支配肌功能改变。了解激光对面神经热效应的安全域为临床应用提供参考。方法　采用不同剂量组设计,观察28只家兔56侧面神经在各组Nd:YAG激光照射后神经升温状况、功能评价、面神经运动状况,支配肌肌电改变。结果　能量密度≤70Jcm2时Nd:YAG激光可致面神经轻度变性;术后3周支配肌功能基本恢复。能量密度≤140Jcm2时激光可致面神经中度变性,术后3周支配肌功能明显下降,6周基本恢复。能量密度为240Jcm2时激光致面神经不可逆损伤,面神经支配肌功能完全丧失。结论　Nd:YAG激光对家兔面神经的影响存在量效关系     

不同能量密度激光照射家兔耳静脉后的温度变化

目的：观察不同波长激光和不同激光能量密度照射家兔耳静脉后的温度改变。方法：采用立体数码体视显微镜,定量测量10只家兔（0只耳朵、80个区域）的静脉主干和I级分支的平均管径大小。采用PDL585nm脉冲染料激光和长脉宽1064nm Nd：YAG激光,分别对5只家兔（10只耳朵、40个区域）的静脉进行激光照射。PDL585nm激光能量密度分别为6、7、8、9、10J/cm^2,1064nm Nd：YAG激光能量密度分别为14、160、180、200、220J/cm^2。利用数码热敏温度仪测量激光照射后的兔耳皮肤温度改变。结果：家兔耳静脉的主干静脉管径为（1.0120±0.1900）mm,I级分支静脉管径为（0.4523±0.1074）mm。PDL585nm激光照射后,兔耳皮肤温度即刻升高至39.9℃～46.0℃;1064nm Nd：YAG激光照射后,兔耳皮肤温度即刻升高至38.6℃～45.4℃。结论：脉冲染料激光PDL585nm、1064nmNd：YAG激光照射均致兔耳皮肤温度升高,并与能量密度呈正比。     

Nd:YAG激光对猴牙牙髓的影响

目的：观察Nd：YAG激光对猴牙牙髓的影响，比较牙面涂布60g／L美蓝和经常规硝酸银脱敏后对激光照射效果的影响情况。方法：以1592、3185、4777mJ／mm^23种能量水平的Nd：YAG激光照射3只猴的30个牙面，用组织病理学方法观察牙髓变化情况。结果：1592mJ／mm^2照射组，不论牙面经何种处理，牙髓反应均与对照组相似，为0级；3185mJ／mm^2照射组，牙髓出现轻度改变；大能量、高频率的4777mJ／mm^2照射则出现广泛性成牙本质细胞变性、坏死。照射面色素的存在增加了激光对牙髓的刺激，氨硝酸银加丁香油酚还原成银沉淀，隔绝了外界刺激对牙本质和牙髓的影响，同样参数的Nd：YAG激光造成的牙髓损害在3组中最小。结论：大能量Nd：YAG激光可造成牙髓组织损伤性反应，照射面经不同的处理可影响Nd：YAG激光的照射效果。     

脉冲Nd:YAG激光照射对犬牙髓的影响

目的：探讨Nd：YAG激光对牙髓的安全阈值。方法：选择4条健康的本地杂种犬，先进行过敏模型制备，随机分为3组，分别给予：33J／cm^2、56J／cm^2和111J／cm^2激光照射，按照即刻、3d、7d、1个月4个时间段处死试验犬，实验牙经过固定、脱钙后，进行组织切片、光镜观察、病理分级。结果：牙髓反应均在3级以下，随激光照射能量的升高牙髓组织病理变化明显。在33～56J／cm^2之间，牙髓组织正常或反应轻微。结论：应用Nd：YAG激光进行牙齿过敏治疗时，其热效应可能对牙髓组织产生影响，33～56J／cm^2的激光能量不会对牙髓组织产生损害，能量较高将导致牙髓组织炎症，所以33～56J／cm^2的能量密度应为进行当次牙齿过敏治疗的安全阈值。     

Nd：YAG激光联合平阳霉素对兔耳静脉作用效应的研究

目的：探讨Nd：YAG激光联合平阳霉素（PYM）对兔耳静脉血管的作用效应。方法：健康新西兰白兔37只（74侧耳）随机分为A、B、C、D4组,A、B、C每组各12只,其中A组（实验组）每只兔耳注射PYM溶液0．3ml（浓度：4mg／ml）,第7d后于注射段行Nd：YAG激光扫描照射（能量密度为2547．8J／cm^2）;B、C组（对照组）分别给予PYM注射、Nd：YAG激光扫描照射;D组（空白组）1只。A、B、C组于第1d、3d、7d、14d、21d、28d各取4只兔耳静脉组织行光镜观察,取第14d、28d组织行透射电镜观察。结果：①光镜下：A组与B组比较,14d、21d、28d的静脉损伤程度有显著性差异（P〈0．05）：A组与C组比较,7d、14d、21d、28d的静脉损伤程度有显著性差异（p〈0．05）。②电镜下：A组与B、C组比较,28d时仍可见内皮细胞水肿,内膜肿胀及附壁血栓。结论：Nd：YAG激光联合平阳霉素较单一处理对兔耳静脉的损伤程度重、损伤作用时间长。     

SD大鼠牙髓增龄变化对Nd：YAG激光照射的应激反应观察

目的：观察增龄牙髓对Nd：YAG激光照射的应激反应变化。方法：观察幼年组（6周龄）、成年组（12周龄）、老年组（72周龄）雄性SD大鼠切牙经不同能量密度脉冲式Nd：YAG激光照射后6h牙髓的组织形态学变化,利用图像分析系统对不同年龄大鼠成牙本质细胞中诱导型热休克蛋白（HSP70）表达的平均光密度值进行分析比较。结果：激光能量密度为1433mJ／mm^2和1910mJ／mm^2时,老年组成牙本质细胞中诱导型HSP70的表达强度显著高于幼年和成年组（P〈0．05）;能量密度为2388mJ／mm^2时,老年组成牙本质细胞中诱导型HSP70的表达强度显著低于幼年和成年组（P〈0．05）,且老年组部分成牙本质细胞变性坏死。结论：老年大鼠牙髓对激光刺激的耐受性下降。     

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（1，064nm）激光在面颈部静脉畸形治疗中的应用：优点及挑战性

Nd：YAG激光是继硬化治疗及手术后治疗面颈部静脉畸形的较新方法。该文回顾了146例头颈部静脉畸形患者．年龄2个月-77．5岁，分析治疗效果及激光的应用参数。72例先前未经任何治疗．74例曾接受治疗。舌及颊黏膜的激光能量密度为103．1J／cm^2，皮肤为90．7J／cm^2，静脉球畸形的激光治疗能量密度为81．2J／cm^2。     

Nd：YAG激光照射治疗牙本质敏感症的能量密度范围的离体牙研究

目的：探索Nd：YAG激光照射牙本质后,既能显著降低其通透性,又不引起表面形态破坏的能量密度范围。方法：10个离体磨牙均切成6个2mm×3mm×4mm的牙本质块,随机分为：空白对照组、Gluma组、50、100、200、450J/cm2激光组。37%磷酸处理,每组随机取8个标本浸入2%亚甲蓝溶液5h,体视显微镜下测量染液渗透深度,另2个标本观察表面形态变化。结果：1）染液渗透深度,空白对照组、Gluma组、50J/cm2,100J/cm2,200J/cm2,450J/cm2激光组分别为（3.211±0.345）、（1.714±0.475）、（3.058±0.193）、（2.603±0.389）、（1.979±0.380）、（1.156±0.397）mm。50J/cm2激光组牙本质通透性与对照组无差异,其余各组与对照组相比均明显下降,且随着激光能量升高,通透性降低。其中200J/cm2激光组的牙本质通透性与Gluma组相当。2）牙本质表面观察,450J/cm2激光组牙本质表面有显著改变,可见大小不一,形态不规则的凹坑。结论：Nd：YAG激光用于治疗牙本质敏感症时,考虑到有效性和安全性,建议能量密度为200~450J/cm2。     

Nd：YAG激光照射对提高人牙周膜成维细胞增殖力的作用

目的观察Nd：YAG激光对人牙周膜成纤维细胞增殖和碱性磷酸酶（ALP）活性的影响。方法采用酶消化组织块法原代培养人牙周膜成纤维细胞，并进行波形蛋白及角蛋白的免疫细胞化学染色，对所培养的细胞进行鉴定。将牙周膜成纤维细胞分组，接受不同能量密度的Nd：YAG激光照射。测定牙周膜成纤维细胞碱性磷酸酶活性并观察其生长情况。结果5个实验组的细胞增殖速度及碱性磷酸酶含量均高于对照组，其中能量密度为60j／cm^2组、80j／cm^2组、100i／cm^2组与对照组相比有统计学的差异。结论低能量密度，短时间的Nd：YAG激光照射能促进牙周膜成纤维细胞的增殖，提高碱性磷酸酶活性。     

A comparison of the effects of Nd:YAG and Ho:YAG laser irradiation on dentine and enamel

This preliminary study was undertaken to investigate the effects of Nd:YAG and Ho:YAG lasers on enamel and dentine of extracted teeth. The Ho:YAG laser (spot size 250 μm, energy density 4160 J/cm²) produced a cleaner puncture in dentine with less melting of the surrounding tissue than did the Nd:YAG laser (spot size 20 μm), energy density 50 000 J/cm²), which produced considerable melting and recrystallization of dentine and was more difficult to control. It was possible to cut enamel and dentine with both lasers, but considerable melted and recrystallized enamel was produced. From the limited observations of this study it appears that the Ho:YAG laser is more suitable for cutting both enamel and dentine than the Nd:YAG laser. More work needs to be done to ascertain the effect on enamel and dentine of modification of the parameters of both lasers.     

Influence of Nd:YAG laser irradiation on an adhesive restorative procedure

Hard tissue modification by means of laser irradiation is becoming popular in dentistry, since it promotes assorted responses between the tooth and the restorative material. Some studies on the bond strength of adhesive systems to Nd:YAG irradiated teeth have shown distinctive behaviors when irradiation was applied before or after the adhesive agent. This study evaluated the microtensile bond strength of a commercial adhesive system to dentin irradiated with Nd:YAG laser after adhesive application but prior to polymerization. The experiment was conducted in vitro, using freshly extracted human teeth as samples. For the microtensile test, the teeth were separated into 4 different groups according to the energy density of laser irradiation: 0, 5, 10 and 50 J/cm2. The data was analyzed with analysis of variance (ANOVA) and LSD tests, and the results indicated that the group that was irradiated with 5 J/cm2 had significantly higher bond strength values. Adhesive penetration on the etched dentin was observed by scanning electron microscopy, where the images showed better adhesive penetration on dentinal tubules after dentin irradiation with 5 J/cm2. Based on the results of this study, it is possible to conclude that irradiation of dentin with the Nd:YAG laser at low energy densities after application of the adhesive but prior to polymerization might be positive for the adhesive restorative process.     

The effects of C02, Nd: YAG and Er: YAG lasers with and without surface coolant on tooth root surfaces

Abstract The objective of this study was to compare and contrast the morphologic changes in tooth root surfaces treated in vitro by scaling and root planing followed by irradiation with the Er: YAG laser using air/water surface cooling and the C0₂ and Nd:YAG lasers, both with and without surface coolant. The experimental unit consisted of 42 freshly extracted teeth which were divided equally and randomly assigned to the following 7 treatment groups: untreated control, S/RP only. CO₂ laser with and without air/water surface cooling, Nd:YAG laser with and without/air water surface cooling, and Er:YAG laser with air/water surface coolant. Specimens treated with CO₂ laser irradiation were subjected to energy densities ranging from 100 to 400 J/cm²: those treated with the Nd:YAG from 286 to 1857 J/cm²: and the Er:YAG was used within a range of 20 to 120 J/cm². The degree of morphologic change following CO₂ and Nd:YAG irradiation appeared directly related to energy density but unrelated to the use of surface coolant. Laser induced surface changes included cavitation, globules of melted and resolidified mineral, surface crazing, and production of a superficial char layer. In contrast, the Er:YAG laser produced root surface changes that might be expected from acid etching, i.e., removal of the smear layer and exposure of the collagen matrix. In addition, sharply denned microfractures of the mineralized structure were noted and unlike the CO₂ and Nd:YAG lasers, there was no evidence of melting or surface char. Given the parameters of this study, it appears that both the CO₂ and Nd:YAG lasers alter the root surface in an undesirable manner. The Er:YAG laser, however, when used at low energy densities shows sufficient potential for root surface modification to warrant further investigation.     

The effects of CO2 laser and Nd:YAG with and without water/air surface cooling on tooth root structure: correlation between FTIR spectroscopy and histology

Morphologic and chemical characterization of root surfaces treated with either the CO₂, laser, Nd:YAG, or Nd:YAG with water/air surface cooling (Nd:YAG-C) was completed using scanning electron microscopy (SEM) and FTIR photoacoustic spectroscopy (FTIR/PAS). Specimens for morphologic analysis consisted of 20 extracted single rooted teeth unaffected by periodontal disease. The specimens were exposed at varying energy densities to a single pass of the laser. SEM examination revealed, for all lasers, a direct correlation between increasing energy densities and depth of tissue ablation and width of tissue damage. The Nd:YAG-C required higher energy densities than either the CO₂ or Nd:YAG lasers to achieve the same relative depth of tissue ablation. Regardless of energy density, and in contrast with other laser types, areas treated with the Nd:YAG-C did not exhibit collateral zones of heat damage. Specimens for spectroscopic examination consisted of 12 disks, 6x2 mm, cut from debrided root surfaces of extracted, unerupted human molars. The spectral results indicate a substantial reduction in the absorption bands attributable to protein and an additional band at 2015 cm^-1 in specimens exposed to the Nd:YAG without water. In the presence of water/air coolant, the band at 2015 cm^-1 appears only at a substanially higher energy density. The spectra of the CO₂ treated specimens, with the char layer present, show a significant reduction in the protein bands and additional bands at 2015 and 2200 cm^-1, that are tentatively assigned to the cyanamide and cyanate ions, respectively. These results suggest a reaction of the organic matrix and mineral with laser exposure.     

Determination of energy density threshold for laser ablation of bacteria An in vitro study

Abstract The Nd:YAG and CO₂ lasers have been shown to be bactericidal at relative low energy densities. However, at energy densities exceeding 120 J/cm²(CO²) and 200 J/cm² (Nd:YAG). laser irradiation also causes irreparable root surface damage. The purpose of this study was to determine, in vitro, the energy density threshold at which microbial ablation could be achieved while inflicting the least amount of damage to the root surfaces of human teeth. Pairs of Escherkhia coli colonies cultured on broth agar were treated with a CO₂ laser using a pulsed waveform at approximate energy densities ranging from 3 to 110 J/cm². One of each colony-pair was then examined by scanning electron microscopy (SEM) and the other subcultured for viable microbes. Roots of extracted teeth were lightly scaled and treated by CO² laser, again with pulsed beam using approximate energy densities of 3 to 110 J/cm²: and examined by SEM. Regardless of the level of energy density, residual bacteria could be subcultured from all laser treated microbial colonies. The inability of the laser to completely obliterate microbial colonies was likely due to: depth of energy penetration, difficulty in precisely overlapping beam focal spots, irregular beam profile, and presence of microbes at the periphery of the beam focal spot. The threshold energy density for bacterial obliteration was determined to be 11 J/cm² and that for root damage was 41 J/cm². Root damage was evident by charring, crater formation, meltdown and resolidification surface mineral, and increasing surface porosity. The results of this in vitro study indicate that when used at an energy density between 11 and 41 J/cm²: the CO² laser may destroy microbial colonies without inflicting undue damage to the tooth root surface.     

Nd:YAG激光治疗牙本质过敏症的临床疗效观察

目的 :探讨Nd :YAG激光治疗牙本质过敏症的疗效。方法 :15 3例患者的 2 70颗患牙 ,随机分为 2组 ,分别用Nd :YAG激光和Gluma脱敏剂进行治疗后观察疗效。结果 :实验组治愈率为 92 .5 9% ,有效率为94.0 7% ;对照组治愈率为 49.62 % ,有效率为 71.84%。结论 :2种治疗方法的疗效有显著性差异 (P <0 .0 1) ,激光治疗牙本质过敏的效果优于Gluma脱敏剂。