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。     

Nd：YAG激光对自酸蚀粘结系统和牙本质粘结力的影响

目的探讨Nd：YAG激光对牙本质自酸蚀粘结系统的影响。方法选用因正畸拔除的新鲜前磨牙42颗，随机分为3组，每组14颗；牙面预备暴露牙本质；分别采用Adper^TM Prompt^TM粘结剂＋F2000树脂充填，Nd：YAG激光照射＋Adper^TM Prompt^TM粘结剂＋F2000树脂充填，Adper^TM Prompt^TM粘结剂＋Nd：YAG激光照射＋F2000树脂充填。评价各组树脂与牙本质之间剪切强度。结果Nd：YAG激光照射＋Adper^TM Prompt^TM粘结剂＋F2000树脂充填组的剪切强度明显大于其余2组，其余2组之间剪切强度对比无明显差异。结论先采用脉冲Nd：YAG激光照射后使用Adper^TM Prompt^TM粘结剂组获得最大粘结力。     

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。     

脉冲Nd:YAG激光照射牙本质后对光固化树脂充填体边缘微渗漏的影响

目的研究脉冲Nd：YAG激光照射牙本质后对光固化树脂充填体边缘微渗漏的影响，以探讨脉冲Nd-YAG激光在龋病治疗中的临床应用意义。方法选用正畸要求拔除的正常双尖牙30颗，随机分为A。B，C三组，每组10颗，用高速裂钻备洞（洞长、宽为3mm；洞深为2mm），A组为对照组，常规酸蚀树脂充填；B，C两组分别用50mJ，10Hz和100mJ，10Hz的脉冲Nd：YAG激光能量照射窝洞牙本质壁30s后树脂充填，分别用体视显微镜和扫描电镜观察充填体边缘和洞壁结合情况。结果．体视显微镜下观察：A组的牙本质洞壁与光固化树脂充填体间染料渗入较多，着色较深；B、C组的牙本质洞壁与光固化树脂充填体间染料渗入较少，着色较浅。扫描电镜下观察：B、C组的牙本质洞壁与光固化树脂充填体间裂隙明显小于未经激光处理的对照组。结论脉冲Nd：YAG激光处理牙本质后进行光固化复合树脂充填，可以减少充填体微渗漏，有利于充填的成功．     

脉冲Nd：YAG激光照射牙本质过敏牙后的扫描电镜观察

本研究应用新鲜离体人牙将面作成牙本质过敏牙模型，以三种不同输出能量的脉冲Ｎｄ：ＹＡＧ激光照射后，用扫描电观察牙本质的形态变化。结果发现，过敏牙面经适当的激光一，牙本质间质产生的熔融层能够严密地封闭牙本质管口，牙本质表面经激光照射后不出现裂纹和球形突起。本研究为临应用脉冲Ｎｄ：ＹＡＧ激光的脱敏治疗提供了形态学证据，本文还就激光能量与牙髓的关系以及有关的临床问题进行了较详细的讨论。     

脉冲Nd:YAG激光照射对人牙釉质光滑面抗酸性的影响

目的：研究单独应用3种不同能量的普通脉冲Nd：YAG激光照射对光滑面牙釉质抗酸性的影响。方法：扫描电镜观察100、150、200mJ激光照射后离体人牙釉质表面的结构变化；并通过人工龋实验测量脱矿液中的釉质钙溶出量，确定单独用激光照射对牙釉质抗酸性的影响；X射线能谱仪(EDX)测量激光照射前后牙釉质中钙磷相对含量的比值的变化，初步探讨激光防龋的机制。结果：不同能量的激光照射可使表面牙釉质发生不同程度的熔化、熔融；100、150、200mJ激光照射组与末用激光照射组之间的釉质钙溶出量无明显差异(P＞0．O5)；激光照射可改变表面釉质的钙磷相对含量，100mJ组与150mJ、200mJ组相比照射前后钙磷比值的变化有显著的统计学差异(P＜0．05)。结论：不同能量的激光照射可使牙釉质表面发生不同程度的改变，但是本研究未发现单独用普通脉冲Nd：YAG激光照射有增强光滑面牙袖质抗酸性的效果。     

脉冲Nd:YAG激光照射对牙髓细胞增殖的影响

目的了解脉冲Nd：YAG激光照射对牙髓细胞增殖的影响。方法应用体外组织细胞培养技术，MTT比色法测量不同能量参数的Nd：YAG激光照射对牙髓细胞增殖的影响。结果80mj20Hz的能量最有利于细胞生长，频率超过40Hz即对细胞生长无促进作用。结论合适的能量能够促进细胞生长。能量过大抑制细胞增长。     

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。     

不同参数的Er：YAG激光离体牙窝洞预备的形态学观察

目的：观察Er：YAG激光对离体人牙进行窝洞预备后的形态学改变,比较不同的能量设置及不同的水气比作用下的预备效果。方法：将10个无龋的离体磨牙随机分为5组（n＝2）,分别用不同Er：YAG激光参数进行窝洞预备。扫描电镜下观察牙釉质和牙本质的形态学改变。结果：经Er：YAG激光照射后,牙釉质呈现出一个粗糙不平的表面,牙本质层清洁,小管开放。在总功率相近的情况下,当水冷却降到50％或切割牙釉质时脉冲能量增加到700 mJ、切割牙本质时脉冲能量增加到400 mJ时,牙釉质及牙本质表面可发生部分熔融改变。结论：Er：YAG激光使用合适的参数进行牙体硬组织的切割安全有效,但在功率相近的情况下,水冷却不足或能量过大（牙釉质＞700 mJ,牙本质＞400 mJ）可损伤牙体组织。     

Nd：YAG激光用于狗牙直接盖髓术的实验研究

目的：观察Ｎｄ：ＹＡＧ激光照射暴露牙髓后的盖髓术疗效。方法：用肉眼和组织学切片法。结果：１０７个狗牙露髓面用３个不同参数（１５９２ｍＪ／ｍｍ２、３１８５ｍＪ／ｍｍ２、４７７７ｍＪ／ｍｍ２）Ｎｄ：ＹＡＧ激光照射５ｓ后用氢氧化钙盖髓，与单纯氢氧化钙组比较，发现：低能量Ｎｄ：ＹＡＧ激光有刺激照射区和侧方修复性牙本质形成、促进创伤愈合作用，而高能量Ｎｄ：ＹＡＧ激光照射则可能引起牙髓变性坏死。结论：低能量Ｎｄ：ＹＡＧ激光有一定的促进创伤愈合作用，但在Ｎｄ：ＹＡＧ激光用于照射露髓面牙髓前，还应该对促进牙本质桥形成的Ｎｄ：ＹＡＧ激光照射条件进行更详细研究。     

Nd：YAG激光照射对大鼠牙髓的影响

本研究目的在于探讨Ｎｄ：ＹＡＧ激光对牙髓的损伤阈值。活体照射１６只大鼠磨牙，进行组织学检查发现：，１Ｋ２０５９２ｍＪ／ｍｍ２能量密度的激光照射未引起牙髓的不可逆变化，是照射的安全阈值，在牙面上涂布６％美蓝可以加强激光的照射效果。牙髓反应最常见的是成牙本质细胞空泡性变、毛细血管充血、出血，大能量则造成冠部牙髓坏死。一般对根髓影响不大     

激光照射与酸性氟磷酸盐联合应用对离体人牙齿釉质脱矿的影响

目的 :研究激光照射及酸性氟磷酸盐 (acidulatedphosphatefluoride ,APF)处理离体人牙齿釉质 ,对牙釉质抗酸性的影响。方法 :10 0、15 0、2 0 0mJ 3种能量的激光照射光滑面及咬合面牙釉质后用 12 .3g/LAPF处理 ,对照组仅用 12 .3g/LAPF处理。将处理过的牙齿置于人工龋液中脱矿 ,测量不同时间后脱矿液中的釉质钙溶出量 ;偏光显微镜下测量人工龋的深度。结果 :酸蚀 10h后 ,实验组釉质钙溶出量少于对照组 (P <0 .0 5 ) ;酸蚀 2 4h后各组之间的钙溶出量无显著的统计学差异 (P >0 .0 5 )。 10 0mJ激光照射咬合面组的人工龋损深度少于其他 3组 (P <0 .0 5 ) ,但 15 0、2 0 0mJ激光照射组与对照组相比无显著的统计学意义 (P >0 .0 5 )。结论 :10 0mJ激光照射后再使用 12 .3g/LAPF可明显增强光滑面及咬合面牙釉质的抗酸性     

The effect of pulpotomy using CO2 and Nd:YAG lasers on dental pulp tissue

The histological response of the dental pulp after laser irradiation was studied. After pulpotomy was performed in the premolar and molar teeth of dogs, the exposed pulp tissue at the root canal opening was lased using either a CO₂ or Nd:YAG laser. The laser parameters were 2 W, 10 ms, 5 times per second for 1, 2 and 3 s for CO₂ laser and 2 W, 20 pulses per second for 1, 2 and 3 s for the Nd:YAG laser. Observations were made 30 and 45 days after treatment. The results revealed that laser irradiation caused carbonization, necrosis, infiltration of inflammation cells, oedema and haemorrhage in the pulp tissue. Under the conditions of this experiment, there was little histological evidence of repair to the treated pulp with a newly formed dentine barrier, which was in contrast to the control samples treated with a calcium hydroxide-containing cement (Dycal).     

Nd:YAG 激光在直接盖髓术中的应用

目的 :观察研究脉冲Nd :YAG激光照射在直接盖髓术中的作用。方法 :选择门诊意外露髓的患者 10 0例 ,随机分为对照组和试验组。对照组采用传统的氢氧化钙直接盖髓术。试验组首先用脉冲Nd :YAG激光 (设置激光脉冲频率为 2 0Hz ,每脉冲能量 40mJ)照射穿髓孔区 5s,再以氢氧化钙封闭穿髓孔。病人于术后 2周、6月、12月分别复诊检查牙髓活力情况 ,记录盖髓术成功率。结果 :12月复诊时对照组成功率 76 % ,试验组成功率 92 % ,统计学分析两者有显著性差异。结论 :适当能量的Nd :YAG激光照射有助于直接盖髓术的成功。脉冲Nd :YAG激光不仅具有清除穿髓孔区牙体组织碎屑、使暴露的牙体组织表面凝固止血、对穿髓孔区灭菌消毒等功能 ,还具有促进牙髓组织细胞再生修复的作用。     

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.     

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。     

3D volume-ablation rate and thermal side effects with the Er:YAG and Nd:YAG laser.

OBJECTIVES: The aim of this investigation was to determine the influence of a variety of parameters on the effectiveness of hard substance ablation and the thermal side effects when using Er:YAG laser (Key I and II, KaVo) and Nd:YAG laser (SunLase 800, Sunrise Technologies/Orbis). METHODS: For this study, ablation and temperature measurements were carried out on 170 dentin slices and 170 extracted teeth via computer-controlled cavity preparation. The Er:YAG laser settings varied from 250-400 mJ/pulse, 3-15 pps and 20-180 s processing time, and in the case of the Nd:YAG laser from 83-100 mJ/pulse, 10-20 pps, and 20-260 s processing time. The ablation rate was measured volumetrically via a 3D sensor. Temperatures were measured for each setting both on the dentin slice and in the pulp of the extracted teeth. The results were analyzed using a t-test for independent samples and a one-way ANOVA (Bonferroni). Also a liner regression analysis was done using Pearson's coefficient. RESULTS: The results show that with the Er:YAG laser, in combination with water-spray cooling, an effective 3D ablation rate (up to 0.017 mm3/pulse = 50 microns linear) can be achieved without raising the temperature of the surrounding tissue. In the case of the Nd:YAG laser, no measurable ablation rate was evident without conditioning of the dentin surface and, in the case of conditioning with black ink, a low ablation rate (0.00004 mm3/pulse = linear 0.2 micron/pulse) was found. SIGNIFICANCE: In contrast to the Er:YAG laser, it is apparent, that with the Nd:YAG laser from a total energy of 80 J onwards, the rise in temperature in the pulp is above 8 degrees C. For that reason, the use of the Nd:YAG laser at higher total energies is not recommended. The temperature rise with the Nd:YAG laser is dependent on the direction of the dentin tubuli. Dentin tubuli running parallel to the surface prevent significant heat penetration, whereas those running in a transverse direction to the surface (= parallel to the laser beam) support the penetration of heat. This finding supports the light-propagating theory for spreading effects of laser beams in dentin.     

Vapor emissions resulting from Nd:YAG laser interaction with tooth structure

The Neodymium:yttrium aluminum garnet (Nd:YAG) dental laser has been cleared by the United States Food and Drug Administration (FDA) for marketing in intraoral soft tissue treatment. The efficacy and safety of the Nd:YAG laser in the treatment of hard dental tissue as well as the effects of dental irradiation on the pulp and periodontium have been investigated. Odors resulting from laser irradiation have been reported, but the nature and toxicity of associated decomposition vapors is unknown and the health consequences of their inhalation have not yet been studied. OBJECTIVES: The purpose of this in vitro study was to identify vapors emitted during interaction of the Nd:YAG laser with carious human enamel and dentin and sound enamel and dentin coated with organic ink. METHODS: Vapor emissions were collected from prepared sections of extracted human teeth receiving laser irradiation of 100 mJ and 10 Hz for a duration of 1, 10, or 60 s. Emissions were collected by means of charcoal absorption tubes, and subsequently analyzed using a Gas Chromatograph equipped with Mass Selective (GC/MS) and Flame Ionization Detectors to identify the chemical constituents of the vapors. RESULTS: No compounds were identified in Nd:YAG laser-treated caries, enamel and dentin. No volatile vapors were identified from samples of tooth materials exposed to the laser for 1 or 10 s. Camphor was positively identified in the test sample which consisted of India ink-coated dentin and the reference sample of India ink-coated glass beads, both exposed to the laser for 60 s. 2,5-norbornadiene was tentatively identified in these samples. The Threshold Limit Value (TLV) of camphor is 2 ppm with a Lethal Dose Level (LDLo) of 50 mg/kg (human oral), while the TLV and LDLo of 2,5-norbornadiene is unknown. SIGNIFICANCE: Occupational and public health safety measures are discussed in this article. Further research is needed to quantify the compounds produced and to determine their toxicity to patients and to dental care providers.