Nd:YAG激光辅助去除陶瓷托槽对托槽的粘接强度及髓腔温度影响的研究

目的　研究国产DL-200型计算机控制脉冲Nd:YAG口腔激光机去除陶瓷托槽的最佳技术参数。方法　观察未使用激光照射组,以及激光功率5 W、照射时间2 s组,功率3 W、照射时间3 s组和功率2 W、照射时间5 s 组,3种参数下激光对陶瓷托槽的粘接强度及髓腔温度的影响。结果　①激光照射后可以显著降低陶瓷托槽的粘接强度,约降低50%,4组间的平均粘接强度差异有统计学意义(P<0·001);②激光照射后各组髓腔温度均升高,各组温度升高有统计学意义(P<0·001),激光功率3 W、照射时间3 s组髓腔温度只升高3·65℃,较其他两组低。结论　国产DL-200型计算机控制脉冲Nd:YAG口腔科激光治疗机激光照射后可以显著降低陶瓷托槽的粘接强度,去除陶瓷托槽的最佳参数是激光功率3 W、照射时间3 s,这一能量不会明显升高牙髓温度。     

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激光联合不同黏结系统对非龋性硬化牙本质黏结强度的影响

目的:通过微拉伸黏结强度实验,检测Nd:YAG激光联合3种不同黏结系统处理的硬化牙本质与复合树脂的黏结强度。方法:选择15颗硬化牙本质视觉分级为3级以上的面磨损牙,将面硬化牙本质分为面积近似相等的两部分,随机分为A(A1、A2)、B(B1、B2)、C(C1、C2)3组,以1W、10Hz Nd:YAG激光处理硬化牙本质表面后,按照随机数字表,使每颗牙分割的两部分进入不同的处理组,A2、C1联合ScotchbondTM处理,Z350复合树脂充填;A1、B1联合Adper Prompt L-Pop处理,Z350复合树脂充填;B2、C2联合Clearfil SE Bond处理,Z350复合树脂充填。置于37℃生理盐水中24h后,制作微拉伸试件,测试黏结强度,在体视显微镜下观察断裂模式并分类。采用SPSS13.0软件包对试件微拉伸黏结强度值做单因素方差分析。结果:Nd:YAG激光联合3种黏结剂处理后的微拉伸黏结强度分别为ScotchbondTM(A2、C1)处理组(22.96±4.93)MPa,Adper Prompt L-Pop(A1、B1)处理组(18.73±4.71)MPa,Clearfil SE Bond(...     

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。     

脉冲Nd:YAG激光照射后牙髓碱性磷酸酶的活性

目的 :探讨脉冲Nd :YAG激光照射后牙髓碱性磷酸酶 (ALP)的活性。方法 :选择 4条健康的本地杂种犬 ,进行牙齿过敏模型制备 ,随机分为 3组 ,分别给予 :33J/cm2 、5 6J/cm2 、111J/cm2 激光照射 ,按照即刻、3d、7d和 1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、染色、光镜观察、灰度值分级。结果 :3组激光能量照射后 ,牙髓成牙本质细胞均有染色 ,以 3d、7d染色较深 ,1月后染色变浅 ,ALP活性降低 ,接近正常牙髓细胞水平。结论 :在本实验条件下 ,牙髓成牙本质细胞碱性磷酸酶活性在不同的观察期相差显著 (P <0 .0 1) ,与激光能量无关 (P >0 .0 5 )。     

液氮冷冻联合Nd:YAG激光对兔耳静脉作用的效果观察

目的:观察液氮冷冻联合Nd:YAG激光照射对兔耳静脉的作用,评估该方法治疗静脉畸形的可行性。方法:将65只白兔随机分为4组。A、B、C为实验组,每组20只;D组为空白对照组,5只。以兔耳背中央静脉为实验模型,A组行液氮冷冻及Nd:YAG激光照射,B组行液氮冷冻,C组行Nd:YAG激光照射,D组不做处理。分别于实验处置后1、3、7、14、21 d对兔耳背中央静脉进行大体、光镜及电镜观察。结果:A组静脉血管内皮细胞、管壁平滑肌及构架结构均有明显损伤破坏,管腔内血栓形成,最终静脉闭锁。B、C组虽有血管内皮细胞损伤及血栓形成,但随后血栓逐渐溶解,血管修复。结论:冷冻联合激光照射对兔耳静脉有较强的损伤作用,具有治疗静脉畸形的可能性。     

预调金属托槽再次黏结前底板处理方法的探讨

目的对预调金属托槽重新黏结前底板的不同处理方法作一探讨。方法选择因正畸需要而拔除的离体前磨牙30颗,首次黏结预调金属托槽,24h后予以去除,以此离体牙齿和托槽为实验标本,将牙齿随机分为3组,每组10颗。A组黏结新托槽;B组和C组黏结旧托槽,其中B组托槽底板经火烧后超声波清洗处理;C组保留底板槽沟内的黏结剂而将底板磨平。0.5h后比较3组的剪切强度及ARI评分。结果3组之间的抗剪切强度无显著性差异,3组黏结剂残留指数比较显示C组样本在去除托槽后黏结剂残留在牙面上较少。结论预调金属托槽再次使用前保留底板槽沟内黏结剂的处理方法可能是一种更好的方法。     

Kr:F准分子激光对牙体硬组织的热效应研究

目的：评价Kr:F准分子激光照射牙齿后，对牙体硬组织的影响。方法；通过测量Kr:F准分子激光照射后牙齿硬组织的温度，并与Nd:YAG激光照射组进行比较。结果：10s,60s时，Kr:F准分子激光组牙齿硬组织的温度升高值明显低于Nd：YAG激光照射组（P＜0．01）。在照射10s-60s时间内，Kr:F准分子激光照射后牙齿硬组织的温度变化值也明显低于Nd:YAG激光照射组（P＜0．01）。结论：Kr:F准分子激光牙齿产热较少。     

Nd：YAG激光照射对兔面神经损伤的实验研究

目的探讨不同能量密度Nd：YAG连续激光对兔面神经的损伤效应及术后再生情况，为Nd：YAG激光治疗腮腺区深部海绵型血管瘤提供依据。方法根据临床治疗功率，采用5种不同能量密度Nd：YAG激光，分别对28只兔面神经进行照射。结果能量密度＜70J／cm2激光致面神经轻度变性，术后3周功能基本正常;能量密度140J／cm2激光致面神经中度变性;术后3周功能明显下降，6周基本恢复正常;能量密度240J／cm2激光致面神经不可逆损伤。结论Nd：YAG激光的热效应是面神经损伤的重要原因，且程度与能量呈正相关。     

脉冲激光辅助去除正畸金属托槽方法初探

目的 探讨脉冲Nd:YAG激光辅助去除正畸金属托槽的可行性,以期为临床提供一种优于机械性去除金属托槽的方法.方法 选择因正畸治疗拔除的50颗前磨牙,粘接托槽后根据随机数字表随机分为5组,每组10颗,实验1-4组分别接受13.0、13.5、14.0、14.5 A电流强度的激光照射,同时给予4.9 N的外力,直至托槽脱落,记录托槽脱落时间及牙髓腔内温度;剩余1组为对照组,使用持针器去除托槽.在体视显微镜下测量并计算粘接剂残留指数(adhesive remnant index,ARI).扫描电镜观察各组釉质表面情况.结果 实验1-4组的托槽脱落时间分别为(67.70 4±7.18)、(35.90±4.28)、(24.90 ±3.76)、(6.90±2.33)s.各组间差异均有统计学意义(P<0.01).实验1-4组牙髓腔内温度分别升高(20.97±3.10)、(12.75±3.14)、(8.99±2.47)、(2.91±1.88)℃,各组间差异均有统计学意义(P<0.05).实验1-4组和对照组Arl分别为(8.55±5.02)%、(15.42±7.37)%、(5.55±3.79)%、(13.72±6.69)%和(74.36±29.44)%,两两比较显示对照组与不同实验组间差异均有统计学意义(P<0.05),实验1-4组间差异无统计学意义(P>0.05).扫描电镜下可见对照组釉面横纹已被破坏,釉质表面粗糙不平;实验组釉质表面清洁,未见划痕、弹坑样及蜂窝样改变.结论 脉冲Nd:YAG激光辅助去除正畸金属托槽是一种可行的方法;与机械法相比,脉冲Nd:YAG激光辅助去除托槽及粘接剂的过程不破坏釉质表面结构.     

Thermal image analysis of electrothermal debonding of ceramic brackets: an in vitro study.

This study used modern thermal imaging techniques to investigate the temperature rise induced at the pulpal well during thermal debonding of ceramic brackets. Ceramic brackets were debonded from vertically sectioned premolar teeth using an electrothermal debonding unit. Ten teeth were debonded at the end of a single 3-second heating cycle. For a further group of 10 teeth, the bracket and heating element were left in contact with the tooth during the 3-second heating cycle and the 6-second cooling cycle. The average pulpal wall temperature increase for the teeth debonded at the end of the 3-second heating cycle was 16.8 degrees C. When the heating element and bracket remained in contact with the tooth during the 6-second cooling cycle an average temperature increase of 45.6 degrees C was recorded.     

A histopathological study of the morphological changes at the apical seat and in the periapical region after irradiation with a pulsed Nd:YAG laser

In this study, the effects of pulsed Nd:YAG laser irradiation on the apical seat and periapical region of instrumented root canals were investigated. One hundred and ninety-two teeth, including incisors and molars (239 root canals), in 18 healthy adult beagle dogs were used. After extirpation of the pulp under anaesthesia, each root canal was shaped up to at least a size 40 K-file, and then laser irradiated using the following parameters: 1 W, 15 pps for 2, 3, and 4 s; 2 W, 15 pps for 2 s. The effectiveness of debris removal and carbonization on the root canal walls immediately laser irradiation were examined and inflammation of the periapical region at 1, 2, and 4 weeks after laser irradiation was examined using light microscopy. Effective debris removal was observed in most cases in the laser-treated groups and was dependent on irradiated energy. Carbonization was observed in the irradiated root canals except at the parameter of 1 W for 2 s. Periapical inflammation was observed at 1 W for 2 s to the same extent as in the control group (P > 0.01). These results suggest that the pulsed Nd:YAG laser is useful for debris removal with no adverse effects immediately after extirpation of the pulp if appropriate parameters are selected.     

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).     

Laboratory evaluations on thermal debonding of ceramic brackets.

The purpose of this laboratory study was to define the working parameters and physiological safety and efficacy of the Dentaurum Ceramic Debonding Unit. Extracted mandibular incisors were utilized because of their low thermal mass and low heat sensitivity. The teeth were embedded in plastic and placed on a turning force measuring apparatus. An electrothermal element was placed in the pulp chamber (filled with a conducting paste). The thermoelement temperature was registered on y-t recorder as was the turning momentum required to remove the ceramic brackets with the Dentaurum Ceramic Debonding Unit. Ceramic brackets from GAC (Allure III), Unitek (Transcend) and Dentaurum (Fascination) using one and two component adhesives (Monolok, Concise), were tested. Scanning electron microscopic views taken after debonding showed predictable (and favorable) adhesive failure at the bracket base/resin interface. No enamel damage was demonstrated. All brackets were removable under three seconds with a clinically reproducible turning force of 85-100 Nmm allowing for intrapulpal temperature increases under the 5 degrees C biocompatible threshold. The Dentaurum Ceramic Debonding Unit provided a safe, reliable, efficient modality of removing ceramic brackets while maintaining a physiologically acceptable rise in pulpal temperature without damage to tooth enamel or pulpal tissue.     

Nd: YAG laser for debonding ceramic orthodontic brackets.

INTRODUCTION: The purpose of this study was to develop an effective method for debonding ceramic orthodontic brackets with a high-peak power Nd:YAG laser. METHODS: Two types of ceramic brackets (single crystal and polycrystalline) were bonded to mandibular bovine teeth with 2 types of bonding resins (4-META/MMA and Bis-GMA). The laser was applied to 2 points on each bracket, each with a 1-pulse-per-second shot. Bond strength and thermal effects of the laser on the dentin surface were assessed at 3 laser energy levels: 1.0, 2.0, and 3.0 joules (J). Shear tests were performed on the irradiated test group and on a nonirradiated control group. ANOVA was used to determine significant differences. RESULTS: The shear test (P < .05) showed that every specimen in the 2.0-J and 3.0-J groups underwent a significant decrease in bonding strength compared with the nonirradiated group. However, the 1.0-J group did not exhibit any such difference. In the 2 former groups, laser irradiation alone was sufficient to debond some specimens. No significant difference was found between bonding resins. The maximum temperature rise measured on the pulpal walls at the lasing points was 5.1 degrees C. CONCLUSIONS: The application of a high-peak power Nd:YAG laser at 2.0 J or more is effective for debonding ceramic brackets.     

Effect of CO2, Nd:YAG, and ArF excimer lasers on dentin morphology and pulp chamber temperature: an in vitro study

This study compared the effect of three laser systems: CO2 (10.600 nm), Nd:YAG (1.064 nm), and ArF excimer (193 nm) lasers on dentin hard tissue and on temperature increases of the pulp chamber. Sixty-six third molar teeth were used and randomly divided into three groups. A class I cavity was made to expose the dentin, and the pulp in the pulp chamber was removed via a hole bored in the cervical area. The pulp chamber was subsequently refilled with silicon grease, and a NiCr/NiSi thermocouple was inserted through the hole into the pulp chamber. The dentin surface was then lased for 30 s at the same settings (3 W, 2 mm spot size, 20 pps) with each laser. The average internal temperature increases were as follows: CO2, 37 degrees C; Nd: YAG, 28 degrees C; and ArF excimer, 1 degrees C. Scanning electron microscopy of the dentin in the occlusal cavity revealed extensive carbonization, isolated balls of recrystallized material, and the presence of smear layer at some dentinal tubule orifices for the CO2 and Nd:YAG lased teeth. Smear layer was also observed for the ArF excimer samples; however, they exhibited far less surface cavities than the others and seemed to undergo little morphological change on the dentin.     

Er:YAG激光应用于年轻恒切牙活髓切断术的研究

目的 观察Er:YAG激光用于年轻恒切牙活髓切断术的临床效果.方法 外伤冠折露髓年轻恒切牙40颗,随机分为2组,每组20颗.激光组用Er:YAG激光行活髓切断和三氧化物多聚体(mineral trioxide aggre-gate,MTA)直接盖髓,常规组用常规方法行活髓切断和MTA直接盖髓,随访12个月并进行临床评价.结果 激光组成功19颗,失败1颗,成功率95%;常规组成功18颗,失败2颗,成功率90%;2组成功率差异无统计学意义(χ2=0.367,P=0.545).结论 对年轻恒切牙应用Er:YAG激光进行活髓切断和MTA直接盖髓保存牙髓活力的近期效果良好.     

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。