Nd∶YAG激光对提高根管治疗术效果的作用机理探讨

用波长1.06μm,输出功率20W的Nd∶YAG激光照射根管壁后,常规根管糊剂+牙胶尖侧压法充填。对照组,直接根管充填。通过测量酚醛树脂在根管横截面中所占面积比值和染料渗入长度,发现实验组和对照组之间无明显差异(P>0.05)。认为单纯激光照射对根尖封闭能力的影响并不明显。激光照射在根管治疗术中的作用可能是通过其它途径。     

脉冲Nd∶YAG激光在根管预备中的临床应用——与超声根管预备、传统手动根管预备比较

为了观察脉冲Ｎｄ∶ＹＡＧ激光在根管预备（以下简称根备）中的作用,我们用Ｎｄ∶ＹＡＧ激光辅助,对３０颗患牙进行根备,根备后即时根充。并与超声根备后即时根充、传统根备后即时根充比较,结果表明：激光组的术后疼痛反应少于超声组与传统组,远期疗效与超声组相仿,而优于传统组。     

联合方法测量工作长度应用于颌骨囊肿受累牙根管治疗的研究

目的：研究颌骨囊肿受累牙根管治疗中采用联合方法测量根管工作长度的效果。方法：选取36 例颌骨囊肿受累患牙需术前 根管治疗的患者,共135 颗患牙,186 个根管,随机分为两组,实验组（93 个根管）采用电测法联合纸尖法测量根管工作长度,对照 组（93 个根管）则采用电测法联合X 线法测量根管工作长度。对比两组根管充填后的充填效果。结果：实验组的根管恰填率为 90.32%,高于对照组的79.57%（P＜0.05）。结论：采用电测法联合纸尖法测量颌骨囊肿受累牙根管工作长度,准确率高,根管充填 效果好且安全。     

Er,Cr:YSGG激光照射对根管封闭效果影响的实验研究

探讨常规根管预备后使用不同能量参数Er,C r:YSGG激光进行根管内照射对根管封闭效果的影响,为此激光在根管治疗领域的临床应用提供重要的实验依据。选择新拔除的单根管牙80颗,分成4组,每组20颗牙。常规根管预备后,分别使用1 W、2 W、3 W Er,C r:YSGG激光于有水条件下进行根管内照射,另选一组不做任何处理,作为阴性对照。扫描电子显微镜下观察根管内壁形态学改变后,常规根管充填,检测根管微渗漏情况。采用单因素方差分析及q检验进行统计学处理。结果可见:(1)形态学观察:与对照组相比,激光照射均可有效去除根管内壁的玷污层及碎屑;牙本质小管口清晰可见;未见熔融及炭化等热损伤改变;其中3 W激光处理后根管内壁形态最为理想。(2)微渗漏检测:与对照组相比,各激光组根管微渗漏深度均显著减少(P<0.05);但各激光组间比较无显著性差异(P>0.05)。综上,使用Er,C r:YSGG激光进行根管内照射可达到较为理想的根管清洁目的,显著改善根管充填后的封闭效果,因此有望在临床上应用提高根管治疗的成功率。     

可调脉宽倍频Nd:YAG激光干预兔耳增生性瘢痕的实验研究

目的:探讨可调脉宽倍频Nd:YAG激光对兔耳增生性瘢痕的治疗作用.方法:制作兔耳增生性瘢痕模型,术后30天对兔耳增生性瘢痕进行可调脉宽倍频Nd:YAG激光干预,观察兔耳瘢痕大体形态和组织病理改变,并采用免疫组化的方法检测兔耳瘢痕治疗前后血管内皮生长因子(vascular endothelial growth factor,VEGF)的表达情况.结果:可调脉宽倍频Nd:YAG激光干预后,兔耳增生性瘢痕出现明显的萎缩,免疫组化检查VEGF表达减弱.结论:可调脉宽倍频Nd:YAG激光可能通过损伤瘢痕组织内的微血管促进兔耳增生性瘢痕萎缩,对早期增生性瘢痕具有治疗作用.     

The effect of the NRT files instrumentation on the quality of the surface of the root canal wall

Purpose: To analyze in vitro, trough scanning electron microscope (SEM), the shaping ability of NRT NiTi rotary system (Mani, Inc, Toshigi-Ken, Japan). Methods: Ten extracted human teeth were cut at the level of the CEJ and prepared with Gates-Glidden burs 4-3-2 and NRT rotary files up to size #35. Irrigation was performed with 7.5 mL of 5% NaOCl and 7.5 mL of 10% EDTA during each canal instrumentation. Following the shaping sequence, a final irrigation was performed with EDTA followed by NaOCl, each left in situ for three minutes. Teeth were then fractured longitudinally, and the coronal, middle, and apical thirds of the canals were inspected with SEM. Three parameters, divided into four different levels (Alfa and Bravo, considered clinically acceptable; Charlie and Delta, considered clinically unacceptable), were used to score the canal morphology: presence and amount of smear layer; presence of organic and inorganic debris; surface profile. Results: SEM assessment revealed that in the coronal and middle third the majority of canals shaped with NRT rotary system presented a clinically acceptable surface. The apical third presented a higher amount of smear layer and dentinal debris instead, compared to the coronal and middle third.Conclusions: NRT files demonstrated that they provided good instrumentation of the coronal and middle third, while being unable to obtain a defects-free surface in the apical third.     

高频电对感染根管消毒作用的初步实验研究

目的:初步验证高频电对感染根管是否具有较理想的消毒作用,并且与氢氧化钙药尖的消毒作用进行初步比较分析。方法:本实验制作10只家兔40颗门齿的感染根管动物模型,其中20颗用高频电消毒为实验组。20颗用氢氧化钙药尖消毒为对照组,消毒前后分别作需氧菌和厌氧菌培养并比较其消毒效果。结果:消毒前实验组和对照组各20个根管的需氧及厌氧菌培养全部阳性。实验组消毒后需氧菌3个阳性根管、厌氧菌2个阳性根管,消毒前后对需氧和厌氧菌杀灭作用的差异均具有极显著性(P<0.005)。对照组消毒后需氧菌13个阳性根管消毒作用的差异有显著性(P<0.05)。对照组消毒后厌氧菌11个阳性根管消毒作用的差异有极显著性(P<0.005)。实验组和对照组分别对需氧和厌氧2个菌种之间消毒作用的差异均无显著性(P>0.05)。实验组和对照组对需氧菌的消毒作用和对厌氧菌的消毒作用的组间差异均具有极显著性(P<0.005)。结论:高频电对感染根管内容物的消毒作用优于氢氧化钙药尖,具有临床应用的可行性。值得进一步研究。     

国产Nd:YAP激光组织热损伤效应的比较研究

目的:通过比较1 341 nm Nd:YAP与临床常用激光器脉冲Nd:YAG和连续Nd:YAG对皮肤、肌肉、静脉和肝脏组织的热损伤效应,了解Nd:YAP激光的作用特点,为其临床应用提供实验依据。方法:以大鼠作为实验对象,分为皮肤、肌肉组和静脉、肝脏组。皮肤、肌肉组:Nd:YAP激光、连续和脉冲Nd:YAG选择能量密度1000 J/cm2、2 000 J/cm2,静脉、肝脏组采用Nd:YAP激光和连续Nd:YAG两种激光器,能量密度选择500 J/cm2和1 000 J/cm2,对组织进行非接触式点状照射。照射过程中观察组织变化和损伤直径大小,并于照射后即刻、3天取材做病理切片,光镜下观察病理变化,比较相同能量密度下三种激光器对组织的热损伤和损伤修复情况。结果:皮肤、肌肉组:Nd:YAP激光在1 000 J/cm2条件下对组织的损伤以热凝固效应为主,2 000 J/cm2条件下组织发生明显气化、有一定的切割作用。相同能量密度下,脉冲Nd:YAP激光气化作用较两种Nd:YAG激光显著,而凝固损伤范围较连续Nd:YAG浅,较脉冲Nd:YAG深。肝脏、静脉组:Nd:YAP激光对肝脏的热凝固效应与Nd:YAG激光近似,气化作用明显;Nd:YAP激光对血管及其周围组织的凝固及气化作用均较连续Nd:YAG激光明显。结论:Nd:YAP激光具有良好的凝固与气化作用。     

Sealing of open dentinal tubules by laser irradiation: AFM and SEM observations of dentine surfaces

Dentin of human teeth is a vital hydrated tissue. It is strongly sensitive to dehydration and drying that are commonly used in preparation of samples for scanning electron microscopy. Experience in examination of dentine surfaces of extracted human third molars using contact mode atomic force microscopy under moist conditions is described. The examined dentine surfaces are modified by laser radiation produced by a pulsed Nd:YAG laser that leads to sealing of open dentinal tubules under suitable conditions that are reached after covering dentine surfaces with dye agents. Out of four investigated dye agents erythrosin solution in water has been found the most suitable and the lower and upper limits of pulse energies for sealing of dentinal tubules have been set.     

Comprehensive histologic analysis of interstitial lipolysis with the 1444 nm wavelength during a 3-month follow-up

A number of near-infrared wavelengths have been proposed and studied for laser lipolysis, but the histologic evaluation of tissue response to laser lipolysis during long-term follow-up has been lacking. A 1444 nm Nd:YAG laser with better absorption in both fat and water has recently attracted attention. The present study was designed to investigate the comprehensive histopathology of 1444 nm Nd:YAG laser-assisted lipolysis at different energy levels during a 3-month follow-up. Laser lipolysis was performed on porcine fat tissue in vivo using a 1444 nm Nd:YAG laser (AccuSculpt?, Lutronic Corporation, Ilsan, Republic of Korea) and the total energies delivered interstitially to 10x10 cm2 areas were 750 J, 1500 J, 2250 J, 3000 J, 3750 J, 4500 J, and 5250 J. Biopsy samples were taken and histologically analyzed immediately after biopsy and at 1, 2, 4, and 12 weeks postoperatively. With a fluence setting above 3000J/100 cm2, inflammation was severe and remained by the 3-month follow-up, resulting in severe scarring of the fat tissue. Below this energy level, mild lobular inflammation in the early phase biopsy had resolved with no scarring by the 3-month follow-up. No histologic changes in the epidermis or dermal connective tissue were present. This study suggested that controlling the energy level is important for clinical applications of laser lipolysis with no significant complications.     

A Cone-Beam Computed Tomographic Study on Mandibular First Molars in a Chinese Subpopulation

The purpose of this study was to conduct a cone-beam computed tomographic (CBCT) investigation on the root and canal configuration of the mandibular first molars, especially the morphology of the disto-lingual (DL) root, in a Chinese subpopulation. A total of 910 CBCT images of the mandibular first molars were collected from 455 patients who underwent CBCT examinations as a preoperative assessment for implants or orthodontic treatment. The following information was analyzed and evaluated: tooth position, gender, root and root canal number per tooth, root canal type of the mesial root(s) and distal root(s), angle of the DL root canal curvature, distance between two distal canal orifices in the teeth with DL root, and angle of disto-buccal canal orifice–disto-lingual canal orifice–mesio-lingual canal orifice (DB-DL-ML). Most of the mandibular first molars (64.9%, n = 591) had two roots with three root canals, and most of the mesial root canals (87.7%, n = 798) were type VI. The prevalence of the DL root was 22.1% (n = 201). The right side had a higher prevalence of DL root than the left side (p<0.05). Additionally, the curvature of the DL root canal were greater in the bucco-lingual (BL) orientation (30.10°±14.02°) than in the mesio-distal (MD) orientation (14.03°± 8.56°) (p<0.05). Overall there was a high prevalence of DL root in the mandibular first molars, and most of the DL roots were curved in different degrees. This study provided detailed information about the root canal morphology of the mandibular first molars in a Chinese subpopulation.     

Fracture mechanics analysis of vertical root fracture from condensation of gutta-percha

A two-dimensional fracture mechanics analysis of vertical root fracture (VRF) in single-canal roots from apical condensation of gutta-percha (gp) is developed. The resulting analytic relation for apical load causing VRF agrees with major trends reported in in-vitro tests on roots subjected to either continuous or, the more clinically relevant, repeating vertical condensation of gp. The model explicitly exposes the role of root canal morphology and dentin fracture toughness on VRF. Ovoid and irregular canals are prone to fracture while the effect of mean root canal radius is modest. Canal taper and instrumentation details may affect VRF only marginally and indirectly. The model predicts dentinal cracks to occur following root canal instrumentation and obturation, which may pose long-term threats to tooth integrity.     

Blue light filtering intraocular lenses in phacoemulsification cataract surgery

Blue light can damage retina and cause age related macular degeneration. After cataract surgery and lens removal retina stays unprotected. Blue light filtering intraocular lenses (IOL) increase protection of the retina. In our prospective study we investigated clinical results after bilateral implantation of Acrysof Natural IOL to 30 patients (N = 60 eyes). In a control group (N = 60 eyes, 30 patients), standard acrysof IOL was implanted bilaterally. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA) and Nd YAG laser capsulotomy rate were measured and compared with control group. Subjective patient's satisfaction and subjective colour perception were also investigated. There was no significant difference in UCVA, BCVA and Nd YAG laser capsulotomy rate between the two groups. High patient's satisfaction was noticed (96.7% of patients would implant Acrysof Natural IOL again). Acrysof Natural IOL enables good visual acuity VA, low rate of Nd YAG laser capsulotomy and high patient's satisfaction without colour perception disturbances.     

In vitro laser ablation of natural marine biofilms

We studied the efficiency of pulsed low-power laser irradiation of 532 nm from an Nd:YAG (neodymium-doped yttrium-aluminum-garnet) laser to remove marine biofilm developed on titanium and glass coupons. Natural biofilms with thicknesses of 79.4 +/- 27.8 microm (titanium) and 107.4 +/- 28.5 microm (glass) were completely disrupted by 30 s of laser irradiation (fluence, 0.1 J/cm2). Laser irradiation significantly reduced the number of diatoms and bacteria in the biofilm (paired t test; P < 0.05). The removal was better on titanium than on glass coupons.     

Ar+激光、Nd:YAG激光辐照亚心形扁藻生物学效应初探

采用Ar^＋激光（488 nm,照射时间分别为10 min、20 min、30 min）、Nd：YAG（1064 nm,照射时间为1 min、2 min、3 min）辐照扁藻,通过细胞计数以及扫描色素的吸收光谱研究激光辐照扁藻的生物效应.研究结果表明：非色素吸收峰的激光可以产生激光生物效应;不同波长,不同剂量的激光辐照扁藻可以表现出相类似的生物效应;Ar＋辐照20 min、Nd：YAG辐照2 min可以刺激扁藻生长,明显提高色素吸收光密度值,促进光合作用的进行.文中对不同激光辐照扁藻所产生的生物效应进行了比较和探讨.     

Nd:YAG激光治疗特殊部位尖锐湿疣的疗效观察

目的：观察Nd：YAG激光治疗位于尿道口、阴道口、肛门及肛周的难治性尖锐湿疣的疗效。方法：将61例特殊部位的尖锐湿疣的患者随机分为实验组（31例）和对照组（30例）,实验组采用Nd：YAG激光机治疗,对照组采用普通CO2激光治疗机,随访半年观察两组的创面愈合情况、治愈率及复发率。结果：采用Nd：YAG激光治疗的实验组一次治愈率为80．64％,高于对照组的一次治愈率56．67％（x^2=4．087,P〈0．05）,但两组的总治愈率无显著性差异（x^2=1．198,P〉0．05）。实验组复发率为22．58％,低于对照组的复发率46．67％。两者有显著性差异（x^2=3．918,P〈0．05）。激光术后第5天实验组的愈合率45．16％高于对照组的愈合率20．00％,两者有显著性差异（x^2=4．380,P〈0．05）;第7天实验组的愈合率为87．09％高于对照组的愈合率60．00％,两者有显著性差别（x^2=4．469,P〈0．05）;第10天实验组的患者全部愈合,愈合率为100％,高于对照组的愈合率83．33％（P=0．024〈0．05）。结论：Nd：YAG激光治疗特殊部位尖锐湿疣效果好,创面愈合快,复发率低。     

Capillary hemangioma (strawberry mark) of infancy: comparison of argon and Nd:YAG laser treatment

Capillary hemangioma of infancy (strawberry mark) is a self-limiting problem, and conservative treatment is recommended. These birthmarks can be associated with a great deal of morbidity. There is definitely a role for a palliative form of treatment without systemic complications or destruction of adjacent tissue. In a 6-year period, 55 patients received 57 Nd:YAG or argon laser treatments. Thirty patients received 31 argon treatments, and 25 patients received 26 Nd:YAG treatments; and 2 received first argon with subsequent Nd:YAG treatments. Although more dramatic successes were noted in the Nd:YAG laser, complications were more frequent and severe. Complications included delayed healing, postoperative bleeding, and some hypertrophic scarring. Complications were seen in 12 percent of all patients, 9 percent of these associated with the Nd:YAG laser.     

新型激光光敏根管消毒剂在牙本质中渗透性的研究

目的：观察新型激光光敏根管消毒剂、甲苯胺蓝和亚甲基蓝在牙本质中的渗透效果,评价三种光敏剂在牙本质中的渗透性。方法：收集新鲜拔除的离体单根管牙90颗,根管预备后随机分为三组。每组30颗。A组为新型激光光敏根管消毒剂组;B组为甲苯胺蓝组;c组为亚甲基蓝组。A、B、C三组实验根管内分别用浸有饱和的新型激光光敏根管消毒剂、甲苯胺蓝和亚甲基蓝的棉捻在根管内停留60秒。沿牙体长轴颊舌纵向劈开,倒置荧光显微镜下观察并拍照,用Photoshop8．01软件测量三种光敏剂渗透入牙本质的平均深度。结果：新型激光光敏根管消毒剂在牙本质内的渗透平均深度为553．25μm,甲苯胺蓝在牙本质内的渗透平均深度为350．75μm,亚甲基蓝在牙本质内的渗透平均深度为168．25μm。结论：新型激光光敏根管消毒剂在牙本质渗透性明显优于甲苯胺蓝和亚甲基蓝,具有良好的牙本质渗透性。     

脱落酸高产菌的激光诱变效应研究

本实验对比紫外、 Ｈｅ Ｎｅ 激光、 Ｎｄ： Ｙ Ａ Ｇ 倍频脉冲激光对脱落酸产生菌的诱变效果。紫外诱变正变率为 ３８４％ ,负变率 ７６９％ ; Ｈｅ Ｎｅ 激光诱变正变率为 ５６％ ; Ｎｄ： Ｙ Ａ Ｇ 倍频脉冲激光诱变正变率为１９６％ 。 Ｎｄ： Ｙ Ａ Ｇ 倍频脉冲激光诱变辐照次数在 ４００ 次时效果较好,所得高产株效价提高率可达 ６０％ 以上     

Molecular level damages of low power pulsed laser radiation in a marine bacterium Pseudoalteromonas carrageenovora

AIM: To study the molecular level damages in a marine bacterium, Pseudoalteromonas carrageenovora, exposed to low power pulsed laser radiation from an Nd:YAG laser. METHODS AND RESULTS: The laser damages in bacterial DNA were monitored by studying the formation of apurinic/apyrimidinic (AP) sites. Molecular probe kits were used for this purpose. Occurrence of lesions in the cell walls was monitored under a transmission electron microscope (TEM). The results showed that laser radiation significantly increased the number of AP sites in the bacterial DNA. This increase corresponded to the laser fluence (J cm(-2)) and to the duration of laser irradiation. TEM observation showed the occurrence of lesions in bacterial cell walls upon laser irradiation. CONCLUSIONS: It is concluded that bacteria exposed to laser irradiation suffers DNA damages and resulted in broken cell walls. These events led to bacterial mortality. These are in addition to the mechanisms reported earlier such as the photochemical reactions occurring inside the cells upon exposure to low power laser. SIGNIFICANCE AND IMPACT OF THE STUDY: These results help us to understand the mechanisms of bacterial mortality on exposure to low power pulsed laser irradiation and are useful in formulating a laser treatment strategy to kill bacteria.