激光促进氟保护漆对牙本质小管的封闭作用

目的 探讨Nd:YAG激光与氟保护漆联合应用对牙本质小管的封闭作用。方法 将24个牙本质块随机分为A、B、C、D4组,均用37%H3PO4处理表面。A组作为对照。B、C、D组均涂以一薄层氟保护漆,然后D组标本经Nd:YAG激光照射。以正常刷牙力度同时刷C、D2组牙本质块10min。所有标本以扫描电镜（scanning electron microscope,SEM）观察并照相。结果 A组显示大量牙本质小管口开放,管口直径约2～3um。B组显示牙本质表面被氟保护漆均匀覆盖。C组显示氟保护漆大部分被刷去。D组显示仍有超过80%的牙本质小管口被氟保护漆所封闭。结论 在同样的刷牙条件下,将Nd:YAG激光与氟保护漆联合应用,仍有大部分牙本质小管口被封闭。     

不同染液对Nd：YAG激光封闭牙本质小管效果的影响

目的：观察不同染液对Nd：YAG激光封闭牙本质小管效果的影响。方法：取4个新鲜拔除的第一恒磨牙,用低速金刚砂盘水平去除冠部牙釉质并暴露牙本质后,在每个牙本质样本的表面各划分出4个面积为2 mm ×3 mm的操作区（共16个区域）;分别用EDTA进行表面处理后,将16个区随机分配到4个组中（n＝4）,其中不涂染液直接激光照射的样本为对照,其他3组样本分别涂20 g／L甲基紫、墨汁、20 g／L亚甲蓝后,用Nd：YAG激光以120 mJ、5 Hz（对应的激光能量密度为200 J／cm2）扫描式照射各操作区20 s;然后常规制备SEM标本,在SEM下观察,同时采集1500×和3000×视野下的典型图像,分别用于计算各组牙本质小管的封闭率和测量小管口的直径。结果：对照组、20 g／L甲基紫组、墨汁组、20 g／L亚甲蓝组的牙本质小管封闭率分别为（10．01±1．71）％、（2．72±0．70）％、（11．18±2．34）％、（36．14±6．30）％,各组间两两相比P＜0．05;小管口直径（μm）分别为2．75±0．26、3．25±0．24、1．61±0．13、1．32±0．14,各组间两两相比 P＜0．05。结论：20 g／L 亚甲蓝染液能明显增强Nd：YAG激光对牙本质小管的封闭作用。     

Comparative evaluation of antibacterial effects of Nd:YAG laser irradiation in root canals and dentinal tubules

The antibacterial effects of the Nd:YAG laser on contaminated root canals and dentinal tubules were observed as the aim of this study. The samples were inoculated with Streptococcus sanguis (NCTC 7853) and Prevotella intermedia (NCTC 93336), and the effects of Nd:YAG laser were tested on these teeth. The specimens were lased with 1.8 W and 2.4 W Nd:YAG laser for 30 s, and the presence of bacteria in tubules was observed under light microscopy. The 1.8 W laser sterilized the tubules in 86.3% of sections inoculated with S. sanguis, whereas 2.4 W laser sterilized in 98.5% of the sections. Both laser powers sterilized all samples inoculated with P. intermedia. The scanning electron microscopic observations supported the light microscopic findings.     

Combined effect of fluoride varnish to Er:YAG or Nd:YAG laser on permeability of eroded root dentine

ObjectiveThis study evaluated the combined effect of fluoride varnish to Er:YAG or Nd:YAG laser on permeability of eroded root dentine.DesignSixty slabs of bovine root dentine (2 × 2 × 2 mm) were eroded with citric acid 0.3% (pH 3.2) during 2 h and then kept in artificial saliva during 24 h. Specimens were randomly assigned in 6 groups (n = 10), to receive the following treatments: fluoride varnish; fluoride varnish + Er:YAG laser; fluoride varnish + Nd:YAG laser; non-fluoride varnish; non-fluoride varnish + Er:YAG laser; non-fluoride varnish + Nd:YAG laser. The Er:YAG (100 mJ, 3 Hz) and Nd:YAG (70 mJ, 15 Hz) were applied for 10 s. Specimens were subjected to further erosive challenges with citric acid 0.3% 4×/day, during 1 min, for 5 days, remaining in artificial saliva between cycles. Dentin permeability was then assessed. Two-way ANOVA demonstrated no significant interaction between laser and varnish (p = 0.858).ResultsNo effect was also detected for the main factor varnish (p = 0.768), while permeability of eroded root dentin was significantly lower when such substrate was laser-irradiated, no matter the laser source (p < 0.001).ConclusionsThis study concluded that Er:YAG and Nd:YAG lasers can be employed to control the permeability of eroded root dentin, regardless of fluoride varnish application.     

Occluding effect of Nd:YAG laser and different dentin desensitizing agents on human dentinal tubules in vitro: a scanning electron microscopy investigation

OBJECTIVES : This in vitro study aimed to microscopically evaluate and compare the occluding effect of the Nd:YAG laser and different dentin desensitizing agents on human dentinal tubules. MATERIALS AND METHODS : The Nd:YAG laser (SunLase? 800) and four commercially available and professionally applied dentin desensitizers (Gluma? desensitizer, Tenure Quick?, Quell? desensitizer, and VivaSens?) were investigated in this study. Sixty-four extracted intact human molars were used. Each dentin surface was divided by shallow indentation into two halves, one of which was used for treatment and the other of which served as a control. The dentin surfaces were etched to remove any smear plugs and to mimic the open dentinal tubules of sensitive dentin using 0.5 M ethylenediaminetetraacetic acid (pH 7.4) for two minutes (applied with a microbrush) and then rinsed with an air-water syringe for 30 seconds. The laser samples (n=16) were randomly divided into four groups of four samples each. These groups were the step-up technique group, the 14-day group, the one-minute group, and the two-minute group. Forty-eight samples were treated with the four tested desensitizing agents and were randomly divided into four groups (n=12/group). Each group was further subdivided into three subgroups (n=4). Samples of the first subgroup were treated for 14 days, while those of the second subgroup were treated once. Samples of the last subgroup were fractured longitudinally after a single treatment. All of the samples were then examined under a scanning electron microscope. RESULTS : The Nd:YAG laser-irradiated dentin showed reduction or complete obliteration of the dentinal tubule lumen; thus, the treatment modified the original dentinal structure. The lased dentin surface in the two-minute group showed bubble-like changes in the area of the dentinal tubules' orifices. Statistically, the two-minute group was found to have a significantly higher percentage of partially or fully occluded tubules than did the one-minute group. All of the studied desensitizing agents produced occlusion of the dentinal tubules; however, the appearance of the precipitates, the level of coverage, and the degree of dentinal occlusion varied among the tested products. CONCLUSION : Throughout the specified period of this study, occlusion and/or narrowing of the open dentinal tubules have been successfully achieved with both treatment approaches.     

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部，电镜观察和测定牙本质通透性，研究激光对牙本质的作用，初步探讨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学差异；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阻塞。提示Ｎｄ：ＹＡＧ激光脱敏，可能存在其他的生物学脱敏机制。     

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     

A comparison between the occluding effects of the Nd:YAG laser and the desensitising agent sensodyne on permeation through exposed dentinal tubules of endodontically treated teeth: an in vitro study

OBJECTIVE: Dentine hypersensitivity may occur due to loss of covering enamel and/or loss of cementum after gingival recession, resulting in exposure of cervical dentine and patency of dentinal tubules. The effect of thermally cooled pulsed neodymium:yttrium-aluminium-garnet (Nd:YAG) laser on the permeability and structural appearance of the root canal wall was investigated in vitro. The aim of this study was to compare the occluding effect of Nd:YAG laser with that of sensodyne on exposed dentine. MATERIAL AND METHODS: Forty freshly extracted human maxillary anterior teeth were collected at random. Root canal obturations were performed using master apical file no. 60 k-type for obturated teeth. All teeth were stored in 100% humidity at 37 degrees C for 48h to allow time for the sealer to set. Dentine of 35 teeth was exposed by removing the cementum, and the remaining five teeth represented a negative control group. Specimens were examined using stereomicroscopy to show the surface topography of the dentine substrate before and after treatment with Nd:YAG laser or sensodyne. RESULTS: A double-blind technique was used when taking measurements of ink penetration (in mm) for each group. Teeth treated by Nd:YAG laser showed the least ink penetration, followed by teeth treated by sensodyne. The positive control group demonstrated complete ink penetration and the negative control group showed no ink penetration. Stereomicroscopic examination of specimens treated with Nd:YAG laser showed deposition on the dentinal surface, and specimens treated with sensodyne showed partial deposition. Untreated specimens were free of deposition and the tubules remained patent. CONCLUSION: There is no significant difference in the occluding effect of Nd:YAG laser and sensodyne toothpaste. Both treatments have a promising effect on the reduction of permeation through exposed dentinal tubules. However, the occluding effect of Nd:YAG laser occurs within seconds whereas that of sensodyne takes at least 3 weeks.     

Nd：YAG激光对Dyract复合体充填微渗漏的影响

目的　观察Nd :YAG激光照射洞缘牙釉质对复合体Dyract充填微渗漏的影响。方法　新鲜拔除的完整离体牙 5 0颗 ,随机分为实验组 ( 2 6颗 )和对照组 ( 2 4颗 )。在样本牙的颊舌面制备V类洞 ,对照组常规完成Dyract充填 ,实验组用Nd :YAG激光照射洞缘牙釉质后再行Dyract充填。所有样本经冷热循环处理后 ,再进行微渗漏实验。用体视显微镜和SEM观察并拍照记录。结果　激光光蚀组充填体边缘微渗漏比对照组明显低 (P <0 .0 5 )。微渗漏实验与扫描电镜观察结果一致。结论　Nd :YAG激光的光蚀作用有助于增强复合体Dyract与牙体组织的结合 ,改善边缘封闭 ,减少微渗漏 ,有利于充填成功     

Nd:YAG激光对鳞状细胞癌CAL-27细胞增殖的影响

目的 研究Nd:YAG激光对鳞状细胞癌（鳞癌）CAL-27细胞的生物学效应。方法 用脉冲1064 nm Nd:YAG激光连续照射体外培养处于对数生长期的鳞癌CAL-27细胞,分组照射后倒置显微镜下观察细胞形态,培养1、3、5 d后利用MTT法测定OD值,以此来研究激光对鳞癌CAL-27细胞增殖的影响。结果 低剂量激光照射时,CAL-27细胞的OD值随着激光照射剂量的增加而升高（P＜0.05）;而高剂量激光照射时,CAL-27细胞的OD值随着激光照射剂量的增加而降低（P＜0.05）。结论 1 064 nm Nd:YAG激光低剂量照射鳞癌CAL-27细胞,细胞表现形态规则、密度增大,增殖活跃;而高剂量照射鳞癌CAL-27细胞后,细胞形态不规则、密度降低,增殖受到抑制,对指导临床应用有一定参考价值。     

Comparative assessment of the sealing ability of Nd:YAG laser versus a new desensitizing agent in human dentinal tubules: a pilot study

Dentinal hypersensitivity is a painful condition that occurs following periodontal treatment. Many treatment alternatives have been considered for this problem, including treatments with laser and dentinal adhesives. This study compared the sealing ability of Nd:YAG laser versus a new resin in scanning electron microscopy (SEM) micrographs. Ten human premolars were sectioned yielding 30 specimens of each premolar, which were randomly divided into three groups. The laser group was irradiated by Nd:YAG laser (1 W, 10 Hz, 60 s), the resin group was treated with the new Seal & Protect resin according to the manufacturer’s instructions, and the third group served as the control group and did not receive any interventions. After preparation and gold coating of the samples, they were photographed by SEM at two magnifications (1500× and 4000×). The number and diameter (μm) of the dentinal tubules were recorded in selected fields, and analysis of variance (ANOVA) and Tukey tests were used to determine significant differences between groups. The ANOVA results revealed significant differences in both the mean number (P < 0.001) and diameter (P < 0.05) among the three groups. Further statistical analysis showed a significant difference between the laser group and the resin group in both outcome measures (P < 0.05). Thus, both Nd:YAG laser and the new resin reduced the number and diameter of open dentinal tubules, a result that also explains the desensitization mechanism of these interventions. We further conclude that application of the new resin is more effective than Nd:YAG laser in minimizing the number and diameter of exposed dentinal tubules.     

六氟硅酸铵溶液封闭牙本质小管的扫描电镜观察

目的:研究不同浓度六氟硅酸铵(SiF)溶液封闭牙本质小管的即刻效果.方法:将32个新鲜拔除的人第三磨牙,分别制备4mm ×4mm ×2mm的牙本质盘,经0.5 mol/L EDTA溶液酸蚀2min后,随机分A、B、C、D、E、F、G7组,A组为空白对照组,B～G组分别使用10、20、30、40、50、100 mg/L的六氟硅酸铵溶液涂抹3 min,扫描电镜观察牙本质小管的封闭效果及小管内堵塞深度,并用Image-pro PLUS,v6.0图像分析软件量化分析.结果:各处理组牙本质小管均有不同程度的封闭,其中50 mg/L为即刻最佳最低有效浓度,并且可渗入牙本质小管内达一定深度;计算各组开放牙本质总面积进行量化分析显示,10 ～ 100 mg/L各浓度SiF各处理组的开放牙本质小管总面积均低于空白对照组(P＜0.05);各处理组开放牙本质小管总面积随着SiF浓度增高而越来越低,其中50 mg/L和100 mg/L牙本质小管封闭效果最好,与其他各组相比均有统计学差异(P＜0.05).结论:50 mg/L以上六氟硅酸铵溶液对牙本质小管有良好的封闭作用.     

蜂胶醇封闭牙本质小管的扫描电镜观察

目的:研究不同浓度蜂胶醇封闭牙本质小管的效果,为蜂胶脱敏治疗提供形态学依据. 方法:将35个新鲜上颌前磨牙随机分为A、B、C、D、E、F、G7组,制作3㎜×3㎜×2㎜牙本质磨片,清洁,酸蚀.A、B、C组分别涂10、20、30 g/L的蜂胶醇,D组涂含氟涂膜,E组作为空白对照组,扫描电镜观察牙本质小管封闭情况,筛选蜂胶最佳浓度(记作X).F组涂抹浓度为X的蜂胶,G组涂含氟涂膜,用牙刷刷洗标本表面,扫描电镜观察牙本质小管封闭情况.结果:30 g/L的蜂胶醇能够完全封闭牙本质小管,且渗入沉淀达一定深度,经过刷牙后封闭效果没有明显减弱.结论:蜂胶对牙本质小管具有良好的封闭作用,在治疗牙齿感觉过敏症方面具有进一步研究价值.     

Er:YAG激光联合3M ESPE Adper Easy-one粘结剂堵塞牙本质小管的体外研究

目的:研究Er:YAG激光联合3M ESPE Adper Easy-one自酸蚀树脂粘结剂堵塞牙本质小管的效果,为其治疗牙本质敏感提供实验室依据。方法:选择因正畸需要拔除的牙体完整、无龋损的前磨牙8个,制备牙颈部牙本质小管暴露的牙本质样本32个,按处理方法不同随机分为4组:空白对照组、Er:YAG激光处理组、3M ESPE Adper Easy-one粘结剂处理组、Er:YAG激光、3M ESPE Adper Easy-one粘结剂联合处理组,扫描电镜下比较牙本质表面超微形态、纵断面的粘结剂牙本质界面的混合层、树脂突的微观表现,观察牙本质小管的堵塞效果。结果:Er:YAG激光联合3M ESPE Adper Easy-one粘结剂组与粘结剂组的堵塞牙本质小管的表面微观形态类似,牙本质小管被完全堵塞;激光处理组的牙本质小管基本完全堵塞;纵断面观察联合组粘结界面可见到清晰的混合层和树脂突,且树脂突深度较粘结剂组明显增加,激光组纵断面牙本质小管内无明显堵塞物。结论:Er:YAG激光与3M ESPE Adper Easy-one粘结剂联合处理能够有效的堵塞牙本质小管。     

Short-term assessment of the Nd:YAG laser with and without sodium fluoride varnish in the treatment of dentin hypersensitivity--a clinical and scanning electron microscopy study

BACKGROUND: The aim of the present study was to evaluate clinically and under scanning electron microscopy (SEM) the efficacy of Nd:YAG laser irradiation alone and in combination with 5% sodium fluoride varnish in the management of dentin hypersensitivity. Methods: The study was conducted on 40 patients divided into four groups who had at least one tooth of Grade III mobility with clinically elicitable dentin hypersensitivity. Following the pretreatment assessment of hypersensitivity using the visual analog scale (VAS) and cold air blast test, the selected tooth in all the groups received 1% citric acid treatment for 1 minute. Group 1 patients received no further treatment; group 2, 3, and 4 patients received additional treatment with 5% sodium fluoride varnish, Nd:YAG laser for 2 minutes, and a combination of 5% sodium fluoride varnish and Nd:YAG laser, respectively. Two hours following treatment, hypersensitivity was again assessed, and the teeth were extracted, sectioned, and scanned using scanning electron microscopy (SEM). RESULTS: The mean VAS score in group 1 showed a 27% increase from baseline, but groups 2, 3, and 4 showed a decrease of 33%, 44%, and 62%, respectively. The mean cold air blast score showed a 22% increase in group 1, but values decreased by 43%, 50%, and 83% in groups 2, 3, and 4, respectively. The number of patent tubules also progressively decreased from group 1 through group 4. CONCLUSIONS: The combination of Nd:YAG laser and 5% sodium fluoride varnish seems to show an impressive efficacy, when compared to either treatment alone, in treating dentin hypersensitivity. The SEM findings seem to relate to the clinical findings in that reduction in number/patency of tubules was associated with improvement in treatment efficacy.     

Bactericidal effect of Nd:YAG laser irradiation on some endodontic pathogens ex vivo

AIM: To define the role of neodymium:yttrium-aluminum-garnet (Nd:YAG) lasers in root canal disinfection along with a minimally invasive treatment concept. METHODOLOGY: The hypothesis was tested ex vivo that Nd:YAG laser irradiation has a bactericidal effect on endodontic pathogens inoculated in root canals. Resultant colony-forming unit counts were associated with observations of bacterial cell structural changes using conventional scanning electron microscopy (CSEM) and environmental scanning electron microscopy (ESEM) on inoculated dentine surfaces, following indirect and direct Nd:YAG laser irradiation, respectively. RESULTS: The Nd:YAG laser irradiation (1.5 W, 15 Hz, four times for 5 s) of Enterococcus faecalis inoculated canals resulted in a significant reduction (P < 0.05, Wilcoxon signed rank test) of the bacterial load, meaning a 99.7% kill, but no sterilization. The CSEM procedure verified that the extent of radiation damage was in line with the total amount of laser energy applied. After 2 h of incubation and three cycles of indirect laser treatment (i.e. through a 1-mm-thick dentine disc), no morphologically intact bacteria of Actinomyces naeslundii or Streptococcus anginosus were discernible. However, when micro-colonies of S. anginosus and specially biofilms of E. faecalis were present after 2 days, the in situ experiment using ESEM and direct laser treatment showed that bacterial eradication was reduced in deep layers. CONCLUSIONS: The Nd:YAG laser irradiation is not an alternative but a possible supplement to existing protocols for canal disinfection as the properties of laser light may allow a bactericidal effect beyond 1 mm of dentine. Endodontic pathogens that grow as biofilms, however, are difficult to eradicate even upon direct laser exposure.     

Nd:YAG激光对不同充填材料牙本质边缘微渗漏的影响

目的 评价Nd:YAG激光对不同充填材料与牙本质之间边缘微渗漏的影响。方法 选用人离体前磨牙36颗,制备V类洞,随机分为激光组和对照组,激光组使用80 rnJ、10 Hz脉冲Nd:YAG激光照射后,分别用全酸蚀粘接树脂、自酸蚀粘接树脂和玻璃离子充填洞型,对照组不使用激光,同样用如前所述的3种材料充填洞型。将所有标本浸泡在2%亚甲基蓝溶液中24 h后,用金刚砂片从颊舌向通过充填物中央纵向切开牙体,显微镜下观察龈壁染料渗透的深度。采用SAS8.0软件对数据进行统计学处理。结果 经Nd:YAG激光照射后尽管3种材料与牙本质之间微渗漏程度均有降低趋势,但只有玻璃离子组激光照射后较未照射组微渗漏降低具有统计学意义(P<0.05)。结论 脉冲Nd:YAG激光照射牙本质壁,在一定程度上可能会减少玻璃离子充填材料与洞壁的微渗漏。     

Clinical evaluation of low-level laser therapy and fluoride varnish for treating cervical dentinal hypersensitivity

The aim of this study was to evaluate in vivo the use of low-level galium-aluminium-arsenide (GaAlAs) (BDP 600) laser and sodium fluoride varnish (Duraphat) in the treatment of cervical dentine hypersensitivity. Twelve patients, with at least two sensitive teeth were selected. A total of 60 teeth were included in the trial. Prior to desensitizing treatment, dentine hypersensitivity was assessed by a thermal stimulus and patients' response to the examination was considered to be a control. The GaAlAs laser (15 mW, 4 J/cm2) was irradiated on contact mode and fluoride varnish was applied at cervical region. The efficiency of the treatments was assessed at three examination periods: immediately after first application, 15 and 30 days after the first application. The degree of sensitivity was determined following predefined criteria. Data were submitted to analysis and no statistically significant difference was observed between fluoride varnish and laser. Considering the treatments separately, there was no significant difference for the fluoride varnish at the three examination periods, and for laser therapy, significant difference (P < 0.05) was found solely between the values obtained before the treatment and 30 days after the first application. It may be concluded that both treatments may be effective in decreasing cervical dentinal hypersensitivity. Moreover, the low-level GaAlAs laser showed improved results for treating teeth with higher degree of sensitivity.     

Morphologic study of Nd:YAG laser usage in treatment of dentinal hypersensitivity

Our previous in vitro study indicated that Nd:YAG laser irradiation on dentin could melt normal dentin surface and close the exposed dentinal tubule orifices without creating surface cracks. This study evaluated the morphologic changes of hypersensitive dentin after Nd:YAG laser irradiation. Thirty patients with clinically diagnosed cervical dentin hypersensitive teeth were treated with a Nd:YAG laser of 30 mJ intensity at 10 pulses per second for 2 min. An impression of the sensitive area was taken before and after laser treatment and then examined with a scanning electron microscope. The impression of the dentin surface after Nd:YAG laser treatment showed no protrusive rods, in contrast with the presence of numerous rods before laser irradiation. Because protrusive rods are a measure of open dentinal tubules, we interpret these data to support the hypothesis that Nd:YAG laser irradiation at specifications of 30 mJ, 10 pulses per second, and 2 min can be used to seal the exposed dentinal tubules.     

Nd: YAG laser irradiation in root canal disinfection

Abstract The purpose of this study was to assess the efficacy of Nd:YAG laser irradiation in disinfecting the root canal system. Seventy-five teeth were uniformly instrumented and sterilized, and their root canals were infected for 60 min with an overnight culture of Enterococcus faecalis in Tryptic Soy Broth. The teeth were divided into 6 groups: 1 - non-infected controls; 2 - infected controls; 3 - infected, laser treated; 4 - infected, laser dummy (dye only); 5 - infected, laser dummy (dye and air-water spray); 6 - infected, NaOCl-treated (reference group). After treatment, the root canals were dried and dentinal shavings removed for a post-treatment culture. Quantitative analysis of bacteria surviving the various treatments were performed, and the bacterial counts for each group were compared. SEM analysis of teeth split longitudinally was used to illustrate the effect of treatment on the smear layer and on surface bacteria. Nd:YAG laser irradiation (group 3) significantly reduced the number of bacteria while NaOCl irrigation (group 6) effectively disinfected the canals.