Effect of SWEEPS and PIPS techniques on dye extrusion in photodynamic therapy procedure after root canal preparation

AimThe aim of this study is to measure and compare the amount of apical extrusion of the methylene blue as photosensitizer using Laser-activated irrigation(LAI) techniques (SWEEPS, PIPS) and photodynamic therapy (PDT).Materials and methods40 single-rooted premolar teeth were selected and their root canals were cleaned and prepared. The photosensitizer, Methylene blue (MB), was used as dye which applied inside the root canals and the access cavities. Then the teeth were randomly allocated to 4 groups. Different techniques (SWEEPS, PIPS, PDT) were used in 3 groups. One group received no activation. Data related to the concentration of the extruded methylene blue was measured using ultraviolet and visible (UV–Vis) absorption spectroscopy. Absorption peak intensity of MB in the wavelength of 668 nm was considered as the concentration index according to Beer Lambert law. Taking into account the normal distribution of this data, one-way ANOVA analysis was used to evaluate the effects of the independent variables on the amount of apical extrusion of the irrigant.ResultsBased on the results of ANOVA analysis, there was no significant difference between the amounts of apical extrusion of MB between different groups (p = 0.628)ConclusionUsing SWEEPS and PIPS techniques, despite diffusion of the photosensitizer, didn't lead to any difference in the amount of apical extrusion. Therefore, these LAI techniques can be used safely for root canal irrigation.     

Nd:YAG激光去除根管内碎屑的实验研究

为解决去除根管壁玷污层的难题，应用扫描电镜观察Ｎｄ∶ＹＡＧ激光根管内照射后根管壁的清洁程度。实验选用离体牙１４颗，随机分为对照组和实验组。对照组进行常规根管预备，实验组在常规根管预备后，应用５０ｍＪ１５Ｈｚ能量设置的Ｎｄ∶ＹＡＧ激光进行根管内照射，冲洗干燥后，所有实验牙进行扫描电镜观察。观察到激光照射后，根管壁表面大部分区域无不规则碎屑，玷污层消失，牙本质小管暴露，呈熔岩状；某些部位可见熔岩状改变与不规则碎屑同时存在；少部分区域与对照组结构相似。结果表明：激光根管内照射可大部分去除玷污层，大大提高根管壁的清洁度，有利于提高根管治疗成功率。     

Antimicrobial efficacy of photodynamic therapy,Nd:YAG laser and QMiX solution against Enterococcus faecalis biofilm

BackgroundLasers have been recommended in final root canal disinfection protocol, however, there is no clear evidence about their efficacy against bacteria in biofilms. The aim of the study was to evaluate and compare the disinfection effect of antimicrobial photodynamic therapy (aPDT), Nd:YAG laser and QMiX solution against Enterococcus faecalis biofilm.MethodsThe study sample consisted of 65 dentine slices, which were inoculated with E. faecalis and incubated anaerobically for three weeks. The dentine discs were randomly allocated to one of the following experimental groups: aPDT (100 mW, 10 mg/ml phenothiazinium chloride, 1 min), Nd:YAG laser (2 W, 15 Hz, 4 × 5 s), QMiX solution (1 min). Positive controls did not receive any treatment and negative controls were treated with 5.25% NaOCl. To harvest surviving adherent cells, each dentine sample was transffered to a test tube containing of TSB, serial ten-fold dilutions were made and aliquot of 1 ml was plated onto blood agar plates and incubated for 48 h. Colony forming units grown were counted and transformed into actual counts based on the dilution factor. The remaining viable cells after each protocol were analysed by FISH.ResultsThe aPDT and the QMiX solution were equally effective, with the reduction rate of E. faecalis CFUs of 98.8% and 99.3% respectively (p = 1.107). The Nd:YAG laser caused 96% reduction of E. faecalis (P < 0.001).ConclusionThe aPDT and the QMiX solution showed similar antibacterial efficacy against old E. faecalis biofilm, followed by Nd:YAG irradiation.     

Effect of photodynamic therapy with two photosensitizers on Streptococcus mutants: In vitro study

Background and objectivesStreptococcus mutans (S. mutans) colonizes the oral cavity and causes dental caries and periodontal diseases. Considering the importance of the treatments that decrease pathogenic microorganisms, the aim of the present research was the assessment of the antimicrobial effect of Photodynamic Therapy (PDT) with Methylene Blue (MB) and Indocyanine Green (IG) photosensitizers on S. mutans.Materials and methodsIn this In vitro experimental study, Sixty four caries-free first premolars were contaminated with 0.5 McFarland S.mutans suspension and were randomly assigned to 4 groups. The teeth in the first group were impregnated with 2% MB while the teeth in the second group were impregnated with 0.2% IG. The teeth in the first group were irradiated with continuous-wave 660 nm dod laser with 40 mw output power, energy density of 2.4 J/cm² and 100% duty cycle for 60 s, while the teeth in the second group were irradiated with continuous -wave 810 nm diode laser with 100 mw out power, density energy of 6 J/cm² and 100% duty cycle for 60 s in contact mode. In the third group, the teeth were suspended in 0.2% Chlorhexidine for 30 s. The fourth group was considered as the control. The teeth were sampled before and after the interventions and the samples were incubated in Blood Agar for 24 h. Afterwards, the number of S. mutans colonies were counted. Data were statistically analyzed by Kruskal-Wallis, Dunn's and Friedman tests.ResultsIn the groups treated with a combination of MB and IG and laser irradiation and also in the Chlorhexidine group, the final number of S. mutans colonies equaled zero. In “MB and IG groups without laser irradiation”, although the amount of microorganisms decreased, but the number of colonies did not reach zero. Pair comparisons by Dunn's test showed that there was a significant difference between “MB and IG groups without laser irradiation” and the other experimental groups p = 0.03).ConclusionPDT with MB and IG photosensitizers and also Chlorhexidine mouthwash, have the ability to completely eradicate S. mutans bacterial colonies.     

The comparison of penetration depth of two different photosensitizers in root canals with and without smear layer: An in vitro study

BackgroundThe main objective of this study is to evaluate the penetration depth of suggested photosensitizers in the lateral wall of the human root canal.Materials & methodsForty extracted single-rooted human teeth with straight canals that extracted for periodontal reasons were collected and stored in the sterile saline until employment in the experiment. Teeth were decoronated to a standard 12 mm root segment using diamond disc. After instrumentation of specimens, the external root surface was sealed with two layers of nail polish to avoid environmental contamination. The apical foramen was subsequently closed with composite material. Teeth were divided randomly in two major groups consist of indocyanine green solution (ICG) and tolonium chloride solution (TCH) with and without EDTA in their subgroups. Specimens in all groups grooved longitudinally with a diamond disc and split in two halves with a stainless steel chisel. The measurements were done by the stereo microscope under 20× magnification in three zones of each specimen and the penetration depth of dye was measured.ResultsThe results of this study showed that the mean of lateral penetration depth of ICG (224.04 μm) was significantly (P < 0.05) higher than TCH (70.15 μm). Regarding to the influence of EDTA, in ICG group without consideration to the different regions, the usage of EDTA improved the mean of lateral penetration depth of ICG, but this improvement was not statistically significant (P > 0.05).ConclusionFurther to the findings of this study, it could be assumed that ICG could penetrate in deeper regions of the root canal wall.     

超声荡洗对根管预备后疼痛及疗程的影响

目的探讨超声荡洗对根管预备后疼痛及疗程的影响。方法采用临床对照研究的方法,将40例牙髓根尖周病患者随机分为超声荡洗组和注射器冲洗组,观察两组根管预备后疼痛程度及疗程。结果对于慢性根尖周炎患者,超声荡洗组在根管预备后疼痛和患者的复诊次数上分别轻于及少于注射器冲洗组（P〈0．05）;对于慢性牙髓炎患者,两组在根管预备后疼痛和复诊次数上差异均无统计学意义（P〉0．05）。结论在根管预备过程中,采用超声荡洗,能够减轻慢性根尖周炎患者根管预备后出现的局部疼痛,同时减少患者根管治疗复诊次数。     

Nd：YAG激光照射咽喉气管粘膜实验研究

本文应用Nd:YAc激光照射家兔、犬和成人喉标本,探讨了Nd:YAG激光照射治疗鼻、咽喉疾患的能量密度,即一定的能量密度有一定的治疗效应和组织学改变。这为临床治疗提供了一定的参考依据。     

激光热消蚀兔颈动脉增生修复的形态学观察

本实验用Ｎｄ：ＹＡＧ激光经金属帽光纤传输，在１８只健康兔颈总动脉造成急性热损伤，于消蚀后即刻至８周动态观察血管壁组织增生修复变化，结果表明，激光消蚀后出现炎症反应和血小板粘附聚集，２周时内皮层恢复正常，但中膜平滑肌细胞呈过度增殖，管腔狭窄和闭塞。此可能是激光血管成形术后再狭窄的机制之一。