Efficacy of Photon-induced Photoacoustic Streaming in the Reduction of Enterococcus faecalis within the Root Canal: Different Settings and Different Sodium Hypochlorite Concentrations

Introduction

The purpose of this study was to determine the effectiveness of laser-activated irrigation by photon-induced photoacoustic streaming (PIPS) in the reduction of Enterococcus faecalis in root canal disinfection, varying laser energy output, and sodium hypochlorite (NaOCl) concentration. For effective removal of the smear layer, the sequence and resting time of the final irrigation steps were modified compared with the standard PIPS protocol.

Assessment of antibacterial activity of 2.5% NaOCl,chitosan nano-particles against Enterococcus faecalis contaminating root canals with and without diode laser irradiation: an in vitro study

Objective: This study was done to evaluate the antibacterial effect of chitosan nano-particles (CNPs) root canal irrigant as a new alternative to Sodium hypochlorite (NaOCl) for disinfection of root canals inoculated with Enterococcus faecalis, with and without laser activation.

Methodology: Sixty single rooted human premolars were decoronated, prepared and had their apical foramina sealed. E. faecalis were incubated in the root canals for 15 days. The teeth were then randomly divided into two experimental groups (n?=?30) according to the disinfection protocol used. In Group I: disinfection was performed using the irrigant solutions only (Saline, 2.5% NaOCl, CNPs). Whereas in Group II, disinfection was done using the same irrigants followed by Diode laser at (980-nm) at 2 W output for 5?×?5?s. Intra-canal bacterial samples were taken before and after canal disinfection to determine the CFU count.

Results: In group I, 2.5% NaOCl was as effective as CNP in eradication and significantly more effective than Saline (p?=?0.008) in eradication of E. faecalis. In Group II, either 2.5% NaOCl or CNP in combination with diode laser irradiation showed a similarly high effect in bacterial eradication.

Conclusions: Within the parameters used in this study, a combination therapy consisting of irrigation followed by diode laser irradiation should be utilized as an effective treatment modality for eliminating E. faecalis from root canal systems.     

Debris Removal from the Mesial Root Canal System of Mandibular Molars with Laser-activated Irrigation

Introduction

The purpose of this study was to compare in vitro the canal and isthmus debridement of manual-dynamic, passive ultrasonic, and laser-activated irrigation with an Er:YAG laser in mesial roots of human mandibular molars.

不同冲洗方法对粪肠球菌感染根管的抗菌性研究

目的比较超声、Er,Cr：YSGG激光及Er：YAG激光辅助1%次氯酸钠（NaOCl）溶液冲洗对人离体牙根管表面粪肠球菌生物膜及根尖区不同深度牙本质小管内粪肠球菌的杀灭效果。 方法单直根管下颌前磨牙42颗,建立粪肠球菌生物膜感染的根管模型,采用随机字表法随机抽取2颗确定建成粪肠球菌生物膜感染根管模型,剩余40颗牙采用随机数字表法按随机对照原则分为5组,每组8颗。A组：5.25% NaOCl联合17%乙二胺四乙酸（EDTA）注射器冲洗;B组：0.9%氯化钠溶液注射器冲洗;C组：1% NaOCl溶液超声荡洗;D组：1% NaOCl溶液Er：YAG激光活化冲洗;E组：1% NaOCl溶液Er,Cr：YSGG激光活化冲洗。按分组进行处理后取样菌落计数,计算灭菌率。使用SPSS 17.0统计软件对实验数据进行方差齐性及正态性检验比较各组间和组内的灭菌率。 结果（1）组间比较：对根管壁表面,各组冲洗方法灭菌率比较,B组（5.74%）相似文献   

Comparison of the Effectiveness of Three Irrigation Techniques in Reducing Intracanal Enterococcus faecalis Populations: An In Vitro Study

IntroductionSeveral irrigation techniques have been recently introduced with the main objective of improving root canal disinfection. This in vitro study aimed at comparing the intracanal bacterial reduction promoted by chemomechanical preparation with 3 different irrigation techniques.MethodsRoot canals from extracted teeth were contaminated with Enterococcus faecalis ATCC 29212 for 7 days and then randomly distributed into 3 experimental groups of 20 teeth each: group 1, conventional irrigation with NaviTip needles inserted up to 3 mm short of the working length; group 2, same as group 1, but supplemented with final irrigant activation by the EndoActivator system; and group 3, irrigation with the EndoVac system. NaOCl and ethylenediaminetetraacetic acid (EDTA) were the irrigants used in all experimental groups. The overall preparation time was kept constant for the groups, but the total volume ranged from 20 mL (groups 1 and 2) to 43 mL (group 3). The control group was irrigated with saline solution (total volume, 43 mL). Samples taken before and after chemomechanical procedures were cultured, and the colony-forming units (CFUs) were counted.ResultsReduction in the bacterial populations was highly significant for all groups. The 3 experimental groups with NaOCl and EDTA as irrigants were significantly more effective than the control group with saline in reducing CFU counts. There were no significant differences between the 3 techniques tested.ConclusionsThere was no evident antibacterial superiority of any of the irrigation techniques evaluated in the present in vitro model.     

Effect of different laser-assisted irrigation activation techniques on apical debris extrusion

Abstract

Objective: The aim of this study was to compare apical debris extrusion when neodymium-doped yttrium aluminium garnet (Nd:YAG) lasers, erbium-doped yttrium aluminium garnet (Er:YAG) or photon-induced photoacoustic streaming (PIPS) are used for irrigation activation.

Materials and methods: A total of 60 extracted human mandibular premolar teeth have similar dimensions were included and the samples were split into four groups according to the irrigation technique (n?=?15): conventional needle irrigation, PIPS, Er:YAG and Nd:YAG. ProTaper Universal system up to F4 was used for root canal instrumentation. Bidistilled water was used as an irrigation solution during instrumentation and irrigation activation. Apically extruded debris was collected into preweighed Eppendorf tubes during instrumentation and irrigation activation procedures. The tubes were then kept in an incubator at 70?°C for 5?days. The initial weight of the tube was subtracted from the final weight and the result was recorded as the weight of dry extruded debris. The data were evaluated statistically using a one-way ANOVA test followed by least significant difference post hoc test (p?<?.05).

Results: Conventional needle irrigation caused significantly less debris extrusion than laser-assisted irrigation activation groups (p?<?.05). Laser-assisted irrigation activation groups caused statistically similar debris extrusion (p?>?.05).

Conclusion: Laser-assisted irrigation activation techniques caused more debris extrusion when compared to conventional needle irrigation.     

Bond strength of self-adhesive resin cement to root dentin. Comparison of photon-initiated photoacoustic streaming technique with needle and ultrasonic irrigation

Abstract

Objective. The aim of this study was to investigate the effects of photon-initiated photoacoustic streaming (PIPS) with various irrigating solutions on the bond strength of a self-adhesive resin cement to root dentin. Materials and methods. Seventy-two mandibular premolar roots were divided into six groups after post space preparation and treated with a needle irrigation with distilled water and NaOCl, ultrasonic irrigation with NaOCl, PIPS with NaOCl, PIPS with EDTA and PIPS with distilled water at 0.3 W, 15 Hz and 20 mJ per pulse for 60 s. Fiber posts were cemented with a newly marketed, self-adhesive resin cement. The data obtained from the push-out tests were analyzed using analysis of variance (ANOVA) and LSD post-hoc tests (p = 0.05). Results. PIPS with distilled water resulted in higher push-out values than those of needle (with both distilled water and NaOCl) and ultrasonic irrigation (p < 0.05). Conclusions. The use of PIPS may provide higher bond strength of self-adhesive resin cement to root dentin than needle and ultrasonic irrigation techniques.     

Smear Layer Removal Using Passive Ultrasonic Irrigation and Different Concentrations of Sodium Hypochlorite

IntroductionThe present study evaluated the effect of passive ultrasonic activation (PUI) of EDTA solution followed by conventional irrigation with 2 concentrations of sodium hypochlorite (NaOCl) on smear layer removal.MethodsFifty single-root mandibular premolars were chemomechanically prepared with ProTaper Universal (Dentsply Maillefer, Ballaigues, Switzerland) nickel-titanium rotary instruments and 1% NaOCl. The roots were cleaved, and the dentin surfaces were analyzed with scanning electron microscopy operated at a low vacuum. Images were obtained from previously demarcated areas in each root canal third. The teeth were reassembled and distributed into 5 groups according to the final irrigation protocols (n = 10): group 1, EDTA/PUI + 1% NaOCl; group 2, EDTA/PUI + 5% NaOCl; group 3, EDTA/CI + 1% NaOCl; group 4, EDTA/CI + 5% NaOCl; and group 5 (negative control), saline solution/PUI. After irrigation, the teeth were reseparated and prepared for conventional high-vacuum scanning electron microscopy of the same dentin surface that was previously analyzed. The amount of debris was classified using a 4-point scoring system. Data were analyzed with Kruskal-Wallis and Dunn tests at α = 0.05.ResultsGroups 1 and 2, which used PUI and different concentrations of NaOCl, were not significantly different; however, they differed significantly from group 3 (P < .05). With respect to canal cleanliness at different root thirds, all groups showed the worst cleaning at the apical third.ConclusionsPUI activation of the EDTA irrigant is required when canal debridement is performed with EDTA and a lower concentration of NaOCl.     

Influence of Endodontic Procedure on the Adherence of Enterococcus faecalis

IntroductionThe purpose of this study was to investigate the effects of instrumentation and irrigation on the initial adherence of Enterococcus faecalis to root canal dentin and to explore initial microbial adhesion to root filling materials.MethodsThe following specimens were prepared: instrumented and uninstrumented dentin, dentin treated with different irrigation protocols, and root filling materials. The number of E. faecalis cells adhered on dentin was measured. The adhesion force of E. faecalis cells on different materials and the roughness of different surfaces were measured. The contact angle of the surfaces was recorded. The results were analyzed using the t test.ResultsInstrumented dentin specimens had a significantly higher amount of E. faecalis adherence than uninstrumented dentin. There were higher numbers of adhering bacteria on the dentin when EDTA was used alone (P < .05) compared with other irrigants alone. The use of chlorhexidine (CHX) as the last irrigant for a certain time resulted in a reduced number of adhering bacteria when the specimens were first exposed to sodium hypochlorite (NaOCl) followed by EDTA. EDTA used alone had the highest adhesion force followed by NaOCl alone and CHX alone (P < .05). Dentin treated with EDTA alone had the highest roughness and contact angle followed by NaOCl alone and CHX alone (P < .05). CHX added as the final irrigant after NaOCl with EDTA irrigation reduced the contact angle (P < .05). Larger amounts of adhering bacteria and higher adhesion force were detected on the surface of gutta-percha and sealer than on the dentin surface (P < .05).ConclusionsInstrumentation and irrigation alter the initial adherence of E. faecalis to root canal dentin and the surface properties of the dentin as well.     

微创开髓下3种根管消毒方法对粪肠球菌清除效果比较

目的:比较微创和常规开髓下的不同根管消毒方法,获得一种基于微创开髓的高效简便的根管消毒方法.方法:将66颗离体上颌第一磨牙随机分为实验组(计算机辅助引导下开髓)和对照组(常规开髓),均预备至ProTaper Univer-sal F2,建立粪肠球菌感染模型.每组再随机分为NaCl0+EDTA冲洗(A)、NaClO+ED...     

Nanobubble-Enhanced Antimicrobial Agents: A Promising Approach for Regenerative Endodontics

IntroductionIn this study, we investigated the properties of nanobubble (NB) water and its effect on smear layer removal and strengthening the efficiency of disinfecting agents used in regenerative endodontic treatment.MethodsNB water was generated in a NB Generator. The NB size, concentration, and pH were measured. Porcine teeth were enlarged to size 60 by using hand-files and irrigated with either NB water or 17% EDTA or received no further irrigation. The ability of irrigants to remove the smear layer was evaluated by using a scanning electron microscope (9 roots/group). Other samples (6 roots/group) were subjected to Vickers hardness test to determine the dentin microhardness. Autofluorescent tetracycline mixed with distilled water or NB water was placed inside the root canal space of porcine teeth, and the depth of medicament penetration into the dentinal tubules was visualized by using fluorescent stereomicroscope (5 roots/group). For the disinfection experiment, human roots were prepared, autoclaved, and inoculated with Enterococcus faecalis for 3 weeks. Canals were then disinfected by (1) standard needle irrigation (SNI) with 5.25% NaOCl, (2) 5.25% NaOCl with ultrasonication (US), (3) 5.25% NaOCl + XP finisher (XP), (4) SNI with 1.5% NaOCl, or (5) SNI with 1.5% NaOCl in NB water (5 roots/group). Teeth were split open and stained with LIVE/DEAD BackLight and visualized by using confocal laser scanning microscope (CLSM) at the coronal, middle, and apical thirds of the canal. The ratio of dead/total bacteria in the dentinal tubules at various depth levels (50, 100, and 150 μm) was calculated.ResultsNB water was more effective in removing smear layer than 17% EDTA and could allow infiltration of tetracycline into the dentinal tubule more than 1 mm. NB water did not alter the dentin microhardness compared with 17% EDTA (P < .05). At 50-μm depth, CLSM analysis showed no statistically significant difference between 1.5% NaOCl in NB water and 5.25% NaOCl with or without irrigation activation at the coronal, middle, and apical root segments (P > .05), ie, these groups had stronger bacterial killing than 1.5% NaOCl (P < .05). At deeper levels (100 and 150 μm), higher concentrations of NaOCl were more effective than 1.5% NaOCl with or without NB water. No statistically significant difference was noted between 5.25% NaOCl with and without irrigation activation at most depth levels (P > .05).ConclusionsNB water can allow smear layer removal and enhance tubular penetration of medicaments without changing dentin microhardness. In large canal models, NB water appears to improve the tubular disinfection capacity of lower concentration of NaOCl up to 50 μm. On the other hand, the use of irrigation activation (US or XP) did not provide any added disinfection into the dentinal tubules compared with SNI. These results suggest that NB water may be a promising adjunct to endodontic irrigants and medicaments.     

根管预备尺寸对Er:YAG激光消毒效果的影响

目的 比较Er:YAG激光在不同根管预备尺寸情况下的消毒效果。方法 368颗离体上颌单直根管前牙,随机分为8组,机用K3镍钛锉预备至以下尺寸: A1组和B1组（#25/0.06）、A2组和B2组（#30/0.06）、A3组和B3组（#35/0.06）、A4组和B4组（#40/0.06）。高压灭菌后,A组接种粪肠球菌,B组接种白念菌。每组冲洗方法均为Er:YAG激光+3% NaOCl,Er:YAG激光+17% EDTA,Er:YAG激光+生理盐水,然后收集各组处理后根管壁表面微生物样本,进行微生物培养和计数,采用GraphPad Prism 5.02软件包分析各组绝对残留菌落数及菌落相对残留率。结果 Er:YAG激光对粪肠球菌与白念菌的消毒效果在预备尺寸为#40/0.06最佳,#35/0.06次之。#40/0.06、#35/0.06的消毒效果与#30/0.06、#25/0.06相比,差异显著（P＜0.05）。结论 在#25/0.06～#40/0.06根管尺寸范围内,Er:YAG激光联合3% NaOCl、17% EDTA和生理盐水冲洗上颌前牙单直根管时,根管预备尺寸不应小于#30/0.06。     

Irrigant flow during photon-induced photoacoustic streaming (PIPS) using Particle Image Velocimetry (PIV)

Objectives

This study aimed to compare fluid movements generated from photon-induced photoacoustic streaming (PIPS) and passive ultrasonic irrigation (PUI).

Materials and methods

Particle Image Velocimetry (PIV) was performed using 6-μm melamine spheres in water. Measurement areas were 3-mm-long sections of the canal in the coronal, midroot and apical regions for PIPS (erbium/yttrium-aluminium garnet (Er:YAG) laser set at 15 Hz with 20 mJ), or passive ultrasonic irrigation (PUI, non-cutting insert at 30 % unit power) was performed in simulated root canals prepared to an apical size #30/0.04 taper. Fluid movement was analysed directly subjacent to the apical ends of ultrasonic insert or fiber optic tips as well as at midroot and apically.

Results

During PUI, measured average velocities were around 0.03 m/s in the immediate vicinity of the sides and tip of the ultrasonic file. Speeds decayed to non-measureable values at a distance of about 2 mm from the sides and tip. During PIPS, typical average speeds were about ten times higher than those measured for PUI, and they were measured throughout the length of the canal, at distances up to 20 mm away.

Conclusions

PIPS caused higher average fluid speeds when compared to PUI, both close and distant from the instrument. The findings of this study could be relevant to the debriding and disinfecting stage of endodontic therapy.

Clinical relevance

Irrigation enhancement beyond needle irrigation is relevant to more effectively eradicate microorganisms from root canal systems. PIPS may be an alternative approach due to its ability to create high streaming velocities further away from the activation source compared to ultrasonic activation.

     

Root Canal Disinfection by Single- and Multiple-instrument Systems: Effects of Sodium Hypochlorite Volume,Concentration, and Retention Time

IntroductionThis ex vivo study evaluated the intracanal bacterial reduction promoted by chemomechanical preparation using a single-file technique varying the volume, concentration, and retention time of sodium hypochlorite (NaOCl) irrigation in comparison with a multifile system.MethodsPalatal roots from extracted maxillary first molars were selected and anatomically matched based on microcomputed tomographic analysis for group distribution. The canals were contaminated with a fresh mixed bacterial culture grown in anaerobiosis and recently obtained from a tooth with apical periodontitis. Specimens were divided into 4 groups of 24 each according to the following preparation protocols: REC-6LOW (Reciproc R50 instrument [VDW, Munich, Germany], 6% NaOCl, low irrigant volume), REC-2.5LOW (R50, 2.5% NaOCl, low irrigant volume), REC-2.5HI (R50, 2.5% NaOCl, high irrigant volume), and BR-2.5HI (BioRaCe [FKG Dentaire, LaChaux-de-Fonds, Switzerland], 2.5% NaOCl, high irrigant volume). The total time of preparation was recorded. Intracanal bacteriologic samples were taken before and after preparation; DNA was extracted and subjected to quantitative polymerase chain reaction.ResultsBacteria were detected in 22 initial samples from the REC-2.5LOW group and in 23 from the other groups. Intragroup analysis showed that all tested preparation protocols were highly effective in significantly reducing the intracanal bacterial counts (P < .001). Intergroup comparison of bacterial reduction levels revealed a statistically significant difference between BR-2.5HI and REC-2.5LOW (P < .05). Counts of bacteria were 2.5 times significantly higher in REC-2.5LOW compared with BR-2.5HI. No other significant differences were found in quantitative findings (P > .05).ConclusionsThe concerted effects of multiple instruments, the high volume of irrigation, and the long retention time of NaOCl irrigant had a positive influence on intracanal disinfection during chemomechanical preparation.     

Disinfection of root canals with photon-initiated photoacoustic streaming

Introduction

This study set out to compare the efficacy of laser-activated and ultrasonically activated root canal disinfection with conventional irrigation, specifically its ability to remove bacterial film formed on root canal walls.

Methods

Seventy human premolars were shaped to an apical size #20, taper .07, sterilized, and contaminated in situ with oral bacteria for 1 week and incubated for 2 more weeks. Irrigation was done with 6% NaOCl (group 1), NaOCl ultrasonically activated with blunt inserts (group 2), or a pulsed erbium:YAG laser at nonablative settings (group 3) for a total of 60 seconds each. Positive and negative controls were also included. Aerobic bacterial sampling was performed, and the incidence of positive samples after 24 and 48 hours as well as bacterial counts (colony-forming units) were determined. Fixed and demineralized sections 1 mm and 4 mm off the apex were Brown-Brenn stained and assessed for remaining intracanal bacteria/biofilm and dentinal tubule penetration.

Results

All 3 canal disinfection protocols significantly reduced bacterial counts (P < .001). None of the 3 techniques predictably generated negative samples, but laser-activated disinfection was superior to the other 2 techniques in this aspect (P < .05). Histologic sections showed variable remaining bacterial presence in dentinal tubules at the 4-mm level and significantly less bacterial biofilm/necrotic tissue remaining at the 1-mm level after laser-activated irrigation (P < .05).

Conclusions

Under the conditions of this combined in situ/in vitro study, activated disinfection did not completely remove bacteria from the apical root canal third and infected dentinal tubules. However, the fact that laser activation generated more negative bacterial samples and left less apical bacteria/biofilm than ultrasonic activation warrants further investigation.     

The effects of calcium hydroxide removal methods on bond strength of Epiphany SE with two irrigation protocols

Abstract

Objective: The purpose of this study was to compare the effects of five calcium hydroxide removal methods on the bond strength of Epiphany SE sealer after canal irrigation with NaOCl+EDTA or NaOCl+MTAD. Materials and methods: The 120 roots were instrumented by using the ProTaper rotary system under irrigation with 2.5% sodium hypochlorite and randomly divided into two major groups according to the final irrigation: 1.3% NaOCl + MTAD and 5% NaOCl + 17% EDTA. For controls, 10 roots from each of the final irrigations with NaOCl + MTAD and NaOCl + EDTA (20 roots) were not filled with Ca(OH)₂. The intra-canal paste, Ca(OH)₂ was applied to each of the 100 remaining roots and stored at 37°C for 7 days. Each group was sub-divided into five sub-groups (n = 10) according to the removal technique for the intra-canal dressing: Group-1: recapitulation with size 30 K file + 3 ml of saline solution, Group-2: recapitulation with size 30 K file + 3 ml of 5% NaOCl, Group-3: using 5% NaOCl + 17% EDTA, Group-4: using 5%NaOCl + 15% citric acid, and Group-5: using 1.3% NaOCl + 5 ml MTAD. The root canals were filled with Resilon and Epiphany SE sealer. The bond strength was measured. Results: The mean bond strength of Epiphany SE to root dentine irrigated with NaOCl + MTAD was lower than that of NaOCl + EDTA. The highest bond strengths were 3.31 ± 0.057 and 2.60 ± 0.054 in the NaOCl + citric acid group when Ca(OH)₂ was applied to roots treated with NaOCl + EDTA and NaOCl + MTAD, respectively (p < 0.05). Conclusion: For root canals treated with NaOCl + EDTA or NaOCl + MTAD, the use of NaOCl + chelating agent for Ca(OH)₂ removal does not adversely affect the bond strength of Epiphany SE to dentin.     

Enhancing the Intracanal Antibacterial Effects of Sodium Hypochlorite with Etidronic Acid or Citric Acid

IntroductionThis study evaluated the bacterial reduction promoted by root canal preparation using irrigation with sodium hypochlorite (NaOCl) alone, associated with etidronic acid (1-hydroxyethane 1,1-diphosphonic acid [HEDP]) or alternated with citric acid, and after a supplementary agitation step.MethodsExtracted mandibular premolars were selected and distributed into 3 groups based on anatomically paired micro–computed tomographic analyses. The canals were contaminated with Enterococcus faecalis for 30 days and then subjected to chemomechanical preparation with a reciprocating instrument under irrigation with NaOCl alone, mixed with HEDP (NaOCl/HEDP), or alternated with citric acid (NaOCl/CA). A supplementary agitation step with the XP-endo Finisher was performed in all groups. Intracanal bacteriological samples were taken before (S1) and after preparation (S2) and after the supplementary approach (S3). DNA was extracted from the samples and subjected to quantitative real-time polymerase chain reaction.ResultsIntragroup analyses revealed a substantial bacterial reduction from S1 to S2 or S3 in all groups (P < .01). The supplementary agitation resulted in S2-to-S3 bacterial reduction of 6%, 68%, and 80% in the NaOCl, NaOCl/HEDP, and NaOCl/CA groups, respectively. Irrigation with NaOCl alone resulted in 53% and 47% of samples negative for bacteria in S2 and S3, respectively. Corresponding figures for NaOCl/HEDP were 75% and 85%, and 44% and 72% for NaOCl/CA. Intergroup analyses of S2 samples showed that NaOCl/HEDP was significantly more effective than the other 2 in reducing the bacterial levels (P < .05). After the supplementary approach, both NaOCl/HEDP and NaOCl/CA were significantly more effective than NaOCl alone (P < .05), with no significant differences between them (P > .05).ConclusionsBoth the freshly combined NaOCl/HEDP solution and the alternate use of NaOCl and citric acid followed by XP-endo Finisher agitation resulted in significantly higher intracanal bacterial reduction than NaOCl alone.     

Comparative Antibacterial Efficacies of Hydrodynamic and Ultrasonic Irrigation Systems In Vitro

Introduction

To ensure root canal treatment success, endodontic microbiota should be efficiently reduced. The in vitro bactericidal effects of a hydrodynamic system and a passive ultrasonic irrigation system were compared.

Methods

Single-rooted extracted teeth (n = 250) were contaminated with suspensions of Enterococcus faecalis ATCC 29212, mixed aerobic cultures, or mixed anaerobic cultures. First, the antibacterial effects of the hydrodynamic system (RinsEndo), a passive ultrasonic irrigation system (Piezo smart), and manual rinsing with 0.9% NaCl (the control) were compared. Colony-forming units were counted. Second, the 2 systems were used with 1.5% sodium hypochlorite (NaOCl) alone or NaOCl + 0.2% chlorhexidine (CHX). The colony-forming units in the treated and untreated roots were determined during a period of 5 days.

Results

Both irrigation systems reduced bacterial numbers more effectively than manual rinsing (P < .001). With NaCl, ultrasonic activated irrigation reduced bacterial counts significantly better than hydrodynamic irrigation (P = .042). The NaOCl + CHX combination was more effective than NaOCl alone for both systems (P < .001), but hydrodynamic irrigation was more effective with NaOCl + CHX than the passive ultrasonic irrigation system.

Conclusions

Both irrigation systems, when combined with NaOCl + CHX, removed bacteria from root canals.     

Impact of Sodium Hypochlorite on Organic Tissue Dissolution in the Periapical Region of Immature Permanent Teeth: An Ex Vivo Study

IntroductionThe purpose of this study was to evaluate the impact of different sodium hypochlorite (NaOCl) irrigation protocols on organic tissue dissolution in the periapical region of simulated immature permanent teeth.MethodsEight single-rooted premolars and 48 samples of porcine palatal mucosa were used. Acrylic resin prototypes were constructed, placing the tissue in close contact with the dental apices. Specimens were then divided into 6 groups (n = 8): 2 control groups of normal saline irrigation with (NS/WA) or without (NS/NA) ultrasonic activation and 4 experimental groups of 1.5% and 2.5% NaOCl irrigation with (NaOCl 1.5%/WA and NaOCl 2.5%/WA) or without (NaOCl 1.5%/NA and NaOCl 2.5%/NA) activation. Root canals were irrigated with 20 mL of the solution for 5 minutes distributed over 4 irrigation cycles. In each cycle, after irrigation, the solution was either kept stagnant or activated for 30 seconds and then replaced. Specimens were weighed on a precision balance before and after the irrigation protocols. Tissue dissolution was measured by the difference between the initial and final weights. One-way analysis of variance was applied followed by the Tukey honestly significant difference test (α = 0.05).ResultsThe NS/NA and NS/WA groups had mean weight reductions similar to the 1.5% NaOCl/NA group (P > .05) and lower than the others (P < .05). The 2.5% NaOCl/NA and 2.5% NaOCl/WA groups had the highest mean weight loss (P < .05), whereas the 1.5% NaOCl/WA group had intermediate values (P < .05).ConclusionsPeriapical tissue dissolution occurred in all groups, with a greater impact observed with 2.5% NaOCl with or without ultrasonic activation.     

Comparison of the Efficacy of Maleic Acid and Ethylenediaminetetraacetic Acid in Smear Layer Removal from Instrumented Human Root Canal: A Scanning Electron Microscopic Study

IntroductionThe aim of this study was to assess, by scanning electron microscopic (SEM) analysis, the ability of 17% EDTA and 7% maleic acid in the removal of the smear layer from the human root canal system.MethodsEighty single-rooted human anterior teeth were subjected to standardized root canal instrumentation (step-back technique) and were irrigated with 2.5% NaOCl after each instrument. Based on the final irrigating solution used, samples were divided randomly into three groups: (1) the EDTA group: 17% EDTA+ 2.5% NaOCl (n = 30), (2) the maleic acid group: 7% maleic acid + 2.5% NaOCl (n = 30), and (3) the control group: 0.9% saline (n = 20). After final irrigation, teeth were prepared for SEM analysis to evaluate the cleaning of the coronal, middle, and apical thirds of radicular dentin by determining the presence or absence of smear layer. The data was statistically analyzed using the Kruskall-Wallis test.ResultsAt the coronal and middle thirds, there was no significant difference between EDTA and maleic acid. Both were equally efficient in the removal of smear layer. In the apical third, maleic acid showed significantly better smear layer removing ability than EDTA.ConclusionFinal irrigation with 7% maleic acid is more efficient than 17%EDTA in the removal of smear layer from the apical third of the root canal system, which is a crucial area for disinfection.