Different Concentrations Of NaOCl Research Articles

Effect of Sodium Hypochlorite Concentration on the Outcome of Full Pulpotomy in Mature Permanent Teeth with Irreversible Pulpitis - A Systematic Review.

To determine the outcome of full pulpotomy in management of mature permanent teeth with irreversible pulpitis when 2.5% versus other concentrations of sodium hypochlorite (NaOCl) were used to achieve haemostasis. Electronic searches were performed in PubMed, Embase, Web of Science, International Clinical Trials Registry Platform, and ClinicalTrials.gov for English language articles until July 2021. Randomised clinical trials and cohort, cross-sectional, and case-control studies where full pulpotomy was performed to manage mature permanent molar teeth with irreversible pulpitis and no periapical radiolucency were included. Newcastle Ottawa Scale and the Cochrane risk of bias tool were used for quality assessment. The success rate for full pulpotomy was documented. The protocol was registered in PROSPERO database (CRD42020177214). Out of 861 studies, four were considered for data analysis. Three studies were single-arm prospective trials on pulpotomy, while one was a randomised control trial comparing pulpotomy and root canal treatment. A combined success rate of 93% from 117 teeth was reported from three studies using 2.5% NaOCl as a haemostatic agent. One study used 5% NaOCl and reported a success rate of 100% (n = 6 teeth). The certainty of evidence substantiated by the GRADE approach was of low quality. Overall quality assessment revealed a considerable risk of bias in three studies. Irrespective of the NaOCl concentration, the success rate of pulpotomy in mature permanent teeth with irreversible pulpitis was high. No study compared the different concentrations of NaOCl as a haemostatic agent. Further, randomised controlled trials are required to investigate the effect of NaOCl concentration for haemostasis on the outcome of pulpotomy.

Comparative evaluation of effectiveness of different concentration of sodium hypochlorite with conventional irrigation method versus ultrasonic irrigation in the elimination of Enterococcus faecalis from root canals: an in-vitro study

Aim: The aim of this study is to compare the decrease in bacterial population in the root canals with 3 different concentrations of NaOCl and with two different irrigation systems Methods and Material: The study was conducted on 70 single rooted extracted teeth. Teeth were decoronated and the apices were sealed with auto polymerizing resin. The teeth were inoculated with a suspension comprising Enterococcus faecalis (E. faecalis). The canals were prepared were divided into three groups based on irrigation technique: Group 1; irrigation with 1% sodium hypochlorite, Group 2; irrigation with 3% sodium hypochlorite & Group 3; irrigation with 5% sodium hypochlorite. All three groups were divided into 2 subgroups. In subgroup A irrigation was done by conventional side vented needle and in subgroup B with passive ultrasonic agitation. A fourth control group was also added in which conventional needle irrigation was done with normal saline. The samples were inoculated on the growth media and the mean colonies units were calculated. Statistical analysis used: The statistical analysis used was Student’s unpaired t-test for intergroup comparison and one-way ANOVA and Tukey’s post hoc test for intragroup comparison. Results: In our study, groups with passive ultrasonic irrigation showed better antimicrobial effect compared to groups which use conventional needle irrigation. Conclusions: Ultrasonic irrigation showed better antimicrobial activity compared to conventional needle irrigation

Comparing the EdgeFile X3, GenEndo, HeroGold, and ProTaper Gold Rotary Instruments Regarding the Effect of Different Concentrations and Temperature of NaOCl on Cyclic Fatigue Resistance.

This research was carried out with the objective of comparison between GenEndo, Protaper Gold, Hero Gold and EdgeFile X3 regarding the effect of different concentrations of NaOCl. About 720 study specimens were included in the study. They were divided into four groups. Each group consisted of 180 files. Group A: GenEndo, Group B: Protaper Gold, Group C: Hero Gold, Group D: EdgeFile X3. Each group of instruments were further subdivided into nine subgroups (n = 20 for each subgroup). Testing of the cyclic fatigue was carried out in artificial canals which were prepared inside the blocks of stainless steel. The stainless steel blocks with artificial canals were established in a receiver that was packed with experimental solutions like distilled water, 5.25% NaOCl and 2.5% NaOCl. The adjustment of temperature was done at 25, 37, and 60°C. The rotation of the instrument was carried out inside the artificial canal as per the instructions of the manufacturer. The instrument was rotated until it got fractured. The time taken by the instrument to fracture was recorded in seconds. The number of cycles to fracture (NCF) was analyzed with the help of the equation (NCF = time to fracture × rpm/60). Surfaces at the site of fracture were examined with the help of a scanning electron microscope (EVOLS10, ZEISS) at magnification (300x and 2000x). It was noticed that there was a statistically significant increase in cyclic fatigue when sodium chloride was used as an endodontic irrigant instead of distilled water. The increase in cyclic fatigue was also observed when 5.25% sodium chloride was used instead of 2.5% sodium hypochlorite. Cyclic fatigue increased on change in temperature from 25 to 37°C and from 37 to 60°C. The difference was statistically significant (p < 0.05). It was observed that resistance against cyclic fatigue on treatment with different irrigation solutions at different temperatures was in the order of GenEndo > Protaper Gold > Hero Gold > EdgeFile X3. The resistance against cyclic fatigue in new NiTi rotary files can be affected significantly by different concentrations of sodium hypochlorite irrigant solution and the GenEndo rotary endodontic instrument has the maximum resistance against cyclic fatigue. Irrigation of the root canal with irrigants, such as sodium hypochlorite (NaOCl) has been recommended strongly. NaOCl is used in the range of 0.5 and 6.5% concentration owing to its antimicrobial activity and tissue dissolution activities, particularly at higher temperatures. It has been postulated that fatigue of rotary endodontic instruments can be influenced by adjoining medium and their concentration.

Employment of In Vitro Technique to Propagate Stevia (Stevia rebaudiana) Plant

The current study was conducted with aim to find an efficient simple protocol for propagation of stevia plant ( Stevia rebaudiana ) In Vitro. Shoot tips, leaves and stem nodes explants were sterilized with different concentrations of NaOCl (0.0, 2.0, 4.0 and 6% v/v) then cultured on MS medium supplemented with 30 g.l-1 sucrose. Results revealed that, no contamination was recorded when using 4.0 % and 6.0 % of NaOCl with (100% and 8.9%) survival at 4.0% and 6.0 % respectively. Moreover, combination of plant growth regulators which were used in this study, have been successfully optimized. However, best combination for number of shoots. explant-1 was found to be (0.4 BAP + 0.2 Kin mg.l-1) for shoot tips explants with an average of 16.44 while (2.0 BAP + 0.25 GA3 mg. l-1) produced maximum average of plant height from shoot tips reached 4.85 cm. For in vitro roots induction, maximum root induction, number and length of roots. Shootlets reached (93.3 %, 9.77 and 9.0 cm) respectively when cultured shootlets on MS medium supplemented with 2.0 mg.l-1 of IBA.

Endodontic infection control practices among Pakistani general dental practitioners: A national cross-sectional questionnaire survey

ObjectiveThis study was aimed at evaluating the self-reported endodontic infection control practices of general dental practitioners in Pakistan. MethodsAn e-questionnaire was sent to 619 general dental practitioners in several WhatsApp groups. Sixteen questions associated with various infection control measures recommended by the ESE were asked, including the use of various isolation methods/rubber dams, the selection of canal irrigants and anti-bacterial solutions, and practices regarding hand hygiene and use of examination gloves. The e-questionnaire also included questions associated with demographics. Data analysis was conducted in SPSS-24. Descriptive statistics were documented as percentages and frequencies. ResultsOf 619 GDPs, 350 responded (56.5% response rate), of whom 43.7% worked in private dental practices. The majority were women (64%), had graduated after 2010 (81.1%), and were 24–34 years of age (78.9%). A total of 72.3% of GDPs used cotton rolls, and 17.4% routinely used rubber dams for endodontic isolation; 89% did not disinfect the operative field; 80% reported using different concentrations of NaOCl during root canal instrumentation; and 0.9% reported not using any irrigant during endodontic procedures. A total of 61.7% reported always using intra-canal medication during multi visit endodontic treatment, among whom 82.5% reported using Ca(OH)2. Finally, 100% of respondents reported using gloves during endodontic treatment. ConclusionThe results indicated that the GDPs tended to follow some of the endodontics quality standards recommended by the ESE, but the overall implementation of all guidelines requires improvement.

In Vitro Evaluation of the Accuracy of Three Electronic Apex Locators Using Different Sodium Hypochlorite Concentrations.

Background and Objectives: The aim of this study was to compare the accuracy of three types of electronic apex locators (EALs) when two different concentrations of NaOCl irrigation solutions are used by two operators. Materials and Methods: After creating the access cavities for 20 single rooted extracted teeth, the actual canal length (ACL) of each canal was determined visually using a #10 file and magnification. The teeth were subsequently inserted in plastic molds filled with alginate. The electronic measurement of root canal length (EWL) was performed using three different electronic apex locators: Root ZX II, Apex ID, and Dual Pex. Two independent operators, an endodontic specialist with 20 years practice and an undergraduate student in the final year of study, performed the irrigation procedures with two different concentrations of NaOCl (2% and 5.25%), and then measured the EWL using each of the EALs. The accuracy of all EALs, was determined in each case by subtracting the EWL from the ACL. Statistical analyses were performed using one-way ANOVA test. Results: In the presence of 2% NaOCl solution, for a margin error of ±0.5 mm, Root ZX II, Apex ID, and Dual Pex presented an accuracy of 90%, 80%, and 85% respectively. The increase in the concentration of the irrigation solution affected the accuracy of Root ZX II and Apex ID for both operators, diminishing it to 75% for the same margin error, but improved Dual Pex's accuracy to 100%. Conclusions: The best accuracy in working length determination was obtained by Root ZX II for 2% NaOCl solution and by Dual Pex for 5.25% NaOCl solution with no significant statistical difference when compared.

Comparison of the effect of NaOCL, curcumin, and EDTA on differentiation, proliferation, and adhesion of dental pulp stem cells.

This study examined the effect of 1.5% NaOCl, 17% EDTA, and curcumin on the proliferation, attachment, and differentiation of dental pulp stem cells (DPSCs) placed on the dentin specimens. MTT assay was performed to evaluate the proliferation of DPSCs on the dentin specimens treated with different concentrations of NaOCl, 17% EDTA, and curcumin (0.97-250μM). Cell-adhering ability of DPSCs was tested via the LDH assay to calculate the attached DPSCs. In addition, the western blotting assay was performed to investigate the expression levels of fibronectin as a cell-adhesion marker and analyze the expressions level of differentiation markers, including DMP-1, OCN, ALP, and DSPP, to detect the odontogenic potential of hDPCs. NaOCl had lower toxicity on DPSCs at lower concentrations (P<0.001). The cytotoxicity of irrigants increased with increased dosage. The difference between the cell-adhesion ability of NaOCl and curcumin was not significant (∼4.4 MU/mL), whereas EDTA (∼3.8 MU/mL) exhibited the lowest release of LDH and less damage to hDPSCs. Regarding fibronectin expression, the pattern differed between irrigants in inducing cell adhesion. NaOCl increased fibronectin expression more than EDTA and curcumin. All the treated groups upregulated the expression of DSPP, DMP-1, OCN, and ALP compared to the control group, in which NaOCl showed a higher effect on the overexpression of differentiation markers. The results showed that all the tested irrigants could be used in regenerative endodontic treatment. However, as an herbal-based and biocompatible irrigant, curcumin exhibited fewer adverse effects than NaOCl and EDTA.

In vitro regeneration of Senna alata (L.) Robx. (Fabaceae): An ancient medicinal plant

Senna alata, a legume of medicinal importance, presents antifungal and antibacterial antioxidant activity. The main limitation is the presence of seeds with integument dormancy within natural populations. This study aimed to establish an efficient protocol for the in vitro propagation and acclimatization of seedlings. The seeds were disinfected with different concentrations of NaOCl; for the regeneration of the shoots, cotyledon segments were inoculated in MS and WPM medium, supplemented with plant growth regulators, auxins (1-NAA and 2,4-D), interaction with cytokinins (TDZ and BAP), and activated carbon. The seedlings were acclimated in nursery conditions using vermiculite, sand, and soil substrates. Using NaOCl (0.5%) for 30 min resulted in 98.0% disinfected seeds while 95.4% of scarified seeds germinated. High node and shoots numbers (8.3 ± 0.4; 12.6 ± 0.8, respectively) were obtained when using the MS medium containing 1-NAA + TDZ (0.1 + 1.0 mg L-1), while the use of MS medium supplemented with 2,4-D + TDZ (0.1 + 1.0 mg L-1) resulted in longer shoots (6.0 ± 0.5 cm). Using WPM medium with IBA + BAP (1.0 + 0.1 mg L-1) improved rooting (14.0 cm ± 1.3) and the number of roots (5.0 ± 0.0) in the treated plants. The vermiculite substrate with sand promoted 81.5% of acclimatized plants. This study allowed obtaining high levels of germination, regeneration in vitro and acclimatization of S. alata.

Effects of concentration of sodium hypochlorite as an endodontic irrigant on the mechanical and structural properties of root dentine: A laboratory study.

AimThe use of high‐concentration sodium hypochlorite (NaOCl) as an endodontic irrigant remains controversial because of its potential impact on the fracture strength of endodontically treated teeth. This study evaluated the effects of using different NaOCl concentrations, with 2‐min‐ethylenediaminetetraacetic acid (EDTA) as the final active irrigant, on the biomechanical and structural properties of root dentine.MethodologyA new test method, which is more clinically relevant, was utilized to calculate the fracture strength of root dentine. Bovine incisors were used to obtain root dentine discs. The root canals were enlarged to mean diameter of 2.90 mm with a taper of 0.06. The resulting discs were divided into five groups (n = 20) and treated with different concentrations of NaOCl (5.25%, 2.5%, and 1.3%) for 30 min plus 17% EDTA for 2 min. The discs were then loaded to fracture by a steel rod with the same taper through the central hole. The fractured specimens were examined by scanning electron microscopy to evaluate changes in the dimensions of the remaining intertubular dentine and the tubular radius. Micro‐hardness was also measured with a Knoop diamond indenter along a radius to determine the depth of dentine eroded by the irrigation. Results were analysed by one‐way anova and the Tukey test. The level of significance was set at α = 0.05.ResultsThe damage by NaOCl increased with its concentration. 5.25% NaOCl greatly reduced the fracture strength of root dentine from 172.10 ± 30.13 MPa to 114.58 ± 26.74 MPa. The corresponding reduction in micro‐hardness at the root canal wall was 34.1%. The damages reached a depth of up to 400 μm (p < .05). Structural changes involved the degradation of the intratubular wall leading to enlarged dentinal tubules and the loss of intertubular dentine. Changes in the microstructural parameters showed positive linear relationships with the fracture strength.ConclusionsWith the adjunctive use of EDTA, NaOCl caused destruction to the intratubular surface near the root canal and, consequently, reduced the root dentine's mechanical strength. The higher the concentration of NaOCl, the greater the effect. Therefore, endodontists should avoid using overly high concentration of NaOCl for irrigation to prevent potential root fracture in endodontically treated teeth.

Effectiveness of root canal irrigation and dressing for the treatment of apical periodontitis: A systematic review and meta-analysis of clinical trials.

Sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) and/or calcium hydroxide (Ca(OH)2 ) are commonly used during root canal treatment. Evaluation of their effectiveness regarding clinical and patient-related outcomes requires further understanding. To assess the effectiveness of root canal irrigation and dressing for the treatment of teeth with apical periodontitis (AP). A search was conducted in the PubMed-MEDLINE, Scopus, EMBASE, Google scholar databases and available repositories, followed by hand searches, until July 2021. Eligibility criteria followed the a priori formulated Population, Intervention, Comparator, Outcomes, Timing, and Study design (PICOTS) framework. Clinical studies restricted to English language were included. The revised Cochrane risk-of-bias tool for randomised trials (RoB 2) was used to assess the quality of included studies. Meta-analyses were performed using the fixed-effect model to obtain Risk Ratio (RR) and 95% Confidence Interval (CI), with sensitivity analysis. Overall quality of evidence of meta-analyses was assessed through the Grading of Recommendations Assessment, Development, and Evaluation tool. The search identified 1357 records of which six fulfilled the inclusion criteria, providing data for 'irrigation' from 212 teeth and for 'dressings' from 438 teeth. Two studies reported no significant difference regarding the outcome 'pain at 7 days' using 2% chlorhexidine vs. 5.25% NaOCl and EDTA or after using different concentrations of NaOCl (1% vs. 5%). No significant difference was detected between different NaOCl concentrations regarding the reduction of AP. A meta-analysis was possible for the comparison of single-visit (SV) versus multiple-visits including the use of Ca(OH)2 demonstrating a significant effect in favour of SV (RR: 1.10; 95% CI: 1.03-1.19; p= .007; I2 = 0). RoB of included studies was moderate to low. The use of Ca(OH)2 for the treatment of AP may not be beneficial. There is scarce or no evidence fulfilling the proposed PICOTS regarding irrigants and dressings. There is moderate certainty that SV treatment is associated with better radiographic evidence of normal periodontal ligament space (strict criteria) compared with the use of Ca(OH)2. Reduction of AP is comparable after irrigation with 1% and 5% NaOCl, whereas postoperative pain at 7 days for the irrigants assessed is similar. PROSPERO database CRD42021260271.

Laser activated irrigation with SWEEPS modality reduces concentration of sodium hypochlorite in root canal irrigation

IntroductionShockwave enhanced emission photoacoustic streaming (SWEEPS) of Er: YAG laser has been proposed to improve the disinfecting efficacy of endodontic treatments. The purpose of this in vitro study was to compare the effects of different concentrations of sodium hypochlorite (NaOCl) combined with SWEEPS root canal irrigation on the removal of Enterococcus faecalis (E.faecalis) in infected bovine root canals. Materials and methodsForty-eight bovine root canals infected with E.faecalis were randomly divided into six groups. The root canals were irrigated by normal saline (NS) in combination with conventional needle irrigation (CI) , NS and different concentrations of NaOCl (0.5%, 1.0%, 2.0%, and 5.25%) in combination with SWEEPS. Then, the remaining live microbes from all specimens before and after root canal irrigation were collected and recovered via plate counting of the colony-forming unit (CFU). The CFU data were statistically analyzed by the Kruskal-Wallis H test. ResultsAfter root canal irrigation, the viable count in each group was significantly reduced (P < 0.05). The bacterial reduction in NS+CI and NS+SWEEPS groups was significantly lower than that in other groups (P < 0.05), and there was no significant difference among the other groups, or between these two groups (P > 0.05). ConclusionsThis study showed that SWEEPS used for root canal irrigation can enhance the effect of low-concentration NaOCl while ensuring the antimicrobial effect.

Effect of different irrigation protocols for applications in regenerative endodontics on mechanical properties of root dentin.

The objective of this study was to evaluate the effect of different concentrations of NaOCl with and without passive ultrasonic irrigation (PUI) on mechanical properties of human dentin for applications in regenerative endodontics (RE). Sixty single-rooted teeth were sectioned into 2 halves (n=120). Dentin bars were produced from one half for flexural strength and the other half was used for microhardness. Specimens were randomly assigned into 10 groups: G1 and G2 (control): distilled water for 30 and 60min, respectively; G3: 1.5%NaOCl for 30min; G4:1.5%NaOCl for 60min; G5: 1.5%NaOCl+PUI for 30min; G6: 1.5%NaOCl+PUI for 60min; G7: 5.25%NaOCl for 30min; G8: 5.25%NaOCl for 60min; G9: 5.25%NaOCl+PUI for 30min; G10: 5.25%NaOCl+PUI for 60min. An increase in NaOCl concentration showed highly significant reduction in mechanical properties. There was no significant difference between 1.5% NaOCl and control group except for specimens treated with PUI for 60min. NaOCl in concentrations recommended for RE did not have a significant effect on mechanical properties of dentin. However, PUI with increased irrigation time might have an effect even with low NaOCl concentration.

Are single-visit regenerative endodontic procedures successful in treating non-vital, immature young permanent teeth?

Design Systematic review.Data sources PubMed and Scopus databases were searched independently by two authors from inception to July 2018 using keywords and index words combined using Boolean terms. Articles were restricted to English and were not excluded based on study design. Conference proceedings, grey literature, letters and commentaries were excluded.Data extraction and synthesis Demographic data (age, sex), study design, pulpal and periapical pre-treatment diagnosis, pre-operative radiographic findings, intra-operative disinfection protocol, intracanal coronal barrier, duration of follow-up, and clinical and/or radiographic and/or histological outcomes after completion of single-visit regenerative endodontic procedures (REPs) on non-vital, immature permanent teeth. Quality of included case reports were assessed according to the Joanna Briggs Institute Critical Appraisal Checklist. Risk of bias assessment of randomised controlled trials was done using Cochrane Collaboration's tool. The quality of the animal study was assessed by the SYRCLE risk of bias assessment tool.Results A total of five case reports, one randomised controlled trial and one animal study were included in the final analysis. All case reports were rated as high quality while the randomised controlled trial was rated moderate-to-low risk of bias. Case reports and the animal study favoured single-visit REPs, while the results from the randomised trial reported only 50% success. Within this limited pool of studies, there were differences in aetiology, location, disinfection protocol (different concentrations of NaOCl and EDTA, saline, chlorhexidine), follow-up time intervals and subjective reporting of radiographic healing, making syntheses challenging.Conclusions Single-visit REPs may offer benefits of reduced treatment time and visits compared to conventional two-visit REPs.

Decontamination of cyst (Globodera spp.) infested potato seed tubers with sodium hypochlorite (NaOCl)

Potato cyst nematode (Globodera spp.) is one of the serious pests of potato worldwide including India. Infested seed tubers and soil are the primary means of spread of cysts to non-infested areas, whereas air, water, human, animals, field equipments, composts, gunny bags are other means of spread. Therefore, a study was carried out with different concentrations of NaOCl under in vitro and in vivo condition to see its decontamination effect on potato cyst nematode (PCN). The results revealed that potato tubers harvested from the PCN infested fields can be completely decontaminated by giving dip treatment in NaOCl (2%) solution for 30 min. and the treated tubers sprouts normally after two months of storage.

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.

The effect of use different concentrations of sodium hypochlorite on cyclic fatigue in reciproc files (in vitro study)

Background: NiTi instruments have a risk of separation due to torsional or flexural fatigue (cyclic fatigue). Chemo-mechanical preparation and cleaning procedures cause the corrosion of endodontic instruments that may weaken the fracture resistance of the instruments. Aim of the Study: To assess resistance to cyclic fatigue of Reciproc files R25 after immersion in different concentrations of sodium hypochlorite in conditions similar to those used in clinical practice. Materials and Methods: The study sample included 40 new Reciproc R25 files according to the G-power program and divided randomly into four groups according to NaOCl concentration (n=10). Files were immersed in NaOCl for 10 minutes at room temperature and for 16mm length as following: Group A no immersion (control), Group B (1% NaOCl), Group C (2.5% NaOCl) and Group D (5.25% NaOCl). The cyclic fatigue resistance was tested in stainless steel artificial canal manufactured reproducing the instrument size and taper, with 120° angle of curvature and 2.5 radius of curvature. The Time to Fracture (TtF) was statically analyzed. Results: According to statistical data for analytical study, the mean of Time to Fracture (TtF) group A control, B, C and D was170.77,153.10,142.32, and 132.59 respectively. One-way ANOVA test indicated no significant differences in mean of TtF between NaOCl concentration groups. Resistance to cyclic fatigue of R25 was not affected by the concentration of NaOCl used in this study (P>0.05). Conclusions: Using different concentrations of NaOCl for 10 minutes did not reduce the resistance to cyclic fatigue of Reciproc R25 files. Keywords: Cyclic fatigue, NaOCl, Reciproc R25.

HIPOCLORITO DE SODIO YÁCIDO HIPOCLOROSO: CAPACIDAD DE DISOLUCIÓN DE TEJIDO ORGÁNICO (ESTUDIOIN-VITRO)

OBJETIVO: Comparar la capacidad de disolución de tejido orgánico de dos soluciones (NaOCl y HOCl), sometiéndolas a diferentes protocolos de tiempo y temperatura MATERIALES y MÉTODOS: Para el presente estudio se obtuvieron 120 muestras de tejido vacuno ex vivo, el cual fue dividido en 10 grupos de 12 muestras cada uno. Se utilizaron 4 soluciones de NaOCl con concentraciones de: 5.25%, 2.5%, 1% y 0.5% respectivamente y una solución de HOCl al 5%. Las muestras fueron observadas a distintos intervalos de tiempo: 1 minuto, 5 minutos, 15 minutos, 30 minutos, 45 minutos y 60 minutos. Así los datos recogidos de las observaciones se basaron en cambios macroscópicos presentes en la superficie de cada muestra y posteriormentefueronanalizadosestadísticamenteendiferentespruebas. RESULTADOS:Los datos fueron analizados con el programa informático Statistica 7.0. El análisis 1 comparó, en los distintos intervalos de tiempo, la capacidad de disolución de tejido orgánico entre las distintas concentraciones del NaOCl y el HOCl, a los 5 minutos y a los 15 minutos, no arrojaron diferencias significativas mientras que 30 a 60 minutos, sí permitieron observar diferencias significativas. En la segunda parte del análisis estadístico se comparó, en los distintos intervalos de tiempo, la valoración entre las dos temperaturas probadas 21oC y37 oC, los resultados obtenidos para los tiempos 1 minuto, 45 minutos y 60 minutos, no permiten observar diferencias significativas. Para los intervalos de 5 minutos, 15 minutos y 30 minutos, sí se observaron diferencias, siempre a favor de las muestras tratadas a 37oC.

Cleaning lateral morphological features of the root canal: the role of streaming and cavitation.

To investigate the effects of ultrasonic activation file type, lateral canal location and irrigant on the removal of a biofilm-mimicking hydrogel from a fabricated lateral canal. Additionally, the amount of cavitation and streaming was quantified for these parameters. An intracanal sonochemical dosimetry method was used to quantify the cavitation generated by an IrriSafe 25mm length, size 25 file inside a root canal model filled with filtered degassed/saturated water or three different concentrations of NaOCl. Removal of a hydrogel, demonstrated previously to be an appropriate biofilm mimic, was recorded to measure the lateral canal cleaning rate from two different instruments (IrriSafe 25mm length, size 25 and K 21mm length, size 15) activated with a P5 Suprasson (Satelec) at power P8.5 in degassed/saturated water or NaOCl. Removal rates were compared for significant differences using nonparametric Kruskal-Wallis and/or Mann-Whitney U-tests. Streaming was measured using high-speed particle imaging velocimetry at 250kfps, analysing both the oscillatory and steady flow inside the lateral canals. There was no significant difference in amount of cavitation between tap water and oversaturated water (P=0.538), although more cavitation was observed than in degassed water. The highest cavitation signal was generated with NaOCl solutions (1.0%, 4.5%, 9.0%) (P<0.007) and increased with concentration (P<0.014). The IrriSafe file outperformed significantly the K-file in removing hydrogel (P<0.05). Up to 64% of the total hydrogel volume was removed after 20s. The IrriSafe file typically outperformed the K-file in generating streaming. The oscillatory velocities were higher inside the lateral canal 3mm compared to 6mm from WL and were higher for NaOCl than for saturated water, which in turn was higher than for degassed water. Measurements of cavitation and acoustic streaming have provided insight into their contribution to cleaning. Significant differences in cleaning, cavitation and streaming were found depending on the file type and size, lateral canal location and irrigant used. In general, the IrriSafe file outperformed the K-file, and NaOCl performed better than the other irrigants tested. The cavitation and streaming measurements revealed that both contributed to hydrogel removal and both play a significant role in root canal cleaning.

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

IntroductionThe 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. MethodsEighty-six extracted single-rooted teeth were mechanically prepared, sterilized, and inoculated with E. faecalis for 4 weeks. Teeth were divided into 9 groups and treated with an Er:YAG laser using a PIPS 600/9 tip at the following parameters: 10 mJ or 20 mJ, 15 Hz, and a 50-microsecond pulse duration at 0.15 W or 0.3 W average power, respectively. Root canals were irrigated with different concentrations of NaOCl (ie, 1%, 3%, and 5% and activated using the adjusted PIPS protocol). The bacterial count was performed immediately after and 48 hours after decontamination and new incubation on an agar plate. ResultsA statistically significant difference in bacterial counts (P < .05) was detected in all groups before and directly after the treatment and in groups treated with 5% NaOCl 48 hours after treatment. Scanning electron microscopic imaging showed an absence of bacteria and biofilm in the scanned areas after treatment with 5% NaOCl. ConclusionsLaser-activated irrigation using 5% NaOCl and a modified PIPS protocol resulted in effective eradication of the bacterial biofilm and removal of the smear layer.

The Effect of Er:YAG Laser Irradiation and Different Concentrations of Sodium Hypochlorite on Shear Bond Strength of Composite to Primary Teeth's Dentin.

Introduction: The aim of this study was to evaluate the effect of various concentrations of NaOCl on shear bond strength of composite resin to dentin of primary teeth, prepared with laser and bur. Methods: In this in vitro study, 48 primary molars were sectioned at mesiodistal direction and were randomly divided into 6 groups; G1: bur, G2: bur + NaOCl 2.5%, G3: bur + NaOCl 5.25%, G4: laser, G5: laser + NaOCl 2.5%, G6: laser + NaOCl 5.25%. One-Step Plus adhesive was applied after phosphoric acid gel and NaOCl over the dentin surfaces for all groups, and composite resin cylinders were bonded to the samples. After thermocycling, shear bond strengths of composite resin to dentin were measured and statistical analyses were done by means of t test and analysis of variance (ANOVA). Results: The mean shear bond strength showed no significant difference between the groups prepared with bur (13.82 ± 3.49) and laser (14.18 ± 3.65) (P > 0.05). The mean difference of shear bond strength between three groups G1, G2 and G3 and between G4, G5 and G6 were not statistically significant (P > 0.05). Scanning electron microscopy (SEM) figures showed an irregular surface in laser groups and fairly complete removal of smear layer from the orifices of the dentinal tubules, in the group in which NaOCl was used. Conclusion: The application of different concentrations of NaOCl does not significantly improve the bond strength in dentin surfaces prepared with laser or bur.