Effect of different irrigation activation techniques on irrigation penetration into the simulated lateral canals.

This study, in which a hundred human teeth with single straight canal were used, focused on the evaluation of contrast solution penetration ability into the simulated lateral canals activated by XP-endo Finisher (XPF), EDDY, Nd:YAG, and Er:YAG laser systems with three different observation methods. The root canals were prepared up to X4 at working length using the ProTaper Next system. The teeth were decalcified and simulated lateral canals were created with #8 K-file at 2, 4, and 6 mm levels. Then the teeth were cleared using methyl salicylate and divided into 5 equal groups according to irrigation activation techniques (CSI, XPF, EDDY, Nd:YAG, and Er:YAG laser). After the contrast solution was activated, images of the simulated lateral canals were obtained by a dental microscope, digital radiography, and CBCT. The contrast solution penetration scores at the 2, 4, and 6 mm levels according to irrigation activation techniques and observation methods were analyzed statistically using Kruskal-Wallis non-parametric analysis of variance Bonferroni test post hoc comparisons. With the other 2 parameters are ignored, the highest and lowest contrast solution penetration were observed at 6 and 2 mm simulated lateral canal levels (p < 0.05), in Er:YAG irrigation activation and CSI technique (p < 0.05), and in direct visual and digital radiographic observation method (p < 0.05), respectively. Within the limits of this study, it was determined that the contrast solution penetration into the simulated lateral canals decreased from the coronal to the apical and achieved with the most effective Er:YAG laser activation technique. In addition, direct visual observation was found to be the best method for the assessment of contrast solution penetration.

The effect of different irrigation solutions and activation techniques on the expression of growth factors from dentine of extracted premolar teeth.

AIM: To evaluate in a laboratory study, the effect of different canal irrigant solutions and activation techniques on transforming growth factor (TGF-ß1), insulin growth factor-1 (IGF-1), bone morphogenetic protein-7 (BMP-7) and vascular endothelial growth factor-A (VEGF-A) release levels from the dentine of extracted premolar teeth. METHODOLOGY: Seventy premolar teeth with single root and canal were used. The lengths of the root segments were standardized to 12 mm, and the root canals were prepared up to size 100 with hand files. All surfaces of the teeth were covered with nail polish except the inner root canal surface. The root canals were irrigated with 1.5% NaOCl. Ten teeth were allocated to the control group. The remaining sixty teeth were divided into 2 main groups according to the chelating agent used (17% EDTA, 10% Citric acid; CA) and 3 subgroups (n = 10) according to irrigation activation technique (conventional syringe irrigation (CSI), passive ultrasonic irrigation (PUI) and Er:YAG laser activation). After the activation procedure, the root segments were placed into eppendorf tubes containing 1 mL of phosphate-buffered saline solution and kept at 37℃. TGF-ß1, IGF-1, BMP-7 and VEGF-A release levels from dentine were measured using the enzyme-linked immunosorbent assay (ELISA) method at 24 h and at day 7. The volume of root canals was calculated using cone-beam computed tomography. The growth factor levels were calculated in ng/mL except VEGF-A (pg/ml). Normality analysis of the data was evaluated with the Kolmogorov-Smirnov test. Statistical analysis was performed using the Mann-Whitney-U and Wilcoxon tests. RESULTS: Regardless of the activation type and sampling time, EDTA caused significantly more IGF release than did CA, whereas EDTA and CA were equally effective for the release of the other growth factors. For either EDTA or CA, the lowest and highest growth factor release levels were observed in the CSI and Er:YAG laser groups, respectively (p < .05). All of the growth factors were released significantly more at 24 h than on day 7 (p < .05). CONCLUSIONS: Irrigation activation techniques with EDTA or CA increased the release levels of all growth factors from the dentine of canal walls in extracted premolar teeth.

Effect of solvent use on postoperative pain in root canal retreatment: a randomized, controlled clinical trial.

OBJECTIVES: The aim of this randomized clinical trial was to assess the effect of solvent use during the removal of root canal filling on postoperative pain after retreatment. MATERIALS AND METHODS: Ninety patients scheduled for root canal retreatment were randomly assigned to one of the following two groups according to the root canal filling removal procedure used: ProTaper retreatment (Dentsply Maillefer, Ballaigues, Switzerland) instruments or ProTaper retreatment instruments in combination with gutta-percha solvent. A single operator performed the retreatments in a single visit. The incidence and intensity of the postoperative pain were rated on a numeric rating scale by patients at 24, 48, and 72 h after retreatment. The analgesic tablet intake number was also recorded. Data were analyzed using Mann­Whitney U, Wilcoxon, and chi-square tests. RESULTS: For the intensity of postoperative pain, the difference between the two groups was not statistically significant. Moreover, no statistically significant difference was found between the two groups in terms of analgesic medication intake (P > 0.05). CONCLUSIONS: The processes involving the use and non-use of a solvent in the removal of root canal fillings were found to be equivalent in terms of postoperative pain intensity and analgesic intake. CLINICAL RELEVANCE: Some in vitro studies claimed that the use of a gutta-percha solvent in the removal of root canal fillings tends to reduce postoperative pain since extrusion of debris was significantly less. This randomized clinical trial indicates that the removal of root canal fillings with or without the use of a solvent was associated with equivalent postoperative pain intensity and analgesic intake. This study is registered in the www.ClinicalTrials.gov database with the identifier number NCT03756363.

Effect of different irrigant activation protocols on push-out bond strength.

The study aimed to evaluate the effect of various final irrigant activation protocols on push-out bond strength of fiber post. Thirty-two single-rooted human maxillar central teeth were sectioned below the cementoenamel junction, instrumented and obturated. Post-space preparation was performed, and roots were randomly divided into eight groups (n = 4) according to the final irrigant activation protocols; distilled water was used as an irrigant in group 1. The other groups were treated with 2.5% NaOCl and 17% EDTA. Conventional syringe irrigation (CSI, no activation) was used in group 2. Irrigation solutions were activated using passive ultrasonic irrigation (PUI, group 3), EndoVac apical negative pressure (ANP, group 4), diode laser (group 5), neodymium:yttrium-aluminum-garnet (Nd:YAG) laser (group 6), erbium:yttrium-aluminum-garnet (Er:YAG) laser (group 7), and Er:YAG laser using with photon-induced photoacoustic streaming (PIPS™) technique (group 8). In all groups, fiber posts (White Post DC, FGM) were luted using Panavia F 2.0 (Kuraray, Osaka, Japan). The specimens were transversally sectioned, and all slices from coronal and apical regions were subjected to push-out tests. The data were calculated as megapascals and analyzed by using two-way analysis of variance followed by post hoc Tukey honestly significant difference (HSD) tests. Removing the smear layer increased the bond strength to dentine when compared with the control group (p < 0.05). The highest bond strength was obtained in the PIPS laser-activated irrigation group (p < 0.05). Coronal root region presented significantly higher bond strength than the apical region (p < 0.05). PIPS laser-activated irrigation showed higher efficiency as a final irrigant activation protocol on push-out bond strength of fiber post.

The Effectiveness of Three Different Irrigant Activation Methods in the Elimination of Enterococcus faecalis from Root Canals.

Background and Objective: Eliminating intracanal Enterococcus faecalis (E. faecalis) is challenging because of its ability to penetrate deep dentinal tubules and its high resistance to many chemicals. This study evaluated the effectiveness of conventional needle irrigation and three different irrigant activation methods in reducing E. faecalis. Methods: The root canals of extracted teeth were shaped, contaminated with E. faecalis, and incubated for three weeks. They were randomly allocated to four experimental groups of 15 teeth each according to the final irrigation method: group 1, conventional needle irrigation; group 2, passive ultrasonic (PU) irrigation; group 3, XP-endo Finisher (XPF); and group 4, laser-activated (LA) irrigation. Bacterial samples were taken and cultured before and after these final irrigation procedures. The colony-forming units were counted, and the bacterial reduction percentages of each group were calculated. The Kruskal-Wallis and Dunnet tests were used for statistical analysis. Results: All irrigant activation methods were significantly more effective than conventional needle irrigation. Although the LA group generated more negative samples than PU, there was no statistically significant difference between the LA and PU groups. LA was significantly more effective than the XPF, whereas PU and XPF were statistically similar. Conclusions: Within the limitations of this study, the final irrigation with LA and PU showed the best reductive effect on E. faecalis colonies. Considering that the LA group had more negative samples, it may be chosen as an alternative to enhance root canal disinfection, especially in difficult cases.

Evaluating the effect of different irrigation activation techniques on the dentin tubules penetration of two different root canal sealers by laser scanning confocal microscopy.

PURPOSE: The aim of this study is to evaluate the effect of different irrigation activation techniques on the dentin tubules penetration of two different sealers by confocal laser scanning microscope (CLSM). METHODS: A hundred premolar teeth were used in this study. The root canals were shaped and irrigated with 5% NaOCl and 17% EDTA using the following final irrigation activation techniques in each group; Group1: Conventional Syringe Irrigation (CSI), Group2: Passive Ultrasonic Irrigation (PUI), Group3: Apical Negative Pressure (EndoVac), Group4: Er:YAG laser and Group5: Er,Cr:YSGG laser. Then the teeth were separated two subgroups according to sealers (AH-Plus and Totalfill-BC). Horizontal sections were obtained at 2, 5, 8 mm distance of apex. Images were obtained with CLSM and the penetration areas of sealers were calculated with four different dentin tubule penetration assessment techniques. The data were statistically analyzed with Kruskal Wallis and Mann Whitney U tests. RESULTS: No significant difference was observed between the sealers (p > .05). EndoVac, Er:YAG and Er,Cr:YSGG laser activation groups were observed to have a significantly higher mean penetration depth, penetration percentage and penetration area than the Control group. There was a significant difference between all regions in all penetration parameters (p < .05). CONCLUSIONS: While the use of resin or bioceramic-based root canal sealers did not affect dentin tubule penetration, the use of activation techniques positively affect the dentin tubule penetration. The average tubule penetration and penetration area assessment techniques are suitable methods for the investigation of dentinal tubule penetration. RESEARCH HIGHLIGHTS: It can be stated that the use of resin or bioceramic based root canal sealers does not affect dentin tubule penetration and the use of irrigation activation techniques during removal of the smear layer positively affects dentinal tubule penetration. In addition, it has been determined that the average tubule penetration and penetration area assessment techniques are suitable methods for the investigation of dentinal tubule penetration.

Comparison of ADAMTS Levels in Pulp Tissue Samples of Healthy and Symptomatic Irreversible Pulpitis Teeth.

INTRODUCTION: The aim of this study was to compare the levels of different A disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS; ie, ADAMTS-1, -4, and -9]) related to the breakdown of the proteoglycans and tissue inhibitor of metalloproteinase 3 (TIMP-3) levels that inhibit ADAMTS in the extracellular matrix of healthy pulp and symptomatic irreversible pulpitis. METHODS: Pulp tissue samples diagnosed with healthy and symptomatic irreversible pulpitis were collected from 48 participants. Healthy and inflamed pulps were directly transferred to Eppendorf tubes (Labosel, Istanbul, Turkey) and stored at -80°C (Nüve-DF490; Nüve, Ankara, Turkey) until further use. Routine root canal treatment procedures for the teeth were performed, after which the treatment process was completed. The levels of ADAMTS-1, -4, and -9 and TIMP-3 were measured in supernatants of human dental pulp tissue extracts using enzyme-linked immunosorbent assay kits (USCN, Wuhan, China). The independent sample t test and 1-way analysis of variance were used for parametric data, and the Kruskal-Wallis and Mann-Whitney U tests were used for nonparametric data. RESULTS: There was a statistically significant difference between ADAMTS-1 and -9 and TIMP-3 levels of the healthy pulp and pulpitis groups (P < .05), but there was no significant difference for ADAMTS-4 levels (P > .05). It was found that the levels of ADAMTS-1 and -9 were higher in the pulpitis group compared with the healthy pulp group, whereas the TIMP-3 level decreased (P < .05). CONCLUSIONS: As a result of this study, it was concluded that ADAMTS-1 and -9 and TIMP-3 might have a role in pulpal inflammation, whereas ADAMTS-4 was not related to pulpal inflammation.

Effect of different light sources in combination with a light-transmitting post on the degree of conversion of resin composite at different depths of simulated root canals.

AIM: The aim of this study was to evaluate the degree of conversion (DC) of composite resin at different depths of simulated immature root canals using light-transmitting plastic post (LTPP) and three different light sources. METHODOLOGY: Composite resin was packed into 60 black plastic cylinders 12mm in length with 4mm internal diameters to simulate immature root canals. LTPPs were inserted into half of the simulated canals and the other half acted as controls. Both the simulated canals with LTPPs and the controls were divided into three groups of 10, and each group was cured using either a quartz-tungsten-halogen (QTH), light-emitting diode (LED), or plasma arc (PAC) curing unit. Specimens were sectioned in three horizontally 24h after curing to represent cervical, middle, and apical levels. DC for each section of composite resin was measured using a Fourier transform infrared spectrophotometer, and data were analyzed using three-way anova and Tukey tests. RESULTS: At the cervical level, no significant differences were found between specimens cured using different light sources or between specimens with and without LTPPs (P>0.05). However, DC was significantly higher in specimens with LTPPs than in those without LTPPs at both the middle and apical levels (P<0.05). The mean DC of all specimens with LTPPs was significantly higher than that of specimens without LTPPs (P<0.05). PAC unit showed lower DC than QTH and LED units at both the middle and apical levels; however, the differences were not statistically significant (P > 0.05). CONCLUSIONS: The results of this study suggest that the use of a LTPP increased the DC of composite resin at the middle and apical levels of simulated immature root canals, but that DC was independent of type of light source.

Comparison of dentin penetration ability of different root canal sealers used with different obturation methods.

This in vitro study aimed to investigate the tubular penetration depth of four different sealers used with two different obturation methods in the apical, middle, and coronal root canal dentin. Eighty-four single-rooted teeth were instrumented until the F4 ProTaper universal rotary file and filled with AH26, AH Plus (Dentsply, DeTrey, Konstanz, Germany), RealSeal (SybronEndo, Orange, CA), and MTA Fillapex (Angelus, Londrina, Brazil) using cold lateral condensation (CLC) and single-cone (SC) obturation techniques. Thereafter, the roots were sectioned longitudinal and prepared for scanning electron microscope evaluation. The maximum and minimum sealers penetration depth into dentinal tubules at the apical, middle, and coronal regions and the average depth of sealer penetration were calculated. The data was statistically analyzed two-way ANOVA and post hoc Tukey and Dunnett tests and independent samples t test using maximum mean values. There was no statistically difference between the obturation methods (p > .05). When the sealers are evaluated within themselves AH26 was affected by obturation methods significantly (p < .05). Also the results revealed a significant difference between root regions (p < .05). AH26 and RealSeal root canal sealers had the highest penetration values with CLC and SC obturation techniques, respectively. The obturation method did not affect the penetration amount of root canal sealers. RealSeal root canal sealer performed better penetration ability than the other sealers. Apical third of the root in all groups showed lowest penetration depth.

Comparison of Neurokinin A, Substance P, Interleukin 8, and Matrix Metalloproteinase-8 Changes in Pulp tissue and Gingival Crevicular Fluid Samples of Healthy and Symptomatic Irreversible Pulpitis Teeth.

INTRODUTION: The aim of this study was to compare levels of neurokinin A (NKA), substance P (SP), interleukin (IL)-8, and matrix metalloproteinase-8 (MMP-8) in pulp tissue and gingival crevicular fluid (GCF) samples of healthy and symptomatic irreversible pulpitis teeth. METHODS: Forty patients diagnosed with healthy and symptomatic irreversible pulpitis teeth were included in this study. NKA, SP, IL-8, and MMP-8 levels were measured using the enzyme-linked immunosorbent assay test after pulp and GCF samples were obtained from healthy (n = 20) and symptomatic irreversible pulpitis teeth (n = 20). GCF sampling of 40 teeth was repeated 1 week later. Routine root canal treatment procedures of the teeth were performed, and the treatment process was completed. As a control group, GCF samples were taken from the contralateral teeth in both groups. Statistical analysis was performed using dependent and independent t tests, analysis of variance, Kruskal-Wallis, Mann-Whitney U tests, and Pearson correlation analysis. RESULTS: Comparing the groups, all mediator levels were significantly higher in the pulp samples in the pulpitis group compared with the healthy group (NKA: P < .001, SP: P = .005, IL-8: P < .001, and MMP-8: P < .001). Likewise, in the pulpitis group, all mediator levels were significantly higher in the first GCF samples compared with the healthy group (NKA: P = .01, SP: P < .001, IL-8: P = .001, and MMP-8: P < .001). CONCLUSIONS: It was observed that NKA, SP, IL-8, and MMP-8 increased significantly in pulp tissue and GCF specimens of symptomatic irreversible pulpitis teeth compared with pulp tissue and GCF specimens of healthy teeth. Second, it was determined that NKA, SP, IL-8, and MMP-8 levels decreased significantly in GCF samples in teeth diagnosed with symptomatic irreversible pulpitis 1 week after the removal of inflamed pulp. Finally, SP, IL-8, and MMP-8 levels were found to be higher in pulp tissue samples of the patients with symptomatic irreversible pulpitis with higher pain scores than those with low pain scores.

Effect of different cavity disinfectants on shear bond strength of composite resin to dentin.

PURPOSE: The aim of this study was to evaluate the effect of different cavity disinfectants on dentin bond strengths of composite resin applied with two different adhesive systems. MATERIALS AND METHODS: One hundred mandibular third molars were sectioned parallel to the occlusal surface to expose midcoronal dentin. The dentin surfaces were polished with waterproof-polishing papers. The specimens were randomly divided into 5 groups of 20 each. In group 1, the specimens were not treated with any cavity disinfectants and served as control. From groups 2 to 5, dentin surfaces were treated with the following cavity disinfectants, respectively; 2% chlorhexidine solution, 2.5% NaOCl, 1% chlorhexidine gel, 3% H2O2. The specimens were then randomly divided into 2 subgroups including ten teeth each to evaluate the effect of different bonding systems. Dentin bonding systems were applied to the dentin surfaces and the composite buildups were created. After the specimens were stored in an incubator for 24 h, the shear bond strength was measured at a crosshead speed of 1 mm/min. The bond strength data were analyzed with one way analysis of variance and Tukey-HSD tests. RESULTS: There was no significant difference between chlorhexidine gel and control groups regardless of the type of the bonding agent (p > 0.05). On the other hand, pretreatment with NaOCl, H2O2 or chlorhexidine solutions had a negative effect on the shear bond strength of self-etching bonding systems. CONCLUSION: The findings of this study suggest that when NaOCl, H2O2 or chlorhexidine solution are used as a cavity disinfectant, an etch-and-rinse bonding system should be preferred.

Effects of different chlorhexidine formulations on shear bond strengths of orthodontic brackets.

OBJECTIVE: To test the hypothesis that the application of different chlorhexidine formulations to the etched enamel will not affect shear bond strength (SBS). MATERIALS AND METHODS: Forty-four freshly extracted human premolars were collected and stored in distilled water. The teeth were etched with 37% phosphoric and were rinsed and dried. The teeth then were divided into four equal groups. While Group 1 served as a control, Groups 2 to 4 were treated before bonding with a chlorhexidine formulation that included solution (2%), gel (1%), and mouthwash (0.2%). Orthodontic brackets were bonded with Transbond XT (3M Unitek, Monrovia, Calif). Bond strength results were evaluated with the use of one-way analysis of variance (ANOVA) (P < .05) and post hoc tests. Modes of failures were verified by means of scanning electron microscopy. RESULTS: Although no statistically significant difference was observed between Groups 1 and 4 (P > .05), both were statistically superior to Groups 2 and 3 (P < .05). In this in vitro study, the observed measures for Groups 2 and 3 (14.5-10.6 MPa) were lower than those for Groups 1 and 4 (27.3-24.9 MPa), but these values were much higher than those required for clinical use (6-8 MPa). CONCLUSION: The hypothesis is rejected. The application of chlorhexidine mouth rinse before bonding had no significant effect on the SBS value, and the application of chlorhexidine solution and gel significantly decreased SBS.

Effect of several laser systems on removal of smear layer with a variety of irrigation solutions.

To evaluate which laser system is more effective on smear layer removal when distilled water or combination of sodium hypochlorite (NaOCl) and ethylenediaminetetraacetic acid (EDTA) are used as irrigants. Ninety-six human mandibular premolar teeth were used. Standard access cavities were prepared and the root canals were enlarged using ProTaper system to size F4 and divided into two equal groups according to final irrigation solution. In Group 1, distilled water was used, whilst 2.5% NaOCI and 17% EDTA solutions were used in Group 2. Each group was divided into four equal subgroups according to the activation procedure. In Subgroups 1A (Control) and 2A, no activation protocol was applied. In other subgroups, Er:YAG laser using photon-induced photoacoustic streaming (PIPS; 1B and 2B), Nd:YAG laser (1C and 2C) and Er,Cr:YSGG laser (1D and 2D) were applied for the activation. Teeth were split longitudinally and subjected to scanning electron microscopy evaluation. Smear layer was scored at 1000× magnification in all thirds. The data were analysed statistically using Kruskal-Wallis and Mann-Whitney U test post hoc comparisons. The samples irrigated with distilled water had greater smear layer scores when compared with the combination of NaOCl and EDTA (p < .05). The efficacy of smear layer removal increased when using laser systems (p < .05). Smear layer was removed more effectively in the coronal and middle levels compared to the apical level (p < .05). The sequential use of NaOCl and EDTA is significantly more effective than distilled water in smear layer removal. Regardless of the type of irrigant, laser activated irrigation enhances smear layer removal. RESEARCH HIGHLIGHTS: The use of laser systems for activation of NaOCl and EDTA is the most effective method in terms of smear layer removal. Photon-induced photoacoustic streaming technique with Er:YAG laser was the most efficient smear layer removal method regardless of the solution used.

The detection of salivary minerals in smokers and non-smokers with chronic periodontitis by the inductively coupled plasma-atomic emission spectrophotometry technique.

BACKGROUND: The purpose of this study was to evaluate the effect of smoking on the salivary minerals in subjects with chronic periodontitis by the inductively coupled plasma-atomic emission spectrophotometry (ICP-AES) technique. METHODS: The study group included 24 subjects-12 smokers and 12 non-smokers-with chronic periodontitis. Clinical measurements and non-stimulated whole saliva were obtained, and the levels of five elements-sodium, potassium, calcium, magnesium, and phosphate-in each specimen were analyzed. RESULTS: When the clinical parameters were compared between groups, only plaque index was significantly higher in smokers than non-smokers (P <0.05). The mean plaque index of smokers and non-smokers was 1.93 +/- 0.51 and 1.51 +/- 0.39, respectively. The results of this study showed that there were no significant differences between groups in the mineral content of saliva. In smokers, there were positive correlations between the levels of calcium, sodium, and magnesium and clinical attachment level. There was also a positive correlation between the level of phosphate and the percentage of bleeding on probing. In non-smokers, there was a negative correlation only between the mean level of sodium and plaque index (P <0.05). CONCLUSIONS: The present study showed that no significant differences were found between the mineral content of saliva of smokers and non-smokers by the ICP-AES technique. It is a useful, fast, and sensitive technique compared to other techniques, and it can be advised for researchers while analyzing the mineral content of saliva.

Effects of endodontic irrigation solutions on mineral content of root canal dentin using ICP-AES technique.

The aim of this in vitro study was to evaluate mineral content of root canal dentin after treatment with several endodontic irrigation solutions. Sixty mandibular anterior teeth extracted for periodontal reasons used. The crowns of the teeth were removed at the cemento-enamel junction. Pulp tissues were removed and the teeth were randomly divided into six groups including 10 teeth each. Root canals were enlarged with gates-glidden burs (# 1, 2, and 3). The groups were treated as follows: group 1, 0.2% chlorhexidine gluconate for 15 min; group 2, 3% H2O2 for 15 min; group 3, 17% EDTA for 15 min; group 4, 5.25% NaOCl for 15 min; group 5, 2.5% NaOCl for 15 min; and group 6, distilled water (control). Dentin chips were obtained using gates-glidden burs (# 4, 5, and 6). The levels of five elements calcium, phosphorus, magnesium, potassium, and sulfur in each specimens were analyzed using ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometry) technique. Changes in the levels of the chemical elements were recorded. The results were then statistically analyzed by one-way ANOVA and Tukey tests. There was a significant decrease in the calcium and phosphorus levels after treatment with all irrigation solutions except for 5.25% NaOCl when compared with the control group (p < 0.05). The K, Mg, and S level changes were not statistically significant (p > 0.05). It has been concluded that endodontic irrigation solutions have an effect on mineral contents of root dentin.

Shear bond strength of three resin based sealers to dentin with and without the smear layer.

Bond strength of root canal sealers to dentin is an important property for the integrity of the sealings of root-canals. The purpose of this study was to test shear bond strength of three endodontic sealers (Diaket, AH Plus and Endo-REZ). The coronal two thirds of ninety extracted human third molars were removed. The smear layer of the exposed dentin surfaces were removed using 17% EDTA followed by 5.25% NaOCl and the teeth were randomly divided into two groups (n = 45). Group 1 was kept as control and in group 2, uniform smear layer was created using waterproof polishing papers. Three-mm long sections of polyethylene tubing were filled with freshly mixed sealer and placed on the dentin surfaces for conducting a shear bond strength test. The data was calculated as MPa and was statistically analyzed using a two way ANOVA, Kruskal-Wallis and Mann-Whitney U tests. A significant difference was found among the bond strength of the sealers, smear layer, and control groups. AH Plus sealer showed the highest bond strength in smear layer removed surfaces (p < 0.05). Pretreatment with EDTA/NaOCl affected bond strength of AH Plus. AH Plus had the highest bond to dentin with or without smear layer.

Effect of EDTA and citric acid solutions on the microhardness and the roughness of human root canal dentin.

The purpose of this study was to evaluate the effect of citric acid and EDTA solutions on the microhardness and the roughness of human root canal dentin. Forty-five human teeth sectioned longitudinally were used. Specimens were randomly divided into three groups of 30 teeth each and were treated as follows: (a) one molar (19%) citric acid (C6H8O7) for 150 s followed by 5.25% NaOCl; (b) 17% EDTA for 150 s and rinsed with 5.25% NaOCl; (c) rinsed with distilled water and served as control. Three groups were then divided into two subgroups of 15 specimens each. The specimens, in first subgroup were subjected to Vicker's testing whereas the second subgroup underwent surface roughness testing. The results were analyzed using one-way ANOVA and Tukey tests. Significant differences were observed in microhardness among the test groups, citric acid group being the least hard (p 0.05). Also, citric acid significantly increased surface roughness.

Comparison of different irrigation activation techniques on smear layer removal: an in vitro study.

The purpose of this study was to evaluate the efficiency of different irrigation activation techniques on smear layer removal. About 80 single-rooted human maxillary central teeth were decoronated to a standardized length.The samples were prepared by using ProTaper system to size F4 and divided into eight equal groups (n = 10) according to the final irrigation activation technique; distilled water was used as an irrigant in Group 1. The other groups were treated with 2.5% NaOCl and 17% EDTA, respectively. Conventional syringe irrigation (CSI) was used in Group 2. Irrigation solutions were activated using passive ultrasonic irrigation (PUI, Group 3), EndoVac apical negative pressure (ANP, Group 4), diode laser (Group 5), Nd:YAG laser (Group 6), Er:YAG laser (Group 7), and Er:YAG laser using with photon-induced photoacoustic streaming (PIPS™, Group 8). Teeth were split longitudinally and subjected to scanning electron microscope (SEM). PIPS showed the best removal of smear layer when compared with PUI, ANP, Nd:YAG, and Er:YAG, but the difference was not statistically significant (P > 0.05). Smear layer scores obtained with PIPS technique were statistically significant different from those of obtained with control, CSI and diode laser groups (P < 0.05). All experimental irrigation techniques except ANP and diode laser removed smear layer more effectively at the coronal and middle levels compared to the apical level (P < 0.05). Irrigation activated/delivered techniques except diode laser have a positive effect on removing of smear layer.

Evaluation of the effect of endodontic irrigation solutions on the microhardness and the roughness of root canal dentin.

The purpose of this study was to evaluate the effect of 0.2% chlorhexidine gluconate on the microhardness and roughness of root canal dentin compared with widely used irrigation solutions. Ninety, mandibular, anterior teeth extracted for periodontal reasons were used. The crowns of the teeth were removed at the CEJ. The roots were separated longitudinally into two segments, embedded in acrylic resin, and polished. A total of 180 specimens were divided into 6 groups of 30 teeth at random according to the irrigation solution used: group 1: 5.25% NaOCl for 15 min; group 2: 2.5% NaOCl for 15 min; group 3: 3% H2O2 for 15 min; group 4: 17% EDTA for 15 min; group 5: 0.2% chlorhexidine gluconate for 15 min; and group 6: distilled water (control). Each group was then divided into 2 subgroups of 15 specimens: groups 1a, 2a, 3a, 4a, 5a, and 6a were submitted to Vickers microhardness indentation tests; groups 1b, 2b, 3b, 4b, 5b, and 6b were used for determination of the roughness of root dentin. The data were recorded as Vickers numbers and Ra, microm for roughness test. The results were analyzed statistically by using one-way ANOVA and Tukey tests. The results indicated that all the irrigation solutions except chlorhexidine significantly decreased microhardness of root canal dentin (p < 0.05); 3% H2O2 and 0.2% chlorhexidine gluconate had no effect on roughness of the root canal dentin (p > 0.05). Although there are many other factors for irrigation solution preference, according to the results of this study, 0.2% chlorhexidine gluconate seems to be an appropriate endodontic irrigation solutions because of its harmless effect on the microhardness and roughness of root canal dentin.