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Aim Methodology Results Conclusions All commercial chelating gels contain EDTA which reacts chemically with sodium hypochlorite (NaOCl). This research aimed to develop a non‐EDTA clodronate gel and to measure physicochemical and functional gel properties of the novel and commercial gels.A 1.37 M clodronate gel was made by combining polyethylene glycol (PEG) 400 and tetrasodium clodronate. File‐Eze™, Glyde™, Odontoprep®, RC‐Prep®, SlickGel™ ES and the clodronate gel were tested in pH, density and viscosity experiments. pH: A pH meter was used at 23°C. Viscosity: A rheometer recorded viscosity at a shear rate of 10/s at 35°C. Free available chlorine (FAC): NaOCl reactivity with the clodronate gel was compared to a 4% NaOCl control by measuring FAC with iodometric titration. Tissue Dissolution: File‐Eze, Glyde, RC‐Prep and clodronate gel mixtures with 4% NaOCl, PBS (phosphate buffered saline) (negative control) and 4% NaOCl (positive control) were tested. Percentage weight losses of porcine palatal mucosa were recorded over 5 min at 35°C. Smear Layer Removal (SLR): Scanning electron micrography and ImageJ software assessed the SLR ability of File‐Eze, Glyde, RC‐Prep, clodronate gel, PBS (negative control) and 15% EDTA (positive control) by calculating the area fraction percentage of the image occupied by open dentinal tubules (AF%).pH: Values ranged from 5.78 ± 0.09 (RC‐Prep) to 11.34 ± 0.05 (clodronate gel). Viscosity: Ranges were 6390 ± 290 (File‐Eze) to 714 ± 50 mPa.s (Odontoprep). FAC: The clodronate gel differed significantly from 4% NaOCl (p < 0.0001, two‐way anova, Šídák's tests), albeit with small absolute differences. Tissue Dissolution: All gel–NaOCl mixtures, except for clodronate gel‐NaOCl, differed significantly to 4% NaOCl (p < 0.0001, one‐way AVOVA, Tukey's multiple comparisons test). Weight losses were: 4% NaOCl, 30.0 ± 3.7%; clodronate gel‐4% NaOCl, 29.2 ± 3.5%; whilst other gel–4% NaOCl mixtures ranged from 2.8 ± 2.0% to −0.6 ± 4.5% and PBS was −0.13 ± 3.3%. SLR Ability: Median AF%s were: 15% EDTA‐9.7%; File‐Eze‐8.7%; clodronate gel‐5.8%; Glyde‐2.5%; RC‐Prep‐2.2%; PBS‐0.22%. All gels differed to 15% EDTA (p < 0.0001, Kruskal–Wallis, Dunn's tests) except File‐Eze.The gels varied in physical properties, but none of them both dissolved organic tissue in NaOCl mixtures and removed smear layer well. Thus, none of the gels tested possessed all functional properties required of a chelating gel for glide path creation. [ABSTRACT FROM AUTHOR]

Abstract: The purpose of this study was to compare the efficacy of different chelating solutions (17% EDTA and 10% citric acid) on the smear layer removal, and their effect on tubular dentin sealer penetration. Sixty root canals were prepared and distributed into four groups (n = 15) according to the final irrigation protocol: G1, final irrigation with 2.5 mL of distilled water; G2, final irrigation with 2.5 mL of 2.5% sodium hypochlorite solution; G3, final irrigation with 2.5 mL of 17% EDTA; and G4, final irrigation with 2.5 mL of 10% citric acid. Five specimens from each group were not filled to assess smear layer removal by scanning electron microscopy. Ten specimens from each group were filled for analysis of sealer penetration into dentinal tubules by confocal laser scanning microscopy. Smear layer removal (Kruskal–Wallis and Dunn's tests) and sealer penetration (F and Tukey's tests) were statistically analyzed with 95% of significance level. G3 and G4 had greater smear layer removal rates in the cervical and middle thirds, in comparison with G1 and G2 (p < .05). G3 and G4 had the highest percentages of sealer penetration in all thirds, in comparison with G1 and G2 (p < .05). Smear layer removal was effective only at the cervical and middle thirds when the chelating solutions were used. Sealer penetration into the dentinal tubules significantly increased in all root thirds when the specimens were treated with both chelating solutions. [ABSTRACT FROM AUTHOR]

The aim of this study was to verify the efficacy of doxycycline used alone or in association with sodium hypochlorite on smear layer removal. The canals of extracted human teeth were instrumented using a stepback technique. At the end of preparation, they were irrigated with doxycycline (Group 1), ethylenediaminetetraacetic acid + sodium hypochlorite (Group 2), doxycycline + sodium hypochlorite (Group 3) and water (Group 4). The dentinal wall of the cervical, middle and apical thirds was graded according to the amount of remaining debris and smear layer. The results were analysed using the Kruskal–Wallis test ( P < 0.05). In Groups 2 and 4, the dentine was completely free and covered with smear layer, respectively. The results from the cervical and middle thirds of Group 3 were worse than those in Groups 1 and 2 ( P < 0.05). In relation to apical third, there were differences ( P < 0.05) between all groups with best results for Group 2. Doxycycline was effective in removing smear layer from cervical and middle thirds. The use of doxycycline + sodium hypochlorite was partially effective in the cervical and middle thirds, but ineffective in the apical third. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the effectiveness of MTAD as the final irrigant to remove the smear layer, compared with that of 17% EDTA, both following root canal irrigation with 5.25% sodium hypochlorite (NaOCl). Fifty-five extracted maxillary and mandibular single-rooted human teeth were prepared by a crown-down technique using rotary 0.04 and 0.06 taper nickel-titanium files. 5.25% sodium hypochlorite was used as the intracanal irrigant. The canals were then treated with 5 mL of one of the following solutions as final rinse: 5.25% sodium hypochlorite, 17% EDTA or MTAD. The presence or absence of smear layer in the coronal, middle and apical portion of each canal was examined with a scanning electron microscope. The results showed that MTAD is an effective final rinse solution for removing the smear layer in canals irrigated with sodium hypochlorite. When 17% EDTA was used as a final rinse, the smear layer was removed from the middle and coronal thirds of canal preparations, but it was less effective in the apical third of the canals. [ABSTRACT FROM AUTHOR]

AbstractAim The purpose of this study was to evaluate the effects of smear layer and canal instrumentation on leakage in root-filled teeth. Methodology Six groups (n = 12) of freshly extracted human canines and premolars with closed apices and single roots were used. Groups A, B, C, and D were instrumented with engine-driven rotary nickel-titanium MCXIM files and Groups E and F were instrumented with conventional stainless steel hand files. Groups A, C, and E were flushed with 3.0 mL of 17.0% REDTA to remove the smear layer prior to obturation. All teeth were flushed with 5.25% NaOCl, then obturated with AH-26 sealer and either the lateral condensation (Groups C–E) or thermomechanical compaction technique (Groups A and B). Copper wire was placed coronally in contact with the gutta-percha in each tooth and, after immersion in 0.9% NaCl solution, a 10 volt dc voltage was connected between each tooth and a stainless steel electrode. The current flow in the circuit was observed for 45 days. One way ANOVA and Duncan’s Multiple Range Test were used to compare Groups A–F at time intervals of 10, 20, 30 and 45 days and identify statistically significant differences. Results Significantly less microleakage occurred when the smear layer was removed and when the canals were obturated with thermoplasticized gutta-percha. Canals instrumented with engine-driven NiTi files exhibited less leakage than hand-instrumented canals irrespective of obturation method. Conclusions Smear layer removal is beneficial to root canal sealing. Obturation with thermoplasticized gutta-percha provides a superior seal whilst canal instrumentation with engine-driven NiTi files reduces the extent of microleakage in root canals. [ABSTRACT FROM AUTHOR]