Influence of sodium hypochlorite/etidronic acid combination and SmearOFF on push-out bond strength of fiber posts to root dentin.

The aim was to evaluate the effects of different irrigation protocols on the bonding ability of fiber posts on root canal dentin through push-out test and the dentin tubule penetration of luting cement by confocal laser scanning microscope (CLSM). Forty-eight single-rooted premolars were divided into six groups (n=8) based on post space irrigation protocols: Saline 0.85%; Etidronate 18% (HEBP); EDTA 17%; NaOCl 5.25%+EDTA 17%; NaOCl 2.5%/HEBP 9% combination; SmearOFF. Two specimens per group were assessed with CLSM. The push-out test and the failure analysis were performed. Whilst EDTA had the highest bond strength at the coronal and middle thirds, it was not statistically significant compared to saline, HEBP, and NaOCl/HEBP at the middle third (p>0.05). Cement/dentin adhesive failures were predominant (41.9%) and the intratubular fluorescence intensity was significant among the groups (p<0.05). EDTA resulted in highest bond strength values and dentinal penetration.

Experimental study of influence of composition on radiopacity of fiber post materials.

This experimental study aims to evaluate the radiopacity of various fiber post materials and to determine the effects of material composition as analyzed by energy-dispersive X-ray spectrophotometry (EDS; EDAX Team Software; EDAX, Inc., Mahwah, NJ) on radiopacity. Five specimens of seven fiber post materials with 2-mm thickness were prepared and digital radiographs were taken with an aluminum stepwedge (SW) and 2-mm-thick tooth slice. The mean gray values (MGVs) of specimens were measured using the histogram function of a computer graphics program (Adobe Photoshop CS6; Adobe System, Inc., San Jose, CA). The MGVs of fiber post materials were compared with an aluminum SW and dentin of equal thickness. The fiber post specimens were examined by scanning electron microscopy and EDS analysis performed for the elementary analysis of material composition. The MGVs of fiber posts ranged between 83.67 ± 3.64 and 57.80 ± 7.08 pixels. Materials were sorted in descending order of MGV as follows: Reforpost, Carbopost, D.T. Light-Post, Easypost, Glassix Radiopaque, Dentolic Glass Fiber Post, and RelyX Fiber Post. All fiber posts demonstrated significantly higher radiopacity values than 2-mm-thick aluminum (p < .05). EDS analysis results indicated that the evaluated fiber posts included various elements for radiopacity in different ratios. All tested fiber post materials showed radiopacity values above the minimum recommendations of the International Organization for Standardization. EDS analysis results indicated that each manufacturer used different compositions of elements like zirconium, barium, titanium, and iron for achieving radiopacity in materials.

Atomic force microscopy and energy dispersive X-ray spectrophotometry analysis of reciprocating and continuous rotary nickel-titanium instruments following root canal retreatment.

The aim was to examine the effect of retreatment process on the surface roughness and nickel titanium (NiTi) composition of ProTaper Universal Retreatment (PTUR; consists of 3 files; D1, D2, D3) and WaveOne Gold (WOG) (primary) instruments. Twenty extracted mandibular molar teeth with severe curved (30-40°) mesial roots were selected and divided into two groups (n = 10) based on the instrument used for the removal of the root canal filling. Before and after using the instruments in two canals, they were subjected to atomic force microscopy (AFM) and energy dispersive X-ray spectrophotometry (EDX) analysis. The EDX analysis data and roughness average (Ra) and root mean square (RMS) values were analyzed statistically using a one-way analysis of variance and post hoc Tukey's test at the 5% significant level. There was no significant difference between the new and used D1 and D2 PTUR and WOG instruments in terms of the Ni composition (p > .05). The Ti contents of the used D2 and D3 PTUR instruments were lower those of the new instruments (p < .05). In both new and used instruments, PTUR and WOG have no difference in terms of Ra and RMS values. (p > .05). The Ra and RMS values of the PTUR and WOG systems significantly increased after removal of the root canal filling (p < .05). The use of PTUR and WOG instruments for removal of root canal filling in severely curved root canals affected the surface topography of the files. The NiTi composition of the WOG instruments was unaffected by the retreatment process.

Effects of etidronate, NaOCl, EDTA irrigation solutions and their combinations on cyclic fatigue resistance of nickel-titanium single-file rotary and reciprocating instruments at body temperature.

The aim of the present study was to compare the effect of etidronic acid (HEBP), NaOCl, and EDTA solutions and their combinations on cyclic fatigue resistance of NiTi RPC Blue (RPC Blue), HyFlex EDM (HEDM), and WaveOne Gold (WOG) instruments having different metallurgic characteristics at the body temperature (37 °C). 100 WOG, 100 RPC Blue, and 100 HEDM NiTi files were randomly divided into 5 groups and immersed in the following solutions: group 1, distilled water; group 2, 6% NaOCl; group 3, 17% EDTA; group 4, 18% HEBP; group 5, 6% NaOCl and 18% HEBP. Then the instruments were rotated in an artificial canal until fracture occurred and the number of cycles to fracture was calculated. A univariate analysis of variance and post hoc Tukey tests were then performed for comparisons using SPSS 21.0 software with the significance level set at P < .05. In all the conditions, there was no difference between the cyclic fatigue resistance of WOG and RPC Blue files (P > .05). In the intragroup comparison, WOG, RPC Blue, and HEDM files showed significantly low cyclic fatigue resistance in group 5 compared to other groups (P < .05). Among the groups, there was no statistically significant difference in the fracture lengths (P > .05). EDTA, NaOCl and HEBP solutions did not affect the cyclic fatigue resistance of the tested files when used without combination. However, the combination of NaOCl and HEBP solutions significantly reduced the cyclic fatigue resistance of the tested files.

Correction: Enhancing antibacterial effect of sodium hypochlorite by low electric current-assisted sonic agitation.

[This corrects the article DOI: 10.1371/journal.pone.0183895.].

Enhancing antibacterial effect of sodium hypochlorite by low electric current-assisted sonic agitation.

BACKGROUND: This research focused on the effects of low electric current (µE)-assisted sonic agitation of sodium hypochlorite on Enterococcus faecalis infected human root dentin. METHODS: Extracted human canine roots were instrumented, sterilized, and experimentally contaminated with E. faecalis. After incubation for 21 days, the presence of the biofilm was confirmed by scanning electron microscopy (n = 3). Roots were randomly divided into seven groups according to decontamination procedures: G1: no treatment; G2: sterile saline; G3: 5.25% sodium hypochlorite; G4: passive ultrasonic irrigation; G5: EndoActivator (Dentsply Tulsa Dental Specialties, Tulsa, OK) agitation (EA); G6: µE agitation; and G7: µE-assisted sonic agitation. Fixed µE amperage and intensities were applied in G6 and G7. Following microbial sampling, bacterial colonies were counted using the direct plating method. RESULTS: Biofilm was not eradicated in any sample. The µE-assisted sonic agitation of sodium hypochlorite revealed the lowest cfu values (p<0.05), whereas there were no significant differences among the passive ultrasonic irrigation, EndoActivator and µE agitation alone (p>0.05). CONCLUSIONS: Based on available evidence, the following conclusions were drawn: The µE-assisted sonic agitation increased the antibiofilm efficiency of sodium hypochlorite than passive ultrasonic irrigation and EndoActivator. The µE-assisted sonic agitation on 5.25% sodium hypochlorite is not capable to eradicate biofilms at 10mA energy level in 60s.