The Efficacy of an Experimental Single Solution versus Alternate Use of Multiple Irrigants on Root Dentin Microhardness

Objectives: This study was carried-out to evaluate and compare the efficacy of various irrigants when used singly or in combination on the microhardness of root canal dentin. Study Design: A total of 50 root-halves were randomly divided into 5 groups immediately after the initial baseline microhardness measurements and treated with: Group-1; 7.5%Ethylenediaminetetraaceticacid (EDTA) + 2.5%sodium hypochlorite (NaOCl), Group-2; 7.5%ethyleneglycol-bis[b-aminoethylether]-N,N,N0,N0-tetraaceticacid (EGTA) + 2.5%NaOCl, Group-3; 7.5%trans1,2diaminocyclohexane NNN',N'tetraaceticacid (CDTA) + 2.5% NaOCl, Group-4; 7.5%EDTA + 2.5% Ethylenediamine (EDA), and Group-5; 1/1 (v/v) EDTA-EDA mixture + 1/1 (v/v) EDTA-EDA mixture. Fifty mL of each solution was used for 1 minute. The reference and post-treatment microhardness values were measured with a Vickers indenter under 80- gram load, 15-second dwell time. Data were analyzed by two-way ANOVA and Bonferroni tests (p=0.05). Results: All solutions decreased microhardness of dentin (p< 0.05). There was statistically significant difference between each group, except Group-1 and 4, after 1st solution application. While Group-2 resulted in a greater re - duction of dentin hardness, Group-5 caused the least change in microhardness values, after 1st solution application (p< 0.05). No statistical difference was observed between Groups 1-4, after 2nd solution application. However, Group-5 showed a significant difference compared with all other groups, after 2nd solution application (p< 0.05). Conclusions: Under the experimental conditions, all tested solutions reduced the microhardness of the root canal dentin. EGTA was the most efficient chelating agent. EDTA-EDA single mixture has led to least change on the microhardness of root denti

Effects of etching and adhesive applications on the bond strength between composite resin and glass-ionomer cements

WOS: 000313707300008PubMed ID: 23329245Objective: This study determined the effects of various surface treatment modalities on the bond strength of composite resins to glass-ionomer cements. Material and Methods: Conventional (Ketac (TM) Molar Quick Applicap (TM)) or resin-modified (Photac (TM) Fil Quick Aplicap (TM)) glass-ionomer cements were prepared. Two-step etch-rinse & bond adhesive (Adper (TM) Single Bond 2) or single-step self-etching adhesive (Adper (TM) Prompt (TM) L-Pop (TM)) was applied to the set cements. In the etch-rinse & bond group, the sample surfaces were pre-treated as follows: (1) no etching, (2) 15 s of etching with 35% phosphoric acid, (3) 30 s of etching, and (4) 60 s of etching. Following the placement of the composite resin (Filtek (TM) Z250), the bond strength was measured in a universal testing machine and the data obtained were analyzed with the two-way analysis of variance (ANOVA) followed by the Tukey's HSD post hoc analysis (p=0.05). Then, the fractured surfaces were examined by scanning electron microscopy. Results: The bond strength of the composite resin to the conventional glass-ionomer cement was significantly lower than that to the resin-modified glass-ionomer cement (p0.05). However, a greater bond strength was obtained with 30 s of phosphoric acid application. Conclusions: The resin-modified glass-ionomer cement improved the bond strength of the composite resin to the glass-ionomer cement. Both etch-rinse & bond and self-etching adhesives may be used effectively in the lamination of glass-ionomer cements. However, an etching time of at least 30 s appears to be optimal.Ege UniversityEge University [2005-Dis-09]This study was supported mainly by Ege University Research Funds (project number 2005-Dis-09). The content is solely the responsibility of the authors and does not necessarily represent the official views of Ege University

The effect of different concentrations of EDTA on instrumented root canal walls

WOS: 000270084800025PubMed ID: 19699113Objective. The purpose of this study was to investigate smear layer removal and erosive capacity of different concentrations of EDTA on instrumented root canal walls. Study design. Forty single-rooted teeth were instrumented using step-back technique and 2.5% NaOCl. The teeth were randomly divided into 4 groups, and final flushes were preformed with different concentrations of EDTA (15%, 10%, 5%, and 1%). All specimens were prepared for scanning electron microscope evaluation. Results. The results showed that there was no significant difference on the smear layer removal between different concentrations of EDTA (P = .1959). Only coronal versus apical thirds showed significant difference regarding presence of smear layer (P = .0176). Whereas 15%, 10%, and 5% EDTA solutions demonstrated similar erosion patterns on the root canal walls (P > .05), 1% EDTA caused restricted erosion (P < .0001). There was no significant difference among the regions in terms of erosion (P = .6399). Conclusion. Lower concentrations of EDTA can be recommended for clinical usage to avoid excessive erosion of root canal dentin. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 622-627

In vitro antimicrobial activity of calcium hydroxide mixed with different vehicles against Enterococcus faecalis and Candida albicans

WOS: 000268052600025PubMed ID: 19615665Objective. The purpose of this in vitro study was to investigate antimicrobial activity of calcium hydroxide (CH) in combination with glycerin, chlorhexidine gluconate (CHX), cetrimide, or distilled water against Enterococcus faecalis and Candida albicans. Study design. Standard holes in the cultivated agar plates were filled with one of the CH preparations and control agents. The zones of microbial inhibition were measured after incubation period. Results. The CH preparations with glycerin and CHX demonstrated more antifungal activity than CH preparations with cetrimide and distilled water. The CH-glycerin preparations had no effect against E. faecalis, and CH-CHX preparation was the most effective medication. Conclusion. Antimicrobial activity of CH may change with the type of the vehicle and against different microorganisms. Enterococcus faecalis was more resistant than C. albicans to CH preparations. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 297-301

Influence of Fiber-reinforced Composites on the Resistance to Fracture of Vertically Fractured and Reattached Fragments

WOS: 000289318600023PubMed ID: 21419307Introduction: The aim of this in vitro study was to evaluate the fracture type and test the effects of 2 different fibers on fracture strength of roots with reattached fragments. The null hypothesis was that adding suitable fibers to the content of dual-cure adhesive resin cement increases the fracture resistance of reattached fragments under vertical forces. Methods: Root canals of 45 teeth were prepared, and the teeth were intentionally fractured into 2 separate fragments. Control groups (n = 7 each) consisted of unfractured teeth with instrumented and obturated or only instrumented root canals. The fractured teeth were divided into 3 groups (n = 15 each), and separated fragments were reattached by using (1) dual-cured resin cement (Clearfil SA), (2) dual-cured resin cement + polyethylene fiber (Construct), or (3) dual-cured resin cement + glass fiber (Stick-Net). Force was applied at a constant speed of 0.5 mrn/min to the root until fracture. Mean load was recorded and analyzed statistically by using Kruskal-Wallis and Dunn tests (P = .05). Fracture types were analyzed by using chi(2) analysis with Yates correction. Results: Stick-Net demonstrated the lowest fracture resistance (P .05). The roots in the control group showed the highest fracture resistance. However, there was no statistically significant difference between the Construct, Clearfil SA, and control groups (P > .05). Conclusions: Separated fragments of vertically fractured teeth can be reattached by using a dual-cured resin or by adding polyethylene fiber (Construct). (J Endod 2011;37:549-553

Comparison of the Cyclic Fatigue Resistance of 5 Different Rotary Pathfinding Instruments Made of Conventional Nickel-Titanium Wire, M-wire, and Controlled Memory Wire

WOS: 000353076700019PubMed ID: 25510316Introduction: This study compared the cyclic fatigue resistance of current nickel-titanium rotary path-finding instruments. Methods: Five types of nickel-titanium rotary pathfinding instruments were used in steel canals with a 90 degrees curvature and a curvature radius of 3 mm (n = 10) and 5 mm (n = 10). The cyclic fatigue of the following instruments was tested at 4 mm from the tip: PathFile (#16 and a .02 taper; Dentsply Maillefer, Ballaigues, Switzerland), G-File (#12 and a .03 taper; Micro-Mega, Besancon Cedex, France), Scout Race (#15 and a .02 taper; FKG Dentaire, La Chaux-de-Fonds, Switzerland), HyFlex GPF (#15 and a .02 taper; Coltene-Whaledent, Allstetten, Switzerland), and ProGlider (#16 with a mean taper of .04125 and a .02 at the first 4 mm from the tip, Dentsply Maillefer). The length of the fractured parts was measured, and the number of cycles to fracture (NCF) was calculated. The data were statistically analyzed using Kruskal-Wallis and MannWhitney tests (alpha =.05). After Bonferroni correction, the new P value was set as .005. Results: The difference in the cyclic fatigue of all the files at both curvatures was statistically significant (P values from .0035 to less than .0001). The ranking of the instruments from the highest to the lowest NCF was as follows: HyFlex GPF, G files, ProGlider, PathFile, and Scout Race. The length of the fractured part of the instruments was similar in all the groups > .05). All the tested instruments had a lower NCF at a curvature radius of 3 mm when compared with a curvature radius of 5 mm (P < .0001). Conclusions: Within the limitations of this study, the cyclic fatigue resistance of the HyFlex GPF instrument was the highest, and the curvature radius had a significant effect on the fatigue resistance

Ultrastructural stages of biofilm development of Escherichia coli on urethral catheters and effects of antibiotics on biofilm formation

WOS: 000242592500005PubMed ID: 17113884Objectives. Biofilm formation on biomaterials by various kinds of bacteria renders the infection chronic, and the bacteria can become resistant to the immune system and antibiotics. Developmental biofilm stages of Escherichia coli on urethral catheters have not yet been thoroughly demonstrated. We aimed to show biofilm formation of E. coli on urethral catheters, and the effects of various antibacterial agents on this formation using scanning electron microscopy. Methods. Using urine infected with uropathogenic E. coli type 04 (105 to 106 colony forming units/mL), biofilm was formed on latex/silicone balloon catheters in a modified Robbin's device. The study included an infected-only group and four antibiotic study groups (ciprofloxacin, cefuroxime, gentamicin, and trimethoprim). The catheters were infused with the antibiotic solutions once before placement in the modified Robbin's devices. Ten 5-mm catheter samples were taken for all groups on the first, fourth, and seventh days. The 4 and 12-hour and 2-day samplings were also taken from the infected-only group. The catheter samples were evaluated by scanning electron microscopy and given scores according to the level of formation. Results. The biofilm layers emerged between 4 and 12 hours after infection in the infected-only group and had developed completely between 12 and 24 hours. The antibiotics, especially cefuroxime, significantly delayed this process for up to 4 days. However, the biofilm had developed completely in almost all catheter samples after 4 to 7 days. Conclusions. Biofilm of E. coli on urethral catheters had completed their maturation at 12 to 24 hours. For short-term urethral catheterization, a single dose of antibiotic can delay the development of biofilm for up to 4 days but eventually cannot prevent it