Bilge Hakan Şen - Academia.edu (original) (raw)

Papers by Bilge Hakan Şen

Turkiye Klinikleri Journal of Dental Sciences Special Topics, 2010

Amaç: Son irigasyonda EGTA, EDTA, CDTA ile NaOCl ya da EDA uygulamasının debris ve smear tabakası... more Amaç: Son irigasyonda EGTA, EDTA, CDTA ile NaOCl ya da EDA uygulamasının debris ve smear tabakasını uzaklaştırma kapasiteleri ile neden oldukları erozyon miktarı araştırıldı.

Objective: We aimed to differentiate dental pulp stem cells (DPSC) to odontoblast-like cells (ODP... more Objective: We aimed to differentiate dental pulp stem cells (DPSC) to odontoblast-like cells (ODPSC) and to investigate their attachment and growth on dentin in the presence of extra calcium by colorimetric assay and scanning electron microscopy (SEM). Methods: After isolation of DPSC, they were differentiated to ODPSC. Standard dentin discs from human molar teeth were prepared. While the dentin discs in Group 1 did not receive any extra treatment, the discs in Group 2 were treated with acidic calcium phosphate precipitation (CPP) solution. In Group 3, the discs were suspended in phosphate buffered saline containing calcium. DPSC or ODPSC (3 Â 10 4 cells/mL) were seeded on all discs and incubated for 7, 14 or 21 days. Attachment and growth of 7-day cell cultures on extra dentin samples were examined by SEM. MTT assay showed that number of cells on dentin surfaces was increased by time periods regardless of type of treatment and cells (p < 0.05). Results: While DPSC and ODPSC showed similar proliferation rates at 7 and 14 days (p > 0.05), the number of ODPSC was higher than DPSC in 21-day samples (p = 0.039). MTT assay showed that number of cells on dentin surfaces was increased by time periods regardless of type of treatment and cells (p < 0.05). Calcium-treated dentin surfaces always had lower number of cells; being significant for only CPP-treated surfaces (p < 0.01). Both types of cells demonstrated good attachment and proliferation on dentin surfaces regardless of type of dentin treatment. Conclusions: Because the nature of dentin surface itself showed good adhesive characteristics with ODPSC and DPSC, additional calcium treatment of dentin surfaces may not be necessary.

Caries Research, 1995

When the root canals are instrumented during endodontic therapy, a layer of material composed of ... more When the root canals are instrumented during endodontic therapy, a layer of material composed of dentine, remnants of pulp tissue and odontoblastic processes, and sometimes bacteria, is always formed on the canal walls. This layer has been called the smear layer. It has an amorphous, irregular and granular appearance under the scanning electron microscope. The advantages and disadvantages of the prescence of smear layer, and whether it should be removed or not from the instrumented root canals, are still controversial. It has been shown that this layer is not a complete barrier to bacteria and if delays but does not abolish the action of endodontic disinfectants. Endodontic smear layer also acts as a physical barrier interfering with adhesion and penetration of sealers into dentinal tubules. In turn, it may affect the sealing efficiency of root canal obturation. When it is not removed, the durability of the apical and coronal seal should be evaluated over a long period. If smear layer is to be removed, EDTA and NaOCI solutions have been shown to be effective, among various irrigation solutions and techniques, including ultrasonics, that have been tested. Once this layer is removed, it should be borne in mind that there is a risk of reinfecting dentinal tubules if the seal fails. Further studies are needed to establish the clinical importance of the absence or presence of smear layer.

Journal of Endodontics, 2012

Introduction: The aim of this study was to investigate the effect of different concentrations of ... more Introduction: The aim of this study was to investigate the effect of different concentrations of cetrimide with or without 5% EDTA solution on the microhardness of human root dentin in vitro. Methods: Twenty-five recently extracted single-rooted human teeth were selected. The roots were split longitudinally into 2 parts. The specimens were randomly divided into the following 5 groups and were treated with 5% EDTA, 5% EDTA + 0.25% cetrimide, 5% EDTA + 0.50% cetrimide, 0.25% cetrimide, and 0.50% cetrimide immediately after the initial baseline microhardness measurements. A standardized volume of 50 mL of each solution was used for 1 minute. The reference microhardness values of untreated specimens were initially measured with a Vickers indenter under a 50-g load and a 10-second dwell time at the midroot level of the root dentin. Posttreatment microhardness values were obtained in the same manner as the initial ones. The decrease in microhardness was calculated as a percentage. Data were analyzed statistically by 1-way analysis of variance (P = .05) and the post hoc Tukey test for multiple comparisons at the same level of significance. Results: All solutions significantly decreased the microhardness of root dentin (P < .05). Although there was no significant difference among the solutions (P > .05), the specimens in the EDTA + 0.50% cetrimide solution group showed the highest change in microhardness. The plain EDTA and plain 0.50% cetrimide groups had similar values. Conclusions: The use of surfactants higher than 0.25% in concentration is questionable for clinical conditions. (J Endod 2012;38:704-707)

Journal of Ege University School of Dentistry, 2011

Journal of Endodontics, 1998

The aim of the present study was to evaluate the effect of 4% titanium tetrafluoride (TiF4) solut... more The aim of the present study was to evaluate the effect of 4% titanium tetrafluoride (TiF4) solution on root canal walls by scanning electron microscopy. Twenty four root canals with or without a smear layer were treated with 4% TiF4 solution. Scanning electron microscopic observation of the smeared canal walls showed that TiF4 solution modified the smear layer and produced a massive structure. In smear-free group, a granular coating was formed on intertubular and intratubular dentin. The stability of this layer was tested further with EDTA and/or NaOCl irrigations on 20 additional specimens. It was observed that none of the solutions was able to remove this modified smear layer. These results may indicate that this extremely stable structure may be advantageous in endodontics, because it can prevent further infection of root canal dentin by sealing off the tubules permanently, and can reduce microleakage by preventing further dissolution and disintegration of the smear layer.

Journal of Clinical and Experimental Dentistry, 2013

Objectives: This study was carried-out to evaluate and compare the efficacy of various irrigants ... more 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 80gram 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 reduction 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).

Turkish Journal of Orthodontics, 1998

Journal of Endodontics, 1999

The purpose of this study was to evaluate the antifungal properties of 0.12% chlorhexidine, 1% Na... more The purpose of this study was to evaluate the antifungal properties of 0.12% chlorhexidine, 1% NaOCI, and 5% NaOCI. Root sections were enlarged and the smear layer was removed in half of the specimens. The specimens were fixed in the wells of tissue culture plates. Each root canal was dispensed with an inoculum of Candida albicans. After 10 days, the root sections were treated with 3 ml of either disinfectant solution for I rain, 5 min, 30 min, and 1 h. Then, root sections were incubated in test tubes having Sabouraud's Dextrose Broth at 37°C for 24 h. In the presence of the smear layer, antifungal activity was observed only in 1-h treatment groups for all solutions. However, in the absence of the smear layer, 5% NaOCI alone started to show antifungal activity after 30 min. The antimicrobial effectiveness of irrigating solutions should be re-evaluated, particularly in patients predisposed to oral candidiasis.

Journal of Ege University School of Dentistry, 2010

To assess the antimicrobial efficacy of super oxidized water (SOW), NaOCl, chlorhexidine, and EDT... more To assess the antimicrobial efficacy of super oxidized water (SOW), NaOCl, chlorhexidine, and EDTA against E. faecalis and C. albicans using disc diffusion (DDT) and direct contact (DCT) tests. In DDT, 20 µl of each solution was impregnated to paper discs and the discs were placed on agar plates containing either microorganism. The inhibition zones were measured after 24 h. In DCT, each solution was placed on the surface of agar plates that had been inoculated with each microorganism. After predetermined periods, transfers were made from the contact area between the test specimen and the cultured agar and from the area that had not been in contact with the test specimens. The results were read as presence/absence of microbial growth and statistical analysis was performed using Kruskal-Wallis and Mann-Whitney U-test test. In the DDT, all solutions exhibited inhibition zones in varying degrees. CHX and EDTA showed significant antimicrobial properties against E. faecalis and C. albicans (p<0.05).

Journal of Endodontics, 2014

This study compared the cyclic fatigue resistance of current nickel-titanium rotary path-finding ... more This study compared the cyclic fatigue resistance of current nickel-titanium rotary path-finding instruments. Five types of nickel-titanium rotary pathfinding instruments were used in steel canals with a 90° 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, Besançon 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 Mann-Whitney tests (α = .05). After Bonferroni correction, the new P value was set as .005. 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 (P &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;gt; .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 &amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;amp;lt; .0001). 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.

Journal of Endodontics, 2006

The bacterial microleakage of four current restorative materials (glass ionomer cement, polycarbo... more The bacterial microleakage of four current restorative materials (glass ionomer cement, polycarboxylate cement, resin modified glass ionomer cement, and flowable composite resin) used as a base over obturated root canals were evaluated during a 5-month period. Sixty single-rooted mandibular premolars were obturated with cold lateral compaction of gutta-percha. The teeth were randomly divided into five groups of 10 teeth each and positive and negative control groups of five. The access openings were filled with one of the tested barrier materials in four groups. In group 5, no barrier material was placed. Samples were incorporated in a model system using Staphylococcus epidermidis as a microbial marker. Results were analyzed with Kaplan-Meier survival analysis (p ϭ 0.05). The sealing ability of all tested materials was better when compared with group 5 (no barrier material) (p Ͻ 0.05). Within the limitations of this study, the glass ionomer cement leaked significantly less when compared with the flowable composite resin (p Ͻ 0.05). (J Endod 2006;32: 1074 -1076

Journal of Endodontics, 2011

Introduction: The aim of this in vitro study was to evaluate the fracture type and test the effec... more Introduction: 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 mm/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 c 2 analysis with Yates correction.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2005

Objective. The aim of this study was to evaluate antifungal effects of calcium-chelating or -bind... more Objective. The aim of this study was to evaluate antifungal effects of calcium-chelating or -binding agents on Candida albicans comparing with conventional antifungal agents.

Journal of Endodontics, 2008

The aims of this study were to compare film and digital radiography in assessing the radiopacitie... more The aims of this study were to compare film and digital radiography in assessing the radiopacities of root canal sealers and to establish the relation in aluminum equivalent values of different methods. Standard disks of 5 different sealers were exposed together with an aluminum step wedge by using occlusal films and storage phosphor plates. Optical density of the sealers was evaluated by transmission densitometry, and mean gray values were determined by digital analysis. The data were analyzed by using two-way analysis of variance (P ϭ .05). Pairwise comparisons were made by using Tukey post hoc and paired t tests (P ϭ .05). The order from the most radiopaque to the most radiolucent sealer was the same for both methods; however, aluminum equivalent values determined by transmission densitometry were significantly higher (P Ͻ .01). Aluminum equivalent values of the 2 radiographic methods were 7%-20% different. The International Standards Organization standard for the radiopacity of dental root canal sealing materials needs modifications for digital systems. (J Endod 2008;34:1101-1104

Urology, 2006

Objectives. Biofilm formation on biomaterials by various kinds of bacteria renders the infection ... more Objectives. 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 O4 (10 5 to 10 6 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. UROLOGY 68: 942-946, 2006.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2000

Objectives. The aim of this study was to evaluate the antifungal effect of ethylenediamine-tetraa... more Objectives. The aim of this study was to evaluate the antifungal effect of ethylenediamine-tetraacetic acid (EDTA) on Candida albicans, comparing it with that of various disinfectants and common antifungal agents. Study design. Two clinical oral isolates and 1 standard strain of C albicans were included in this study. Main contents of the test solutions were sodium hypochlorite, EDTA, chlorhexidine, hexetidine, benzalkonium chloride, povidone-iodine, nystatin, and ketoconazole. The agar diffusion method was used to determine the antifungal effects of the solutions. Zones of inhibition were recorded and the results were analyzed statistically by using a 2-way analysis of variance.

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2001

Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology, 2004