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Now showing 1 - 10 of 12
  • PublicationOpen Access
    Effect of polymerization time and home bleaching agent on the microhardness and surface roughness of bulk-fill composites: A scanning electron microscopy study
    Objective: The aim of this study is to evaluate the microhardness and surface roughness of two different bulk-fill composites polymerized with light-curing unit (LCU) with different polymerization times before and after the application of a home bleaching agent. Materials-methods: For both microhardness and surface roughness tests, 6 groups were prepared with bulk-fill materials (SonicFill, Filtek Bulk Fill) according to different polymerization times (10, 20, and 30 s). 102 specimens were prepared using Teflon molds (4 mm depth and 5 mm diameter) and polymerized with LCU. 30 specimens (n = 5) were assessed for microhardness. Before home bleaching agent application, the bottom/top (B/T) microhardness ratio was evaluated. After bleaching agent application, the microhardness measurements were performed on top surfaces. Roughness measurements were performed in 72 specimens (n = 12) before and after bleaching application. Additionally, for SEM analyses, two specimens from all tested groups were prepared before and after bleaching agent application. The data B/T microhardness ratio before bleaching was analyzed by two-way ANOVA and Tukey's HSD test. The data from the top surface of specimens' microhardness before and after bleaching were analyzed using Wilcoxon signed-rank test, Kruskal-Wallis, Mann-Whitney U tests. The data from surface roughness tests were statistically analyzed by multivariate analysis of variance and Bonferroni test (p < 0.05). Results: The B/T microhardness ratio results revealed no significant differences between groups (p > 0.05). Comparing the microhardness values of the composites' top surfaces before and after bleaching, a significant decrease was observed exclusively in FB30s (p < 0.05). No significant differences in surface roughness values were observed when the groups were compared based on bulk-fill materials (p > 0.05) while the polymerization time affected the surface roughness of the SF20s and SF30s groups (p < 0.05). After bleaching, surface roughness values were significantly increased in the SF20s and SF30s groups (p < 0.05). Conclusion: The clinicians should adhere to the polymerization time recommended by the manufacturer to ensure the durability of the composite material in the oral environment.
  • PublicationOpen Access
    Reactions of Subcutaneous Connective Tissue to Mineral Trioxide Aggregate, Biodentine (R), and a Newly Developed BioACTIVE Base/Liner
    (2020-05-01T00:00:00Z) Karabulut, Baris; DÖNMEZ, NAZMİYE; Goret, Ceren Canbey; Atas, Cafer; Kuzu, Ozlem; DÖNMEZ, NAZMİYE
    Aim. There is an increasing interest in the application of BioACTIVE materials to achieve hard tissue formation and maintain pulp vitality. Mineral trioxide aggregate (MTA) and Biodentine (R) are BioACTIVE materials used for pulp capping. Recently, dental researchers have produced BioACTIVE glass-incorporated light-curable pulp capping material. The study is aimed at evaluating the subcutaneous connective tissue reactions to MTA, Biodentine (R), ACTIVA BioACTIVE Base/Liner. These materials were placed in polyethylene tubes and implanted into the dorsal connective tissue of Sprague Dawley rats. The presence of inflammation, predominant cell type, calcification, and thickness of fibrous connective tissue was recorded by histological examination 7, 30, and 60 days after the implantation procedure. Scores were defined as follows: 0 = none or few inflammatory cells, no reaction; 1 = = 125 cells, severe reaction. Fibrous capsule thickness, necrosis, and formation of calcification were recorded. ANOVA and post hoc Dunnett-s tests were used for statistically analyses (p<0.05). Results. In terms of oedema, inflammation, fibrous capsule, and necrosis, no significant differences were found in any time period for any material. MTA and Biodentine (R) showed higher calcification than in the ACTIVA BioACTIVE on day 30, and the difference was statistically significant (p<0.05). After 60 days, while calcification was not seen in the control group, it was observed in the test groups. There was a statistically significant difference between the control and the others. Conclusion. All materials were well tolerated by the tissues in the 60-day evaluation period. One notable finding is the presence of dystrophic calcification in the connective tissue adjacent to the newly developed BioACTIVE Base/Liner material. Therefore, this new BioACTIVE Base/Liner material may be safely recommended to clinicians as a pulp capping material.
  • PublicationOpen Access
    Characterisationand microleakage of a new hydrophilic fissure sealent-Ultraseal XT®hydro™.
    sealant, UltraSeal XT® hydro™ (Ultradent Products, USA), and to investigate its in vitro resistance to microleakage after placement on conventionally acid etched and sequentially lased and acid etched molars. Material and Methods: The sealant was characterised by Fourier transform infra-red spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and Vickers indentation test. Occlusal surfaces of extracted human molars were either conventionally acid etched (n=10), or sequentially acid etched and laser irradiated (n=10). UltraSeal XT® hydro™ was applied to both groups of teeth which were then subjected to 2,500 thermocycles between 5 and 55°C prior to microleakage assessment by fuchsin dye penetration. Results: UltraSeal XT® hydro™ is an acrylate-based sealant that achieved a degree of conversion of 50.6±2.2% and a Vickers microhardness of 24.2±1.5 under standard light curing (1,000 mWcm-2 for 20 s). Fluoride ion release is negligible within a 14-day period. SEM and EDX analyses indicated that the sealant comprises irregular submicron and nano-sized silicon-, barium-, and aluminium-bearing reduce microleakage (Mann-Whitney U test, p<0.001). The lased teeth presented enhanced
  • PublicationOpen Access
    Knowledge, stress levels, and clinical practice modifications of Turkish dentists due to COVID-19: a survey study
    (2021-03-01T00:00:00Z) Sarıalioğlu Güngör, Ayça; Dönmez, Nazmiye; Uslu, Yeşim Şeşen; SARIALİOĞLU GÜNGÖR, AYÇA; DÖNMEZ, NAZMİYE
    Dentists are exposed to the highest risk of occupational respiratory and droplet infections by working face-to-face with patients. The aim of this study was to investigate the knowledge of symptoms and modes of transmission of COVID-19, stress levels and clinical practice modifications of Turkish dentists during the COVID-19 pandemic. An online survey (15 questions) was sent to Turkish dentists from May 5 to 12 May, 2020. The survey comprised questions about dentists’ demographic characteristics, their knowledge about COVID-19, stress levels and the measures taken in dental clinics against COVID-19. This study included a total of 1,095 Turkish dentists. The data were expressed as frequency with percentage values for overall variables. Dentists were most familiar with high fever among the symptoms of COVID-19 (99.4%) and 99.2% of them reported that COVID-19 was transmitted with eye, mouth and nasal mucosa contact on surfaces contaminated with the droplets of infected persons. While the stress levels of females were higher than males, the stress levels of dentists with more than 20 years of professional experience were found to be lower. Regarding the precautions to be taken as a preventive measure when working again, 86.6% of the dentists took precautions by increasing daily patient care intervals and only 38.4% of the dentists wore an N95 mask. During this pandemic, knowing the conditions about when the treatments can be applied and the precautions to be taken will shed light on dentistry staff. Current recommendations of national authorities about the coronavirus should be followed.
  • PublicationOpen Access
    Comparison of the micro-tensile bond strengths of four different universal adhesives to caries-affected dentin after ER:YAG laser irradiation
    (2019-04-01) Donmez, NAZMİYE; Gungor, Ayca Sarialioglu; Karabulut, Baris; Siso, Seyda Herguner; DÖNMEZ, NAZMİYE; SARIALİOĞLU GÜNGÖR, AYÇA
    The micro-tensile bond strengths (micro-TBSs) of four universal adhesive systems, applied in two different bonding techniques, to carries-affected dentin after Er:YAG laser irradiation were investigated. Twenty-four extracted human molars were divided into four groups, according to the adhesive systems used. Each group was subdivided into two subgroups, depending on the bonding method used: the etch-and-rinse procedure or self-etch procedure. The carious lesions were irradiated using an Er:YAG laser. Resin composites were used to restore the adhesive-treated dentin surfaces. After 2,500 thermal cycles, the vertical composite resin-dentin sticks obtained were subjected to micro-TBS tests. One tooth in each group was examined using scanning electron microscopy (SEM). There were statistically significant differences (p<0.001) in micro-TBS values between universal adhesives. The results of this study suggested that universal adhesives applied both with self and total etch technique can be used for adhesive restorations to caries-affected dentin after Er:YAG laser irradiation. If lasers are preferred as a caries removal method, choosing a dentin bonding agent containing MDP may be recommended in clinical practice due to the property of increasing the bonding strength.
  • PublicationOpen Access
    Can Fiber Application Affect the Fracture Strength of Endodontically Treated Teeth Restored with a Low Viscosity Bulk-Fill Composite?
    (2019-01-01) Dalkilic, Evrim Eliguzeloglu; Kazak, MAĞRUR; Hisarbeyli, DUYGU; Fildisi, MEHMET ALİ; Donmez, NAZMİYE; Arisu, Hacer Deniz; DALKILIÇ, EVRIM; KAZAK, MAĞRUR; HİSARBEYLİ, DUYGU; FİLDİŞİ, MEHMET ALİ; DÖNMEZ, NAZMİYE
    Objective: The aim of this study is to evaluate the effects of different fiber insertion techniques and thermomechanical aging on the fracture resistance of endodontically treated mandibular premolar teeth restored using bulk-fill composites. Materials and methods: Eighty human mandibular premolar teeth were randomly divided into eight groups: Group IN, Group BF, Group PRF1, Group PRF2, Group IN-TMA, Group BF-TMA, Group PRF1-TMA ,and Group PRF2-TMA. Group IN (intact) and Group IN-TMA (intact but subjected to thermomechanical aging) served as control groups. In the other six groups, endodontic treatment was performed and standardized mesio-occluso-distal (MOD) cavities were prepared. In BF, PRF1, and PRF2, the cavities were restored with bulk-fill composite only, bulk-fill/Ribbond, and bulk-fill/additional Ribbond, respectively. In BF-TMA, PRF1-TMA, and PRF2-TMA, the teeth were subjected to thermomechanical aging after the restorations. All of the teeth were fractured on the universal testing machine. Fracture surfaces were analyzed with a stereomicroscope. Results: Control groups showed significantly higher fracture strengths than tested groups (P<0.05). No statistically significant difference was observed among the tested groups (P>0.05). Most of the favorable fractures were seen in PRF1, PRF2, and PRF2-TMA. Most of the unfavorable fractures were seen in BF-TMA. Conclusions: Although fiber insertion with different techniques did not increase the fracture strength of teeth restored with bulk-fill composites, it increased the favorable fracture modes. Thermomechanical aging did not change the fracture strength of the groups.
  • PublicationOpen Access
    Development of Dentin Bonding Systems from Past to Present
    (2019-10-01T00:00:00Z) Kazak, Mağrur; Dönmez, Nazmiye; DÖNMEZ, NAZMİYE
  • PublicationOpen Access
    The impact of Er:YAG laser enamel conditioning on the microleakage of a new hydrophilic sealant-UltraSeal XT (R) hydro (TM)
    UltraSeal XT hydro is a new hydrophilic, light-cured, methacrylate-based pit and fissure sealant which has been developed by Ultradent Products, USA. The sealant is highly filled with a 53 wt.% mixture of inorganic particles which confer both thixotropy and radiopacity. The principal purpose of this study was to investigate the microleakage of UltraSeal XT hydro as a function of different enamel etching techniques. The occlusal surfaces of sound, extracted human molars were either acid etched, Er:YAG laser irradiated or successively laser irradiated and acid etched. UltraSeal XT hydro was applied to each group of teeth (n = 10) which were subjected to a thermocycling process consisting of 2500 cycles between 5 and 50 °C with a dwell time of 30 s. Microleakage assessments were then carried out using 0.5% fuchsin dye and optical microscopy. The microleakage score data were analysed using the Kruskal-Wallis, Mann-Whitney U test with Bonferroni adjustment. No significant differences in microleakage were noted between the individually acid etched and laser-irradiated groups (p > 0.05); however, teeth treated with a combination of laser irradiation and acid etching demonstrated significantly lower microleakage scores (p < 0.001). Electron microscopy with energy-dispersive X-ray analysis revealed that the mineral filler component of UltraSeal XT hydro essentially comprises micrometre-sized particles of inorganic silicon-, aluminium- and barium-bearing phases. Laser etching increases the roughness of the enamel surface which causes a concentrated zoning of the filler particles at the enamel-sealant interface.
  • PublicationOpen Access
    Effect of Er:YAG laser enamel conditioning and moisture on the microleakage of a hydrophilic sealant
    (2018-07-01) Guclu, Zeynep Asli; Hurt, Andrew Paul; Donmez, NAZMİYE; Coleman, Nichola Jayne; DÖNMEZ, NAZMİYE
    For a given sealant, successful pit and fssure sealing is principally governed by the enamel conditioning technique and the presence of moisture contamination. A new generation of hydrophilic resin sealants is reported to tolerate moisture. This study investigates the impact of Er:YAG laser pre-conditioning and moisture contamination on the microleakage of a recent hydrophilic sealant. Occlusal surfaces of extracted human molars were either acid etched (n = 30), or successively lased and acid etched (n = 30). Ten teeth from each group were either air-dried, water-contaminated, or saliva-contaminated prior to sealing with UltraSeal XT® hydro™. Samples were inspected for penetration of fuchsin dye following 3000 thermocycles between 5 and 50 °C, and the enamel–sealant interfaces were observed by scanning electron microscopy (SEM). Signifcant diferences in microleakage were evaluated using the Mann–Whitney U test with Bonferroni adjustment (p = 0.05). Laser pre-conditioning signifcantly reduced dye penetration irrespective of whether the enamel surface was moist or dry. Microleakage of water-contaminated acid etched teeth was signifcantly greater than that of their air-dried or saliva-contaminated counterparts. SEM analysis demonstrated good adaptation in all groups with the exception of water-contaminated acid etched teeth which exhibited relatively wide gaps. In conclusion, this hydrophilic sealant tolerates the presence of saliva, although water was found to impair its sealing ability. Laser pre-conditioning signifcantly decreases microleakage in all cases.
  • PublicationOpen Access
    The Effect of Calcium Phosphate-containing Desensitizing Agent on the Microtensile Bond Strength of Multimode Adhesive Agent
    (2017-08-01) Siso, S. H.; Donmez, NAZMİYE; Kahya, D. S.; Uslu, Y. S.; DÖNMEZ, NAZMİYE
    Objective: The aim of this study was to investigate the effect of calcium phosphate containing desensitizing pretreatments on the microtensile bond strength (MTBS) and microleakage of the multimode adhesive agent to dentin. Materials and methods: In this study, twelve noncarious, freshly extracted human third molar teeth for MTBS and 20 premolar teeth for the microleakage test were used. The teeth were restored using Clearfil Universal Bond + Clearfil APX and Teeth mate Desensitizer (TMD). For MTBS test, Group 1: Self-etch, Group 2: Etch and rinse (G1 and 2, nondesensitizer treatment served as a control), Group 3: TMD/self-etch, Group 4: Acid-etch/TMD/etch and rinse. For microleakage test, Class V adhesive cavities (3 mm × 2 mm × 2 mm) were prepared and restored as mentioned before. The restored teeth were subjected to thermal cycling. The MTBS test was performed in all procedures. The MTBS data were submitted to a one-way ANOVA and post hoc Tukey test (P P Results: Control groups exhibited a higher mean MTBS value than TMD groups, and there were statistical differences between the groups. TMD groups also demonstrated significantly less microleakage than control groups (P Conclusions: This study proves that the application of TMD with a multimode adhesive bonding system produced significantly lower MTBS and microleakage.