Mehmet Yildiz

Intrinsic and extrinsic discoloration of dimethacrylate and silorane based composites.

OBJECTIVE The purpose of this study was to evaluate the intrinsic and extrinsic color change of dimethacrylate and silorane-based composites. MATERIALS AND METHODS Five contemporary composites were included within the study (Filtek LS Low Shrink Posterior Restorative [SIL], Filtek SupremeXT [SPR], Filtek Z250 [Z25], Filtek P60 [P60], and Admira [ADM]). Twenty-five specimens (8-mm diameter, 1.5-mm thickness) were prepared for each composite. After baseline color measurements were taken, specimens were immersed in 4 staining solutions (red wine, coffee, cola, and tea) or distilled water (n=5). After a 24-h and 1-month immersion, the color values of each specimen were remeasured and the color change values (ΔE(ab)(*)) were calculated. Statistical analyses were evaluated by one-way ANOVA and Tukey HSD test. RESULTS Amongst the solutions, red wine had the highest ΔE(ab)(*) value in all the composite restoratives. After the final measurement, ADM exhibited the lowest discoloration, whereas SPR exhibited the highest color change. Additionally, the color change for SIL after 1 month in distilled water was higher than the clinically accepted cut-off of 3.3. This change was correlated with an increasing L value according to the multiple regression analysis. CONCLUSION All of the restorative materials used in this study were susceptible to staining by commonly consumed beverages drinks, especially red wine and coffee; however, in water, only SIL became whiter with time.

The Effect of Surface Treatments on the Bond Strength Between CAD/CAM Blocks and Composite Resin.

PURPOSE The aim of this study was to evaluate the microtensile bond strength of three computer-aided design/computer-aided manufacturing (CAD/CAM) blocks repaired with composite resin using three surface treatment techniques. METHODS AND MATERIALS Three different CAD/CAM blocks were used in this study: (1) Lithium disilicate, (2) feldspar ceramic, and (3) resin nano ceramic. All groups were further divided into four subgroups according to surface treatment: control, roughened with bur (B); roughened with bur and 5% Hydrofluoric acid (HF); roughened with bur and sandblasting (HF); and roughened with bur and CoJet (C). After surface treatments on each group, a silane and bonding agent were applied, and ceramics were repaired with a nano-hybrid composite. Then, the repaired ceramics were cut with a low-speed diamond saw for microtensile bond testing. Microtensile bond tests for 40 specimens per subgroup were carried out with a universal testing machine. The data were analyzed with ANOVA, Tukeys, and LSD at the 95% significance level. RESULTS Mean bond strengths (MPa) of subgroups B, HF, S, and C were: 0, 29.8, 0, 23.3 for lithium disilicate ceramic; 26.4, 22.3, 22.4, 22 for feldspar ceramic; 54.8, 25.3, 42.1, 25.7 for resin nano ceramic. For subgroups B and S of lithium disilicate ceramics, bonding failed during specimen preparation. No significant differences were observed among all CoJet groups. In subgroups B and S, resin nano ceramics showed the highest bond strength. In feldspar groups, subgroup B showed higher bond strength than the other subgroups. CONCLUSION This study demonstrates that lithium disilicate porcelain blocks required etching for repairing with composite material. Surface treatments did not increase the bond strength in feldspar ceramic groups and reduced the bond strength in resin nano ceramic groups.

Quality of curing in relation to different light sources by measuring hardness, degree of conversion and depth of cure

Abstract This study was to determine the quality of curing of second generation light emitting diode (LED-II) compared to a first generation LED (LED-I) and conventional halogen (quartz tungsten halogen) light curing unity by measuring depth of cure, degree of polymerisation and surface hardness. Filtek Z-250 hybrid composite resin (3M-ESPE, Germany), with shade A2, was used in this study. One quartz tungsten halogen/light curing unit (LCU) (Hilux, Benlioglu Dental, Turkey), one LED-I-LCU unit (Elipar Freelight 3M-ESPE, Germany) and one LED-II-LCU (Elipar Freelight, 3M-ESPE, Germany) were used for polymerisation of the composite resin. The depth of cure was obtained with scrape test, degree of cure was measured with Fourier transform infrared spectrometer (Spectrum-One, Perkin-Elmer, USA) and surface hardness was calculated with surface hardness tester (Micromet-2001, Buehler, Dusseldorf, Germany). The data were analysed by Kruskal Wallis and Mann Whitney-U. The polymerisation depth of LED-I-LCU was significantly lower than that of the other LCUs (p<0·05). However, no significant differences were obtained among all tested systems in point of degree of cure and surface hardness at 2 mm depth. Within the limitations of this study, although LED-I showed lower depth of cure, all tested systems appear suitable for routine clinical practice for polymerisation of the composite resin.

Effect of composite resin filling material implantation into connective tissue of rabbits on oxidative stress in erythrocytes

AbstractRecently, there have been considerable developments regarding aesthetic restorative materials (composite resins). They were used for front teeth in the past and more recently used for posterior teeth. The aim of our study was to investigate the effect of implantation of composite resin filling material into the connective tissue of rabbits. For this purpose, in 7 rabbits before and 1 and 7 days after composite implantation, xanthine oxidase activities and malondialdehyde levels were measured. They significantly increased. One day and 7 days after implantation, total (enzymatic plus non-enzymatic) superoxide scavenger activity, and non-enzymatic superoxide scavenger activities in erythrocyte significantly increased. Additionally, both baseline and 7th day superoxide dismutase activity was higher than in the 1st day. 7th day catalase activities were increased when compared to both baseline and 1st day values.

Lipid peroxidation and DNA oxidation caused by dental filling materials

Background/purpose The two direct dental restorative materials most commonly used today are silver-mercury amalgam and resin-based composites. The purpose of this study was to examine the effects of these two restorative materials and substances released by these into the oral environment on lipid peroxidation and DNA oxidation after entering the blood circulation. Materials and methods Blood samples from 41 patients were collected before and 24 hours after the application of these restorative materials. The 8-hydroxydeoxyguanosine/deoxyguanosine ratio in these samples was measured to determine oxidative DNA damage, and malondialdehyde levels were measured to define lipid peroxidation. The paired samples t test and Pearson correlation analysis were used for the analysis of variables (α = 0.05). Results While no statistically significant difference was observed after amalgam filling application in terms of DNA oxidation, a significant difference was observed after composite application (P < 0.05). Furthermore, a significant increase was determined in malondialdehyde levels of two materials (P < 0.05). In both amalgam and composite applications, a significant difference was observed before and after application in terms of released substances (mercury and unpolymerized monomer, respectively, P < 0.001). Conclusion Mercury increased lipid peroxidation and Bis-GMA and TEGDMA dental resins increased both lipid peroxidation and DNA oxidation markers.

The effects of different polishing techniques on the staining resistance of CAD/CAM resin-ceramics

PURPOSE The purposes of this study were to evaluate the staining resistance of CAD/CAM resin-ceramics polished with different techniques and to determine the effectiveness of the polishing techniques on resin-ceramics, comparing it with that of a glazed glass-ceramic. MATERIALS AND METHODS Four different CAD/CAM ceramics (feldspathic ceramic: C-CEREC Blocs, (SIRONA) and three resin-ceramics: L-Lava Ultimate, (3M ESPE), E-Enamic, (VITA) and CS-CeraSmart, (GC)) and one light cure composite resin: ME-Clearfil Majesty Esthetic (Kuraray) were used. Only C samples were glazed (gl). Other restorations were divided into four groups according to the polishing technique: nonpolished control group (c), a group polished with light cure liquid polish (Biscover LV BISCO) (bb), a group polished with ceramic polishing kit (Diapol, EVE) (cd), and a group polished with composite polishing kit (Clearfil Twist Dia, Kuraray) (kc). Glazed C samples and the polished samples were further divided into four subgroups and immersed into different solutions: distilled water, tea, coffee, and fermented black carrot juice. Eight samples (8 × 8 × 1 mm) were prepared for each subgroup. According to CIELab system, four color measurements were made: before immersion, immersion after 1 day, after 1 week, and after 1 month. Data were analyzed with repeated measures of ANOVA (α=.05). RESULTS The highest staining resistance was found in gl samples. There was no difference among gl, kc and cd (P>.05). Staining resistance of gl was significantly higher than that of bb (P<.05). Staining resistances of E and CS were significantly higher than those of L and ME (P<.05). CONCLUSION Ceramic and composite polishing kits can be used for resin ceramics as a counterpart of glazing procedure used for full ceramic materials. Liquid polish has limited indications for resin ceramics.

HASTANE İŞLETMELERİNDE STOK YÖNETİMİ İÇİN ABCve VED ANALİZLERİNİN UYGULANMASI

Gunumuz rekabet kosullarinda, urun ya da hizmetini son kullaniciya zamaninda sunabilen isletme, diger isletmelere karsi stratejik ustunluk kazanmaktadir. Ozellikle bu kurumlarin hastane olduklari dusunuldugunde bu, daha da onem kazanmaktadir. Hastaneler, insan sagligi acisindan hayati onem arz etmektedir. Hasta tedavisinin aciliyet ve reddedilmezlik gostermesi ve yatarak tedavi goren hastalara hizmet vermesi bakimindan hastaneler 24 saat calisan organizasyonlardir. Bu nedenle hastanelerde hizmetlerin aksamasina neden olmayacak kadar yeterli miktarda cesitli ilac, tibbi malzeme ve diger destek malzemelerinin stokta her zaman bulundurulmasi gerekmektedir. Bu calismada, bu sureclerin daha etkin yonetilebilmesi icin ABC ve hastaneler icin onemli olan VED analizi uygulanarak faaliyetlerin siniflandirilmasi ve onem derecesine gore siralanmasi amaclanmistir. Ayrica ilgili calisma sonucunda, ilgili hastanenin tibbi sarf malzemelerin depo mevcudu ile sistem mevcudunun tutarli olmasi amaclanmistir. Calismada nicel ve nitel arastirma yontemleri ile tanimlayici arastirma tasarimi kullanilmistir. Veriler rastgele orneklem yontemiyle secilmistir. Saha calismalari ile satin alma, lojistik ve depo yonetim birimleri ve kullanilan bilgi sistemlerinden yararlanilmistir. Calismada sadece acil bolumune ait 127 kalem stoklara ait veriler dikkate alinmistir. Calisma hastanenin cok buyuk ve cok fazla depo birimi bulundugundan sadece acil bolumuyle sinirlandirilmistir. Inceleme kapsaminda sadece tek kullanimlik tibbi malzemeler inceleme kapsamina alinmistir.

Reactions of connective tissue to self-etching/priming dentin bonding systems: oxidative stress, tumor necrosis factor α expression, and tissue reactions

Background/Purpose Few data have been published concerning tissue and systemic responses to resinous dental materials. The aim of this study was to compare and evaluate the biocompatibility of four kinds of dental self-etching/priming adhesives by measuring tissue responses, local and systemic tumor necrosis factor (TNF) a expression, and oxidative stress parameters. Materials and methods Eighty rats were equally divided into 10 groups. Four dental adhesives (Clearfil SE Bond, iBond, Clearfil Protect Bond, and Adper Prompt L-Pop) were applied to connective tissue of the rats. In the control group, rats were operated on with no material being applied. Biocompatibilities of the bonding agents were evaluated according to tissue responses, histopathologic and biochemical TNF-a expressions, and levels of malondialdehyde, glutathione, superoxide dismutase and glutathione peroxidase activities 1 week and 1 month after initiation of treatment. Results All neutrophil levels and edema formation between the iBond group and the other groups were statistically significant after 1 week. Fibroblast levels in the Clearfil SE Bond group were higher than all other groups. Vascularization levels statistically differed between the Clearfil SE Bond and iBond groups, and between the Adper Prompt L-Pop and control groups. Tissue TNF-a levels statistically differed in all groups other than the control group. At the end of 1 month, the neutrophil level in the iBond group was higher than that in the control group. The differences in fibroblast levels after 1 month were statistically significant between the Clearfil SE Bond and Clearfil Protect Bond groups, and between the control and iBond groups. Tissue TNF-a levels were higher in the iBond, Clearfil Protect Bond, and Adper Prompt L-Pop groups than in the Clearfil SE Bond and control groups. Conclusion There were no statistical differences in levels of serum TNF-a and oxidative stress parameters in any groups during the course of the study. The four different adhesive systems exhibited different degrees of local toxicity to the subsurface of the skin of rats, but no systemic toxicity was detected.