Mine Betül Üçtaşlı

The Effect of Occlusal Loading on the Microleakage of Class V Restorations

OBJECTIVE This in vitro study evaluated the microleakage of Class V cavities restored with a resin composite and different adhesive systems after occlusal loading. METHODS & MATERIALS Standardized box-shaped Class V cavities were prepared on the buccal side of 135 non-carious human premolars. The teeth were randomly divided into three groups of 45 premolars each and restored as follows: Group 1-two-step total-etch adhesive (Single Bond, 3M) + resin composite (Supreme, 3M ESPE); Group 2-two-step self-etch adhesive (Clearfil SE, Kuraray) + resin composite and Group 3-one-step self-etch adhesive (Xeno III, Dentsply) + resin composite. The restorations were finished with aluminum oxide discs (Sof-Lex, 3M). Fifteen teeth in each group received 10,000 x 100 N and 250 N occlusal loads, respectively, and the remaining 15 teeth served as the control. The premolars were immersed in 2% methylene blue for 24 hours. The dye penetration was examined under a stereomicroscope, and the results were statistically analyzed by Kruskal Wallis, Mann-Whitney U and Wilcoxon Signed Rank tests to determine differences between the groups. RESULTS Gingival margins showed more dye penetration than occlusal margins in all the tested groups (p<0.05). In all the tested adhesive systems, 100 N occlusal loading did not change dye penetration; however, Groups 1 and 2 exhibited better marginal sealing than Group 3 at the enamel margins under 250 N occlusal loading. CONCLUSION Within the limitations of this in vitro study, it may be concluded that enamel margins provided better marginal sealing than dentin/cementum margins and the two-step self-etch adhesive exhibited better marginal sealing than an all-in-one adhesive at the enamel margins under 250 N occlusal loading.

The effect of different adhesive system applications on push-out bond strengths of glass fiber posts

PURPOSE Over the past years, the adhesion of fiber posts luted with simplified adhesive systems has been a matter of great interest. The aim of this study was to assess the post retentive potential of a self-adhesive resin cement using different adhesive systems to compare the push-out bond strengths of fiber posts. MATERIALS AND METHODS The post spaces of 56 mandibular premolar roots were prepared and divided into 4 experimental groups and further divided into 2 subgroups according to testing time (n=7). The fiber posts (Rely X Fiber Post) were luted with a self-adhesive resin cement (RelyX Unicem) and one of the following adhesive systems: no adhesive, a total-etch adhesive resin (Single Bond), a two-step self-etch adhesive resin (Clearfil SE Bond) and a one-step self-etch adhesive resin (Clearfil S3 Bond). Each root was cut horizontally, and 1.5 mm thick six root segments were prepared. Push-out tests were performed after one week or three months (0.5 mm/min). Statistical analysis were performed with three-way ANOVA (α=.05). RESULTS Cervical root segments showed higher bond strength values than middle segments. Adhesive application increased the bond strength. For one week group, the total-etch adhesive resin Single Bond showed higher bond strength than the self-adhesive resin cement RelyX Unicem applied without adhesive resin at middle region. For 3 months group, the two-step self-etch adhesive resin Clearfil SE Bond showed the highest bond strength for both regions. Regarding the time considered, Clearfil SE Bond 3 months group showed higher bond strength values than one week group. CONCLUSION Using the adhesive resins in combination with the self-adhesive resin cement improves the bond strengths. The bond strength values of two-step self-etch adhesive resin Clearfil SE Bond improved as time passes.

Comparison of time-dependent changes in the surface hardness of different composite resins

Objective: The aim of this study was to evaluate the change in surface hardness of silorane-based composite resin (Filtek Silorane) in time and compare the results with the surface hardness of two methacrylate-based resins (Filtek Supreme and Majesty Posterior). Materials and Methods: From each composite material, 18 wheel-shaped samples (5-mm diameter and 2-mm depth) were prepared. Top and bottom surface hardness of these samples was measured using a Vickers hardness tester. The samples were then stored at 37°C and 100% humidity. After 24 h and 7, 30 and 90 days, the top and bottom surface hardness of the samples was measured. In each measurement, the rate between the hardness of the top and bottom surfaces were recorded as the hardness rate. Statistical analysis was performed by one-way analysis of variance, multiple comparisons by Tukeys test and binary comparisons by t-test with a significance level of P = 0.05. Results: The highest hardness values were obtained from each two surfaces of Majesty Posterior and the lowest from Filtek Silorane. Both the top and bottom surface hardness of the methacrylate based composite resins was high and there was a statistically significant difference between the top and bottom hardness values of only the silorane-based composite, Filtek Silorane (P < 0.05). The lowest was obtained with Filtek Silorane. The hardness values of all test groups increased after 24 h (P < 0.05). Conclusion: Although silorane-based composite resin Filtek Silorane showed adequate hardness ratio, the use of incremental technic during application is more important than methacrylate based composites.

Microtensile Bond Strength of Self-Adhesive Resin-Based Dental Cement to Bleached Enamel

This study investigated the effectiveness of bleaching agents on the micro tensile bond strength (µTBS) of self-adhesive luting cement and enamel. A total of 126 samples were prepared from the labial surfaces of permanent human maxillary central incisors and assigned into three groups with 42 samples each as: control, enamel bleached with 10% hydrogen peroxide (HP), and enamel bleached with 10% carbamide peroxide (CP). Rely X Unicem® (3 M, ESPE) was used as self-adhesive resin cement. The total testing period for bleaching was selected as 14 days and the bleaching agents were applied 8 hours a day. The statistical one-way ANOVA model and Tukey HSD multiple comparison test (α = .01) were used to assess the differences. The control group demonstrated the highest value (18.245 MPa) while HP and CP showed the much lower values of 11.150 and 14.222 MPa, respectively. Bleaching agents affect the µTBS negatively. Failure analysis of the fracture surfaces demonstrated that almost all samples showed adhesive failures at the cement-enamel interface.

Post boşluğuna bağlayıcı uygulamalarının kendinden bağlanabilen rezin siman kullanılarak yapıştırılan fiber postların push-out bağlanma dayanımlarına etkileri

Amac: Asiri kron harabiyeti gosteren endodontik tedavili dislerin restorasyonunda kullanilan fiber post sisteminin post bosluguna baglayici rezin uygulanarak ya da uygulanmadan iki farkli kendinden baglanabilen rezin simanla yapistirilmasinin, push-out baglanma dayanimi uzerine etkilerinin incelenmesidir. Gerec ve Yontem: Calismada kullanilan cekilmis 80 adet 1. kucuk azi disi kok kanal preparasyonlari yapildiktan sonra fiber postun (RelyX Fiber Post) yapistirilmasinda kullanilan materyallere gore 4 gruba ayrildi. Grup 1 RelyX Unicem, Grup 2 RelyX Unicem + Adper Easy One, Grup 3 Clearfil SA Cement, Grup 4 Clearfil SA Cement + S3 Bond kullanilarak yapistirildi. Ornekler 24 saat ve 1 aylik surelerde etuvde bekletildikten sonra fiber postun apikal, orta ve koronal bolgelerinden 1 mm’lik horizontal 6 kesit alindi ve push-out baglanma dayanimlari degerlendirildi. Gruplarin karsilastirilmasinda tek yonlu varyans analizi ve Tukey HSD testleri, bekletme surelerinin karsilastirilmasinda bagimsiz degiskenler t-testi kullanildi (α=0.05). Bulgular: Hem 24 saat hem de 1 aylik olcum sonuclarina gore en yuksek baglanma dayanim degerleri Rely X Unicem + Adper Easy One grubunda gozlendi. En zayif baglanti 24 saat sonrasinda postun apikal bolgesinden alinan kesitlerde goruldu, bunu orta ve koronal bolgeler izledi. 1. ay sonunda, apikal ve orta bolge kesitleri benzerlik gosterirken (p>0.05), her iki bolge de koronal bolgeden daha dusuk degerler gosterdi (p<0.05). Apikal ve orta bolgelerde RelyX Unicem + Adper Easy One diger gruplara gore daha yuksek baglanma dayanimi degerleri gosterdi (p<0.05). Sonuc: Bu in vitro test kosullari altinda post simantasyonunda, kendinden baglanabilen rezin simanlarin uygun baglayicilar ile birlikte kullaniminin baglanma dayanimini arttirdigi soylenebilir.