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    Effect of desensitizers on the microleakage of previously restored Class V resin composite restorations
    (Taylor & Francis Ltd, 2016) Ozsoy, Alev; Eren, Meltem Mert; Gurbuz, Ozge; Dikmen, Benin; Cilingir, Aylin; Erdemir, Ugur
    Objectives: The aim of this in vitro study was to evaluate the effect of different desensitizers' application on the microleakage of previously restored Class V composite resin restorations. Materials and methods: Class V cavities were prepared on the buccal surfaces of 40 extracted human third molars. Forty box-shaped cavities were divided into four groups, based on the desensitizers used (n = 10). All teeth were restored with the same bonding agent and composite material. No desensitizer was applied in the control group. In the experimental groups, BisBlock, Gluma and Universal bonding agents were the desensitizers. The desensitizers were applied after completion of composite restorations according to manufacturers' instructions. All specimens were then thermocycled at 5-55 degrees C, with a 10-s dwell time for 500 cycles. The samples were then immersed in 0.5% methylene blue dye for 24 h, sectioned into two equal halves, evaluated for microleakage using a stereomicroscope at 30x magnification and scored on a scale of 0-3. The data were analysed using the Kruskal-Wallis test at the significance level p < 0.05. Results: There were no significant differences in microleakage after desensitizer application (p > 0.05). However, based on the obtained numerical values in our study, while the BisBlock and bonding groups showed lower microleakage at the occlusal margin, BisBlock, Gluma and bonding group showed lower microleakage at the gingival margin compared to the control group. Conclusions: The application of desensitizers as a post-treatment option could be considered an advisable procedure to minimize microleakage.
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    Effect of surface conditioning methods on the microtensile bond strength of repair composite to indirect restorative materials
    (Taylor & Francis Ltd, 2019) Mumcu, Emre; Erdemir, Ugur; Ozsoy, Alev; Tekbas-Atay, Meltem; Oezcan, Mutlu
    This study evaluated the effect of surface conditioning methods on the microtensile bond strength (mu TBS) of a restorative composite to indirect restorative materials. Blocks (5 x 5 x 4 mm(3)) (N = 72) of (a) Zirconia (In-Ceram Zirconia, Vita) (ZR), (b) lithium disilicate glass ceramic (IPS Empress II, Ivoclar Vivadent) (LD), (c) Indirect resin composite (Gradia, GC) (GR) were fabricated (n = 24 per group) and divided randomly into three groups: 1-Control: no conditioning, 2-Silane coupling agent, 3-Hydrofluoric acid (9.5%) (HF)+silane. Each block was duplicated in resin composite. The adhesion surfaces were conditioned with airborne-particle abrasion (110 mu m Al2O3 particles). Half of the conditioned blocks received no bonding and the other half one coat of bonding (ED Primer II, Kuraray). Each conditioned block was bonded to a composite block with a resin luting agent (Panavia F2.0, Kuraray). The blocks were sectioned into 1 mm(2) microsticks and tested for microtensile bond strength (mu TBS) (0.5 mm/min) in a mu TBS testing machine. Failure types were evaluated under stereomicroscope and Scanning Electron Microscope (SEM). Data were analyzed using three-way ANOVA, Bonferroni corrected and independent sample t-tests (p < 0.05). Significant effect of the bonding (p < 0.001) and surface conditioning (p < 0.001) were observed in all groups. The highest mean bond strength values were obtained in the bonded, HF etched and silanized groups of ZR, LD and GR (12.4 +/- 2.9, 28.1 +/- 1.5 and 27.2 +/- 2 MPa, respectively). HF acid + silane increased the repair bond values in all materials. Majority of the failure types were adhesive for ZR group, whereas HF + silane conditioned LD and GR groups presented predominantly cohesive failures in the cement.