No abstract

No abstract

<p><strong>Objective</strong>: This study evaluated the microtensile bond strength of a universal adhesive system applied to deep dentin under different bonding strategies. <strong>Material</strong> <strong>and Methods</strong>: Fifteen human third molars had the coronal portion removed exposing deep dentin and were assigned into 3 groups according to the adhesive system: G1(control): 2-steps totaletch (Adper Single Bond 2, 3M ESPE); G2: 1-step self-etch universal adhesive (Scotchbond Universal, 3M ESPE); G3:2 steps total-etch universal adhesive (Scotchbond Universal, 3M ESPE). Composite buildups were performed on the dentin surfaces and after water storage for 24 h, teeth were sectioned to obtain 40 bonded beams per group with sectional area of 0.9 mm2 . The specimens were submitted to the microtensile bond strength (µTBS) test until failure. Statistical analyses were computed using one-way ANOVA (p = 0.05). <strong>Results</strong>: The mean µTBS (in MPa) were G1 = 22.27, G2 = 22.85 and G3 = 20.3. After statistical analysis, no significant differences were observed among the groups. <strong>Conclusions</strong>: Universal adhesive system performed similarly to the total-etch adhesive and was not affected by the adhesion strategy.</p><p> </p><p><strong>KEYWORDS </strong></p><p>Microtensile; Adhesive system; Dentin.</p>

SUMMARY Objectives: To evaluate the influence of ferrule effect and mechanical fatigue aging on glass-fiber post push-out bond strength (PBS) to root-canal dentin at different root thirds of premolars. Methods and Materials: Thirty-two sound maxillary premolar teeth were collected, and randomly assigned to two experimental groups (n=16): ‘Remaining Dentin Ferrule’ (RDF) = coronal crown cut 2.0 mm above the cemento-enamel junction (CEJ); ‘Without Dentin Ferrule’ (WDF) = coronal crown cut at the cemento-enamel junction. Teeth were endodontically treated, post spaces were prepared up to 10.0-mm depth from CEJ, and glass-fiber posts were cemented using a dual-cure self-adhesive composite cement. Standardized cores were built using a light-cure composite, upon which tooth cores were prepared using a 1.5-mm taper ogival-end diamond bur. Crowns were handmade using self-cure acrylic resin and cemented using the aforementioned composite cement. Half of the specimens were subjected to 1,200,000 cycles of mechanical fatigue in a chewing simulator (F = ‘Fatigue’), while the other half were stored in distilled water at 37°C for 1 week (C = ‘Control’). All specimens were horizontally sectioned into 1.0-mm thick slices prior to PBS test; the failure modes were assessed using stereomicroscopy and scanning electron microscopy (SEM). Data were analyzed for each root third using two-way analysis of variance (ANOVA) followed by Tukey HSD post-hoc test; frequency distribution was compared by Chi-square test (α=0.05) and post-hoc comparisons with Bonferroni. Results: The mean PBS in MPa (SD) were = RDF_F = 10.4 (2.9); WDF_F = 6.9 (1.7); RDF_C = 14.5 (2.7); WDF_C = 14.2 (2.9). Similar PBS were found for the root thirds. For all root thirds, significant differences were found for both the factors Dentin Ferrule and Fatigue, and their interaction (p&lt;0.05). The lowest PBS was found for specimens without dentin ferrule subjected to chewing fatigue (p&lt;0.001). Most failures occurred at the composite cement/dentin interface, followed by mixed and composite cement/glass-fiber post interfacial failures. There was a significant increase in mixed failures for the WDF_F group (p&lt;0.001). Conclusion: Absence of 2.0-mm remaining dentin ferrule in premolars resulted in a higher decrease of the glass-fiber posts’ PBS to dentin after mechanical fatigue, irrespective of root third.