The influence of storage time and cutting speed on microtensile bond strength

Purpose: The aim of this study was to verify the influence of the storage time and the cutting speed during specimen preparation on the bond strength of a single-bottle adhesive to dentin. Materials and Methods: A flat dentin surface was exposed in 36 human third molars. The adhesive system (Single Bond) was applied according to the manufacturer's instructions, and composite resin crowns (Z250) were constructed incrementally. Specimens were stored for 10 min, 24 h, or 1 week in distilled water at 37degreesC before being longitudinally sectioned in both the "x" and "y" directions at different cutting speeds (0.5, 1.6, and 2.6 m/s) to obtain sticks with a cross-sectional area of approximately 0.8 mm(2). The specimens were tested in a tensile load machine (0.5 mm/min) and the fracture mode analyzed. A two-way ANOVA with storage time (3 levels) and cutting speed (3 levels) as factors was used to compare the mean microtensile bond strengths. Results: Highly significant main effects and interaction (p < 0.0001) were detected. The highest mean bond strength was obtained with a storage time of 1 week and cutting speed of 2.6 m/s. The lowest mean was found when the specimens were prepared immediately after composite resin placement and sliced at 0.5 m/s. Conclusion: Both the storage time and the cutting speed may affect the bond strength results. Therefore, these variables must be controlled in microtensile bond strength tests.6171

Rivaroxaban with or without aspirin in stable cardiovascular disease

BACKGROUND: We evaluated whether rivaroxaban alone or in combination with aspirin would be more effective than aspirin alone for secondary cardiovascular prevention. METHODS: In this double-blind trial, we randomly assigned 27,395 participants with stable atherosclerotic vascular disease to receive rivaroxaban (2.5 mg twice daily) plus aspirin (100 mg once daily), rivaroxaban (5 mg twice daily), or aspirin (100 mg once daily). The primary outcome was a composite of cardiovascular death, stroke, or myocardial infarction. The study was stopped for superiority of the rivaroxaban-plus-aspirin group after a mean follow-up of 23 months. RESULTS: The primary outcome occurred in fewer patients in the rivaroxaban-plus-aspirin group than in the aspirin-alone group (379 patients [4.1%] vs. 496 patients [5.4%]; hazard ratio, 0.76; 95% confidence interval [CI], 0.66 to 0.86; P<0.001; z=−4.126), but major bleeding events occurred in more patients in the rivaroxaban-plus-aspirin group (288 patients [3.1%] vs. 170 patients [1.9%]; hazard ratio, 1.70; 95% CI, 1.40 to 2.05; P<0.001). There was no significant difference in intracranial or fatal bleeding between these two groups. There were 313 deaths (3.4%) in the rivaroxaban-plus-aspirin group as compared with 378 (4.1%) in the aspirin-alone group (hazard ratio, 0.82; 95% CI, 0.71 to 0.96; P=0.01; threshold P value for significance, 0.0025). The primary outcome did not occur in significantly fewer patients in the rivaroxaban-alone group than in the aspirin-alone group, but major bleeding events occurred in more patients in the rivaroxaban-alone group. CONCLUSIONS: Among patients with stable atherosclerotic vascular disease, those assigned to rivaroxaban (2.5 mg twice daily) plus aspirin had better cardiovascular outcomes and more major bleeding events than those assigned to aspirin alone. Rivaroxaban (5 mg twice daily) alone did not result in better cardiovascular outcomes than aspirin alone and resulted in more major bleeding events