RESUMEN
OBJECTIVE: This study aims to evaluate the effects of exposure time and irradiance on the dentin bonding properties (microtensile bond strength (µTBS) and nanoleakage (NL)) of the Clearfil Universal Bond Quick (CUQ) adhesive and Scotchbond Universal Adhesive (SBU) immediately and after 2 years of water storage. MATERIAL AND METHODS: Hence, 128 human molars were randomly assigned to 16 groups based on adhesive strategy, irradiance/exposure times, and storage time for each universal adhesive tested. The adhesives were applied using the etch-and-rinse and self-etch strategies and were light-cured using four different irradiance/exposure times: 1400 mW/cm2 for 5 s (1400 × 5), 1400 mW/cm2 for 10 s (1400 × 10), 3200 mW/cm2 for 5 s (3200 × 5), and 3200 mW/cm2 for 10 s (3200 × 10). Then, each sample was restored and sectioned into a resin-dentin bonded stick to be tested for µTBS and NL (immediately and after 2 years of water storage). The mean µTBS and NL of all resin-dentin bonded sticks from the same hemi-tooth (factor time) were statistically analyzed using a three-way ANOVA and Tukey's test (a = 0.05). RESULTS: Despite a significant decrease in the µTBS values for all groups after 2 years of water storage, the 3200 × 5 group showed higher µTBS values, whereas the 3200 × 10 group showed lower µTBS values for both universal adhesives tested. Although a significant increase in the NL values was observed for all groups after 2 years of water storage, the 3200 × 10 group showed higher NL values than the other groups (p < 0.001). CONCLUSION: Results indicate that light-curing the adhesive layer with 14-16 J/cm2 led to an improvement in the stability of the resin-dentin adhesive interface. A longer exposure time (10 s) coupled with a higher irradiance (3200 mW/cm2) resulted in a greater degree of degradation of the adhesive interface. CLINICAL SIGNIFICANCE: To guarantee better stability of the adhesive interface, clinicians could be preferred a light-cured universal adhesive layer with 14-16 J/cm2. Higher irradiances should be avoided.
Asunto(s)
Recubrimiento Dental Adhesivo , Cementos Dentales , Humanos , Recubrimientos Dentinarios/química , Recubrimiento Dental Adhesivo/métodos , Dentina , Cementos de Resina/química , Agua/química , Resistencia a la Tracción , Ensayo de Materiales , Adhesivos , Resinas Compuestas/químicaRESUMEN
PURPOSE: To evaluate the microtensile bond strength (µTBS) and nanoleakage (NL) of several universal adhesives to eroded dentin (ED), using etch-and-rinse (ER) or self-etch (SE) strategies, and to characterize the surface using two pH cycling models to erode dentin (citric acid and a soft drink). MATERIALS AND METHODS: Molars were eroded either by soft-drink or citric acid cycling, or were left untreated as control (SD). For each surface, the following adhesives were applied: 1. All-Bond Universal; 2. Ambar Universal; 3. Clearfil Universal; 4. Futurabond U; 5. One Coat 7 Universal; 6. Peak Universal Bond; 7. Prime&Bond Elect; 8. Scotchbond Universal; 9. Tetric n-bond Universal, and 10. Xeno Select. After application of the composite, specimens were sectioned into composite-dentin sticks and tested under tension (0.5 mm/min). Selected sticks from each tooth were used to assess NL. The occlusal dentin surfaces after erosive cycling were examined using SEM. Data were analyzed by three-way ANOVA and Tukey's post-hoc test (a = 0.05). RESULTS: In ED, there was no difference in µTBS and NL between ER and SE strategies (p > 0.61). Most µTBS and NL values obtained for ED were, respectively, lower and higher than those for SD (p < 0.01), being worse for citric acid ED (p < 0.001). Citric-acid-eroded dentin showed more enlarged tubules, with partial loss of peritubular dentin when compared to soft-drink eroded dentin. CONCLUSION: The different pH cycling models reduced µTBS and increased NL of the composite/eroded-dentin interface; however, in ED, the performance of the universal adhesives did not depend on the adhesive strategy used.