Browsing by Author "Martins Moura, Maria Elisa"

This study aimed at evaluating the microtensile bond strength (MTBS) and fractographic features of dentine-bonded specimens created using universal adhesives applied in etch-and-rinse (ER) or self-etching (SE) mode in combination with modern ion-releasing resin-modified glass-ionomer cement (RMGIC)-basedmaterials after load cycling and artificial saliva aging. Two universal adhesives (FTB: Futurabond M+, VOCO, Germany; SCU: Scotchbond Universal, 3M Oral Care, USA) were used. Composite build-ups were made with conventional nano-filled composite (AURA, SDI, Australia), conventional resin-modified glass ionomer cement (Ionolux VOCO, Germany), or a (RMGIC)-based composite (ACTIVA, Pulpdent, USA). The specimens were divided in three groups and immersed in deionized water for 24 h, load-cycled (350,000 cycles; 3 Hz; 70 N), or load-cycled and cut into matchsticks and finally immersed for 8 months in artificial saliva (AS). The specimens were cut into matchsticks and tested for microtensile bond strength. The results were analyzed statistically using three-way ANOVA and Fisher’s LSD post hoc test (p < 0.05). Fractographic analysis was performed through stereomicroscope and FE-SEM. FTB showed no significant drop in bond strength after aging. Unlike the conventional composite, the two RMGIC-based materials caused no bond strength reduction in SCU after load-cycle aging and after prolonged aging (8 months). The SEM fractographic analysis showed severe degradation, especially with composite applied on dentine bonded with SCU in ER mode; such degradation was less evident with the two GIC-based materials. The dentine-bond longevity may be influenced by the composition rather than the mode of application (ER vs. SE) of the universal adhesives. Moreover, the choice of the restorative material may play an important role on the longevity of the finalrestoration. Indeed, bioactive GIC-based materials may contribute to maintain the bonding performance of simplified universal adhesives over time, especially when these bonding systems are applied in ER mode.

The aim of this study was to evaluate the physicochemical properties of experimental adhesives containing tailored fluoridated calcium phosphate fillers. Five experimental resins were formulated, one contained no calcium phosphate filler (Control) and the other four resins contained 40 wt% of calcium phosphate fillers doped with increasing concentrations of fluoride: adhesives CaP (no fluoride), CaP-2F (2 wt% F), CaP-4F (4 wt% F), and CaP-8F (8 wt% F). Resin specimens were prepared for a three-point bending test to evaluate the elastic modulus (E) and flexural strength (FS) at 24 h and after 2 months of water storage. Disk-shaped specimens were prepared to analyze the water sorption (Ws) according to ISO 4049. The degree of conversion (DC) of the tested resins was also assessed through FTIR. Statistical analysis was performed with ANOVA and Tukey’s test (p < 0.05). The addition of F-CaP particles at 0 and 2 wt% fluoride had no effect on the DC (p > 0.05) compared to the filler-free resin. However, these same experimental resins showed the highest E after water storage. All resins had a significant reduction of the FS after water storage (p < 0.001), but at a lower percentage rate for those experimental resins containing fluoride-free CaP or fluoride-doped CaP- 2F. These latter experimental resins achieved similar Ws to control the filler-free resin. Conversely, those resins containing 4 or 8 wt% fluoride-doped CaP had a significant Ws increase (p < 0.05). In conclusion, the incorporation of calcium phosphate particles without fluoride or with 2 wt% fluoride may represent a promising strategy to generate adhesive resins with specific physicochemical properties. Fluoride incorporation in CaP fillers for dental resin adhesive should be performed at low concentrations in order to avoid excessive water sorption and a decrease of polymerization.

Objectives. To evaluate the bonding ability and nanoleakage of an universal adhesive applied to dentin after zoledronate-containing primer (zol-primer) before and after mechanical load cycling. Materials and Methods. Flat superficial dentin surfaces were exposed on human molars and ascribed to one of the following adhesion procedures (n=6): 1-Adper Single Bond Universal (SBU) applied in etch-and-rinse mode, 2- SBU applied as etch-and-rinse after the application of zol-primer, 3- SBU applied in self-etch strategy, and 4- SBU applied as self-etch after the use of zol-primer. Half of bonded teeth were processed for microtensile bond strength test after 24h and further were cut and surveyed after 200,000 mechanical cycles. Silver-impregnated specimens were assayed for interface nanoleakage by SEM. Data were analyzed by two-way ANOVA and Tukey’s test (p<0.05). Results. At immediate evaluation, the four presented similar bond strengths, whilst both groups bonded with etch-and-rinse technique had significant bond strength reduction after mechanical load (p<0.05), with higher drop for zol-primer group. No negative effects were found for self-etch strategy (p>0.05) in microtensile test. Lower nanoleakage was observed for etch-and-rinse specimens treated with zol-primer. However, noteworthy reduction of adhesive layer thickness was observed with the combination of zol-primer and self-etch strategy. Conclusion. It can be concluded that zol-primer should not be used along with an universal adhesive in etch-and-rinse mode, but its application before self-etch application provides minor alterations.