Erick Kamiya Coppini

Color Stability and Polymerization Behavior of Direct Esthetic Restorations

OBJECTIVES The current study evaluated the effect of accelerated artificial aging (AAA) on the color stability (CS) and degree of conversion (DC) of nanofilled and nanohybrid resin composites associated to different adhesive systems in direct esthetic restorations. MATERIAL AND METHODS Eighty bovine incisors were used to obtained dentin blocks (4 × 4 × 1 mm). The restorative systems were bonded to the blocks and photoactivated according to the manufacturers instructions. Three adhesive systems were used: Adper Scotchbond Multi-Purpose (conventional of three steps), Tetric N-Bond (conventional of two steps) and ClearFill SE Bond (self-etching). Also, two composites were used: Filtek Z350 XT (nanofilled) and IPS Empress Direct (nanohybrid). The restorations were made using a silicone mold placed on top of the prepared dentin blocks (N = 10). CS was measured after 300 hours of AAA by means of ultraviolet light using a spectrophotometer and CIE L*a*b* parameters on the top surface of the composite and at the bonded interface. The DC was performed using Fourier transform infrared spectroscopy (N = 10). Data were analyzed using two-way analysis of variance and Tukeys test (α = 0.05). RESULTS The adhesive systems had no significant influence on the color stability (ΔE) of either the restoration surface (α = 0.90) or the bonded interface (α = 0.78). However, composite influenced the color as measured by ΔE and isolated coordinates (α < 0.001). The nanohybrid composite showed increased DC values (67%) compared with the nanofilled (61%) with statistically significant differences (α < 0.001). CONCLUSIONS The adhesive system did not affect the final color of direct esthetic restorations. The nanohybrid composite demonstrated a higher DC and increased color stability after AAA compared to the nanofilled composite. CLINICAL SIGNIFICANCE The long-term color stability of composite restorations is a critical aspect of esthetic restorative procedures. Optimal Polymerization behavior of resin composite as indicated by the degree of conversion also influence on the color stability after artificial aging of composite restorations.

Active application of primer acid on acid-treated enamel: Influence on the bond effectiveness of self-etch adhesives systems

Aim: Evaluate the composite‐to‐enamel bond after passive or active application of self‐etching primer systems on polished or pre‐etched enamel with phosphoric acid. Materials and Methods: Two self‐etch adhesives systems (SEAS) were used: Clearfil SE Bond and Easy Bond. Third human molars were divided into 8 groups (N = 10). The crown of each tooth was sectioned into halves and the mesial/distal surfaces were used. The adhesives were actively or passively applied on enamel with or without prior phosphoric‐acid etching. Resin composite cylinders were built after adhesive application. After stored in relative humidity for 24 hr/37°C the specimens were subjected to microshear test in universal testing a machine at a crosshead speed of 0.5 mm/minute. The results were analyzed with three‐way ANOVA and the Tukey test. The enamel‐etching pattern was evaluated under SEM. Results: The 2‐step SEAS system presented significantly higher adhesive bond strength means (47.37 MPa) than the 1‐step (36.87 MPa). A poor enamel‐ etching pattern was observed in active mode showing irregular and short resin tags, however there was not compromised the bond strength. Conclusion: Active or passive application produced similar values of bond strength to enamel regardless of enamel pretreatment and type of SEAS.

Influence of Fluorescent Dye on Physical-Mechanical Properties of Luting Cements for Confocal Microscopy Analysis

Aims: To evaluate the influence of a fluorescent dye (rhodamine B) on the physical and mechanical properties of three different luting cements: a conventional adhesive luting cement (RelyX ARC, 3M/ESPE), a self‐adhesive luting cement (RelyX U‐200, 3M/ESPE), and a self‐etching and self‐adhesive luting cement (SeT PP, SDI). Materials and Methods: The cements were mixed with 0.03 wt% rhodamine B, formed into bar‐shaped specimens (n = 10), and light cured using an LED curing unit (Radii, SDI) with a radiant exposure of 32 J/cm2. The Knoop hardness (KHN), flexural strength (FS), and Youngs modulus (YM) analyses were evaluated after storage for 24 h. Results: Outcomes were subjected to two‐way ANOVA and Tukeys test (P = 0.05) for multiple comparisons. No significant differences in FS or YM were observed among the tested groups (P ≥ 0.05); the addition of rhodamine B increased the hardness of the luting cements tested. Conclusion: The addition of a fluorescent agent at 0.03 wt% concentration does not negatively affect the physical–mechanical properties of the luting cement polymerization behavior. Microsc. Res. Tech. 77:986–988, 2014.