Microleakage in class II restorations of two bulk fill resin composites and a conventional nanohybrid resin composite: an in vitro study at 10,000 thermocycles

Abstract

Background The contraction presented by resin composites causes an increase in stress at the tooth-resin interface, causing micro-gaps that allow microleakage. This study aims to evaluate the degree of in vitro marginal microleakage in class II restorations with two bulk fill resin composites compared to a conventional nanohybrid resin composite. Methods The present study was an in vitro experimental design. A total of 30 standardized class II cavities were prepared in 15 human molars (mesially and distally). These cavities were later distributed in 3 groups according to the type of resin. Groups A and B were restored with bulk fill resin composites (Filtek—3 M/ESPE and Tetric N-Ceram—Ivoclar/Vivadent respectively) in a single increment of 4 mm. Group C was restored with the Filtek Z350 XT – 3 M/ESPE resin composite and two increments of 2 mm. Later, the restorations were subjected to 10,000 thermocycles between 5 °C to 55 °C and immersed in a silver nitrate solution (1 M for 24 h). The crowns were then sectioned mesiodistally and observed under the stereomicroscope to determine the degree of marginal microleakage at the occlusal and cervical areas. The results were analyzed with the Kruskal–Wallis and the Mann–Whitney U statistical tests. Results There were no statistically significant differences regarding the degree of microleakage between the three types of resin composites in the occlusal and cervical areas (p > 0.05). Similarly, there were no significant differences after comparing each resin type in its occlusal and cervical area (p > 0.05). Conclusion Filtek Bulk Fill and Tetric N-Ceram Bulk Fill resin composites showed no statistically significant differences with the conventional nanohybrid resin composite Filtek Z350XT at both occlusal and cervical areas.

Adhesive Strength in Dentin Conditioned with 18% Ethylenediaminetetraacetic Acid versus 35% Phosphoric Acid: In Vitro Study with 1-Year Artificial Aging

“…In the present study, a technique of 10,000 thermal cycles equivalent to 1 year of clinical aging was applied. In contrast, Imbery et al [ 13 ], Kim et al [ 6 ] and Deng et al [ 32 ] used sodium hypochlorite (NaClO) between 10% and 12% for 1 to 3 h as a method of artificial aging, which is equivalent to 60,000 thermal cycles (6 years of aging) [ 29 , 33 ]. It should be noted that these differences could also be associated with other factors, such as the use of a different type of resin composite, the pH of the adhesive and the use of a higher light intensity (1200 mW/cm 2 ), for curing the adhesive and resin composite system.…”

“…Subsequently, 10,000 thermocycles between 5 +/− 2 °C and 55 +/− 2 °C were applied to all sample units. The exposure to each bath was 30 s, and the transfer time between baths was 10 s. [ 29 ]…”

In Vitro Color Stability Evaluation of Three Polished and Unpolished Nanohybrid Resin Composites Immersed in a 0.12% Chlorhexidine-Based Mouthwash at Different Times

“…The esthetic expectations of patients have increased over the years, and this has led to an increase in the clinical use of resin composites [ 1 , 2 , 3 , 4 ].…”

“…The resin composites consist of a resin matrix and inorganic particles that have been chemically and physically designed to meet esthetic requirements. For this reason, they come in different colors or shades that resemble enamel and dentin [ 2 , 3 , 4 ]. Among its advantages as a restorative material is its chromatic similarity to teeth.…”

“…In recent years, there have been improvements in resin composite formulation mainly through the use of nanotechnology. Nanohybrid resin composites contain nanoscale inorganic particles dispersed in the resin matrix that result in a more polished surface, less shrinkage, color stability and improved esthetics [ 3 , 4 , 7 ]. However, despite the advancement in resin composite technology, a major problem is color stability in the oral cavity [ 1 , 5 , 8 ].…”