Evaluating flexure properties, hardness, roughness and microleakage of high-strength injectable dental composite: an in vitro study

Abstract

Background Recently, a new generation of high-strength fowable dental composites has been introduced by manufacturers. The manufacturers claim that these materials have enhanced mechanical and physical properties and are suitable for use in a wide range of direct anterior and posterior restorations, even in high-stress bearing areas. Aim The objective of this study was to assess certain physical and mechanical properties of these recently introduced high-strength fowable composites in comparison to conventional multipurpose dental composites. Methods Four types of high-strength fowable composites (Genial Universal FLO, Gaenial Universal Injectable, Beautifl Injectable, and Beautifl Flow Plus) were tested in experimental groups, while a nanohybrid conventional composite (Filtek Z350 XT) was used as the control. For fexure properties, ten rectangular samples (2×2×25 mm) were prepared from each composite material and subjected to 5000 cycles of thermocycling. Samples were then subjected to fexural strength testing using the universal testing machine. Another twenty disc-shaped specimens of dimensions (5 mm diameter×2 mm thickness) were fabricated from each composite material for surface roughness (Ra) (n=10) and hardness (VHN) test (n=10). All samples underwent 5000 cycles of thermocycling before testing. Additionally, microleakage testing was conducted on 60 standardized class V cavities prepared on molar teeth and divided randomly into fve groups (n=12). Cavities were then flled with composite according to the manufacturer’s instructions and subjected to thermocycling for 1000 cycles before testing using methylene blue solution and a stereomicroscope. Results All tested materials were comparable to the control group in terms of fexural strength and surface roughness (p>0.05), with Gaenial Universal FLO exhibiting signifcantly higher fexural strength compared to the other fowable composite materials tested. However, all tested materials demonstrated signifcantly lower elastic modulus and surface hardness than the control group (p<0.05). The control group exhibited higher microleakage scores, while the lowest scores were observed in the Gaenial Universal FLO material (p<0.05) Conclusion The physical and mechanical behaviors of the diferent high-strength fowable composites investigated in this study varied. Some of these materials may serve as suitable alternatives to conventional composites in specifc applications, emphasizing the importance of dentists being familiar with material properties before making material selections.