Evaluation of New Hollow Sleeve Composites for Direct Post-Core Construction

Abstract

The preset shape and diameter of a prefabricated FRC post rarely follows the anatomy of the root canal. To solve this problem, a new hollow sleeve composite (HSC) system for post-core construction was developed and characterized. A woven fiber was impregnated with two types of resins: Bis-GMA or PMMA, and rolled into cylinders with outer diameter of 2 mm and two different inner diameters, namely 1.2 or 1.5 mm. The commercial i-TFC system was used as a control. Dual-cure resin composite was injected into these sleeves. Additionally, conventional solid fiber post was used as the inner part of the sleeve. The three-point bending test was used to measure the mechanical properties of the specimens and the fracture surface was examined using an electron microscope (SEM). The HSC (1.5 mm, Bis-GMA) revealed a statistically similar flexural modulus but higher flexural strength (437 MPa) compared to i-TFC (239 MPa; ANOVA, p < 0.05). When a fiber post was added inside, all values had a tendency to increase. After hydrothermal accelerated aging, the majority of specimens showed a significant (p < 0.05) decrease in flexural strength and modulus. SEM fracture analysis confirmed that the delamination occurred at the interface between the outer and inner materials. The HSC system provided flexibility but still high mechanical values compared to the commercial system. Thus, this system might offer an alternative practical option for direct post-core construction.

Influence of New Sleeve Composite on Fracture Behavior of Anterior Teeth with Flared Root Canals

“…The new experimental sleeve composite, group C, had a higher loading value than the other groups as well as the highest percentage of favorable fractures. Although group C has a flexural modulus value close to that of group B, it has a higher maximum bending stress value than does group B [ 21 ]. Additionally, group C features multi-directional fibers [ 21 ], which increased Krechel’s factor and improved the reinforcement effect of this material [ 28 ].…”

“…Although group C has a flexural modulus value close to that of group B, it has a higher maximum bending stress value than does group B [ 21 ]. Additionally, group C features multi-directional fibers [ 21 ], which increased Krechel’s factor and improved the reinforcement effect of this material [ 28 ]. Furthermore, as in the group B, the relatively less luting resin used in the new sleeve system contributed to reducing the rate of non-favorable fractures.…”

“…Group C (Sleeve composite group): the sleeve composites were prepared in accordance with the methods of a previous study [ 21 ], and used E-glass sheets (hollow) were adjusted to lengths of 10 mm. The MI post was cut to 15 mm for core restoration.…”

“…Although many fiber posts have featured unidirectional fibers, experimental sleeve composites of three-dimensional woven structures have previously demonstrated a promising performance; this novel structure exhibits the same flexural modulus as thin dentin and can be customized easily into various shapes [ 21 ]. Furthermore, this sleeve composite showed the highest flexural modulus and maximum bending stress in comparison with commercial fiber post systems.…”