To improve the strength of large cavities, different types of fiber reinforcements are used. Polyethylene and glass fibers are two popular options, each with its own set of benefits. This study evaluated the fracture resistance and failure mode of two types of fiber reinforcements: short glass fiber-reinforced composites and ultra-high molecular weight polyethylene fibers in MOD cavities. To evaluate fracture resistance, eighty sound extracted lower third molar teeth were randomly divided into five groups (n = 16): intact teeth (positive control) (R1), unrestored teeth (negative control group) (R2), nanohybrid resin composite group (R3), SFRC group (R4), and Ribbond fibers group (R5). Teeth in groups R2, R3, R4, and R5 received standardized MOD cavities and were restored accordingly. R2 group left unrestored. In group R3, the prepared cavities were restored using a nanohybrid resin composite, in group R4, flowable SFRC was used as a base with nanohybrid composite layered over it. In group R5, a piece of Ribbond meshwork was applied in a U-shaped pattern, followed by the application of nanohybrid composite. Fracture resistance was determined using a universal testing machine. Following fracture, the teeth were examined visually and photographed via camera to determine the mode of failure. Intact teeth had the highest fracture resistance (3201.4 ± 123.4), followed by the SFRC group, the Ribbond fiber group, and the nano-hybrid resin composite group with values of 2132.9 ± 169.5, 2084.5 ± 177.2, and 1576.8 ± 118.3, respectively. Unrestored teeth had the lowest mean fracture resistance value of 354 ± 32.8. There was a statistically significant difference among all groups (P < 0.001), except for SFRC group and Ribbond fibers group which did not differ significantly (p = 0.436). Regarding failure mode results, intact teeth showed the highest repairability rate (75%), followed by the SFRC group (62.5%), the Ribbond fibers group (50%), and the nanohybrid resin composite group (31.3%). The unrestored teeth had the lowest repairability rate (12.5%). In terms of intergroup comparison, there was a significant difference among all groups (p = 0.05). Short glass and polyethylene fiber-reinforced composites have a positive impact on the fracture resistance and repairability of restored MOD cavities.
Fadah et al. (Wed,) studied this question.