Diametral tensile strength on restorative dental composite: Contrasting results from the addition of PMMA fiber filler

Dental composite as restorative materials is mostly used because of its aesthetics, good adhesive properties, and minimal preparation. However, almost half of the composite restoration failure can be caused by a crack, which is triggered from the use of irregular and angulated silica particles as composite fillers. These also tend to decrease the Diametral Tensile Strength (DTS) value as one of the mechanical properties. This study aims to compare the DTS value of dental composite with and without PMMA fiber. Twenty samples were divided into two groups, dental composite without PMMA fiber filler as the control group (70% silica particle filler) and dental composite with PMMA fiber filler (65% silica particle filler, 5% PMMA fiber filler). The DTS test was carried out using the Universal Testing Machine (Lloyd) with 5.6 N load and 1 mm/minute crosshead speed. Then, the fracture surface of the samples was evaluated using Scanning Electron Microscope (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) using JEOL JED-2300. The result of DTS value on the control group was 38.74±3.05 MPa while the fiber group was 28.39±3.21 MPa, which is supported by SEM observations that revealed the presence of the nanofiber on the fiber group with the percentage of the silica concentration (±30%) on the EDS observations was lower than the control group. So, it can be concluded that the fiber reinforcement has lowered silica concentration, which decreased DTS value than the control group. Further research shall investigate the fiber diameter, phase of crystallization, binding interaction between silica and fiber as filler, and also the optical properties akin to natural tooth appearances on the cervical region.