Influence of the Addition of Short Aramid and Polypropylene Fibers in Dental Matrices for Poly(Methyl Methacrylate) Prostheses

Poly(methyl methacrylate) (PMMA) is widely used in various dental applications; however, its stiffness and consequent inherent fragility restrict its performance under masticatory mechanical load, thus damaging dental prostheses. In this study, short aramid and polypropylene (PP) fibers were incorporated into a heat‐polymerizable PMMA matrix to evaluate their effects on mechanical, viscoelastic, and morphological properties. Fibers with lengths of 3 and 5 mm were added in volumetric fractions of 1, 2.5, and 5 vol%. The aramid‐reinforced composites exhibited better performance, with flexural strength increasing from 90.0 ± 17.6 MPa (neat PMMA) to 119.2 ± 2.2 MPa and tensile strength reaching 55.4 ± 4.6 MPa, indicating efficient stress transfer due to improved interfacial adhesion. Dynamic mechanical analysis (DMA) revealed an increase in the storage modulus and a reduction in damping (tan δ ), indicating restricted molecular mobility and improved structural integrity. In contrast, PP reinforced systems exhibited limited efficiency, with flexural strength reduced to 65.3 ± 7.5 MPa despite the increase in tensile modulus, highlighting the detrimental effect of intermediate interfacial compatibility. Overall, the effectiveness of reinforcement depends on fiber properties, interfacial adhesion, geometry, and stress transfer mechanisms, highlighting the importance of fiber‐matrix compatibility for optimizing mechanical and viscoelastic performance and enabling more reliable PMMA‐based dental materials. These findings provide insight into the design of PMMA‐based composites for improved mechanical reliability in dental applications.