Evaluating the Mechanical Properties of 3D-Printed Denture Base Resin Modified with Grapefruit Seed Skin Particles

Background: Polymethyl methacrylate (PMMA) remains the primary material for denture bases. Despite being the standard denture base material, PMMA often suffers from mechanical weaknesses and microbial colonization, leading to compromised denture performance over time. Grapefruit seed skin particles (GSSPs) are rich in flavonoids that have antifungal activity. When these materials are incorporated into denture base acrylic resins, they have enhanced antifungal properties but can also affect the material’s strength and durability.

Purpose: This study aimed to investigate the impacts of incorporating different concentrations of GSSPs into 3D-printed resin on particle interactions with resin and the mechanical strength of the resulting composites.

Methods: A total of 90 specimens were fabricated using a Digital Light Processing (DLP) 3D printer. A total of 30 specimens were used for flexural strength, 30 specimens were used for tensile strength, and 30 specimens were tested for surface hardness. GSSPs were added at 0.0, 5.0, and 7.0 wt.% concentrations, which were established to be the appropriate ranges through pilot experiments. The flexural and tensile strengths were evaluated with a universal testing machine, whereas the surface hardness was measured using a Durometer Shore Hardness Scale. Fourier Transform Infrared Spectroscopy (FTIR) was used to determine the interactions between the resin and the particles and the degree of conversion (DC). Field emission scanning electron microscopy (FE-SEM) was employed to assess the particle distribution, porosity, and fracture patterns.

Results: In comparison with the control group, the GSSP-einforced specimens presented significant improvements in DC, flexural strength, tensile strength, and hardness. FE-SEM images revealed reduced porosity at higher concentrations, with evidence of brittle fracture characteristics.

Conclusions: Incorporating GSSPs into 3D-printed denture base resin improves the mechanical properties, suggesting a promising approach for enhancing the performance of denture base materials.