Photoactivated nano-graphene oxide enhanced polymethyl methacrylate: Mechanical and anti-biofilm properties for orthodontic applications
Year: 2025
Type: article
Abstract: • Photoactivated nano-graphene oxide (nGO) composites maintain the mechanical properties of polymethyl methacrylate (PMMA) while providing significant anti-biofilm functionality. • Under blue light, nGO exerts a potent photodynamic effect, leading to a dose-dependent reduction in Streptococcus mutans viability. • A 2% nGO loading was found to be optimal, achieving the highest microhardness and enhancing surface durability for orthodontic appliances. • This approach enables on-demand biofilm control without compromising the structural integrity of the material. This study investigated the concentration-dependent effects of photoactivated nano-graphene oxide (nGO) on the mechanical properties and anti-biofilm efficacy of polymethyl methacrylate (PMMA) for orthodontic applications, aiming to mitigate white spot lesions. Sixty PMMA specimens were fabricated with nGO loadings of 0% (control), 1%, 2%, 5%, and 10% by weight (n=12/group). Rod-shaped samples (n=30) were evaluated for three-point flexural strength, while disc-shaped samples (n=30) underwent vickers microhardness testing and anti-biofilm assessment against Streptococcus mutans biofilms. All samples were photoactivated (380-515 nm, 1500 mW/cm², 5 minutes) prior to biofilm testing. Statistical analysis was performed using one-way ANOVA with Tukey's post-hoc test (P < 0.05). The 1% nGO composite demonstrated optimal flexural strength (72.04 ± 18.85 MPa), comparable to control (70.90 ± 22.88 MPa), while the 10% nGO group showed catastrophic mechanical failure (18.81 ± 15.43 MPa; P < 0.001). Peak microhardness was observed at 2% nGO (20.08 ± 1.06 VHN vs 17.03 ± 2.50 VHN control). Anti-biofilm activity revealed a dose-dependent response, with bacterial reduction increasing from 42.9% (1% nGO) to 90.1% (10% nGO). Photoactivated nGO-PMMA composites exhibit a critical trade-off between mechanical and anti-biofilm properties. The 1-2% nGO provide the optimal balance, maintaining ISO-compliant mechanical performance while delivering clinically significant biofilm reduction. Concentrations exceeding 5%, despite superior anti-biofilm efficacy, compromise mechanical integrity below clinically acceptable thresholds for orthodontic devices.
Authors: Mohammad Emad Sharifi, Atefe Saffar Shahroudi, Amirhossein Mirhashemi, Maryam Pourhajibagher
Institution: Tehran University of Medical Sciences
Language: English
Subfield: Orthodontics
Field: Dentistry
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $2,610
OpenAlex ID: W4416625152