Photoactivated Nano-Graphene Oxide Enhanced Polymethyl Methacrylate: Mechanical and Anti-Biofilm Properties for Orthodontic Applications Publisher Pubmed

Summary: Can adding nano-graphene oxide (nGO) improve orthodontic materials? Research suggests a 1-2% nGO balance mechanical strength and biofilm reduction, but too much nGO weakens them. #Orthodontics #NanoMaterials

Sharifi ME ; Saffar Shahroudi A ; Mirhashemi A ; Pourhajibagher M
Source: Photodiagnosis and Photodynamic Therapy Published:2025

Abstract

Background: 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. Materials and methods: 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 min) prior to biofilm testing. Statistical analysis was performed using one-way ANOVA with Tukey's post-hoc test (P < 0.05). Results: 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). Conclusion: 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. © 2025 The Author(s). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license. http://creativecommons.org/licenses/by-nc-nd/4.0/