Water aging stability and antibacterial efficacy of polymethyl methacrylate resin incorporating ε-poly-L-lysine and 2-methacryloyloxyethyl phosphorylcholine.

STATEMENT OF PROBLEM: Polymethyl methacrylate (PMMA) has been commonly used for dental appliances. However, it lacks inherent antibacterial properties, thus increasing the risk of oral diseases such as gingival inflammation and denture stomatitis. Given that PMMA-based appliances should offer prolonged intraoral service, the functionalization of PMMA with antibacterial activity and mechanical integrity after water aging is crucial to improve its clinical applicability. PURPOSE: The purpose of this in vitro study was to evaluate the mechanical characteristics, protein resistance, and antibacterial efficacy of a previously designed novel antibacterial PMMA resin co-incorporating ε-poly-L-lysine (ε-PL) and 2-methacryloyloxyethyl phosphorylcholine (MPC) after 3 months of water aging in artificial saliva to simulate oral conditions. MATERIAL AND METHODS: Four experimental groups were established based on the previous research: PMMA (Control), PMMA containing 1.5% ε-PL, PMMA containing 1.5% MPC, and PMMA containing 1.5% ε-PL and 1.5% MPC. Specimens underwent 3 months of water aging in artificial saliva at 37 °C with weekly solution replacement. The flexural strength (n=12) was determined by a 3-point bend test, and surface topography and roughness were determined via atomic force microscopy (n=6). Protein adsorption was determined by the Micro bicinchoninic acid (BCA) assay, and antibacterial efficacy was measured via live or dead fluorescence staining and metabolic activity assay (n=6). Statistical evaluation used Shapiro-Wilk testing followed by ANOVA and Tukey HSD or Welch and Games-Howell tests (α=.05). RESULTS: The flexural strength, surface topography, and roughness demonstrated no significant intergroup differences (P>.05), indicating that the ε-PL and MPC modifications did not compromise mechanical performance relative to the Control after water aging. In addition, the co-incorporation of 1.5% ε-PL and MPC enhanced the antibacterial efficacy of PMMA without increasing protein adsorption compared with the Control (P<.05). CONCLUSIONS: This novel PMMA resin showed antibacterial efficacy without compromising mechanical integrity and protein adsorption after 3 months of water aging, suggesting its potential for dental clinical application.