Available online 5 December 2022

Polymethyl methacrylate (PMMA) is commonly used in dentistry, including as a denture base material. However, the colonization of a PMMA surface by microbial microorganisms could increase the risk of oral diseases such as denture stomatitis and gingivitis. The development of PMMA with antibacterial properties should improve its clinical application, but whether adding ε-poly-L-lysine (ε-PL) and 2-methacryloyloxyethyl phosphorylcholine (MPC) provides antimicrobial effects is unclear.

This in vitro study aimed to develop a novel antibacterial PMMA resin containing the natural nontoxic antibacterial agent ε-PL and the protein repellent agent MPC. The mechanical properties, protein repellency, and antimicrobial activities of the resin were then evaluated.

Different mass fractions of ε-PL and MPC were mixed into PMMA as the experimental groups, with unaltered PMMA as the control group. The flexural strength (n=10) and surface roughness (n=6) of the resulting mixtures were measured to determine their mechanical properties. The antiprotein properties were measured by using the micro bicinchoninic acid method (n=6). The antimicrobial effect of the resin was assessed using live/dead staining (n=6) and methyltransferase (MTT) assays (n=10). According to the variance homogeneity and normal distribution results, 1-way analysis of variance followed by the Tukey honestly significant difference test or the Welch test and the Games-Howell test were used (α=.05 for all tests).

No significant differences were found in the flexural strength values and surface roughness of the specimens containing 1.5% MPC and 1.5% ε-PL compared with those of the control (P>.05). The addition of ε-PL to the PMMA resin alone significantly increased its bactericidal properties (P<.05). Adding both ε-PL and MPC further increased the antibacterial activity of the PMMA resin without increasing protein adhesion more than in the control group.

The incorporation of both ε-PL and MPC into PMMA improved its antibacterial capacity without affecting its mechanical properties and did not increase protein adhesion. Therefore, the novel PMMA fabricated in this study shows promise for dental applications.

Heat-polymerized acrylic resin (Nature; Kunshan) was prepared by following the manufacturer’s instructions. ε-PL powder (P192512; Aladdin) with mass fractions of 0%, 0.75%, 1.5%, 2.25%, and 3% was mixed with PMMA (Table 1).41 After the optimum filling mass fraction of ε-PL was determined according to the flexural strength (FS) results, MPC (BD157718; Bidepharm) was continually incorporated into the PMMA resin at mass fractions of 0%, 0.75%, 1.5%, 2.25%, and 3% (Table 2), as reported previously.

The FS of the PMMA resin with ε-PL is shown in Figure 1. The differences between the 0.75% to 1.5% ε-PL groups and the control group were not significant (P>.05). However, further addition of ε-PL (2.25% to 3%) reduced the FS mechanical properties of the resulting materials (P<.05). Therefore, the 1.5% ε-PL group was selected as the experimental group for further MPC powder addition. The results depicted in Figure 2 indicate that the addition of 0.75% and 1.5% MPC did not affect the FS of the

Porous PMMA surfaces are prone to microbial colonization during use, leading to various oral diseases, including denture stomatitis that has been reported to occur in 20% to 70% of denture wearers.11 Hence, reducing microbial colonization on acrylic resin dentures will reduce the risk of oral diseases and their corresponding systemic complications. In the present study, a novel PMMA resin with antibacterial properties was designed, and its physical properties were investigated. The addition of

Based on the findings of this in vitro study, the following conclusions were drawn:

A novel cationic peptide PMMA resin containing both ε-PL and MPC was developed.

The novel PMMA resin could inhibit the formation of oral biofilms and elicit contact sterilization without compromising the FS and surface roughness and, to some extent, improve the protein-repellent properties compared with those seen with ε-PL addition alone.

© 2022 by the Editorial Council for the Journal of Prosthetic Dentistry.