Enhanced anti-microbial properties of clear aligner resin containing zwitterionic material

This study evaluated the mechanical and anti-bacterial properties of photocurable clear aligner resin (TC-85) incorporated with zwitterionic material, 2-methacryloyloxyethyl phosphorylcholine (MPC). Three experimental solutions were synthesized using 2-methacryloyloxyethyl phosphorylcholine (MPC) and clear aligner resin (TC-85). A group without any experimental solution served as a control. Specimens were fabricated by adding mixture of solutions to customized mold followed by post-curing procedure. Mechanical properties of the experimental groups were evaluated by tensile strength test, three-point flexural test, stress relaxation and creep test. Biological properties were evaluated through colony forming unit assay, MTT assay, and protein adsorption test. Incorporation of MPC into clear aligner resin achieved protein repellent and anti-microbial capabilities without compromising the mechanical properties. Tensile strength and three-point flexural test along with creep, stress relaxation test did not show significant difference in the mechanical properties. Addition of 1%, 2%, or 3% MPC into clear aligner resin significantly reduced the amount of bovine serum albumin adsorbed and proteins adsorbed from brain heart infusion medium by 1/3 ~ 1/4 that of a control (p < 0.001). The mixture of clear aligner resin with 3% MPC inhibited biofilm growth, reducing CFU counts by 40% compared to that of a control. Incorporating zwitterionic material with clear aligner resin TC-85 demonstrated an anti-biofouling activity while preserving its original mechanical properties, which may be a promising strategy to overcome the limitation of current clear aligner treatment.