Mechanical and optical properties of additively manufactured denture base resin in different colors modified with antimicrobial substances: An in vitro study

Abstract

Statement of problem

Acrylic denture base resins are subject to colonization by oral and nonoral bacteria, contributing to the onset of denture stomatitis. However, how the addition of antimicrobial substances affects the mechanical and optical properties of additively manufactured denture base resin remains unclear.

Purpose

The purpose of this in vitro study was to investigate the surface roughness, color stainability, and flexural strength of antimicrobial-modified, additively manufactured polymethyl methacrylate (PMMA) denture base resin in tooth and gingiva colors.

Material and methods

Three antibacterial agents, e-poly-L-lysine+ methacryloyloxyethyl phosphorylcholine (e-MP), silver nanoparticles (AG-P), quaternized ammonium monomer (QA-P) synthesized via the reaction of octyl bromide and DMAEMA, were separately incorporated into tooth- or gingiva-colored 3-dimensionally (3D) printable PMMA specimens, simulating an implant-supported overdenture base or the artificial teeth (n=80). Unaltered specimens served as controls. Autopolymerizing acrylic resin was used to attach titanium matrix housings to gingiva-colored specimens. All specimens underwent coffee thermal cycling (CTC) comprising 10 000 cycles between 5 °C and 55 °C, and their color coordinates were measured. Surface roughness, color change (ΔE00), and flexural strength were calculated before and after CTC. The results were analyzed and compared by using ANOVA and the Tukey post hoc test (α=.05).

Results

All antibacterial agent-incorporated specimens showed lower ΔE00 values than the control (P=.001), with eM-P exhibiting the least color change (P=.001). The control group had the highest post-CTC roughness (Ra) values (P<.001), while all test groups demonstrated higher flexural strength than the control (P=.001). CTC had no significant effect on flexural strength (P>.115).

Conclusions

The addition of antimicrobial agents to 3D printable implant overdenture base resin in tooth and gingiva color affected the materials’ surface properties, color stainability, and flexural strength. Smoother surface, lower color stainability, and higher flexural strength were observed with the addition of eM-P.