Physical properties, microbial adhesion, and biocompatibility of additively manufactured ceramic-reinforced resin: Effect of zwitterionic polymer content

Statement of problem

Studies focusing on the effect of zwitterionic polymer content on the physical and biological properties of additively manufactured (AM) ceramic-reinforced resin for dental applications are lacking.

Purpose

The purpose of this in vitro study was to evaluate the effect of different concentrations of 2-methacryloyloxyethyl phosphorylcholine (MPC) on the surface properties, mechanical properties, microbial adhesion, and cellular responses of ceramic-reinforced resins.

Material and methods

Four different groups of AM resins filled with 60 wt% silicate-based composites and varying concentrations of MPC were prepared: 0 wt% (CRN), 1.1 wt% (CRM1), 2.2 wt% (CRM2), and 3.3 wt% (CRM3). Test specimens were fabricated from the resins using digital light processing and were tested for surface roughness (S_a and R_a), flexural strength and modulus, Vickers hardness (HV), and contact angle. The adhesion of oral microbes (Streptococcus mutans and Streptococcus gordonii), cytotoxicity, and cell viability of tested resins were also assessed. One-way analyses of variances and post hoc analyses using the Bonferroni correction and Tukey HSD tests were conducted to detect statistical differences among the groups (α=.05).

Results

CRM2 exhibited significantly lower R_a (P=.020) and S_a (P=.013) values than CRM3, as well as greater flexural strength (P=.002) and modulus (P=.049), HV (P<.001), and contact angle (P=.015). CRM3 showed significantly lower flexural strength and modulus, HV, and contact angle than CRN (all P<.001). Both CRM2 and CRM3 exhibited significantly reduced adhesion of S. gordonii and S. mutans compared with CRN (all P<.001). Regardless of MPC content, the tested resins demonstrated biocompatibility and showed no signs of cytotoxicity.

Conclusions

Incorporating low-concentration MPC into AM ceramic-reinforced resins significantly changed the surface properties, mechanical properties, microbial adhesion, and biocompatibility. CRM2 provided an optimal balance between structural integrity and bacterial-repellent activity while maintaining biocompatibility.