Effects of adding graphene fibers to polymethyl methacrylate on biocompatibility and surface characterization.

Statement of problem: Interim fixed prostheses are used provisionally to provide esthetics and maintain function until placement of the definitive prosthesis. Polymethyl methacrylate (PMMA) has been widely used as an interim material but has mechanical limitations that can be improved with the addition of nanomaterials such as graphene fibers (PMMA-G). However, studies on the biocompatibility of this material are lacking.

Purpose: The purpose of this in vitro study was to determine the biocompatibility and cytotoxic effects of PMMA compared with PMMA-G in periodontal ligament stem cells (PDLSCs) by measuring the viability and cell apoptosis of those cells subjected to different concentrations of both compounds by elution, as well as the surface characterization of these materials.

Material and methods: Sterile Ø20×15-mm specimens of PMMA and PMMA-G were covered with Dulbecco modified Eagle medium for 24 hours to be the subsequent eluent. PDLSCs were seeded in 6 plates of 96 wells at dilutions 1/1, 1/2, 1/4, and 1/8 for each material. Three plates for the cell viability assay with MTT and 3 plates for the cell apoptosis assay with Hoechst 33342 staining were used in turn to subdivide the measurements at 24, 48, and 72 hours. The Kruskal-Wallis test was used to compare the data obtained in the different dilutions at different times and the Mann-Whitney test to compare both materials. Topography and wetting were analyzed for surface characterization. The Student t test of paired measurements was used to compare the different surfaces for each parameter (α=.05 for all tests).

Results: In both the cell viability assay (MTT) and the cell apoptosis assay, the test did not identify statistically significant differences in PMMA and PMMA-G with respect to the control group in the different dilutions at different times (P>.05). When comparing both materials, no statistically significant differences (P=.268) were found in either trial. PMMA-G had lower roughness and kurtosis and higher wetting than PMMA.

Conclusions: Both PMMA and PMMA-G were found to be biocompatible materials with no significant differences between them after cell viability and apoptosis testing. PMMA-G had higher wettability and lower roughness than PMMA.