Introduction: Polymer 3D printing has gained wide applications in the medical field. Polyamide 12 has been used to reconstruct bony defects. Coating its surface with calcium phosphate compounds, as hydroxyapatite, could enhance its bonding with bone. In this study, a simple innovative surface treatment was introduced by applying light-cured cement to coat 3D-printed polyamide 12 specimens with hydroxyapatite.

Methods: Polyamide 12 powder was printed by selective laser sintering to produce 40 disc-shaped specimens (15 mm diameter x 1.5 mm thickness). The specimens were divided randomly into two main groups: 1) a control (untreated) group, where the surface of the specimens was left without any modifications; and 2) a treated group, where the surface of the specimens was coated with hydroxyapatite by a new method using a light-cured dental cement. Each group was further subdivided into two subgroups according to the immersion in simulated body fluid (SBF). The first subgroup was not immersed in SBF and was left as printed, while the second subgroup was immersed in SBF for 15 days (n = 10/subgroup). The surfaces of the control and treated specimens were examined using an environmental scanning electron microscope (SEM) and energy-dispersive X-ray analysis (EDXA) before and after immersion in SBF.

Results: The SEM micrographs of the control 3D-printed polyamide 12 specimens illustrated the agglomerated 3D-printed particles with minimal porosity. Their EDXA revealed the presence of carbon, nitrogen, and oxygen. This surface was not affected by immersion in SBF, as detected by SEM and EDXA. The microstructure of the coated specimens showed deposited clusters of calcium and phosphorus on the surface, in addition to carbon, nitrogen, and oxygen. This coat was stable after immersion, as detected by SEM and EDXA.

Conclusions: Using light-cured cement could be considered a simple method to coat the 3D-printed polyamide 12 with hydroxyapatite.