Influence of white pigment on the properties of polylactic acid scaffolds for 3D printing: in vitro and in vivo analysis

Polylactic acid (PLA) is a widely used polymer in tissue engineering due to its biocompatibility, biodegradability, and easy processing. However, to this day, white and translucent PLA are used indistinctly in the field though there are several studies that establish changes in the materials properties in the presence or absence of pigments. Here, we proposed an in vitro and in vivo methodology with 3D-printed scaffolds to further examine how their surface structure and cellular response vary. We observed surface structure, pore size, and porosity, and conducted in vitro cell assays. In vivo, male Wistar rats were used to collect histological samples and analyze the inflammatory response. DS revealed that the translucent scaffold contained 61.37 ± 3.96 wt% carbon and 38.64 ± 3.95 wt% oxygen and measured 8.96 ± 0.85 mm in diameter and 0.97 ± 0.3 mm in width, while the white scaffold showed 56.28 ± 1.82 wt% carbon and 43.66 ± 1.92 wt% oxygen and measured a diameter of 9.15 ± 0.56 mm and width of 1.01 ± 0.2 mm. The white PLA scaffold showed better structure and 67% porosity with larger pores compared to the translucent scaffold, which had 53% porosity and smaller pores. Both types were accepted by fetal osteoblast cells, but the translucent scaffold was associated with large foreign-body cells. Moreover, PLA's pigment increases surface tension, which helps the material maintain its shape as it cools and produces a better surface structure.