Biocompatibility of 3D-printed Composite Materials

Objectives: 3D printing is finding promising applications in dentistry. 3D printed resin materials have recently been introduced in the market as temporary materials for crowns (TC): 3Delta temp (DeltaMed), NextDent C&B MFH, Freeprint temp (Detax), Temp print (GC Corporation). This in-vitro study aimed to investigate the biological effect on human oral keratinocytes (HOKs) of 3D printed resin materials in comparison to materials that have longer been used for TC: Luxatemp (Dmg) and Grandio disc (Voco).

Methods: Disc-shaped specimens of the different materials, having a diameter of 20 mm and 1.5 mm thickness, were printed with a D20II 3D printer (Rapidshape, Heimsheim, Germany). Postprocessing was carried out according to the manufacturer's specifications. Cad/Cam specimens were milled out of Grandio disc with a MCX5 machine (Sirona, Bensheim, Germany). Luxatemp specimens were manufactured directly in a mold. Specimens were lightly ground on a P1400 silicon carbide paper. HOKs were cultured in 24-wells in keratinocyte growth medium-2 (KGM-2). The specimens were immersed in KGM-2 and these elutions were used to further culture HOKs. Cytotoxicity was examined by XTT assay in four time-points (Day 1, 2, 3 and 6). The adhesion of keratinocytes to the surface of polished discs of the different materials was evaluated through SEM. Mann-Whitney-Test was used for statistical analysis.
Results: All materials tested caused in time increasing cytotoxic effects on the investigated keratinocytes. Eluates of the Cad/Cam specimens showed the least cytotoxic effect throughout the observation period. The results were statistically significant (p-values <0.05). Grandio disc was the only material showing a survival of the cells after 6 days. Luxatemp presented a lower cytotoxic effect compared to all the 3D-printed materials.

Conclusions: Cad/Cam and conventional polymers present a lower cytotoxicity than 3D printed resin materials, probably due to a lower elution of residual monomers.