In vitro cytotoxicity of different dental resin-cements on human cell lines

Abstract

Adhesive resin-cements are increasingly used in modern dentistry. Nevertheless, released substances from resin materials have been shown to cause cellular toxic effects. Disc-shaped specimens from 12 different resin cements and one conventional zinc phosphate cement were prepared and used for direct stimulation of five different human cell lines via transwell cell culture system or in an indirect way using conditioned cell culture media. Cytotoxicity was determined using LDH and BCA assays. All tested cements led to a decrease of cell viability but to a distinct extent depending on cell type, luting material, and cytotoxicity assay. In general, cements exhibited a more pronounced cytotoxicity in direct stimulation experiments compared to stimulations using conditioned media. Interestingly, the conventional zinc phosphate cement showed the lowest impact on cell viability. On cellular level, highest cytotoxic effects were detected in osteoblastic cell lines. All resin cements reduced cell viability of human cells with significant differences depending on cell type and cement material. Especially, osteoblastic cells demonstrated a tremendous increase of cytotoxicity after cement exposure. Although the results of this in vitro study cannot be transferred directly to a clinical setting, it shows that eluted substances from resin cements may disturb osteoblastic homeostasis that in turn could lead to conditions favoring peri-implant bone destruction. Thus, the wide use of resin cements in every clinical situation should be scrutinized. A correct use with complete removal of all cement residues and a sufficient polymerization should be given the utmost attention in clinical usage.

Fig. 1

Cytotoxicity of luting cements after direct stimulation evaluated with the LDH assay. The cytotoxicity (LDH assay) of resin cements and zinc phosphate cement (Hoffmann’s PC) was evaluated in endothelial EA cells (A), immortalized oral epithelial OKF6 cells (B), immortalized PDL cells (C), immortalized human fetal osteoblastic hFOB cells (D), and Saos-2 cells (E) after direct stimulation using a transwell cell culture system for 6 (light gray bars) and 24 h (dark gray bars). Treatment with 1% Triton X-100 was used as positive control (=100% cytotoxicity). Mean ± SEM were calculated and one-way ANOVA and the post hoc Dunnett test were applied (*=P < 0.05)

Fig. 2

Cytotoxicity of luting cements after indirect stimulation evaluated with the LDH assay. The cytotoxicity (LDH assay) of resin cements and zinc phosphate cement (Hoffmann’s PC) was evaluated in endothelial EA cells (A), immortalized oral epithelial OKF6 cells (B), immortalized PDL cells (C), immortalized human fetal osteoblastic hFOB cells (D), and Saos-2 cells (E) after indirect stimulation using conditioned media for 6 (light gray bars) and 24 h (dark gray bars). Treatment with 1% Triton X-100 was used as positive control (=100% cytotoxicity). Mean ± SEM were calculated and one-way ANOVA and the post hoc Dunnett test were applied (*=P < 0.05)

Fig. 3

Cell viability after direct stimulation with luting cements evaluated with the BCA assay. Cell viability (BCA assay) of endothelial EA cells (A), immortalized oral epithelial OKF6 cells (B), immortalized PDL cells (C), immortalized human fetal osteoblastic hFOB cells (D), and Saos-2 cells (E) was evaluated after direct stimulation with resin cements and zinc phosphate cement (Hoffmann’s PC) using a transwell cell culture system for 24 h. Cells treated with cell culture inserts without cement specimen served as control (=100% cell viability). Mean ± SEM were calculated and one-way ANOVA and the post hoc Dunnett test were applied (*=P < 0.05)

Fig. 4

Cell viability after indirect stimulation with luting cements evaluated with the BCA assay. Cell viability (BCA assay) of endothelial EA cells (A), immortalized oral epithelial OKF6 cells (B), immortalized PDL cells (C), immortalized human fetal osteoblastic hFOB cells (D), and Saos-2 cells (E) was evaluated after direct stimulation with resin cements and zinc phosphate cement (Hoffmann’s PC) using conditioned media for 24 h. Cells stimulated with nonconditioned cell culture media served as control (=100% cell viability). Mean ± SEM were calculated and one-way ANOVA and the post hoc Dunnett test were applied (*=P < 0.05)