Comparative In Vitro Biocompatibility Study of the Two Orthodontic Bonding Materials of Different Types

Abstract

In the present study, the in vitro biocompatibility and cell response to two commonly used orthodontic bonding materials of different types, one self-curing and one light-curing, were examined and compared in indirect and direct cell culture systems. The study was conducted on fibroblasts and macrophages as in vitro models to study the biocompatibility of dental materials. Differences were found between the light- and self-curing material in cytotoxicity and effects on fibroblasts' proliferation in indirect cell culture systems as well as in macrophages response in vitro in both direct and indirect cell culture systems. Based on the obtained results, we can conclude that the self-curing material is generally more cytotoxic for fibroblasts compared to the light-curing, while macrophages' response to these materials was dependent on the macrophages' state and differed between the examined materials. This indicates that more attention should be paid when choosing and applying these materials in practice due to their toxicity to cells. Prior to their use, all aspects should be considered regarding the patient's conditions, associated problems, microenvironment in the oral cavity, etc. Further studies on in vivo models should be conducted to fully understand the potential long-term effects of the use of mentioned materials in orthodontics.

Keywords: biocompatibility; fibroblasts; in vitro; macrophages; orthodontic bonding materials.

Figure 1

The effect of (a) one-, (b) three-, and (c) seven-day extracts of materials on the viability of L929 cells; SC—self-curing material; LC—light-curing material; (*) p < 0.05, (**) p < 0.01, (***) p < 0.001.

Figure 2

The effect of (a) one-, (b) three-, and (c) seven-day extracts of materials on the proliferation of L929 cells; SC—self-curing material; LC—light-curing material; (*) p < 0.05, (**) p < 0.01, (***) p < 0.001.

Figure 3

The effect of the material extracts on metabolic activity of macrophages: (a) effect of SC-material’s extract on LPS-stimulated macrophages, (b) effect of SC-material’s extract on unstimulated macrophages, (c) effect of LC-material’s extract on LPS-stimulated macrophages and (d) effect of LC-material’s extract on unstimulated macrophages; results are presented as mean ± SD (*) p < 0.05, (**) p < 0.01, (***) p < 0.001; SC—self-curing; LC—light-curing material.

Figure 4

The effect of suspension of material particles on the metabolic activity of macrophages: (a) effect of materials on LPS-stimulated macrophages, (b) effect of materials on unstimulated macrophages; results are presented as mean ± SD (*) p < 0.05, (**) p < 0.01, (***) p < 0.001; SC—self-curing; LC—light-curing material.

Figure 5

The microscopic appearance of the macrophages incubated with a suspension of SC (a–h) and LC (i–p) material particles and control media (q–t); phase contrast, objective magnifications 10× (scale bar shows 100 µm) and 20× (scale bar shows 50 µm).