Cytotoxicity Comparison of Eight Bulk Fill Restorative Materials

Objectives: Bulk fill composites were developed to fill large preparations as a replacement for amalgam in posterior teeth. As products gain popularity with clinicians, it is important to determine their biocompatibility and cytotoxicity. The purpose of this study was to compare the biocompatibility of six bulk-fill restorative materials to two Giomer concept products using a human fibroblast cell model.
Methods: Pellets were prepared and placed in culture medium to create a surface area to volume ratio of 3 cm²/ml. Materials analyzed included 1) Filtek Bulk Fill Flowable Restorative (3M Espe), 2) Tetric EvoCeram (Ivoclar Vivadent), 3) Filtek Bulk Fill Posterior Restorative (3M Espe), 4) SuperFil SDR Flow (Dentspy Caulk), 5) Vivid Bulk Fill Composite (Pearson Dental Supplies), 6) Tetric EvoFlow Bulk Fill (Ivoclar Vivadent), 7) Beautifil-Bulk Flowable (Shofu Dental Corporation), and 8) Beautifil-Bulk Restorative, (Shofu Dental Corporation). Culture media samples containing pellet extracts were used to treat human dermal fibroblasts (ZenBio, Research Triangle Park, NC) for 24 hours. Cytotoxicity parameters (colorimetric MTT assay) were compared between cells treated with the different extracts and to negative control set to 100% cell viability.
Results: In general, fibroblasts treated with bulk-fill composite material extracts demonstrated significantly higher cell death compared with untreated control (p=0.01, ANOVA single factor test). The first six bulk fill materials listed in Methods demonstrated cell viability between 67 and 79%. The two Giomer concept bulk fill materials, number 7 and 8 as listed in Methods, demonstrated a cell viability lower than 10% compared to control.
Conclusions: The two Giomer-based bulk fill materials showed significantly higher levels of cytotoxicity, possibly due to a higher fluoride level. However, several long-term clinical studies demonstrated the safety of Giomer materials. A different cytotoxicity model could potentially better replicate the physiological situation in vivo, which might produce more clinically relevant results.