In vitro effect of light-cure dental adhesive on IL-6 release from LPS-stimulated and unstimulated macrophages

The objective of this study was to measure IL-6 release from LPS-stimulated and -unstimulated macrophages exposed to extracts from fresh and aged Scotchbond Multipurpose Plus™ adhesive disks (5 mm in diameter by 2 mm in thickness) light cured for 10, 20, or 40 s. One set of disks was aged for 16 weeks at 4°C. Extracts were prepared by incubating three disks in 1 mL of serum-free culture medium for 72 h at 37°C. Then macrophages (RAW 264.7) were exposed to the extracts (6.25–50 μL) for 72 h at 37°C/5% CO₂. Supernatants were analyzed for cytokine levels (ELISA), and the monolayer of cells was assessed for viability (MTT assay). Unlike adhesive disk age, curing time affected cell viability. Disk extracts cured for 10 s were more cytotoxic (p < 0.05) than were extracts from 20- or 40-s cured disks. Macrophage release of IL-6 was stimulated significantly (p < 0.01) by extracts from fresh 10-s cured disks, up to 777 pg/mL and by 2 μg/mL of LPS (1174 pg/mL). The LPS response was significantly (p < 0.05) suppressed by 50 μL of extracts, which may be related to the enhanced cytotoxicity exhibited by LPS in combination with extracts. This study has demonstrated the possibility that IL-6 release is stimulated by light-cure dental adhesive applications using 10-s curings. © 2003 Wiley Periodicals, Inc. J Biomed Mater Res 65A: 89–94, 2003