Dental implant surface chemistry and energy alter macrophage activation in vitro

Objectives: To determine the effects of dental implant surface chemistry and energy on macrophage activation in vitro.

Materials and methods: Disks made from two clinically used implant materials (titanium [Ti], titanium zirconium alloy [TiZr]) were produced with two different surface treatments (sandblast/acid-etch [SLA], hydrophilic-SLA [modSLA]). Surface roughness, energy, and chemistry were characterized. Primary murine macrophages were isolated from 6- to 8-week-old male C57Bl/6 mice and cultured on test surfaces (Ti SLA, TiZr SLA, Ti modSLA, TiZr modSLA) or control tissue culture polystyrene. mRNA was quantified by quantitative polymerase chain reaction after 24 h of culture. Pro- (IL-1β, IL-6, and TNF-α) and anti-inflammatory (IL-4, IL-10) protein levels were measured by ELISA after 1 or 3 days of culture.

Results: Quantitatively, microroughness was similar on all surfaces. Qualitatively, nanostructures were present on modSLA surfaces that were denser on Ti than on TiZr. modSLA surfaces were determined hydrophilic (high-energy surface) while SLA surfaces were hydrophobic (low-energy surface). Cells on high-energy surfaces had higher levels of mRNA from anti-inflammatory markers characteristic of M2 activation compared to cells on low-energy surfaces. This effect was enhanced on the TiZr surfaces when compared to cells on Ti SLA and Ti modSLA. Macrophages cultured on TiZr SLA and modSLA surfaces released more anti-inflammatory cytokines.

Conclusions: The combination of high-energy and altered surface chemistry present on TiZr modSLA was able to influence macrophages to produce the greatest anti-inflammatory microenvironment and reduce extended pro-inflammatory factor release.