Surface contamination of dental implants assessed by gene expression analysis in a whole-blood in vitro assay. A preliminary study

Aim We aimed at evaluating pyrogen contamination of dental implants made of titanium and zirconia by using gene expression analysis in a whole-blood in vitro assay. Material and Methods Titanium and zirconia implants (five each) were incubated in human whole blood. Samples were assayed for gene expression levels of toll-like receptor 4 (TLR4), TLR9, interleukin (IL)-1 beta, nuclear factor kappa-light-chain-enhancer of activated B-cells (NF-kB), tumour necrosis factor (TNF)-a, and Fas-associated protein with death domain (FADD) as indicators of surface contamination resulting in lipopolysaccharides (LPS)-stimulated TLR- or TNF-mediated immune responses. Gene expression was assayed using real-time quantitative polymerase chain reaction (RT-qPCR). Non-stimulated blood from the same donor served as a negative control, and blood stimulated with LPS served as a positive control. After dry-heat treatment with dry heat, all implants were re-analysed as described above. Results Both implant systems contained surface contaminants evoking a pro-inflammatory response similar to that induced by LPS. After dry-heat treatment, gene expression was significantly decreased to levels similar to those of negative control samples. Conclusions The results demonstrated LPS-like surface-bound contaminants in both tested implant systems. Depyrogenation with dry heat seems to be an effective means of reducing such contamination in dental implants.