ABSTRACT
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)-1ß, nuclear factor 'kappa-light-chain-enhancer' of activated B-cells (NF-kB), tumour necrosis factor (TNF)-α, 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.
Subject(s)
Blood Cells/immunology , Cytokines/immunology , Dental Implants , Equipment Contamination/prevention & control , Pyrogens/immunology , Blood Cells/metabolism , Culture Techniques , Cytokines/metabolism , Decontamination/methods , Dental Materials , Fas-Associated Death Domain Protein/metabolism , Gene Expression Profiling , Humans , Interleukin-1beta/metabolism , Male , NF-kappa B/metabolism , Pilot Projects , Pyrogens/isolation & purification , Pyrogens/metabolism , Surface Properties , Titanium , Toll-Like Receptor 4/metabolism , Toll-Like Receptor 9/metabolism , Tumor Necrosis Factor-alpha/metabolism , ZirconiumABSTRACT
Interleukin (IL)-8 secreted from osteoblasts and peripheral blood monocytes increases in patients with aseptic hip-implant loss and in patients with mucositis after dental implant insertion. We explored in vitro the possibility of an IL-8-mediated inflammatory response as a consequence of contact between different dental implant surfaces and human blood. Titanium and zirconia implants were incubated in human blood. Nonstimulated blood served as negative, while blood stimulated with bacterial lipopolysaccharides (LPS) served as positive control. After depyrogenization, to examine the possible role of LPS, implants were again submerged in blood. Gene-expression of IL-8 and its receptor was measured by real-time quantitative polymerase chain reaction. In a receptor mediated, but LPS-independent manner, titanium implants led to a more pronounced increase in IL-8 gene expression when compared with zirconia implants. Depyrogenization resulted after 24 h in zirconia implants in decreased IL-8 gene expression. Altered IL-8 expression could indicate aseptic, at least LPS-independent implant loss, which may be an additional feature in the manifestation of peri-implantitis, possibly triggered by microscopically small implant-particles. Hence, opening a new field of investigations to further understand the possible mechanism underlying the manifestation of implant failure.
Subject(s)
Blood Cells/metabolism , Dental Implants/adverse effects , Gene Expression Regulation , Interleukin-8/biosynthesis , Receptors, Interleukin-8/biosynthesis , Zirconium/adverse effects , Female , Humans , Lipopolysaccharides/pharmacology , Male , Zirconium/chemistryABSTRACT
OBJECTIVE: The aim of this in vitro study was to assess lipopolysaccharide microleakage at conical implant-abutment connections of two-piece dental implants in terms of the expression levels of genes involved in lipopolysaccharide-mediated proinflammatory cytokine production. MATERIALS AND METHODS: Two implant systems with conical implant-abutment connections were inoculated with lipopolysaccharide and submerged in human whole blood. Positive-control blood samples (without implants) were stimulated with 4 µg/ml, 2 µg/ml, 200 ng/ml, and 20 ng/ml lipopolysaccharide. Sampling was performed after 1, 8, and 24 h of incubation. Changes of gene expression levels of Toll-like receptor 9, tumor necrosis factor-α, nuclear factor kappa light chain enhancer of activated B cells, interleukin-1ß, and interferon-γ were assessed by real-time quantitative PCR. In addition, protein expression levels of interleukin-6, tumor necrosis factor-α, interleukin-1ß, and interferon-γ were determined by immunoassay. RESULTS: Changes in cytokine expression at the genomic and proteomic levels indicated lipopolysaccharide leakage at the interfaces of both tested implant systems, although some implants showed no sign of microleakage. Any tested concentration of lipopolysaccharide stimulated similar gene expression. CONCLUSIONS: Conical implant-abutment connections of two-piece dental implants do not prevent microleakage on a molecular level. Changes in lipopolysaccharide-induced proinflammatory cytokine gene expression facilitate the detection of lipopolysaccharide microleakage at implant-abutment interfaces. CLINICAL RELEVANCE: Small amounts of lipopolysaccharide released from intra-implant cavities can stimulate a detectable immunological response in human whole blood and may induce alveolar bone resorption via the osteoclast-activating pathway.
