IADR Abstract Archives
Investigating Short-Term Failures of Percutaneous Titanium Implants Using Synchrotron Radiation
Objectives: To investigate the chemistry and distribution of products released from commercially pure Ti implants used in bone anchored hearing aids (BAHs). To study the associated immunological response and to assess any correlative relationships between these features.
Methods: Peri-implant inflamed mixed connective tissues associated with early failures to osseointegrate (<6 weeks) were obtained at time of implant loss (n=6). Tissue sections were prepared to 5µm and mounted onto ultra-pure fused silica slides. Immediately adjacent serials sections were kept for H&E and immunological stains. Samples were interrogated using X-ray fluorescence spectroscopy (XRF) and X-ray absorption near-edge structure (XANES) at beamline I18, Diamond Light Source. A 5.7keV incident X-ray beam was focused to achieve a 3µm resolution with 100ms irradiance times collecting data with a Si-drift detector (Hitachi, Japan). Ti distribution maps were extracted from data and their associated chemistry analysed.
Results: Ti features were observed heterogeneously throughout all tissues interrogated and showed highly variable sizes ranges from single pixels (<3µm) to large agglomerated features (>50µm). Immunohistochemical stains revealed large inflammatory regions consisted of predominately CD68 (monocytes/ macrophages) and CD3 (T-lymphocytes) positive cells. Extensive XANES analysis conducted revealed only a disordered TiO2 species likely representative of the BAH surface oxide. Correlative analysis revealed a positive relation between large cellular infiltrates and regions with high concentrations of Ti. Smaller isolated Ti features were also observed sporadically without an associated cellular response.
Conclusions: A heterogenous distribution of disordered TiO2 was observed in all tissues interrogated. Immunohistochemical analysis revealed inflammatory infiltrates dominated by CD68 and CD3 positive cells were correlated with regions containing high concentrations of Ti. Whilst this observation does not prove a direct causal relationship it suggests that these stimuli may have an immunomodulatory effect that could influence osseointegration.
Methods: Peri-implant inflamed mixed connective tissues associated with early failures to osseointegrate (<6 weeks) were obtained at time of implant loss (n=6). Tissue sections were prepared to 5µm and mounted onto ultra-pure fused silica slides. Immediately adjacent serials sections were kept for H&E and immunological stains. Samples were interrogated using X-ray fluorescence spectroscopy (XRF) and X-ray absorption near-edge structure (XANES) at beamline I18, Diamond Light Source. A 5.7keV incident X-ray beam was focused to achieve a 3µm resolution with 100ms irradiance times collecting data with a Si-drift detector (Hitachi, Japan). Ti distribution maps were extracted from data and their associated chemistry analysed.
Results: Ti features were observed heterogeneously throughout all tissues interrogated and showed highly variable sizes ranges from single pixels (<3µm) to large agglomerated features (>50µm). Immunohistochemical stains revealed large inflammatory regions consisted of predominately CD68 (monocytes/ macrophages) and CD3 (T-lymphocytes) positive cells. Extensive XANES analysis conducted revealed only a disordered TiO2 species likely representative of the BAH surface oxide. Correlative analysis revealed a positive relation between large cellular infiltrates and regions with high concentrations of Ti. Smaller isolated Ti features were also observed sporadically without an associated cellular response.
Conclusions: A heterogenous distribution of disordered TiO2 was observed in all tissues interrogated. Immunohistochemical analysis revealed inflammatory infiltrates dominated by CD68 and CD3 positive cells were correlated with regions containing high concentrations of Ti. Whilst this observation does not prove a direct causal relationship it suggests that these stimuli may have an immunomodulatory effect that could influence osseointegration.