Methods: SIL dishes were subjected to a glow discharge treatment. A number of dishes were Ti-coated by radiofrequency magnetron-sputtering, and characterized with Rutherford backscattering spectrometry (RBS), and X-ray photoelectron spectroscopy (XPS). Osteoblast-like cells were cultured on the dishes, and were given: A-no stretching; B-60 minutes 4% cyclic stretching; C-60 minutes stretching on Ti; D-intermittent stretching (4 times 15 minutes). Up to day 24, proliferation, alkaline phosphatase (ALP) activity, and calcium (Ca) content were analysed. Specimens were observed with scanning electron microscopy (SEM), and confocal laser scanning microscopy (CLSM). All samples were present in 6-fold, and data were analyzed with ANOVA/Tukey tests.
Results: The coating was 50 nm thick, did not delaminate, and contained Ti:O as 1:1. Cell detachment regularly was observed on SIL, but never on Ti-coatings. Proliferation significantly increased in response to Ti-coatings and to mechanical stretching, with intermittent strain showing the highest cell numbers. ALP activity was lower after loading, and on Ti-coatings. Lowest levels of Ca were found on Ti coatings, whereas highest levels occurred after intermittent strain. SEM revealed the abundant presence of collagen fibers and calcium phosphate depositions. CLSM confirmed that matrix formation was lower on Ti-coated substrates.
Conclusions: 1-Osteoblast-like cells demonstrate increased responses to enlarged amounts of stimuli vs. prolonged stimuli. 2-Results obtained on silicone rubber substrates, can not be translated towards the situation around metallic implant materials.