Behaviour of human osteoblastic cells cultured on plasma-sprayed titanium implants in the presence of nicotine

Objectives: The aim of this work was to analyse the behaviour of human bone marrow osteoblastic cells cultured on the surface of routinely used plasma-sprayed titanium implants in the presence of plasmatic and salivary nicotine levels reported in smokers. Material and methods: Human bone marrow cells (first subculture) were seeded on titanium implants and cultured for 35 days in alpha-minimal essential medium supplemented with 10% foetal bovine serum, 50 mu g/ml ascorbic acid, 10 mM beta-glycerophosphate and 10 nM dexamethasone. Seeded implants were exposed to nicotine, 10-1 mg/ml, from days 1 to 35, and characterized for cell morphology, viability/proliferation, alkaline phosphatase (ALP) activity and matrix mineralization. Results: Low levels of nicotine, 10 and 50 ng/ml, representative of the plasma concentrations reported in smokers, did not cause significant effects in the cell behaviour, although a small induction in cell growth and functional activity appeared to occur. Higher nicotine levels, 0.01-1 mg/ml, within those attained in saliva through tobacco use, caused evident dose-dependent effects in osteoblastic cell behaviour, i.e., a stimulatory effect in cell growth, ALP activity and matrix mineralization, at concentrations up to 0.2 mg/ml, and a deleterious effect at higher levels. Conclusions: Considering the high tissue diffusion potential of nicotine, the results suggest the possibility of a direct modulation of the osteoblast activity as a contributing factor to the overall effect of nicotine in the bone microenvironment around dental implants.