Biological glass coating on ceramic materials: in vitro evaluation using primary osteoblast cultures from healthy and osteopenic rat bone

ZrO2 and Al2O3 substrates were successfully coated by a double layer of a s ilica-based glass named RKKP, using a low-cost firing technique. RKKP is a glass well known for its bioactivity; therefore, a RKKP coating on Al2O3 or ZrO2, allows to combine the excellent mechanical properties of these stron g ceramic substrates with its bioactivity. ZrO2 samples were easily coated using a double layer of RKKP by a simple enamelling technique. To accommoda te the thermal expansion coefficient mismatch between Al2O3 and RKKP, this substrate was coated using a multilayered composite approach. All of the co atings were characterised from a morphological and compositional point of v iew, and an extensive biological evaluation was performed using fresh rat o steoblasts. Osteoblast primary Cultures were derived from the trabecular bo ne of femoral condyles harvested from intact (NB) and osteopenic (OB) rats. After characterisation of their phenotype, osteoblasts were seeded on mate rial samples of ZrO2 or Al2O3 coated with RKKP, and cultured for 7 days. Ce ll proliferation (MTT test) and cell differentiation (alkaline phosphatase activity) were evaluated at the end of the experiment, to assess osteoblast behaviour in the presence of biomaterials and determine if the results wer e related to the host bone quality. Results of both materials showed a good level of biocompatibility. In particular, MTT significant higher values we re detected in NB cultures on ZrO2-RKKP samples; ALP activity significantly increased in NB cultures on Al2O3-RKKP and in OB cultures on both coated s amples. (C) 2001 Elsevier Science Ltd. All rights reserved.