A comparative study of various assays for in vitro biocompatibility assessment of experimental zirconia

摘要

Four different assays, monitoring different aspects of cellular activity were used to assess the in vitro biocompatibility of three experimental zirconias (ZrO_2-A, ZrO_2-B and ZrO_2-C) with minor chemical modifications. The assays used were Neutral red uptake, MTT, alamarBlue and a live/dead cell stain. No cytotoxic effect was detected in the extracts from the three test zirconia samples using Neutral red uptake and MTT assays. However, a variation in response was observed in cells cultured directly on the surface of three test zirconias using the alamarBlue assay. The three test zirconia substrates showed no toxic effect after 1 and 2 days in culture. After 5 days in direct contact with the experimental zirconias, a significant decrease in cell activity was observed on sample ZrO_2-B, which was confirmed by fluorescence microscopy, showing a layer of dead cells (stained by thidium homodimer-1) on the sample surface. The findings from this study indicated that great care is required when selecting assays to assess the biocompatibility of modified materials with regard to the type and sensitivity of the assay and culture conditions.