Biomaterials are divided in two main categories, according to the tissue response:

Bioinert: this terms refers to any material that - when implanted in humans - has the smallest possible response for the surrounding tissue.

Bioactive: the bioactivity refers to materials that - when implanted in humans- they interact with the surrounding bones and sometimes even with the soft tissues.

In general, the metals are usually bioinert materials, the ceramics could be bioinert, bioactive or biodissolved and the polymers could be either bioactive or biodissolved.

Biomaterilas should be biocompatible with the host organism i.e. they shouldn't develop inflammation, they shouldn't be cytotoxic, carcinogenetic and allergiogenic. Furthermore, they shouldn't be aborted from the organism.

Mechanical properties: The mechanical properties of the biomaterials are of great importance. There properties should be similar with the tissue to be replaced. The mechanical properties include resistant in pressure, in tension and in rotation.

Sterilization: The implanted materials should be easily sterilized for the avoidance of any contamination.

Time of implantation - Temparature changes: The material should be implanted in a few minutes, so as to eliminate any possible contamination. Moreover, there should be no temperature changes in order not to damage the surrounding tissues.

References

Johnna S. Temenos, Antonios G. Mikos. "Injectable biodegradable materials for orthopedic tissue engineering". Biomaterials 21 (2000) 405 - 2412.

H. Kawahara. "Bioceramics for hard tissue replacement". Clinical Materials 2 (1987) 181 - 206.

Io Alexandropoulou (2007). Tissue Engineering: creation of a digital and physical implantation model for the reconstruction of the cranial bone. Diploma Thesis, Department of Product and Systems Design Engineering -University of the Aegean.