Response of rat and guinea-pig subcutaneous tissue to implanted human roots containing collagen/hydroxyapatite preparations

Summary. The root canals of extracted human roots were cleaned and enlarged. The roots were sterilized before insertion of test materials of collagen, hydroxyapatite or a mixture; saline was used as a control. The roots were implanted subcutaneously in rats or guinea-pigs. After 30 and 180 days, the embedded roots were prepared for histological examination. In the rat, the tissue reaction was similar whether the roots were filled with collagen, collagen/hydroxyapatite or saline; there was ingrowth of granulation tissue. The canals of teeth filled with hydroxyapadte showed mature fibrous tissue around islands of the material. The response in guinea-pigs was similar, except that the roots stimulated some bone formation.