Biocompatibility of the polyurethane resin of the castor bean inserted into the alveolar bone of the dog

The biocompability of the polyurethane resin of the castor bean (Ricinus vu lgaris) was studied following its insertion into the alveolar bone of dogs, after extraction of their premolar teeth. The resin was left to polymerise in the dental alveolus. Excess of material due to polymerisation was remov ed and polishing was employed to smooth and adapt the occlusal surface to t he margins of the alveolar bone. This allowed a perfect suture of the mucos a together with the periosteum. The resin remained in the dental alveolus f or 90 days. It was observed that the polyurethane was replaced by osteoid a nd bone tissues and no immune or inflammatory reactions were detected. Ther e has been work on and discussion about the use of the polyurethane in graf ts, prostheses and orthoses. Attention was paid to all the surgical steps, in particular the preservation of the periosteal integrity. Further researc h is being followed in our Department in order to test the biocompatibility of the material presented in this paper when used together with metallic o r ceramic implants.