Background: Recently our group developed two polymeric biomaterials (BioM1, BioM2) with photodynamic antimicrobial surface activity for periodontal regeneration. The aim of the present study was to analyse biocompatibility and osseointegration of these materials in an ovine bone model.

Material and Methods: In BioM1 urethane dimethacrylate and in BioM2 tri-armed oligoester-urethane methacrylate were used and substituted with a mixture of ß-tricalcium phosphate and Temoporfin (meso-tetra(hydroxyphenyl)chlorin, mTHPC). Both materials were implanted in bone defects in the femur (n=16) and tibia (n=8) of 8 female domestic sheep. Bone specimens were harvested and histomorphometrically analysed after 12 months of implantation. Detailed information upon the size of biomaterial remnants, bone volume, soft tissue volume and bone-to-implant contact in a 250µm thick region-of-interest (ROI) around the implanted material was obtained.

Results: After 12 months of implantation, remnants of BioM1 showed a mean square size of 17.4 mm² while 12.2 mm² was estimated for BioM2. Original defect size was 19.6 mm² at baseline. For BioM1 a total bone value of 30.3% and for BioM2 of 8.4% was estimated (p<0.001). A soft tissue proportion of 3.3% was detected for BioM1 and 29.5% for BioM2 (p<0.001). BioM1 showed a bone-to-implant contact of 81.9% in the femur and 56.2% in the tibia (p=0.005). A much smaller bone-to-implant contact of 8.5% in the femur and 16.4% in the tibia was detected for BioM2. Further, BioM2 was affected by tissue encapsulation and inflammation.

Conclusions: BioM1 shows favourable osseointegrative and biocompatible characteristics. Further studies that investigate the suitability of BioM1 for periodontal regeneration are needed.