Effect of bioresorbable fibres (Polyfibre) and a bioresorbable foam (Polyfoam) on new bone formation. A short term experimental study on the rabbit skull.

The aim of the study was to evaluate two bioresorbable polylactic acid (PLA) filler materials in a guided bone regeneration (GBR) model system. The first was Polyfibre, a fibrous PLA filler material. Polyfoam, the second material tested, consisted of a spongy PLA filler material. In each group there were eight rabbits. In test rabbits a flap was raised uncovering the calvaria. A hemispherical PLA dome was filled with Polyfibre or Polyfoam material and periphereal blood and anchored onto the calvaria. Eight rabbits with the same domes, filled with blood alone, served as controls. The rabbits were sacrificed at 1 or 2 months. Histomorphometric measurements of regenerated total tissue volume, bone height and bone volume were carried out in undecalcified sections under a light microscope. At 1 month the totally filled volume attained 87% (range 82-91) in the fibre group, including 25% (23-27) fibres, 87% (85-95) in the foam group, including 15% (15-16) foam, and 55% (16-100) in the controls. The volume of mineralized bone was 12% (7-15) in the fibre group, 15% (12-18) in the foam group and 6% (1-11) in control domes. Bone height attained 48% (27-79) in the fibre group, 37% (31-58) in the foam group and 45% (14-67) in the control group. At 2 months, tissue volume attained 86% (85-87) including 26% (22-29) fibres, bone volume attained 13% (7-21) and bone height attained 56% (42-78) in the Polyfibre group. In the Polyfoam group, they were 83% (55-99) including 18% (15-19) foam, 13% (7-24) and 49% (29-74). In control domes, tissue volume was 82% (35-100), bone volume 20% (9-27) and bone height 86% (60-100). The Polyfibre and Polyfoam material was excellently integrated. No adverse reactions were found in the surrounding tissues. Direct bone apposition was observed onto the material. In conclusion, Polyfibre and Polyfoam material had a positive effect on initial bone and tissue formation but was a hindrance to increasing tissue volume, bone volume or bone height at 2 months compared to control specimens. The Polyfibre and Polyfoam material provoked no adverse reactions in the surrounding tissues and allowed for extensive angiogenesis.