Enhancement of bone regeneration using resorbable ceramics and a polymer-ceramic composite material

The aim of this experimental study M;as to evaluate the use of resorbable i mplants for the repair of non-loaded skeletal defects. Porous ceramic impla nts of alpha -TCP, of glass-ceramic, and of solid composite implants of gla ss-ceramic/polylactic acid 8 mm in diameter and 2 mm in thickness were fabr icated and implanted pressfit into biparietal, full-thickness defects of th e calvaria of 60 adult rats. Twenty rats received unfilled defects and serv ed as controls. Fluorochrome labeling of bone formation was performed durin g the observation period. Five animals from each group were evaluated after 6, 13, 26, and 52 weeks. The control defects showed incomplete regeneratio n, with bone formation extending 1.66 mm, on average, into the defect after 52 weeks. In the group of alpha -TCP implants, histologic evaluation indic ated that the bone formed during initial stages had undergone resorption La ter on, so that bone repair after 52 weeks was not significantly enhanced, with an average depth of 1.83 mm of bone ingrowth. The glass-ceramic implan ts exhibited extensive bone formation and nearly complete repair of the cal varial defect, with 3.90 mm of bone ingrowth into the implant pores. Degrad ation of the ceramic was nearly complete, with a few remaining particles su rrounded by soft tissue. The composite implants showed a negligible bone in growth of 0.63 mm, on average. Soft tissue had invaded the polylactic acid implant body, but no bone formation had taken place at the surface of the e mbedded ceramic particles. Degradation of the polymer was not complete afte r 52 weeks. It is concluded that the balance between degradation and bone f ormation is delicate and that chemical events and cellular reaction during degradation may counteract complementary bone ingrowth. (C) 2001 John Wiley & Sons, Inc.