P. Passi et al., Plain and drug loaded polyphosphazene membranes and microspheres in the treatment of rabbit bone defects, J MAT S-M M, 11(10), 2000, pp. 643-654
Citations number
35
Categorie Soggetti
Multidisciplinary
Journal title
JOURNAL OF MATERIALS SCIENCE-MATERIALS IN MEDICINE
The healing of periodontal surgical defects was studied in rabbits, using p
olyphosphazenes (POP) membranes and microspheres, both plain or drug-enrich
ed.
POP polymers having amino acid ester as backbone substituents, are used sin
ce they resorb and undergo hydrolytic degradation to ammonia, phosphate and
amino acids.
Fourteen animal were operated in tibia, and other fourteen at angle of the
mandible, that was reached by extraoral access. Bone defects were performed
in tibiae, and covered either with POP or with poly-tetrafluoroethylene (P
TFE) membranes, while other rabbits served as controls. The animals were sa
crificed after one and two months, and the tibiae taken and processed for o
ptical microscopy.
Similar surgical defects were made in mandible, and POP membranes were plac
ed over the breaches, some of which were filled with POP microspheres, both
alone or mixed with granular hydroxyapatite. For comparison, two rabbits w
ere treated with PTFE membranes, while other two served as controls. The an
imals operated at the mandible were all sacrificed after one month, and the
operated bones taken and processed for histology.
It was found that POP membranes were very effective in promoting the healin
g in tibiae, while less satisfactory results were found in the animals trea
ted with PTFE membranes and in controls. In mandible, the healing occurred
without a clear relationship with the grafted microgranular material or the
membrane, since repairing bone was found also in controls. In any case, bo
th POP membranes and microspheres showed excellent biocompatibility, as no
inflammatory cells or macrophages were found in the surrounding tissue. Thi
s property was completely independent from the presence of drug, since the
matrix-entrapped drugs, released in the tissue, did not hamper the bone hea
ling. It was also found that POP, by itself, has a positive effect in stimu
lating the bone repair. (C) 2000 Kluwer Academic Publishers.