Characterization of nano-hydroxyapatite silica gel and evaluation of its combined effect with Solcoseryl paste on bone formation: An experimental study in New Zealand rabbits

Abstract

Objective

Characterization of nano-hydroxyapatite (n-HAp) silica gel bone substitute and evaluation of its combined effect with Solcoseryl paste on bone formation experimentally in New Zealand rabbits.

Materials and methods

Characterization of the n-HAp silica gel granules (NanoBone^®, Artoss GmbH, German) was done by the SEM, EDX analysis and TEM. Simulated bone defect (10 × 5 × 1 mm) was constructed from metallic mold to standardize the amount of the grafting materials. Two defects (10 × 5 × 1 mm) were created in the parietal bones of 12 New Zealand White rabbits. The rabbits were randomly divided into 4 groups with 3 rabbits/group (n = 6 defects/group). Group (C): The defects were left empty for natural bone healing (control group), group (S): The defects were filled with the pre-weighed Solcoseryl^® paste (Legacy Pharmaceuticals Switzerland GmbH, Switzerland), group (N): the defects were filled with the pre-weighed NanoBone and group (SN): the defects were filled with Solcoseryl paste/NanoBone mixture (1:1 by Vol. %). The rabbits were sacrified on day 14; the defects were removed, prepared for histological assessment and histomorphometric analysis. The amount of bone formation was statistically analyzed by ANOVA and Post-hoc test (p < 0.05).

Results

The SEM revealed the highly rough, porous n-HAp silica gel granules. The TEM revealed the interconnected porosities within the silica matrix and the platelet like shape of the n-HAp crystals. The Ca: P ratio of the n-HAp silica gel granules was 1.74. Histological evaluation revealed absence of new bone formation in group C while calcification in most of osteoid tissue areas was evident in all experimental groups with evident wide bone marrow cavities in S group. The NS group possessed the highest significant bone area percentage.

Conclusions

The interconnected porosities and the highly rough surface of n-HAp silica gel granules provided biomimetic bone substitute material that promotes new bone formation. Solcoseryl/NanoBone mixture (1:1 vol %) has a synergistic osteoinductive effect quantitatively and qualitatively on bone formation.

Clinical significance

Acceleration of post-operative bone healing in certain clinical cases where physiologic or pathologic conditions could impair the vascularization process.