Bone tissue modelling and remodelling following guided bone regeneration in combination with biphasic calcium phosphate materials presenting different microporosity

The aim of this study was to investigate bone regeneration following application of a novel biphasic calcium phosphate (BCP I) composed of microstructured granules of 90% β-tricalcium phosphate (β-TCP)/10% hydroxyapatite (HA) compared to BCP non-microstructured biphasic calcium phosphate with a composite of 60% hydroxyapatite/40% β-TCP (BCP II) and a deproteinized bovine bone mineral (DBBM) at surgically created defects in the mandible of minipigs in a combined approach with guided bone regeneration (GBR).

Sixteen minipigs were used for the study. Lower premolars P2, P3, P4 and first molar M1 were extracted. Following 3 months of healing, two defects with a width and depth of 7 mm were created bilaterally in the mandible. The different grafting materials were randomly placed in the created defects and covered by means of a collagen membrane. After 3 and 8 weeks, biopsies were sampled. All specimens were evaluated with descriptive histology and histomorphometric evaluations complemented by micro-CT scan analysis.

All three biomaterials presented with higher bone volume at 8 weeks compared to 3 weeks (P < 0.0442). BCP I and DBBM demonstrated a significant higher amount of bone formation compared to BCP II at 8 weeks (P < 0.0328). BCP I also demonstrated a significant higher percentage of remaining graft volume compared to the other test groups both at 3 and 8 weeks (P < 0.0001 to P < 0.0003). Congruently, defects containing BCP I showed a significant higher amount of mineralized tissue compared to the other groups.

All the three test materials performed well with regard to bone formation at 8 weeks. BCP I showed significant higher amounts of newly formed bone despite a higher remaining graft volume compared to the other groups. With regard to the regenerative outcome, all the three materials can be recommended for clinical use.