Guided bone regeneration using beta-tricalcium phosphate with and without fibronectin-An experimental study in rats

This histomorphometric study compared bone regeneration potential of beta-tricalcium phosphate with fibronectin (β-TCP-Fn) in critical-sized calvarial defects (CSDs) in rats to assess whether fibronectin (Fn) improved new bone formation.

Critical-sized calvarial defects were created in 30 adult male Sprague Dawley rats, which were divided into four groups according to the time of euthanasia (6 or 8 weeks of healing) and type of filling (β-TCP-Fn/6 weeks, β-TCP/6 weeks, β-TCP-Fn/8 weeks and β-TCP/8 weeks). The primary variables related to new bone formation were augmented area (AA) and gained tissue (GT; sum of mineralized bone matrix [MBM] and bone substitute [BS]). Secondary variables were the diameter of the defect, MBM, non-mineralized tissue (NMT) and BS.

A total of 29 rats and 58 histological samples were evaluated, 28 (48.3%) samples obtained at 6 weeks and 30 (51.7%) at 8 weeks, homogeneously distributed between right and left sides. Thirteen (22.4%) were treated with β-TCP-Fn, 16 (27.6%) with β-TCP and 29 (50%) were controls. At 8 weeks, histomorphometric analysis showed significant differences in AA using β-TCP and β-TCP-Fn versus controls (p = 0.001 and p = 0.005, respectively). Bone turnover expressed as % within the target area was slightly higher but not statistically significant in the β-TCP-Fn than in β-TCP (MBM) at 6 weeks versus 8 weeks (p = 0.067 and p = 0.335, respectively). Finally, the total GT area in mm² was higher using β-TCP-Fn as compared to β-TCP (p = 0.044).

β-TCP-Fn was slightly but non-significantly more effective than β-TCP without Fn for improving the volume of regenerated bone in CSDs of rats, possibly allowing a more efficient bone remodelling process. This effect however should continue being investigated.