Imaging of Nano-hydroxyapatite/chitosan Scaffolds Using a Cone Beam Computed Tomography Device on Rat Calvarial Defects with Histological Verification

Objectives: Τhis study aims at determining the ability of cone beam computed tomography (CBCT) to visualize critical-size defects (CSD) created at rat calvaria and filled with 75/25 w/w nano-hydroxyapatite/chitosan (nHAp/CS) scaffolds, prior to their histological investigation.

Materials And Methods: Thirty adult Sprague Dawley rats, 15 males and 15 females, were used. Two CSD, 5 mm in diameter, were bilaterally trephined in the parietal bone. The right CSD was filled with nHAp/CS scaffold, while the left CSD remained empty, as the control group. Two female rats died post-operatively. Rats were euthanized at 2, 4, and 8 weeks post-surgery. Twenty-eight specimens (15 × 2 × 10 mm) were resected-containing both CSDs-and then scanned using a NewTom VGi CBCT imaging unit (Verona, Italy). The manufacturer's software trace region profile tool (NNT v6.2, Verona, Italy) was used in selected axial slices. The greyscale value (in HU) and the traced/selected region of interest (ROI, in mm) of those areas were automatically calculated. Subsequently, all specimens were histologically examined.

Results: An increased HU (P = 0.000), was observed in the experimental group relative to the control group. The ROI of CSD (in mm) was significantly reduced (P = 0.001) from the fourth to the eighth week in both groups. No statistically significant difference between male and female rats (P = 0.188) was observed with respect to HU.

Conclusions: The nHAp/CS scaffolds are easily visualized using a particular high-resolution CBCT device.

Clinical Relevance: Both the CBCT measurements and also the histological results suggest that the nHAp/CS scaffold presence contributes to new bone formation in rat calvarial CSD.