Purpose: To perform vertical bone augmentation on rat parietal bone by coating the inner surface of dense polytetrafluoroethylene (d-PTFE) domes with hydroxyapatite (HA) using Erbium Yttrium Aluminum Garnet (Er:YAG) pulsed laser deposition in a rat model.
Methods: The d-PTFE plate surface, α-tricalcium phosphate (α-TCP) coating, and HA coating were measured using scanning electron microscopy and X-ray diffraction to confirm the replacement of α-TCP with HA via high-pressure steam sterilization. The dome was glued to the center of the rat parietal bone and closed with periosteal and epithelial sutures. The rats were euthanized at 4, 8, and 12 weeks postoperatively, and the d-PTFE dome and surrounding tissues were harvested for radiological and histological evaluation.
Results: In a group without HA coating (control group), a small amount of layered neosteum was observed in the d-PTFE dome. Conversely, a new balloon-shaped bone was observed in a HA-coated group (experimental group). Bone growth and number of bone beams were higher in the HA-coated group from 4 to 12 weeks postoperatively than those in the control group. However, no significant differences in bone mineral density values or bone bridge widths were observed.
Conclusions: The HA coating enhanced bone augmentation without bone replacement. Histological findings indicated that the new bone comprised normal bone tissue with cartilage lumen and matrix. Therefore, our results indicate that bone augmentation with a HA coating may be mediated by endochondral ossification, a process similar to that of ectopic ossification.
Keywords: Artificial bone replacement material; Endochondral ossification; ErYAG pulsed laser deposition; Hydroxyapatite; Vertical bone augmentation.