RESUMO
OBJECTIVE: To detect the expression of growth factors relating to bone reconstructions in microscrew-bone interface of implanted titanium microscrews near the extraction wounds, and to determine the influence of healing process on the growth factors. METHODS: Eight male Beagle dogs (age 18 months) were divided into experimental and control groups. Titanium microscrews were implanted near an extraction wound in the dogs in the experimental group, while the controls had implantation without extraction wounds. The dogs were sacrificed at 1, 3, 8, 12 weeks, respectively. Immunohistochemistry and in situ hybridization sections were performed to detect the expression of TGF-beta, TNF-alpha, osteocalcin (OC) protein and Cbfal mRNA. RESULTS: The experimental group had higher levels of expression of TGF-beta, TNF-alpha protein and Cbfa1 mRNA than the controls, with significant differences appearing at week one for TNF-alpha (P<0.05), week three for TGF-beta and TNF-alpha (P<0.05), and week eight for Cbfa1 mRNA (P<0.05). The expression of OC increased over time and reached peak at week eight (P<0.05). CONCLUSION: Microscrews implanted near extraction wounds can maintain stability. Severe inflammation occurs in the early stage of healing, but does not sustain. Bone remodeling remains active over the healing process. But prolonged healing phase without force loading could weaken the remodeling.