Immunohistochemical change of bone surrounding immediately loaded self-drilling miniscrews
Dept. of Dentistry/박사
Objectives: To elucidate the histological and immunohistochemical change of bone surrounding immediately loaded self-drilling miniscrews and to see whether there is difference in the healing process between cortical bone and trabecular bone.Materials and methods: 64 tapered self-drilling miniscrews were inserted on 4 mature beagle dogs and loaded immediately for 0, 1, 3, 6 weeks. After harvesting the tissue blocks, miniscrew were carefully removed. All tissue sections were stained with H&E for general morphology. Proliferating cells were detected by Proliferating Cell Nuclear Antigen (PCNA). For detection of bone mineralization, Alkaline Phosphatase (ALP) antigen was used. Osteoclasts were identified by Tartrate-Resistant Acid Phosphatase (TRAP) staining. Programmed cell death was detected by TUNEL assay kit.Results: In mandibular molar area, zone of altered nuclear morphology was observed at 0 and 1 week. As a result, crater-like cortical marginal bone loss was observed after 3 weeks. There was no sign of remineralization throughout the experiment. Cell proliferation and differentiation was observed at 1 week. Osteoid formation was started from preexisting bone toward the miniscrew interface. Bone resorption was highly increased at 3 weeks and decreased at 6 weeks. Miniscrew surface was covered with either new bone or fibrous matrix after 6 weeks.Conclusions: The bone-implant interface responds to mechanical stress by modifying the quantity and quality of its structure. Cortical bone, which is important in the primary stability of miniscrews, showed poor adaptation to the mechanical stress. The remarkable adaptation of trabecular bone may offer the prolonged support. Within the limit of this study, we can conclude that trabecular bone and fibrous matrix seems to play a key role in the prolonged stability of miniscrews when the cortical bone can no longer provide stable interface.