Effect of PTH and corticotomy on implant movement under mechanical force

Abstract

Background Osseointegrated implants are considered as clinically non-movable. Parathyroid hormone (PTH) is known to play a significant role in the regulation of bone remodeling and in intermittent, low doses, result in osteoanabolic effects. This study aimed to investigate the effects of PTH and corticotomy, both under traction force, on osseointegrated implants. Methods Four implants—two in each hemimandible—were placed in each of the three study mongrels. Each mongrels were designated as control, normal dose PTH (PTH-1), and high dose PTH (PTH-2) groups, with each groups further subdivided into non-surgery and surgery groups. After osseointegration, mechanical force with NiTi closed coil springs (500g) was applied around each implants. Corticotomy was performed around one of four implants in each mongrels. Parathyroid hormone was administered locally on a weekly basis for 20 weeks. Clinical movement of the implants were evaluated with the superimposed 3D- scanned data, bone- microarchitectural and histologic examinations Results Superimposition analysis showed continuous movement of the implants in PTH-1 group. Movement was further justified with lowest bone implant contact (adjusted BIC; 44.77%) in histomorphometric analysis. Upregulation of bone remodeling around the implant was observed in the normal dose PTH group. In the surgery subgroups, the remarkably higher adjusted BIC compared to the non-surgery subgroups indicated increased bone formation around the implant surface. Conclusion The results indicate that the balance of osseointegrated implants in bone remodeling can be shifted via various interventions. Clinical Relevance Upregulated bone remodeling by PTH and corticotomy under continuous mechanical force showed the possible implications on the clinical implant movement.