A potential therapeutic approach to overload-induced bone loss around implant: parathyroid hormone (PTH)

The clinical use of dental implants has a high success rate, but overload-induced bone loss around implant is not uncommon in patients with implant-supported denture especially those with long cantilever designs and greatly harmful to the long-term implant success. The mechanism underlying the bone loss is thought to be the imbalance of bone remodeling involving a detrimental positive feedback activated by overloading. While surgical regenerative treatments may be useful in promoting bone regeneration, extra suffering and risk of infection have to be fully recognized. To date, no optimal method is available to solve this problem. We hereby propose a novel therapy that may potentially improve this condition. Many studies have shown that parathyroid hormone (PTH), an anabolic agent targeting bone, is effective in reversing bone loss caused by osteoporosis with negative bone remodeling in clinical studies. Moreover, PTH has the potential to accelerate the bone healing in patients with fracture and fracture nonunion and improve osseointegration of implant inserted in pre-existed bone defect via its anabolic effect to increase bone formation in animal model studies. Specifically for alveolar bone, PTH is associated with effective bone regeneration in patients with severe periodontitis. What is more, PTH and mechanical loading has a synergistic effect on bone formation, which is in favor of bone healing under physiological loading. The mechanisms underlying its anabolic effect may involve increased osteoblasts activity, prolonged osteoblasts life-span and recruitment of new osteoblasts from marrow stromal cells. Furthermore, PTH could activate resting lining cells to initial de novo bone formation. Considering these actions of PTH, we hypothesize that PTH may be a potential treatment for overload-induced bone loss around implant.