Non-radioactive strontium as a supplement to enhance osseointegration

Introduction: Due to its positive results on bone tissue, strontium also began to be used as an adjuvant in bone neoformation processes, mainly maxillofacial surgical procedures. Objective: To assess if the nonradioactive strontium (Sr) supplementation enhances the osseointegration of titanium implants in rats. Material and method: Seventy male rats (Rattus Norvegicus) were randomly divided into 5 groups, according to the systemic supplementation: Control-saline solution; SRAN50-strontium ranelate (SRAN) 50mg/kg/day; SRAN625-SRAN 625mg/kg/day; SCAR/SCHL30-strontium carbonate and strontium chloride (SCAR/SCHL) 30mg/kg/day; SCAR/SCHL365-SCAR/SCHL 365mg/kg/day. The drugs were administered via gavage, once a day, starting 15 days before surgery (1 titanium implant in each tibia), and persisted for 15 or 60 days. The right tibiae were used for biomechanical (removal torque) and immunohistochemical (Osteocalcin – OCN, and bone morphogenetic protein-BMP-2) evaluation. The left were used for microtomographic, and histomorphometric evaluation. Result: Increased removal torque for SRAN625 and SCAR/SCHL365 were observed when compared with the Control, in 15 days. However, no differences were found in the 60-days period among the groups. Microtomographic evaluation showed larger bone volume at 60 days, compared to 15 days, for all groups but SCAR/SCHL30. When all groups were compared, no differences were seen in the 15-days period, while in the 60-days SRAN625 and SCAR/SCHL365 were statistically higher than the Control. In the immunohistochemical analysis, higher doses (SRAN625 and SCAR/SCHL365) led to an increase of BMP-2 in 15 days. Histomorphometric analysis revealed no differences among the groups regarding bone-to-implant-contact and bone area around the implant threads. Conclusion: This study suggests that higher concentrations of systemic Sr lead to variably improved osseointegration-related parameters regarding the biomechanical and microtomographic evaluation.