Non-radioactive strontium as a supplement to enhance osseointegration

Abstract 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 non-radioactive 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.