Strontium Ranelate Improves Alveolar Bone Healing In Estrogen-Deficient Rats

Background This study evaluated the impact of strontium ranelate on tooth-extraction wound healing in estrogen-deficient and estrogen-sufficient rats.Methods Ninety-six Wistar rats (90 days of age) were allocated into one of the following groups: sham-surgery+water (estrogen-sufficient); ovariectomy+water (estrogen-deficient), sham-surgery+strontium ranelate (625 mg/kg/d) (strontium/estrogen-sufficient); ovariectomy+strontium ranelate (625 mg/kg/d) (strontium/estrogen-deficient). Water or strontium ranelate were administrated from the 14th day post-ovariectomy/sham surgery until euthanasia. Maxillary first molars were extracted at 21 days after sham/ovariectomy surgery. Rats were euthanized at 10, 20, and 30 days post-extractions. The following parameters were analyzed inside tooth-extraction wound: proportion of newly formed bone (bone healing/BH), number of cells stained for tartrate-resistant acid phosphatase (TRAP) and immunohistochemical staining for five bone metabolism-related markers (osteocalcin [OCN], osteopontin [OPN], bone sialoprotein [BSP], osteoprotegerin [OPG] and receptor activator of NF-KB ligand [RANKL]).Results The estrogen-deficient group presented lower BH than all other groups at 20 and 30 days post-extraction (P < 0.05). The number of TRAP-stained cells was higher in the estrogen-deficient group than in estrogen-sufficient group at 30 days post-extraction (P < 0.05). The strontium /estrogen-sufficient group exhibited stronger staining for OCN, when compared to the estrogen-sufficient and estrogen-deficient groups (P < 0.05). Both strontium ranelate-treated groups presented higher staining of OPN and BSP than both untreated groups (P < 0.05). The strontium/estrogen-sufficient group demonstrated stronger staining for OPG than the estrogen-deficient group (P < 0.05). The estrogen-sufficient group and both groups treated with strontium ranelate showed lower expression of RANKL than the estrogen-deficient group (P < 0.05).Conclusions Strontium ranelate benefited BH and the expression of bone markers in tooth-extraction wound in estrogen-deficient rats whereas its benefits in estrogen-sufficient rats were modest.