Effect of curcumin on bone tissue in the diabetic rat: repair of peri-implant and critical-sized defects

This study determined the effect of curcumin on bone healing in animals with diabetes mellitus (DM). One hundred rats were divided into five groups: DM + PLAC, DM + CURC, DM + INS, DM + CURC + INS, and non-DM (CURC, curcumin; PLAC, placebo; INS, insulin). Critical calvarial defects were created and titanium implants were inserted into the tibiae. Calvarial defects were analyzed histometrically, and BMP-2, OPN, OPG, RANKL, Runx2, Osx, beta-catenin, Lrp-5, and Dkk1 mRNA levels were quantified by PCR. The implants were removed for a torque evaluation, the peri-implant tissue was collected for mRNA quantification of the same bone-related markers, and the tibiae were submitted to micro-computed tomography. The DM + CURC + INS and non-DM groups exhibited greater closure of the calvaria when compared to the DM + PLAC group (P < 0.05). Increased retention of implants was observed in the DM + CURC, DM + CURC + INS, and non-DM groups when compared to the DM + PLAC group (P < 0.05). CURC improved bone volume and increased bone-implant contact when compared to DM + PLAC (P < 0.05). In calvarial samples, CURC favourably modulated RANKL/OPG and Dkk1 and improved beta-catenin levels when compared to DM + PLAC (P < 0.05). In peri-implant samples, Dkk1 and RANKL/OPG were down-regulated and BMP-2 up-regulated by CURC when compared to DM + PLAC (P < 0.05). CURC reverses the harmful effects of DM in bone healing, contributing to the modulation of bone-related markers.