RESUMEN
BACKGROUND: Bone demineralization has shown to be advantageous in autogenous onlay bone grafts and in pre-osteoblasts cultures, but such procedure has never been evaluated in particulate bone grafts. This study aimed to investigate the role of two demineralizing agents in the repair of the 8-mm critical-size defects in rats' calvaria. METHODS: Eighty adult male Wistar rats were randomly assigned to one of eight groups as follows: particulate autogenous bone demineralized with citric acid for 15 seconds (CA15), 30 seconds (CA30), or 60 seconds (CA60); particulate autogenous bone demineralized with tetracycline hydrochloride for 15 seconds (TCN15), 30 seconds (TCN30), or 60 seconds (TCN60); blood clot (NC), and non-demineralized autogenous bone (PC). The calvariae were harvested at 30 and 60 postoperative days (n = 5) for blinded histological and histometric analysis of the percentage area of newly formed bone within the defects. RESULTS: In the NC and TCN groups, bone formation was limited to the margins of the defects at 30 postoperative days, whereas complete closure was present in all the specimens from CA15 group. Both at 30 and 60 postoperative days, histomorphometry showed significant higher area of newly formed bone in specimens demineralized with CA than in those demineralized with TCN or non-demineralized (P < 0.05). TCN appeared to impair bone neoformation, as its use produced similar or inferior results compared to blood clot. CONCLUSIONS: Demineralization of particulate bone grafts with CA during 15s enhanced the regeneration of critical-size defects and may be a promising adjuvant in regenerative procedures. TCN seems to be improper for this purpose.