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Updated: Mar 17, 2026

Half-segmental Diaphyseal Bone Defect Model in Rats for Evaluating Bone Substitute Performance in Load-bearing Regions
Published on: December 30, 2025
Effect of hydroxyapatite on critical-sized defect
Ryoe-Woon Kim1, Ji-Hyoung Kim1, Seong-Yong Moon2
1Graduate School of Dentistry, Chosun University, Gwangju, South Korea.
Background:
Xenologous or synthetic graft materials are commonly used as an alternative for autografts for guided bone regeneration. The purpose of this study was to evaluate effectiveness of carbonate apatite on the critical-size bone defect of rat's calvarium.
Methods:
Thirty-six critical-size defects were created on 18 adult male Sprague-Dawley rat calvaria under general anesthesia. Calvarial bones were grinded with 8 mm in daimeter bilaterally and then filled with (1) no grafts (control, n = 10 defects), (2) bovine bone mineral (Bio-Oss®, Geistlich Pharma Ag. Swiss, n = 11 defects), and (3) hydroxyapatite (Bongros®, Bio@ Inc., Seongnam, Korea, n = 15 defects). At 4 and 8 weeks after surgery, the rats were sacrificed and all samples were processed for histological and histomorphometric analysis.
Results:
At 4 weeks after surgery, group 3 (42.90 ± 9.33 %) showed a significant difference (p < 0.05) compared to the control (30.50 ± 6.05 %) and group 2 (28.53 ± 8.62 %). At 8 weeks after surgery, group 1 (50.21 ± 6.23 %), group 2 (54.12 ± 10.54 %), and group 3 (50.92 ± 6.05 %) showed no significant difference in the new bone formation.
Conclusions:
Bongros®-HA was thought to be the available material for regenerating the new bone formation.

