Effect of enamel matrix derivative liquid combined with synthetic bone substitute on bone regeneration in a rabbit calvarial model

Objectives This study aimed to verify the effectiveness of EMD-liquid in combination with a synthetic bone substitute in a rabbit calvarial model. Material and methods Four 7-mm outer diameter circular slits were created in the calvaria of 10 New Zealand white rabbits, and polycarbonate cylinders were inserted into the slits. Two experimental groups were established: (1) EMD-liquid + bone substitute (Osteon III®; biphasic calcium phosphate (BCP), β-TCP/HA = 40:60) and (2) saline + bone substitute (Osteon III®; BCP). The cylinders were filled with saturated graft materials and covered with polycarbonate caps. Micro-CT and histomorphometric evaluation were conducted. Results In the histomorphometric analysis, new bone formation was significantly higher in the bone substitute (BS) + EMD-liquid group than in the BS only group at both 5 and 10 weeks ( p < 0.01). There were statistically significant differences in the material area between the bone substitute and bone substitute + EMD-liquid groups at only 5 weeks ( p < 0.05). The BS + EMD-liquid group demonstrated reduced material area to a greater extent. In micro-CT analysis, the BS + EMD-liquid group (27.04 ± 8.06 at 5 weeks, 28.49 ± 9.22 at 10 weeks) showed a significantly higher percentage of mineralized tissue volume at both 5 and 10 weeks ( p < 0.05) than the BS only group. Conclusion EMD-liquid enhances new bone formation when combined with BCP bone substitute in an animal model. Moreover, the EMD-liquid + BS has significantly lesser material area than BS alone, indicating accelerated graft degradation. Further studies on types of graft materials are required to verify the effect of EMD-liquid and to optimize its regenerative potential. Clinical relevance This study suggests that EMD-liquid may have beneficial effect on bone regeneration with synthetic bone substitute.