Rethinking bone substitutes in GBR: Can synthetic materials match the standard of care?

Reconstructing lateral bone defects remains one of the key challenges in implant dentistry. While guided bone regeneration (GBR) has become a well-established approach, the choice of grafting material is still evolving. For decades, deproteinized bovine bone mineral (DBBM) has been considered the standard of care. But its  limitations—particularly its slow resorption and its animal origin—have driven the search for effective synthetic alternatives.

Against this background, this study aimed to evaluate whether a fully synthetic bone substitute could achieve outcomes comparable to the current clinical standard in GBR. We therefore investigated a novel bilayered biphasic calcium phosphate (BBCP) material designed to mimic natural bone. It consists of an α-tricalcium phosphate (TCP) core with a nanocrystalline hydroxyapatite (HA) coating (approximately 90% α-TCP and 10% HA), which aims to balance stability and resorption.

To evaluate this, we used a standardized preclinical model of lateral bone defects in six beagle dogs, with four defects created in the maxilla of each animal. These defects were intentionally designed as critical-size defects with limited self-healing capacity, allowing us to assess the true regenerative potential of the materials. A critical-size defect model was chosen because such defects do not heal spontaneously and therefore provide a standardized setting to assess the effectiveness of regenerative interventions; in this study, defects of approximately 10 × 8 × 6mm were created.

Four treatment modalities were compared:

• BBCP alone (T)
• DBBM as a positive control (PC)
• A 1:1 combination of both materials (M)
• An untreated negative control (NC)

All defects were treated according to the principles of GBR using a resorbable membrane. After a healing period of 11 weeks, the animals were sacrificed and the samples were analysed using micro-computed tomography (micro-CT) and histological methods (Figure 1).