Effect of crushing on the occupying volume ratio of mineralized xenograft in collagenated biomaterials: an in vitro study.

PURPOSE: This study aimed to (1) establish the occupying volume ratio (OVR), defined as the proportion of mineralized particulates within grafted sites, using particulate xenografts mixed with either saline or platelet-rich fibrin (PRF), and (2) evaluate how hydration and mechanical manipulation influence OVR in collagenated block-type xenografts. METHODS: Three particulate xenografts and their corresponding collagenated blocks were evaluated. Particulate grafts were mixed with either saline or PRF. Collagenated blocks were assessed under 3 conditions: original, after saline hydration, and after mash-up, defined as mechanical crushing following hydration. All samples were compressed into standardized resin boxes (10×10×10 mm). Micro-computed tomography was used to quantify mineralized volume and calculate OVR. RESULTS: Significant effects of material type (P<0.01) and application condition (P=0.04) were observed for particulate grafts. The OVRs were 48.45±11.89% for saline and 44.24±10.37% for PRF. Among the tested materials, deproteinized porcine bone mineral (DPBM)-OX demonstrated the highest OVR under both conditions and showed significantly greater values than deproteinized bovine bone mineral (DBBM) and DPBM-TG (P<0.05). In collagenated blocks, OVR decreased significantly in a stepwise manner, from 52.40±7.37% in the original state to 41.91±8.75% after hydration and 33.66±6.07% after mash-up. Following mash-up and standardized recompression within the mold, the mean OVRs were reduced to 35.12±5.97% for DBBM, 37.77±1.85% for DPBM-TG, and 28.10±5.12% for DPBM-OX. CONCLUSIONS: Collagenated xenografts undergo a significant reduction in mineral volume density following hydration and mechanical manipulation, which may compromise space maintenance and graft stability. These findings highlight the importance of careful graft handling to preserve volume and optimize regenerative outcomes.