Phycogenic bone substitutes for sinus floor augmentation: Histomorphometric comparison of hydroxyapatite and biphasic calcium phosphate in a randomised clinical pilot study.

Aims: While numerous materials are available for sinus floor elevation, plant-based alternatives still hold promise of overcoming concerns about allogeneic or xenogeneic materials. Thus, the present authors designed a randomised clinical trial to histologically compare an almost pure hydroxyapatite (HA) to a biphasic calcium phosphate comprising 80% β-tricalcium phosphate (β-TCP) and 20% hydroxyapatite (β-TCP/HA), all of phycogenic origin. Materials and methods: Twenty patients scheduled for lateral window sinus floor elevation were randomised to either an HA or a β-TCP/HA group. Biopsy specimens were taken 3 months after sinus floor elevation and during implant surgery after 6 months. One ground section per biopsy specimen (N = 40) was stained, scanned and histomorphometrically analysed for new bone, old bone, soft tissue, graft, bone infiltration of graft, bone-to-graft contact and penetration depth. Results: At 6 months, more new bone was seen in the β-TCP/HA group (P = 0.011), whereas more residual graft was present and in more extensive contact with new bone in the HA group. More pronounced alterations, and smaller particle sizes, of graft surrounded and infiltrated by bone were seen in the β-TCP/HA group. The less extensive bone-to-graft contact in the β-TCP/ HA group reflected a more advanced state of resorption, while infiltration of residual graft material by bone was also increased in this group. Conclusions: Proper healing was seen in both groups, with the graft materials guiding the formation of new bone, which grew especially well through the particles of the highly osteoconductive and resorptive β-TCP/HA material. HA was very stable, without significant resorption, but was extensively in contact with new bone after 6 months.