A Comparison of Three Calcium Phosphate-Based Space Fillers in Sinus Elevation: A Study in Rabbits

Purpose: Subsinus bone regeneration procedures are reliable and known to be effective with the use of biomaterials alone. Nevertheless, many types of biomaterials are available, and the efficacy of each in terms of bone formation and resorption rate has rarely been compared. This study aimed to compare bone formation, resorption rate, osteoconductivity, and three-dimensional volume changes of three biomaterials often used for alveolar ridge augmentation. Materials and Methods: Rabbits underwent bilateral sinus elevation using three different types of space fillers: bovine hydroxyapatite (BHA), beta-tricalcium phosphate (ß-TCP), or biphasic calcium phosphate (BCP). Animals were sacrificed at 1 week, 5 weeks, and 6 months. Samples were subjected to microcomputed tomography and histologic examination. Qualitative analysis was performed on nondecalcified sections, and quantitative histomorphometric analysis was conducted using scanning electron microscopy. Volume differences in augmented bone were calculated at different time points. Results: All three particulated biomaterials promoted osteogenesis in this particular animal model. At 6 months, biomaterial resorption rates were significantly different across the three groups. The highest resorption rate was found with ß-TCP, in which only 6.7% of the baseline particle surface remained. At 6 months, bone was in close contact with the BHA particles, constituting a composite network; in contrast, BCP particles were often surrounded by soft tissue. Within each group, no significant differences in volume were found at the different time points. Conclusions: Despite the limitations of the study, the three studied biomaterials proved to be effective in promoting osteogenesis. High resorption rates and complete replacement of the biomaterials by bone seemed to withstand intrasinusal pressure. Further investigations in humans should consider longer follow-up periods.