Bone Graft Packing and Its Association with Bone Regeneration in Maxillary Sinus Floor Augmentations: Histomorphometric Analysis of Human Biopsies

SIMPLE SUMMARY: Following tooth loss, the jaw bone undergoes gradual atrophy of the tooth-bearing alveolar process which poses a major challenge for dental implant therapy. In order to compensate for the decreasing bone height and bone volume in the upper jaw, bone graft particles can be inserted into the maxillary sinus (maxillary sinus floor augmentation). The native bone ideally integrates these particles, proving an increased bone supply for subsequent implant placement. Despite the longstanding clinical application of this surgical procedure, there is still no scientific rationale for whether particulate bone grafts should be compressed or lightly packed. We therefore evaluated the spatial distribution of bone substitute particles in human maxillary sinus biopsies and investigated the association between bone graft packing and bone regeneration 6 months after maxillary sinus floor augmentation. In fact, bone graft particles were not homogeneously distributed over the length of biopsies. With increasing distance from the native bone of the sinus floor, the number of predominantly small, densely packed bone graft particles increased, which appeared to be detrimental to graft integration. These findings suggest that excessive compaction of bone graft particles should be avoided in order to optimise the macrostructural environment for bone regeneration in maxillary sinus floor augmentations. ABSTRACT: Research in maxillary sinus floor augmentation (MSFA) focussed on the optimisation of microstructural parameters such as microporosity and particle size of bone substitute particles (BS). However, little is known about the impact of BS packing and the corresponding (void) interparticular space on bone regeneration. The aim of this study was to characterise the spatial distribution of BS and its association with BS integration 6 ± 1 months after MSFA. Histological thin-ground sections of 70 human sinus biopsies were histomorphometrically analysed: In serial zones of 100 µm proceeding from the sinus floor (SF) up to the apical end of the biopsy, we measured the distribution of BS particles within these zones in terms of volume (BSV/TV), number and size of BS particles, interparticle spacing (BS.Sp) and bone-to-BS contact. BS particles were not homogeneously distributed over the length of biopsies: The first 200 µm directly adjacent to the SF represented a zone poor in BS particles but with high osteogenic potential. Graft packing density increased from the SF towards the apical part of the AA. Integration of BS particles was inversely associated with the distance to the SF and the graft packing density. A high packing density through excessive compaction of BS particles should be avoided to optimise the macrostructural environment for bone regeneration.