The vertical course of bone regeneration in maxillary sinus floor augmentations: A histomorphometric analysis of human biopsies

BACKGROUND Maxillary sinus floor augmentation (MSFA) is a well-established and predictable augmentation method in severely resorbed maxillae. However, data on the vertical course of bone graft consolidation within the maxillary sinus are rare. The aim of the present study was to quantify the vertical distribution of new bone formation in MSFA and to characterize the vertical gradient of bone graft consolidation. MATERIAL AND METHODS 85 human sinus biopsies were harvested 6±1 months after MSFA. Histological thin-ground sections were prepared and histomorphometrically analysed. The volume of newly formed bone (nBV/TV) was measured in serial zones of 100 μm proceeding from the bottom of the sinus floor up to the apical top of the biopsy. The gradient of nBV/TV within the augmentation area was determined by the vertical distribution of nBV/TV along these zones. RESULTS In the premolar region, nBV/TV slightly declined from 20.4% in the zone adjacent to the sinus floor to 17.7% at a distance of 8 mm. The gradient was steeper in the molar region: nBV/TV decreased from 18.7% to 12.8%. This decline was even more distinct when the volume fraction and the height of the residual bone of the sinus floor were low. CONCLUSION New bone formation follows a gradient from native bone of the sinus floor towards the apical part of the augmentation area. The distance to primordial bone thus plays a critical role for bone regeneration in MSFA, particularly in the molar region. This article is protected by copyright. All rights reserved.