Volume Changes of Grafted Autogenous Bone in Sinus Augmentation Procedure

Abstract Purpose: To evaluate associations between the osseous remodeling and the 3-dimensional features of both the grafted bone and the recipient site, as well as the density of the grafted bone, and to assess the relation between the degree of bone resorption and the type of autogenous bone-grafting procedure or the source (block or particulate bone from iliac crest or block bone from chin). Patients and Methods: A retrospective chart review of patients receiving sinus lifting and grafting procedures for implant positioning was conducted: radiographic analysis of the volume and area of both sinuses and autogenous bone grafts was performed, as per Smolka et al and Krennmair et al. The volumetric remodeling—measured at 1 year after implant positioning as the percentage of residual bone (%R)—was correlated, with Spearman analysis, to 3-dimensional features of both graft and recipient sites. All quantities correlated with %R at a statistically significant level were used for 2-dimensional and multidimensional visualizations with scattergrams. Results: Twenty-five iliac crest or chin grafts were inlay positioned in the maxillary sinuses of patients. Computed tomography scans, taken before implant positioning and after 1 year, showed a 1-year negligible volume remodeling for block graft from chin (97.9%) but slightly greater resorption values (%R) for particulate and block grafts from iliac crest (93.8% and 83.3%, respectively). Three- and four-dimensional scattergrams of significant data resulting from Spearman correlation tests (particulate and block grafts both from iliac crest) showed a variation of the remodeling pattern dependent on 3-dimensional features, namely inlay graft thickness, surface area of the graft in contact with basal bone, volume of the recipient site, and surface area of the graft projecting into the sinus cavity. Conclusions: Retrospective data analysis shows that iliac crest grafts positioned on a small basal bone volume (#2.5 mL) may point to a very favorable remodeling of the volume when the particulate graft is molded to a thickness of less than 4mm,with a reduced surface area protruding into the sinus (#5 cm2). Bone blocks with a reduced contact surface and with basal bone (#4 cm2) also display minimal resorption.