A histomorphometric comparison of anorganic bovine bone (ABB) and calcium sulfate (CaS) used in sinus augmentation procedures: a study in sheep

Aim The selection of an appropriate grafting material is one of the factors that are important in achieving adequate bone formation following sinus grafting. Histologic and histomorphometric examination is the best method for evaluating the outcome of a sinus augmentation procedure as one can evaluate both the degree of vital bone formation and the implant-bone interface. The aim of the present study was to perform a histologic and histomorphometric comparison between anorganic bovine bone (ABB) and calcium sulfate (CaS) in sinus augmentation procedures in sheep. Materials and methods Twelve adult female sheep were used in the present study. In each animal one sinus was randomly selected to receive ABB, whereas the contralateral side received CaS. An equal volume of graft material was used (3,5 cm3) within each sinus cavity. At 3 and 6 months, following implant placement, a group of 6 animals was euthanized, and specimens retrieved with a 5 mm trephine bur to be processed for histology. Results New bone formed directly on the surface of the ABB particles without gaps or formation of fibrous connective tissue. The graft particles served as a scaffold for the new bone formation and the material appeared to be highly osteoconductive. There was an increase in the amount of newly formed bone from 3 months (21%) to 6 months (39%) with a corresponding decrease in the amount of residual grafted material from 39% to 32%. Also in the CaS augmented sinuses there was an increase from 3 months (19%) to 6 months (37%);the decrease in the residual grafted material was from 27% at 3 months to 9% at 6 months. The bone-implant contact (BIC) increased over time for both materials, reaching 45% for ABB and 40% for CaS at 6 months. Conclusions The regenerated bone appeared to be able to grow in close apposition to dental implants. Moreover, ABB complete resorption did not seem to be a prerequisite for new bone formation and implant integration. On the other hand, CaS quick resorption processes did not seem to prevent the formation of bone in tight contact with the implant surface. Both materials seemed to be suitable for sinus augmentation procedures.