The effects of bovine BMP associated to HA in maxillary sinus lifting in rabbits

Abstract

This study examines the efficacy of using bone morphogenetic protein of bovine origin associated with other biomaterials in maxillary sinus floor augmentation procedures in rabbits (Oryctolagus cuniculus). Various approaches have been attempted to obtain sinus lifting with pre-existing tissue, but all of them have been considered inadequate, because such tissue offers very low bio-quality, requiring additional materials to stimulate bone neo-formation. For this purpose, autogenous bone is considered to be the best grafting material, but harvesting it results in great discomfort for the patient. Biomaterials from human beings or other animals are used as a substitute. In this study, four different grafting materials were used: lyophilized bovine bone powder, absorbable collagen flakes, natural hydroxyapatite (nHA) and synthetic hydroxyapatite (sHA), in nine animals divided into two groups: (A) control group (left sinus)--using just graft material, and (B) BMP group (right sinus)--using graft material with 0.5 mg bovine bone morphogenetic protein (BMPb). The observation periods were of 8 and 12 weeks duration and sequential bone neo-formation polyfluorochrome tracers (alizarin complex, calcein, and tetracycline) were subcutaneously injected, to evaluate the periods of new bone deposition. After the animals were sacrificed, the material was obtained and examined under a fluorescent microscope and also activated by UV light and the conclusion reached that the newly formed bone increase was of 33.34% when compared to the control group at 8 weeks At 12 weeks, the bone deposition in the "BMP" group was not significant while in the "control" group there was continuous growth. This difference showed that the BMP stimulated bone formation during the early periods of healing (8 weeks), although it altered the normal cycle of bone deposition over the longer period (12 weeks). The graft material showed increasing reabsorption, but the natural HA did not show significant alterations. The results of this new animal model indicated that the BMPb used, although facilitating osteoinduction, might not be sufficient to promote qualitative and quantitative bone neo-formation, which could guarantee better prognoses. The BMPb material studied may possibly become an alternative to autogenous grafts causing less discomfort for the patient.