An injectable biphasic bone substitute in sinus augmentation

Sammanfattning: This thesis concerns a new synthetic, injectable bone substitute,Cerament™, primarily developed for treatment of vertebral fractures.The purpose of the thesis was to investigate the properties of the newbone substitute, that is, whether it can contribute to the generation ofnew bone formation needed for placement of future dental implants.When the amount of bone in the upper jaw is insufficient, primarystability of dental implants cannot be achieved. Sinus augmentationis a well-established method for increasing the bone volume. Thistechnique can be performed with autologous bone graft and / orbone substitute.Autologous bone graft can be harvested eitherfrom a local sourcein the oral cavity or from an extraoral source. The iliac crest is acommon donor site for bone grafts when large quantities are needed,but bone harvesting from the iliac crest require surgery under generalanesthesia resulting in an increased morbidity and higher costs.The thesis is based on study I-IV, both animal experimental studiesand clinical applications. The question is what gains can be achievedwith the use of a bone substitute. Therefore, to start with, study Ianalyzed and compared the costs of local bone grafts from the oralcavity and extra-oral bone grafts from the iliac crest. In addition,post-operative health parameters were analyzed for those patientswho underwent sinus augmentation, performed under generalanesthesia, with bone graft from the iliac crest. Finally, the total costof sinus augmentation, performed under general anesthesia, with iliacbone graft was calculated and analyzed with respect to the cost ofsurgery, anesthesia, hospitalization and sick leave. 9To achieve a broader understanding of the properties of thebone substitute study II and III were performed. Firstly, ananimalexperimental study in rats, with the intention to investigate if and towhat extent Cerament™onlay is able to stimulate new bone growthon a cortical bone surface.Secondly, an animal experimental rat studythat analyzed and estimated to what extentCerament™, in an onlayapplication, adds strength to the osseointegration of a titanium screw,measured as removal torque resistance.Further, to investigate theeffect of a titanium screw without any bone substitute on a corticalbone surface analyzed with regard to bone remodeling. Finally, as aclinical application (study IV), sinus augmentation with Cerament™was performed in four patients. The patients received either pureCerament™or Cerament™mixed with autologous bone chips.The studies resulted in the following: Costs for sinus augmentationwith iliac graft are several times larger than those for policlinicprocedures. Most patients, who received iliac graft surgery, hadrecovered after 14 days. LoP (loss of production) constituted 41% ofthe total cost for sinus augmentation with iliac bone graft. Cerament™guided bone generation from a cortical surface on rats’ tibia. Thesecond animal study displayed no difference in torque resistancebetween screws embedded in Cerament™and controls. Sinusaugmentation in a mixture of bone chips and 50-75% Cerament™rendered new bone formation after 6-11 months.Conclusion:There are gains to be made, in both economic andmorbidity terms, by using Cerament™. When applied as an onlay,Cerament™is capable of guiding and generating new bone formationon rats’ tibia. In sinus augmentation, Cerament™has been proven togenerate new bone without any adverse reactions. Future researchshould clarify how the clinical findings made in this thesis can beapplied in the orofacial environment.