An injectable biphasic bone substitute in sinus augmentation

Abstract: 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 new bone substitute, that is, whether it can contribute to the generation of new bone formation needed for placement of future dental implants. When the amount of bone in the upper jaw is insufficient, primary stability of dental implants cannot be achieved. Sinus augmentation is a well-established method for increasing the bone volume. This technique can be performed with autologous bone graft and / or bone substitute. Autologous bone graft can be harvested either from a local source in the oral cavity or from an extraoral source. The iliac crest is a common donor site for bone grafts when large quantities are needed, but bone harvesting from the iliac crest require surgery under general anesthesia resulting in an increased morbidity and higher costs. The thesis is based on study I-IV, both animal experimental studies and clinical applications. The question is what gains can be achieved with the use of a bone substitute. Therefore, to start with, study I analyzed and compared the costs of local bone grafts from the oral cavity and extra-oral bone grafts from the iliac crest. In addition, post-operative health parameters were analyzed for those patients who underwent sinus augmentation, performed under general anesthesia, with bone graft from the iliac crest. Finally, the total cost of sinus augmentation, performed under general anesthesia, with iliac bone graft was calculated and analyzed with respect to the cost of surgery, anesthesia, hospitalization and sick leave. 9 To achieve a broader understanding of the properties of the bone substitute study II and III were performed. Firstly, an animal experimental study in rats, with the intention to investigate if and to what extent Cerament ™ onlay is able to stimulate new bone growth on a cortical bone surface. Secondly, an animal experimental rat study that analyzed and estimated to what extent Cerament ™ , in an onlay application, adds strength to the osseointegration of a titanium screw, measured as removal torque resistance. Further, to investigate the effect of a titanium screw without any bone substitute on a cortical bone surface analyzed with regard to bone remodeling. Finally, as a clinical application (study IV), sinus augmentation with Cerament ™ was performed in four patients. The patients received either pure Cerament ™ or Cerament ™ mixed with autologous bone chips. The studies resulted in the following: Costs for sinus augmentation with iliac graft are several times larger than those for policlinic procedures. Most patients, who received iliac graft surgery, had recovered after 14 days. LoP (loss of production) constituted 41% of the total cost for sinus augmentation with iliac bone graft. Cerament ™ guided bone generation from a cortical surface on rats’ tibia. The second animal study displayed no difference in torque resistance between screws embedded in Cerament ™ and controls. Sinus augmentation 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 and morbidity terms, by using Cerament ™ . When applied as an onlay, Cerament ™ is capable of guiding and generating new bone formation on rats’ tibia. In sinus augmentation, Cerament ™ has been proven to generate new bone without any adverse reactions. Future research should clarify how the clinical findings made in this thesis can be applied in the orofacial environment.