Bone augmentation in sinus floor elevation by octacalcium phosphate collagen composite

摘要

Introduction: Synthetic octacalcium phosphate (OCP) has become recognized as a highly osteoconductive bone substitute material based on in vitro and vivo studies . OCP enhances osteoblastic cell differentiation in vitro in a dose-dependent manner . Furthermore, the dose-dependent stimulatory capacity of OCP was confirmed in vivo implantation with collagen matrix in rat critical sized calvaria defect W. OCP has higher solubility than be-ta tricalcium phosphate (be-ta TCP) therefore more resorbable than beta TCP in vivo . It has been shown that OCP combined with collagen (OCP/Collagen) facilitates bone regeneration in comparison with OCP itself . The osteoconductivity of OCP/Collagen has been demonstrated also in critical-sized bone defect of dog . After that, we examined the effect of OCP/Collagen on bone regeneration in human small bone defect and confirmed the healing at the defect. In this study, we performed sinus floor elevation for bone augmentation by OCP/Collagen as a preparation for dental implant treatment in clinical patient. Experimental methods: OCP was prepared according to a method of synthesis by mixing calcium nad phosphate solution . Particle size of OCP was 300 - 500 micrometer in diameter. OCP/Collagen was molded in the shape of a disc, 9 mm diameter, and 1.5 mm thick. Then OCP/Collagen was sterilized using electron beam irradiation at 15kGy. The protocol of the clinical trial was submitted and approved by the research ethics commitee of the Tohoku University Graduate School of Dentistry. In this study, we performed sinus floor elevation in a 41-years old man at left sinus under local anesthesia. 19 OCP/Collagen discs (approximately 1.8 cc) were used in this surgery. We observed the healing at operative region and confirmed having infection or allergy, or not and radiographic examination or CT scan was performed at 3 or 6 months after operation. Furthermore, we performed bone biopsy at the same time of placement of dental implant and we examined the newly formed bone historically. Result: There was no abnormality for healing, no infection and no allergic reaction for the entire period. OCP or OCP/Collagen does not have radiopacity under normal X-ray condition. However, radiopacity of OCP/Collagen implanted in sinus increased with time. CT scan showed radiopacity at 3 months after implantation. At 6 months, the radiopacity of that was almost same as surrounding bone of that in cancellous bone. Histological analysis showed the normal bone tissue including a little remaining impants. Discussion: These results showed that OCP/Collagen could convert to bone tissue in clinical use of sinus floor elevation. It was suggested that OCP/Collagen could be a suitable material for bone augmentation.