Improvement of the Obliteration of Non-Critical Size Defects by Using a Mixture of Bone Dust and Bone Replacement Material (Bioactive Glass S53P4)

Background/Objectives: Obliterates such as autologous bone dust (BD) or the synthetic bioactive glass S53P4 (BA) are frequently used for the obliteration of non-critical size defects (NCSDs), especially in otosurgery. Both obliterates have advantages and disadvantages, so that the combination of both for the obliteration of NCSDs is analysed. Methods: As part of a large animal project with sheep, four NCSDs were created in the calotte of thirteen animals using a drill. These were filled with BD, BD and BA, or BA, and the reference defect remained empty. After three weeks, the explanted calottes were examined with regard to their newly formed bone using digital volume tomography, bone density measurement, fluorochrome sequence labelling, and histological analysis. In addition, human cell culture analyses were carried out on the quality of the BD. Results: BD collected at 7.000 and 15.000 rpm shows a higher activity of new bone formation. In combination with BA, bone is formed centripetally and centrifugally. Defect filling with BA and BD shows a higher bone density and compactness than BD alone. Conclusions: BD should be harvested at a speed of less than 15.000 rpm. Using this BD in combination with BA to obliterate NCSDs enables the defect to be obliterated quickly and completely, with more newly formed bone, creating a bone network with incorporated BA. Further studies are needed to investigate the long-term stability of this obliteration and to determine which other parameters of the extraction can increase the amount of vital BD.