Comparison of nanoparticular hydroxyapatite pastes of different particle content and size in a novel scapula defect model

Nanocrystalline hydroxyapatite (HA) has good biocompatibility and the potential to support bone formation. It represents a promising alternative to autologous bone grafting, which is considered the current gold standard for the treatment of low weight bearing bone defects. The purpose of this study was to compare three bone substitute pastes of different HA content and particle size with autologous bone and empty defects, at two time points (6 and 12 months) in an ovine scapula drillhole model using micro-CT, histology and histomorphometry evaluation. The nHA-LC (38% HA content) paste supported bone formation with a high defect bridging-rate. Compared to nHA-LC, Ostim(®) (35% HA content) showed less and smaller particle agglomerates but also a reduced defect bridging-rate due to its fast degradation The highly concentrated nHA-HC paste (48% HA content) formed oversized particle agglomerates which supported the defect bridging but left little space for bone formation in the defect site. Interestingly, the gold standard treatment of the defect site with autologous bone tissue did not improve bone formation or defect bridging compared to the empty control. We concluded that the material resorption and bone formation was highly impacted by the particle-specific agglomeration behaviour in this study

A quantification of regenerated bone tissue in human sinus biopsies: influences of anatomical region, age and sex

Objectives: Sinus augmentation is a standard procedure to increase vertical bone supply for dental implants in the atrophic posterior maxilla. Despite the longstanding application of this method, information about some basic factors that could potentially influence bone regeneration after sinus augmentation is rare. The objective of this study was therefore to quantify the impact of the maxillary region (premolar/molar) and patients' age and sex on bone regeneration after sinus grafting. Material and methods: Sinus augmentation procedures were performed in 107 patients (66 female: 52.8 ± 11.0 years, 41 male: 50.6 ± 11.3 years). After 6 ± 1 months, 201 sinus biopsies were harvested and histomorphometrically analysed. Height (oldHt) and bone volume fraction of pristine bone (oldBV/TV), as well as the amount of new bone (newBV/TV) and bone‐to‐bone substitute contact (BBSC) in the augmentation area, were assessed. Results: In women, newBV/TV in the augmented sinus decreased significantly by 0.22 ± 0.08% per year. In men, no similar trend was observed. There were strong influences of the maxillary region and the dimensions of the host bone. In the premolar region, newBV/TV was 23.1 ± 7.9% and 25.1 ± 10.1%; in the molar region, newBV/TV averaged 20.4 ± 9.4% and 17.8 ± 8.8% for women and men, respectively. The greater the thickness of the wall of the sinus floor (mainly in the former premolar region), the greater was the amount of new bone tissue formed in the spaces in‐between bone substitute particles. Conclusions: These empirical results derived from a large human sample, link factors that influence the quality of biomaterial integration to the known clinical risks for the success of dental implants.Karoline Maria Reich, Christian Domitian Huber, Patrick Heimel, Christian Ulm, Heinz Redl, Stefan Tang

The effect of diclofenac sodium-loaded poly(lactide-co-glycolide) rods on bone formation and inflammation:a histological and histomorphometric study in the femora of rats

Abstract Implants made of poly(lactide-co-glycolide) (PLGA) are biodegradable and frequently provoke foreign body reactions (FBR) in the host tissue. In order to modulate the inflammatory response of the host tissue, PLGA implants can be loaded with anti-inflammatory drugs. The aim of this study was to analyze the impact of PLGA 80/20 rods loaded with the diclofenac sodium (DS) on local tissue reactions in the femur of rats. Special emphasis was put on bone regeneration and the presence of multinucleated giant cells (MGCs) associated with FBR. PLGA 80/20 alone and PLGA 80/20 combined with DS was extruded into rods. PLGA rods loaded with DS (PLGA+DS) were implanted into the femora of 18 rats. Eighteen control rats received unloaded PLGA rods. The follow-up period was of 3, 6 and 12 weeks. Each group comprised of six rats. Peri-implant tissue reactions were histologically and histomorphometrically evaluated. The implantation of PLGA and PLGA+DS8 rods induced the formation of a layer of newly formed bone islands parallel to the contour of the implants. PLGA+DS rods tended to reduce the presence of multi-nucleated giant cells (MGCs) at the implant surface. Although it is known that the systemic administration of DS is associated with compromised bone healing, the local release of DS via PLGA rods did not have negative effects on bone regeneration in the femora of rats throughout 12 weeks

Performance Test of Focal-Plane Modules of the DSSC X-ray Imager

The DSSC mega-pixel X-ray imager is being developed for experiments at the European XFEL for low energies between 0.5 keV and 6 keV. The smallest unit comprises the electronics for the operation and readout of 512-by-128 pixels. The current version is based on miniaturized silicon-drift detector (mini-SDD) cells. A future active sensor type based on DEPFETs is currently available in a smaller format of 64-by-64 pixels and uses the same electronics. For both detector types, the readout ASIC comprises a filter for analog signal processing, an 8-bit ADC for digitization, and a memory to store up to 800 images on pixel level. Due to versatility of the control system, both detector types can be flexibly operated at different types of X-ray sources (radioactive, synchrotron, FEL). We present the operation and results of the small-format DEPFET module and the first full-format mini-SDD module at a synchrotron beam line of Petra II

Histomorphometric Analysis of Callus Formation Stimulated by Axial Dynamisation in a Standardised Ovine Osteotomy Model

The cyclic axial dynamisation of a stabilised fracture is intended to promote callus formation and bone healing. Most studies focused on biomechanical properties or the quantity of new bone formation. Far less is known about the quality of newly formed callus tissues, such as tissue distribution and arrangement within the callus. The aim of this current study was to investigate the effect of cyclic, axial dynamisation on the quantity and quality of callus in an established delayed fracture healing model. In 41 sheep transverse osteotomies with a gap size of 3 mm were stabilised with a unilateral external fixator. In 32 of these, fracture ends were axially stimulated with displacement amplitudes of 0.8 mm, 0.4 mm, 0.2 mm, or 0.0 mm, respectively, for six weeks. In the remaining 9 sheep of the control group, an additional external fixator was mounted to achieve almost total rigidity. Animal material originating from a past animal experiment was reanalysed in this study. Histological thin-ground sections were histomorphometrically analysed regarding the histological structure and composition of the defect region. A slight tendency towards an increase in size of total callus area, area of new bone (nB.Ar), and cartilage (Cg.Ar) was detected with increasing displacement amplitudes compared to the control group. At the anterior callus side nB.Ar and Cg.Ar were significantly larger than at the posterior side in all groups independent of treatment. Regarding the quality of callus, areas of very compact bone were predominant in the treatment groups whereas in the control group a slight shift to more porous bone was observed. No difference of callus compactness was observed between the anterior and the posterior side. The established method to assess the local compactness of callus areas is a useful tool to quantitatively determine the spatial distribution of new bone tissue within the callus. The application of this method in combination with biomechanical testing might reveal interesting relations between tissue distribution and bone strength that, with traditional histomorphometry, cannot be identified