Resorption Of Material Research Articles

Early Results of the Study of Reparative Peculiarities of Various Osteoplastic Materials in Experimental Bone Defects

Purpose. To determine the optimum osteoplastic material for activation of reparative osteogenesis and substitution of traumatic defects in metaepiphyseal spongy bone tissue.Material and methods.Comparative experimental morphological study was performed on 12 matured male Chinchilla rabbits with body weight 2500-2800g. A model of critical defects of spongy bone tissue was used. Bone defects were filled with 3 types of osteoplastic material: composite calcium sulphate bone cement; xenogenous hydroxyapatite-based material with granulated paste of synthetic peptides (P-15); β-tricalcium phosphate-based material with gauging liquid (calcium phosphate bone cement).Results.Implantation of calcium sulphate bone cement showed rapid osteogenesis stimulation at terms 1.5 months and reduction of newly formed bone tissue mass by 3rd month due to active resorption of the residual material. Implantation of hydroxyapatite-based material with P-15 resulted in osteogenesis stimulation on its surface however because of its mechanical instability and absence of active resorption of that material only a moderate formation of bone trabeculae was observed. At implantation of β-tricalcium phosphate-based material an active resorption of osteoplastic material, formation of trabecular system and its reorganization into trabecular network of femoral metaepiphyseal spongy bone accompanied by the formation of mature bone trabeculae was noted by month 3.Conclusion. Mechanical stability of osteoplastic material and subsequent gradual resorption as well as formation of mature bine trabeculae indicates the efficacy of β-tricalcium phosphate-based material.

Strontium(II) and mechanical loading additively augment bone formation in calcium phosphate scaffolds.

Calcium phosphate cements (CPCs) are widely used for bone-defect treatment. Current developments comprise the fabrication of porous scaffolds by three-dimensional plotting and doting using biologically active substances, such as strontium. Strontium is known to increase osteoblast activity and simultaneously to decrease osteoclast resorption. This study investigated the short- and long-term in vivo performances of strontium(II)-doted CPC (SrCPC) scaffolds compared to non-doted CPC scaffolds after implantation in unloaded or load-bearing trabecular bone defects in sheep. After 6 weeks, both CPC and SrCPC scaffolds exhibited good biocompatibility and osseointegration. Fluorochrome labeling revealed that both scaffolds were penetrated by newly formed bone already after 4 weeks. Neither strontium doting nor mechanical loading significantly influenced early bone formation. In contrast, after 6 months, bone formation was significantly enhanced in SrCPC compared to CPC scaffolds. Energy dispersive X-ray analysis demonstrated the release of strontium from the SrCPC into the bone. Strontium addition did not significantly influence material resorption or osteoclast formation. Mechanical loading significantly stimulated bone formation in both CPC and SrCPC scaffolds after 6 months without impairing scaffold integrity. The most bone was found in SrCPC scaffolds under load-bearing conditions. Concluding, these results demonstrate that strontium doting and mechanical loading additively stimulated bone formation in CPC scaffolds and that the scaffolds exhibited mechanical stability under moderate load, implying good clinical suitability. © 2017 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res 36:106-117, 2018.

Early Results of the Study of Reparative Peculiarities of Various Osteoplastic Materials in Experimental Bone Defects

Purpose. To determine the optimum osteoplastic material for activation of reparative osteogenesis and substitution of traumatic defects in metaepiphyseal spongy bone tissue. Material and methods. Comparative experimental morphological study was performed on 12 matured male Chinchilla rabbits with body weight 2500-2800g. A model of critical defects of spongy bone tissue was used. Bone defects were filled with 3 types of osteoplastic material: composite calcium sulphate bone cement; xenogenous hydroxyapatite-based material with granulated paste of synthetic peptides (P-15); β-tricalcium phosphate-based material with gauging liquid (calcium phosphate bone cement). Results. Implantation of calcium sulphate bone cement showed rapid osteogenesis stimulation at terms 1.5 months and reduction of newly formed bone tissue mass by 3rd month due to active resorption of the residual material. Implantation of hydroxyapatite-based material with P-15 resulted in osteogenesis stimulation on its surface however because of its mechanical instability and absence of active resorption of that material only a moderate formation of bone trabeculae was observed. At implantation of β-tricalcium phosphate-based material an active resorption of osteoplastic material, formation of trabecular system and its reorganization into trabecular network of femoral metaepiphyseal spongy bone accompanied by the formation of mature bone trabeculae was noted by month 3. Conclusion. Mechanical stability of osteoplastic material and subsequent gradual resorption as well as formation of mature bine trabeculae indicates the efficacy of β-tricalcium phosphate-based material.

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.

Effect of the up-front heat treatment of gelatin particles dispersed in calcium phosphate cements on the in vivo material resorption and concomitant bone formation.

Calcium phosphate cements (CPCs), consisting of a mixture of calcium phosphate powders and setting liquid, have been widely used in orthopedic applications. One of the drawbacks of CPCs is their poor resorbability in the living body, which hinders substitution with natural bones. One of the strategies to facilitate the resorption of CPCs is the incorporation of bioresorbable or water-soluble pore-generating particles (porogens), such as gelatin, in the CPC matrices. In spite of numerous reports, however, little is known about the effect of the dissolution/resorption rate of the porogens on concomitant bone regeneration. In the present study, we prepared preset CPCs dispersed with 10 mass% of low-endotoxin gelatin particles 200-500 μm in diameter having different heat-treatment histories, therefore exhibiting different dissolution rate, and then the obtained CPC/gelatin composites were evaluated for in vivo resorption and concomitant in vivo bone formation behaviors. As the results, the dispersion of gelatin particles markedly promoted in vivo resorption of CPC, and enhanced concomitant bone formation, connective tissue formation, osteoblast proliferation, and vascularization. The dissolution/resorption rate was able to be controlled by changing the up-front heat-treatment temperature. In particular, when CPC/gelatin composites were implanted in distal metaphysis of rabbits, the optimum dissolution/resorption was attained by heat-treating gelatin particles at 383 K for 24 h before dispersing in CPC. Quick resorption of calcium phosphate cement and concomitant bone formation by dispersing properly heat-treated with gelatin particles.

Relevance of osteoclast-specific enzyme activities in cell-based in vitro resorption assays

Cell-based in vitro resorption assays are an important tool to simulate the in vivo biodegradation of resorbable bone graft materials and to predict their clinical performance. The present study analyses the activity of osteoclast-specific enzymes as potential surrogate measures for classical pit assay, which is not applicable on irregular structured materials. Osteoclasts derived from human peripheral blood mononuclear cells were cultivated on different surfaces: calcium phosphate bone cements (CPC), dentin discs, osteoblast-derived extracellular matrix (ECM) and tissue culture polystyrene as control. Pit formation on the resorbable materials was investigated and correlated with the activity of tartrate resistant acid phosphatase (TRAP), carbonic anhydrase II (CAII) and cathepsin K (CTSK). Furthermore, the relation between intra- and extracellular enzyme activities was examined for TRAP and CTSK during resorption of the different materials. Resorbed area of CPC correlated with intracellular TRAP activity and intracellular CAII activity. Highest resorption was detected at around pH 7.2. Resorbed area on dentin correlated with the extracellular CTSK activity and extracellular TRAP activity and was maximal at around pH 6.8. Osteoclasts cultivated on cell-derived mineralised ECM showed a good correlation between both extracellular TRAP and CTSK activity and the release of calcium ions. Based on these data a different regulation of TRAP and CTSK secretion is hypothesised for the resorption of inorganic calcium phosphate compared to the resorption of collagenous mineralised matrix.

The Balance between Bone Formation and Material Resorption in Unidirectional Porous β-Tricalcium Phosphate Implanted in a Rabbit Tibia

We examined the balance between bone formation and material resorption in β-tricalcium phosphate, with unidirectional pores (porosity of 57%) and micropore structure. Using an animal bone defect model, rapid bone formation reached to the center of the material, while the material remained at the same period. Histomorphometric analysis showed that the sum total area of formed bone and material gradually increased with time throughout the experiment. These results indicate that the balance between bone formation and material resorption in this material is satisfactory.

Late-term healing in an augmented sinus with different ratios of biphasic calcium phosphate: a pilot study using a rabbit sinus model.

PurposeThe aim of this pilot study was to determine the osteoconductivity and dimensional stability of augmented sinuses using different ratios of biphasic calcium phosphate (BCP) in a rabbit sinus model.MethodsEach sinus of New Zealand white rabbits (2.5–3.5 kg) was assigned to one of two groups: BCP with a hydroxyapatite to β-tricalcium phosphate (HA:β-TCP) ratio of 70:30 (group TCP30) and BCP with an HA:β-TCP ratio of 30:70 (group TCP70). After preparing a window in the antral wall of a sinus, the Schneiderian membrane was elevated, and the applicable material was grafted. A fluorochrome calcein green was injected five days before euthanizing the animals at four months post-surgery. The specimens were analyzed histologically, histomorphometrically, and by using micro-computed tomography (micro-CT).ResultsMicro-CT analysis revealed that the total augmented volume and the new bone volume did not differ significantly between the two groups whereas the resorption of materials was greater in the TCP70 group. The trabecular thickness, number, and separation also did not differ significantly between the two groups. Histomorphometrically, the areas of total augmentation, new bone, and residual material, as well as the ratio of new-bone-material contact did not differ significantly between the groups. Histologically, the residual particles were more scattered in the TCP70 group than in the TCP30 group. The fluorescence of the calcein green did not differ notably between the two groups.ConclusionsThe osteoconductivity and dimensional stability of the two BCPs with different ratios tested in this study were comparable after four months of healing. Therefore, we conclude that both BCPs show promise as a bone substitute for sinus augmentation.

Minimally Invasive Alveolar Ridge Preservation Utilizing an In Situ Hardening β-Tricalcium Phosphate Bone Substitute: A Multicenter Case Series.

Ridge preservation measures, which include the filling of extraction sockets with bone substitutes, have been shown to reduce ridge resorption, while methods that do not require primary soft tissue closure minimize patient morbidity and decrease surgical time and cost. In a case series of 10 patients requiring single extraction, in situ hardening beta-tricalcium phosphate (β-TCP) granules coated with poly(lactic-co-glycolic acid) (PLGA) were utilized as a grafting material that does not necessitate primary wound closure. After 4 months, clinical observations revealed excellent soft tissue healing without loss of attached gingiva in all cases. At reentry for implant placement, bone core biopsies were obtained and primary implant stability was measured by final seating torque and resonance frequency analysis. Histological and histomorphometrical analysis revealed pronounced bone regeneration (24.4 ± 7.9% new bone) in parallel to the resorption of the grafting material (12.9 ± 7.7% graft material) while high levels of primary implant stability were recorded. Within the limits of this case series, the results suggest that β-TCP coated with polylactide can support new bone formation at postextraction sockets, while the properties of the material improve the handling and produce a stable and porous bone substitute scaffold in situ, facilitating the application of noninvasive surgical techniques.

Reconstruction of oro-facial region; challenges and opportunities

Event Abstract Back to Event Reconstruction of oro-facial region; challenges and opportunities Ashraf A. Ayoub1, Randa Al Fotawi1, K E. Tanner2, Matthew J. Dalby3 and Kurt Naudi1 1 University of Glasgow, Glasgow Dental Hospital & School, United Kingdom 2 University of Glasgow, Biomedical Engineering Division, School of Engineering, United Kingdom 3 University of Glasgow, Institute of Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, United Kingdom Background: Surgical reconstruction of functional and aesthetic defects, particularly following ablative cancer surgery, is often compromised by limited vascularity and the associated donor site morbidity. A compromised vascular bed is a major obstacle for the successful uptake of a micro-vascular flap. Aim: Investigate a novel approach of using an injectable scaffolding into a pedicled muscle flap for reconstruction of a critical size mandibular defect. Materials and Methods: Under general anesthesia bone marrow was aspirated from both the rabbit’s anterior iliac crest. Cells were cultured and expanded according to a validated standard protocol before application in the surgical defect[1]. A critical size bony defect, 20mm x 15mm, was created in the rabbit’s mandibular body[2]. A fixation plate was applied at the inferior border to maintain the mandibular integrity, while the superior border was maintained. A pedicled masseter muscle flap was rotated and adapted to fill the created surgical defect. An injectable calcium sulfate/hydroxyapatite scaffolding material (Cerament Spine Support) loaded with BMP-7 and mesnechymal stem cells was injected into the muscle flap to induce bone formation. Animals were sacrificed at three months following surgery. The quality of bone regeneration was assessed using Cone Beam Computerised Tomography (CBCT), micro CT and histological assessment. Results: In all the cases sporadic areas of bone regeneration were detected within the muscle flap. In some cases the volume of newly formed bone was more than the volume of bone resected to the create the defect. Bone formation was in close proximity to the injectable scaffold material. Micro CT showed a different trabecular pattern in the regenerated bone to the native bone tissue. Fig 1 Micro CT showing new bone formed in the defect. Histologically, the regenerated tissue consisted of a mixture of mature bone with clear Haversion structure and areas of woven bone. Some areas of fibrous tissue “muscle metaplasia” was detected between the newly generated bone and the surrounding muscle fibres. New bone formation was either from the defect edges or Fig 2 Undecalcified section stained with Goldner’s trichrome, showing resorption of the graft material and new bone formation. Conclusions: The muscle flap acted as a bioreactor for bone induction under the influence of calcium sulfate/hydroxyapatite, stem cells and BMP-7. Three months is insufficient for complete restoration of the bony defect. The new bone formation concentrated around the areas of the injected cells and material. Randa Alfotawi was funded by King Saud University, Ministry of Higher Education; Bone Support AB (Lund, Sweden) is thanked for provision of the Cerament™ bone cements

The influence of different geometries of matrix/scaffold on the remodeling process of a bone and bioresorbable material mixture with voids

Since internal architecture greatly influences crucial factors for tissue regeneration, such as nutrient diffusion, cell adhesion and matrix deposition, scaffolds have to be carefully designed, keeping in mind case-specific mechanical, mass transport and biological requirements. However, customizing scaffold architecture to better suit conflicting requirements, such as biological and mechanical ones, remains a challenging issue. Recent advances in printing technologies, together with the synthesis of novel composite biomaterials, have enabled the fabrication of various scaffolds with defined shape and controlled in vitro behavior. Thus, the influence of different geometries of the assemblage of the matrix and scaffold on the remodeling processes of living bone and artificial material should be investigated. To this end, two implant shapes are considered in this paper, namely a circular inclusion and a rectangular groove of different aspect ratios. A model of a mixture of bone tissue and bioresorbable material with voids was used to numerically analyze the physiological balance between the processes of bone growth and resorption and artificial material resorption in a plate-like sample. The adopted model was derived from a theory for the behavior of porous solids in which the matrix material is elastic and the interstices are void of material.

Mechanisms of in Vivo Degradation and Resorption of Calcium Phosphate Based Biomaterials.

Calcium phosphate ceramic materials are extensively used for bone replacement and regeneration in orthopedic, dental, and maxillofacial surgical applications. In order for these biomaterials to work effectively it is imperative that they undergo the process of degradation and resorption in vivo. This allows for the space to be created for the new bone tissue to form and infiltrate within the implanted graft material. Several factors affect the biodegradation and resorption of calcium phosphate materials after implantation. Various cell types are involved in the degradation process by phagocytic mechanisms (monocytes/macrophages, fibroblasts, osteoblasts) or via an acidic mechanism to reduce the micro-environmental pH which results in demineralization of the cement matrix and resorption via osteoclasts. These cells exert their degradation effects directly or indirectly through the cytokine growth factor secretion and their sensitivity and response to these biomolecules. This article discusses the mechanisms of calcium phosphate material degradation in vivo.

En face OCT

Summary“En face” OCT (Spectral Domain and Swept Source) realizes frontal section of the retina or C‐scans. “En face” OCT software informs immediately the layer of the cuts; it joins viewing images “en face” and B‐scan with the graphical representation of their different scans.Normal retinal layers have their specific reflectivity.Atrophy can occur at different stages of many retinal diseases, and at different retinal layers. On “en face” OCT, there are 2 main areas to consider in case of atrophy in retinal diseases: ‐ the inner nuclear layer which may presents pseudocystic lesions that reflect a damage inducing optic nerve atrophy, ‐ the outer retinal layers in degenerative retinal diseases such as age related macular degeneration (AMD), genetic diseases such as Stargardt's macular dystrophy, retinitis pigmentosa, MacTel type 2 and in inflammatory diseases such as Serpiginous and Birdshot retino choroidopathies. The pseudocystic lesions might represent a mitochondrial dysfunction inducing degeneration of Muller cells.The outer retinal damage can be related to material resorption (drusen, pseudodrusen, PED), disappearance of choriocapillaris, ellipsoid disruptions .”En face” has increased the understanding of atrophy in retinal disease.

Novel bone substitute material in alveolar bone healing following tooth extraction: an experimental study in sheep.

Electrospun cotton wool-like nanocomposite (ECWN) is a novel synthetic bone substitute that incorporates amorphous calcium phosphate nanoparticles into a biodegradable synthetic copolymer poly(lactide-co-glycolide). The objectives of this study were to develop a tooth extraction socket model in sheep for bone graft research and to compare ECWN and bovine-derived xenograft (BX) in this model. Sixteen cross-bred female sheep were used. Bilateral mandibular premolars were extracted atraumatically. Second and third premolar sockets were filled (Latin-square allocation) with BX, ECWN or left unfilled. Resorbable collagen membranes were placed over BX and selected ECWN grafted sockets. Eight sheep per time period were sacrificed after 8 and 16weeks. Resin-embedded undemineralised sections were analysed for descriptive histology and histomorphometric analyses. At 8weeks, there were with no distinct differences in healing among the different sites. At 16weeks, osseous healing followed a fine trabecular pattern in ECWN sites. Non-grafted sites showed thick trabeculae separated by large areas of fibrovascular connective tissue. In BX grafted sites, xenograft particles were surrounded by newly formed bone or fibrovascular connective tissue. There were no statistically significant differences in bone formation across the four groups. However, ECWN sites had significantly less residual graft material than BX sites at 16weeks (P=0.048). This first description of a tooth extraction socket model in sheep supports the utility of this model for bone graft research. The results of this study suggested that the novel material ECWN did not impede bone ingrowth into sockets and showed evidence of material resorption.

Application of a Collagenated Biphasic Calcium Phosphate Loaded with Fibroblast Growth Factor-2 in the Rabbit Sinus: A Pilot Study.

The aim of this study was to determine the effect of collagenated biphasic calcium phosphate (CBCP) loaded with fibroblast growth factor-2 (FGF-2) on bone regeneration in a rabbit sinus model. Bilateral sinus augmentations were performed using either FGF-2-loaded CBCP (FGF-2 group) or CBCP only (control group) in 10 rabbits. The experimental animals were euthanized at 2 weeks (n = 5) or 4 weeks (n = 5) postoperatively. Volumetric analyses were done by means of microcomputed tomography and histomorphometry. The volumes of total augmentation, new bone, residual material, and fibrovascular tissue were significantly greater in the FGF-2 group than in the control group at 2 weeks, but the differences between the two groups had disappeared by 4 weeks. Histologically, the healing patterns, such as new bone formation and the resorption of residual material, did not differ notably between the two groups. The results of the histometric analysis did not correspond to those of the volumetric analysis. The areas of total augmentation, new bone, residual material, and fibrovascular tissue, and the number of blood vessels did not differ significantly between the FGF-2 and the control groups at either time point. CBCP loaded with FGF-2 resulted in the early promotion of new bone; however, it failed to produce superior bone regeneration in a later stage of healing.

Episodic construction of the Tatra granitoid intrusion (Central Western Carpathians, Poland/Slovakia): consequences for the geodynamics of Variscan collision and Rheic Ocean closure

The Tatra granitoid pluton (Central Western Carpathians, Poland/Slovakia) is an example of composite polygenetic intrusion, comprising many magmatic pulses varying compositionally from diorite to granite. The U–Pb LA-MC-ICP-MS zircon dating of successive magma batches indicates the presence of magmatic episodes at 370–368, 365, 360, 355 and 350–340 Ma, all together covering a time span of 30 Ma of magmatic activity. The partial resorption and recycling of former granitoid material (“petrological cannibalism”) was a result of the incremental growth of the pluton and temperature in the range of 750–850 °C. The long-lasting granitoid magmatism was connected to the prolonged subduction of oceanic crust and collision of the Proto-Carpathian Terrane with a volcanic arc and finally with Laurussia, closing the Rheic Ocean. The differences in granitoid composition are the results of different depths of crustal melting. More felsic magmas were generated in the outer zone of the volcanic arc, whilst more mafic magmas were formed in the inner part of the supra-subduction zone. The source rocks of the granitoid magmas covered the compositional range of metapelite–amphibolite and were from both lower and upper crust. The presence of the inherited zircon cores suggests that the collision and granitoid magmatism involved crust of Cadomian consolidation age (c. 530 and 518 Ma) forming the Proto-Carpathian Terrane, crust of Avalonian affinity (462, 426 Ma) and melted metasedimentary rocks of volcanic arc provenance.

The effects of combined low level laser therapy and mesenchymal stem cells on bone regeneration in rabbit calvarial defects

ObjectiveThis study evaluated the effect of Low Level Laser Therapy (LLLT) and Mesenchymal Stem Cells (MSCs) on bone regeneration. Background dataAlthough several studies evaluated the effects of MSCs and LLLT, there is little information available regarding in vivo application of LLLT in conjunction with MSCs. MethodsForty-eight circular bone defects (6mm in diameter) were prepared in the calvaria of 12 New-Zealand white rabbits. The defects of each animal were randomly assigned to 4 groups: (C) no treatment; (L) applying LLLT; (SC) filled with MSCs; (SCL) application of both MSCs and LLLT. LLL was applied on alternate days at wavelength of 810nm, power density of 0.2W/cm2 and a fluency of 4J/cm2 using a Gallium–Aluminum–Arsenide (GaAlAs) diode laser. The animals were sacrificed after 3weeks and then histological samples were evaluated to determine the amount of new bone formation and the remaining scaffold and inflammation. ResultsThe histological evaluation showed a statistically significant increase in new bone formation of LLLT group relative to the control and the other two experimental groups (p<0.05). There was no significant difference in bone formation of the control group compared to experimental groups filled with MSCs. Laser irradiation had no significant effect on resorption of the scaffold material. In addition, inflammation was significantly reduced in LLLT group compared to the control defects and the other two experimental groups. ConclusionLow level laser therapy could be effective in bone regeneration but there is no evidence of a synergistic effect when applied in conjunction with MSCs.

Acceleration of Alveolar Ridge Augmentation Using a Low Dose of Recombinant Human Bone Morphogenetic Protein-2 Loaded on a Resorbable Bioactive Ceramic

The aim of the present study was to evaluate the effect of a porous silica-calcium phosphate composite (SCPC50) loaded with and without recombinant human bone morphogenetic protein-2 (rhBMP-2) on alveolar ridge augmentation in saddle-type defects. Micro-granules of SCPC50 resorbable bioactive ceramic were coated with rhBMP-2 10mg and then implanted into a saddle-type defect (12 × 7mm) in a dog mandible and covered with a collagen membrane. Control groups included defects grafted with SCPC50 granules without rhBMP-2 and un-grafted defects. Bone healing was evaluated at 8 and 16weeks using histologic and histomorphometric techniques. The increase in bone height and total defect fill were assessed for each specimen using the ImageJ 1.46 program. The release kinetics of rhBMP-2 was determined invitro. The height of the bone in the grafted defects and the total defect fill were statistically analyzed. SCPC50 enhanced alveolar ridge augmentation as indicated by the increased vertical bone height, bone surface area, and bone volume after 16weeks. SCPC50-rhBMP-2 provided a sustained release profile of a low effective dose (BMP-2 4.6 ± 1.34 pg/mL per hour) during the 1- to 21-day period. The slow rate of release of rhBMP-2 from SCPC50 accelerated synchronized complete bone regeneration and graft material resorption in 8weeks. Successful rapid reconstruction of the alveolar ridge by SCPC50 and SCPC50-rhBMP-2 occurred without any adverse excessive bone formation, inflammation, or fluid-filled voids. Results of this study suggest that SCPC50 is an effective graft material to preserve the alveolar ridge after tooth extraction. Coating SCPC50-rhBMP-2 further accelerated bone regeneration and a considerable increase in vertical bone height. These findings make SCPC50 the primary choice as a carrier for rhBMP-2. SCPC50-rhBMP-2 can serve as an alternative to autologous bone grafting.

Medium-Term Function of a 3D Printed TCP/HA Structure as a New Osteoconductive Scaffold for Vertical Bone Augmentation: A Simulation by BMP-2 Activation

Introduction: A 3D-printed construct made of orthogonally layered strands of tricalcium phosphate (TCP) and hydroxyapatite has recently become available. The material provides excellent osteoconductivity. We simulated a medium-term experiment in a sheep calvarial model by priming the blocks with BMP-2. Vertical bone growth/maturation and material resorption were evaluated. Materials and methods: Titanium hemispherical caps were filled with either bare- or BMP-2 primed constructs and placed onto the calvaria of adult sheep (n = 8). Histomorphometry was performed after 8 and 16 weeks. Results: After 8 weeks, relative to bare constructs, BMP-2 stimulation led to a two-fold increase in bone volume (Bare: 22% ± 2.1%; BMP-2 primed: 50% ± 3%) and a 3-fold decrease in substitute volume (Bare: 47% ± 5%; BMP-2 primed: 18% ± 2%). These rates were still observed at 16 weeks. The new bone grew and matured to a haversian-like structure while the substitute material resorbed via cell- and chemical-mediation. Conclusion: By priming the 3D construct with BMP-2, bone metabolism was physiologically accelerated, that is, enhancing vertical bone growth and maturation as well as material bioresorption. The scaffolding function of the block was maintained, leaving time for the bone to grow and mature to a haversian-like structure. In parallel, the material resorbed via cell-mediated and chemical processes. These promising results must be confirmed in clinical tests.

The use of anatomically drop-shaped bioactive glass S53P4 implants in the reconstruction of orbital floor fractures—A prospective long-term follow-up study

An isolated fracture of the orbital floor needs reconstruction if there is a clear herniation of adipose tissue or of the rectus inferior muscle into the maxillary sinus. A prospective study was carried out treating 20 patients with an isolated blow-out fracture of the orbital floor or with a combined zygomatico-orbito-maxillary complex fracture, using a newly designed anatomically drop-shaped implants made of bioactive glass (BAG) S53P4. Computed tomography (CT) was performed immediately postoperatively to confirm the correct position of the plate. The patients were followed up for an average of 32 months clinically and radiologically with magnetic resonance imaging (MRI) for an average of 31 months. None of the patients had any signs of complications related to the implant and the clinical outcome was very good. None of the patients had persisting diplopia. The level of the pupillas was normal in 15 of 20 patients. Minor hypo-ophthalmos ranging from 0.5 to 1.0 mm was observed in three patients, and moderate hypo-ophthalmos of 2.0 mm was seen in one patient. Hyperophthalmos of 1.0 mm was seen in one patient. Minor enophthalmos on the operated side ranging from 0.5 to 1.0 mm was seen in eight patients. Mild to moderate paraesthesia of the infraorbital nerve was observed in six patients. The immediate postoperative CT and the long term follow-up MRI revealed that the drop-shaped BAG implants retained their correct position in the orbital floor and did not show any evidence of losing their original shape or material resorption. No adverse tissue reaction was associated with the material. Due to the anatomical drop shape, the implants could successfully maintain the orbital volume and compensate for the retrobulbar adipose tissue atrophy.