Bone Substitution Research Articles

Local Antibiotic Delivery Ceramic Bone Substitutes for the Treatment of Infected Bone Cavities and Bone Regeneration: A Systematic Review on What We Have Learned from Animal Models.

the focus of this study is to evaluate if the combination of an antibiotic with a ceramic biomaterial is effective in treating osteomyelitis in an infected animal model and to define which model and protocol are best suited for in vivo experiments of local bone infection treatment. a systematic review was carried out based on PRISMA statement guidelines. A PubMed search was conducted to find original papers on animal models of bone infections using local antibiotic delivery systems with the characteristics of bone substitutes. Articles without a control group, differing from the experimental group only by the addition of antibiotics to the bone substitute, were excluded. a total of 1185 records were retrieved, and after a three-step selection, 34 papers were included. Six manuscripts studied the effect of antibiotic-loaded biomaterials on bone infection prevention. Five articles studied infection in the presence of foreign bodies. In all but one, the combination of an antibiotic with bioceramic bone substitutes tended to prevent or cure bone infection while promoting biomaterial osteointegration. this systematic review shows that the combination of antibiotics with bioceramic bone substitutes may be appropriate to treat bone infection when applied locally. The variability of the animal models, time to develop an infection, antibiotic used, way of carrying and releasing antibiotics, type of ceramic material, and endpoints limits the conclusions on the ideal therapy, enhancing the need for consistent models and guidelines to develop an adequate combination of material and antimicrobial agent leading to an effective human application.

Bacterial Growth in Unsealed Bone-grafting Products

The aim of this study was to simulate reusing an opened package of bone substitute (BS) under typical clinical conditions, by analyzing bacterial growth in samples of resealed packages of alloplast and xenograft BS following different time periods up to a week. The experiment was performed in 2 stages: dry stage and wet stage. In the dry stage, BS samples were exposed to air for 15 minutes and then were sealed again in their original package. After several "aging" periods [no aging (t0), 24hours (t1), and 1week (t7)], BS samples were plated onto brain heart infusion agar and were incubated at 37°C for 24 hours under aerobic conditions. Bacterial colonies were enumerated and colony forming units per 1mL was calculated. In the wet stage, the experiment was repeated but BSs were left to age in a brain heart infusion broth to simulate a more supporting humid environment to encourage bacterial growth. In the dry stage of the experiment, no bacterial growth was detected in both xenograft and alloplast samples (colony forming units/mL=0), in any of the time points (t0, t1, t7). In the wet stage, average bacterial growth was 0 for both groups in t0. In t1: 1.14 × 10 4 ±4.16 × 10 3 for the xenograft and 7.73 × 10 5 ± 9.99 × 10 5 for the alloplast. In t7: 1.64 × 10 9 ±1.82 × 10 8 in the xenograft compared with 8.86 × 10 8 ±4.00 × 10 8 for the alloplast. Analysis of variance with repeated measures showed a significant difference in comparison of the 2 BSs for each time group (t1 and t7) ( P <0.005). Under dry conditions, in a resealed package, there was no bacterial growth for up to 1 week for both BSs. Once the BSs are introduced to a humid environment, which supports bacterial growth, the xenograft BS allowed more rapid bacterial growth, compared with the alloplastic BS.

Vancomycin Loaded Amino-Functionalized MCM-48 Mesoporous Silica Nanoparticles as a Promising Drug Carrier in Bone Substitutes for Bacterial Infection Management.

Orthopedic infections due to biofilm formation in biomaterial-based implants have become challenging in bone tissue engineering. In the present study, in vitro antibacterial analysis of amino-functionalized MCM-48 mesoporous silica nanoparticles (AF-MSNs) loaded with vancomycin is analyzed for its potential as a drug carrier for the sustained/controlled release of vancomycin against Staphylococcus aureus. The effective incorporation of vancomycin into the inner core of AF-MSNs was observed by alternation in the absorption frequencies obtained by Fourier transform infrared spectroscopy (FTIR). Dynamic light scattering (DLS) and high resolution-transmission electron microscopy (HR-TEM) results show that all the AF-MSNs had homogeneous spherical shapes with a mean diameter of 165.2 ± 1.25nm, and there is a slight change in the hydrodynamic diameter after vancomycin loading. Furthermore, the zeta potential of all the AF-MSNs (+ 30.5 ± 0.54mV) and AF-MSN/VA (+ 33.3 ± 0.56mV) were positively charged due to effective functionalization with 3-aminopropyl triethoxysilane (APTES). Furthermore, cytotoxicity results show that the AF-MSNs have better biocompatibility than non-functionalized MSNs (p < 0.05), and results prove AF-MSNs loaded with vancomycin show better antibacterial effect against S. aureus than non-functionalized MSNs. Results confirm that bacterial membrane integrity was affected by treatment with AF-MSNs and AF-MSN/VA by staining the treated cells with FDA/PI. Field emission scanning electron microscopy (FESEM) analysis confirmed the shrinkage of bacterial cells and membrane disintegration. Furthermore, these results demonstrate that amino-functionalized MSNs loaded with vancomycin significantly increased the anti-biofilm and biofilm inhibitory effect and can be incorporated with biomaterial-based bone substitutes and bone cement to prevent orthopedic infections post-implantation.

Reconstructive Peri-Implantitis Therapy by Using Bovine Bone Substitute with or without Hyaluronic Acid: A Randomized Clinical Controlled Pilot Study

The present pilot study aimed to assess clinical and radiographic efficiencies of bovine bone substitute (BBS) merged with hyaluronic acid (HA) in peri-implantits reconstructive surgery. Peri-implantitis (diagnosed 6.03 ± 1.61 years of implant loading) bone defects were randomly treated either with BBS plus HA (test group) or BBS alone (control group). Clinical parameters including peri-implant probing depth (PPD), bleeding on probing (BOP), implant stability (ISQ), and radiographic changes in vertical and horizontal marginal bone (MB) levels were assessed at six months postoperatively. New temporary and permanent screw-retained crowns were made at two weeks and three months postoperatively. Data were analyzed using parametric and non-parametric tests. In both groups, 75% of patients and 83% of implants achieved treatment success after six months (no BOP, PPD <5 mm, and no further MB loss). Clinical outcomes improved over time within groups; however, without significant difference between them. ISQ value obtained significant increases in the test compared to the control group at six months postoperatively (p < 0.05). The vertical MB gain was significantly greater in the test group compared to the control (p < 0.05). Short-term outcomes suggested that BBS merged with HA could improve clinical and radiographic outcomes in peri-implantitis reconstructive therapy.

The Effects of Alloplastic Bone Substitute and Enamel Matrix Derivative on the Preservation of Single Anterior Extraction Sockets: A Tomographic Evaluation.

This study was designed to assess the use of enamel matrix derivative (EMD; Emdogain, Straumann) and alloplastic bone substitute (BoneCeramic [BC], Straumann) in postextraction alveolar sockets. A total of 45 patients requiring anterior single tooth extractions and subsequent implant placement were recruited and randomly assigned to one of three treatment groups. Postextraction sockets were filled with BC or BC + EMD, or were left to heal spontaneously. Tomographic dimensional changes were measured immediately following tooth extraction and at the 6-month follow-up. Computed tomographic (CT) scans were taken with a radiographic stent within 48 hours of extraction (CT1) and at 6 months (CT2). Paired comparisons related to the mean horizontal reduction of the vestibular crest (VC) showed significant differences between sockets left to heal spontaneously (Group 1) and the two groups filled with BC (Group 2) and BC + EMD (Group 3): 1.7 mm for Group 1 and 0.9 mm for Groups 2 and 3 (P < .05). Thus, the use of alloplastic bone substitute alone or with EMD resulted in better preservation of postextraction socket dimensions. No differences in socket preservation were found between Group 2 (BC) and Group 3 (BC + EMD). Int J Periodontics Restorative Dent 2023;43:e117-e124. doi: 10.11607/prd.5820.

Tricalcium Phosphate as a Bone Substitute to Treat Massive Acetabular Bone Defects in Hip Revision Surgery: A Systematic Review and Initial Clinical Experience with 11 Cases

The use of tricalcium phosphate (TCP) as a bone substitute is gaining increasing interest to treat severe acetabular bone defects in revision total hip arthroplasty (rTHA). The aim of this study was to investigate the evidence regarding the efficacy of this material. A systematic review of the literature was performed according to the PRISMA and Cochrane guidelines. The study quality was assessed using the modified Coleman Methodology Score (mCMS) for all studies. A total of eight clinical studies (230 patients) were identified: six on TCP used as biphasic ceramics composed of TCP and hydroxyapatite (HA), and two as pure-phase ceramics consisting of TCP. The literature analysis showed eight retrospective case series, of which only two were comparative studies. The mCMS showed an overall poor methodology (mean score 39.5). While the number of studies and their methodology are still limited, the available evidence suggests safety and overall promising results. A total of 11 cases that underwent rTHA with a pure-phase ceramic presented satisfactory clinical and radiological outcomes at initial short-term follow-up. Further studies at long-term follow-up, involving a larger number of patients, are needed before drawing more definitive conclusions on the potential of TCP for the treatment of patients who undergo rTHA.

Complication and Infection Risk Using Bone Substitute Materials to Treat Long Bone Defects in Geriatric Patients: An Observational Study

Background and Objectives: he treatment of large bone defects in geriatric patients often presents a major surgical challenge because of age-related bone loss. In such patients, the scarcity of healthy makes autologous grafting techniques hard to perform. On the one hand, clinicians' fear of possible infections limits using bone substitute materials (BSM). On the other hand, BSM is limitless and spares patients another surgery to harvest autologous material. Materials and Methods: To address the aptness of BSM in geriatric patients, we performed a retrospective analysis of all patients over the age of 64 years who visited our clinic between the years 2011-2018. The study assessed postoperative complications clinically and healing results radiologically. The study included 83 patients with bone defects at the distal radius, proximal humerus, and proximal tibia. The defect zones were filled with BSM based on either nanocrystalline hydroxyapatite (NHA) or calcium phosphate (CP). For comparison, a reference group (empty defect, ED) without the void filling with a BSM was also included. Results: 106 patients sustained traumatic fractures of the distal radius (71.7%), proximal humerus (5.7%), and proximal tibia (22.6%). No difference was found between the BSM groups in infection occurrence (p = 1.0). Although not statistically significant, the BSM groups showed a lower rate of pseudarthrosis (p = 0.09) compared with the ED group. Relative risk (RR) of complications was 32.64% less in the BSM groups compared with the ED group. The additional beneficial outcome of BSM was demonstrated by calculating the number needed to treat (NNT). The calculation showed that with every six patients treated, at least one complication could be avoided. Radiological assessment of bone healing showed significant improvement in the bridging of the defect zone (p < 0.001) when BSM was used. Conclusions: In contrast to previous studies, the study showed that BSM could support bone healing and does not present an infection risk in geriatric patients. The NNT calculation indicates a wider potential benefit of BSM.

Exosome-Functionalized, Drug-Laden Bone Substitute along with an Antioxidant Herbal Membrane for Bone and Periosteum Regeneration in Bone Sarcoma.

Developing advanced methods for effective bone reconstructive strategies in case of critical bone defects caused by tumor resection, trauma, and other implant-related complications remains a challenging problem in orthopedics. In the clinical management of bone diseases, there is a paradigm shift in using local drugs at the injury site; however, the dead space created during the surgical debridement of necrotic bone and soft tissues (periosteum and underlying muscle) leads to ineffective bone formation, thereby leading to secondary complications, and thus calls for better regenerative approaches. In this study, we have utilized an exosome-functionalized doxorubicin-loaded biodegradable nanocement (NC)-based carrier along with a Cissus quadrangularis (CQ) extract-laden antioxidant herbal membrane for simultaneously managing the periosteum as well as bone formation in the tumor resection model of osteosarcoma. We initially evaluated the efficacy of scaffolds for in vitro mineralization and bone formation. To examine the in vivo effectiveness, we developed a human osteosarcoma cell line (Saos-2)-induced tumor xenograft model with a critical-sized bone defect. The findings revealed that doxorubicin released from NC was successful in killing the tumor cells and was present even after 30 days of implantation. Additionally, the incorporation of exosomes aided the bone formation, resulting in around a 2.6-fold increase in the bone volume compared to the empty group as evaluated by micro-CT. The herbal membrane assisted in the development of periosteum and mineralizing bone callous as validated through histological and immunofluorescence analysis. Thus, our findings describe a one-step biomaterial-based cell-free approach to regenerate bone in osteosarcoma and prevent further fracture due to the complete development of periosteum and lost bone.

Entire Papilla Preservation Technique with Enamel Matrix Proteins and Allogenic Bone Substitute for the Treatment of Isolated Intrabony Defects: A Prospective Case Series.

The aim of this study was to evaluate the outcomes of a modified entire papilla preservation technique (EPPT) in the treatment of isolated intrabony defects in patients diagnosed with stage III periodontitis. A total of 18 intrabony defects were treated: 4 one-wall, 7 two-wall, and 7 three-wall. Mean probing pocket depth reductions of 4.33 mm (P < .0001), clinical attachment level gains of 4.87 mm (P < .0001), and radiographic defect depth reductions of 4.27 mm (P < .0001) were observed at 6 months. Changes in gingival recession and keratinized tissue were not statistically significant. It can be concluded that the proposed modification of the EPPT is useful in the treatment of isolated intrabony defects.

Alveolar Ridge Preservation and Restoration with Titanium-Reinforced d-PTFE Membranes and Bone Substitutes of Severely Resorbed Sockets: A Pilot Case Series Study.

This pilot case series study reports the dimensional alveolar bone changes after reconstruction of severely resorbed postextraction sockets treated with a mixture of particulate bone allograft and xenograft in combination with titanium-reinforced dense polytetrafluoroethylene (Ti-d-PTFE) membranes. Ten subjects who required premolar or molar extraction were included. Bone grafts were protected with Ti-d-PTFE membranes, utilizing an open-healing environment; membranes were removed 4 to 6 weeks after extraction, and implants were placed 6.7 months (mean) after extraction (T1). One patient required additional augmentation to correct an apical undercut of the alveolar process that was present preextraction. All implants integrated well and showed an implant stability quotient (ISQ) value between 71 and 83. The mean horizontal ridge width reduction from baseline (extraction) to T1 was 0.8 mm. Throughout the study, the mean vertical bone gain increase ranged from 0.2 mm to 2.8 mm (mean keratinized tissue width increase: 5.8 mm). The ridge preservation/restoration technique showed good preservation and restoration of severely resorbed sockets as well as improved amounts of keratinized tissue. If implant therapy is required after tooth extraction and severely resorbed sockets are present, the use of a Ti-d-PTFE membrane is a realistic option.

Characterization and Applicability of a Bone Spheroid Model for the Evaluation of Cytocompatibility of Bone Substitutes

In vitro cell-based tests are an important preclinical step for the safety assessment of biomaterials and drugs. Three-dimensional cell culture models (3D) may improve the limitations of the usual 2D models, as they better simulate a physiological environment. This work describes the characterization of a 3D spheroid model of MC3T3-E1 murine preosteoblasts for the testing of bone-substitute materials and investigates its adequacy to some of the most employed cell viability tests. The spheroids presented structural stability for 28 days in culture, with a regular spheroidal aspect, compact surface, and dense inner structure, with high potential for mineralization, but a time-dependent reduction in size. The use of colorimetric tests (MTT, XTT, and NRU) did not achieve satisfactory optical densities and did not correlate with cell density in the 3D model, as the aggregates remain strongly stained even after dye extraction steps. On the other hand, the LDH test achieved appropriate optical density and a high correlation with cell density (r2 = 0.77) and identified a dose–response for a well-known cytotoxic polymer (latex), while no toxicity was identified for biocompatible PLA wires. These results indicate that material testing with 3D bone cell models requires a careful choice of test methods and parameters.

Injection of a Bone Substitute in the Treatment of Unicameral Bone Cysts.

Simple bone cysts are benign bony lesions. Treatment strategies are varied for this particular pathology. It remains controversial as to what the ideal treatment strategy is. Recently, bony substitute injections have emerged as a potential option for treatment. This paper aimed to describe our institution's experience in using bony substitute injections to treat unicameral bone cysts. A retrospective review of consecutive patients over an 84-month period at a tertiary paediatric hospital was performed. Information regarding patients' presentation, diagnosis, and management was recorded and summarised. A total of 15 patients were included in our study, with a mean follow-up of 118 weeks. 86.7% of patients demonstrated clinical resolution (absence of pain at the latest follow-up) and 80% of patients demonstrated radiographic resolution. Only one patient sustained a subtrochanteric fracture post-index operation, whilst two others demonstrated redevelopment of cystic architecture on follow-up. This study demonstrates that bone substitute injection is potentially a minimally invasive and seemingly successful technique in the treatment of unicameral bone cysts and other simple bone lesions. Further randomised and comparative studies are required to confirm and validate our findings.

15-Year Retrospective Study on the Success Rate of Maxillary Sinus Augmentation and Implants: Influence of Bone Substitute Type, Presurgical Bone Height, and Membrane Perforation during Sinus Lift.

To evaluate the success rate of bone grafts and implants carried out at the Latin American Institute for Research and Dental Education (ILAPEO), considering the following: (i) the different pure bone substitutes (autogenous, xenogeneic, and alloplastic), (ii) the presurgical bone height, and (iii) how the treatment is compromised when membrane perforation occurs during sinus lift in maxillary sinus surgeries. Material and Methods. The initial sample comprised 1040 records of maxillary sinus lifting surgeries. After evaluation, the final sample retained 472 grafts performed using the lateral window technique with a total of 757 implants. The grafts were divided into 3 groups: (i) autogenous bone (n = 197), (ii) xenogenous bovine bone (n = 182), and (iii) alloplastic material (n = 93). One calibrated examiner classified the sample into two groups based on the residual bone height (<4 mm and ≥4 mm) of the area of interest measured on parasagittal sections of tomographic images. Data on membrane perforation occurrences in each group were collected; qualitative variables were described using frequency, expressed as percentages. The Chi-square test was used to analyze the success of the graft types and the survival rate of the implants as a function of the grafted material and the residual bone height. The Kaplan-Meier survival analysis was used to calculate the survival rate of bone grafts and implants according to the classifications adopted in this retrospective study. The success rate of grafts and implants was 98.3% and 97.2%, respectively. There was no statistically significant difference in the success rate among the different bone substitutes (p = 0.140). Only 8 grafts (1.7%) and 21 implants (2.8%) failed. There was a greater success rate for both grafts (96.5%) and implants (97.4%) when the bone height was ≥4 mm. The success rate in the 49 sinuses in which the membrane was perforated was 97.96% for the grafts and 96.2% for the implants. The follow-up periods after rehabilitation ranged from 3 months to 13 years. Within the limitations of the data analyzed in this retrospective study, maxillary sinus lift was a viable surgical technique that enabled implant placement with a predictable long-term success rate, regardless of the type of material used. The presence of membrane perforation did not interfere with the success rate obtained for grafts and implants.

Novel Synthetic Carbonate Apatite as a Bone Substitute in Implant Treatments: Case Reports.

Bone graft materials are often used in implant treatment to optimize functional and esthetic outcomes. The requirements for bone grafting materials are the ability to maintain space for bone regeneration to occur and the capability of being resorbed by osteoclasts and replaced with new bone tissue occurring in passive chemolysis and bone remodeling. Carbonate apatite (CO3Ap) granules (Cytrans Granules, GC) are a chemically synthetic bone graft material similar to autogenous bone minerals and more biocompatible than allografts and xenografts. The aim of this report is to evaluate the efficacy of CO3Ap granules in implant treatments when used alone or in combination with autogenous bone. The clinical findings and the radiographic and histologic assessments in three cases of immediate implant placement and lateral and vertical guided bone regeneration are reported. Despite the short-term follow-ups, histologic findings showed that CO3Ap granules were efficiently resorbed and replaced bone in clinical use. Furthermore, the clinical findings showed that CO3Ap granules maintained their morphology around the implant. This limited short-term case report suggests that this bone substitute is effective. However, further clinical studies and long-term reports of this new biomaterial are needed.

Evaluation of Stability of Implants Placed Simultaneously with Lateral Window Sinus Augmentation using Putty Alloplastic Bone Substitute: A Prospective Interventional Study

Introduction: Lateral window sinus augmentation is done to augment the vertical sinus height for implant placement. Putty alloplasts have been used due to their longer resorption time and provide resistance to implant insertion. Although, widely used, the stability and bone loss around implants placed simultaneously following sinus augmentation with putty bone graft has not been evaluated. Aim: To evaluate the effect of putty alloplastic bone substitute on implant stability. Materials and Methods: This prospective interventional study was conducted in the Outpatient Department (OPD) of Oral and Maxillofacial surgery at SGT Dental College and Research Institute, Gurugram, Haryana, India. The duration of the study was two years and 11 months, from December 2014-November 2016. A total of 15 implants were placed simultaneously after lateral window sinus augmentation. Primary implant stablity measurements were done using Resonance Frequency Analysis (RFA). Vertical Bone Height (VBH), Maximum Insertion Torque (MIT) and Crestal Bone Loss (CBL) were measured till six months of follow-up. The data was analysed using standard statistical analyses with Shapiro-Wilk-test, Wilcoxon signed-rank test and Spearman’s correlation co-efficient. Results: The mean age of the study participants was 58±3.04 years. A total of 15 implants were placed in 12 patients. Adequate primary stability was achieved with MIT &gt;36 N/cm2 in 9/15 patients whereas, in 6/15 patients the MIT was ≤36 N/cm2 . The implants showed 100% survival rate. Postoperative bone gain obtained was in the range of 7.89 mm to 11.9 mm, with a mean of 9.92 mm. Acceptable levels of implant stability were obtained after six months. Conclusion: Within the limitations of the study, it can be concluded that, putty bone alloplast can serve as an adequate bone substitute in simultaneous implant placement after lateral window sinus augmentation and help in achieving stability.

Bone Substitute Options for Spine Fusion in Patients With Spine Trauma-Part I: Fusion Biology, Autografts, Allografts, Demineralized Bone Matrix, and Ceramics.

Spinal trauma accounts for a large portion of injuries to the spine area, particularly as societies are entering an era of aging populations. Consequently, spine fractures accompanied by osteoporosis are becoming more prevalent. Achieving successful fusion surgery in patients with spine fractures associated with osteoporosis is even more challenging. Pseudarthrosis in the spine does not yield clinically favorable results; however, considerable effort has been made to achieve successful fusion, and the advancement of bone graft substitutes has been particularly crucial in this regard. Autograft bone is considered the best fusion material but is limited in use due to the quantity that can be harvested during surgery and associated complications. Accordingly, various bone graft substitutes are currently being used, although no specific guidelines are available and this mainly depends on the surgeon's choice. Therefore, the purpose of this review, across part I/II, is to summarize bone graft substitutes commonly used in spine surgery for spine fusion in patients with spine trauma and to update the latest knowledge on the role of recombinant human bone morphogenetic protein-2.

Treatment of a Soft Tissue Depression with a Xenograft Bone Substitute at the Second Stage of an Implant Procedure: A Case Report.

Following the extraction of a compromised tooth, the edentulous alveolar ridge undergoes physiologic bone remodeling, which may create a bone volume too deficient for implant placement. Guided bone regeneration (GBR) provides a predictable treatment option to increase the alveolar bone volume for implant placement, but a soft or hard tissue deficiency may remain even after this augmentation procedure has been completed. These deficiencies can be especially challenging in the esthetic zone, where patient expectations and esthetics often determine the satisfaction of the treatment outcome. This paper presents a case report of a xenograft bone substitute used at the second-stage surgery and abutment insertion to provide a solution to these deficiencies even after the patient had undergone a GBR procedure, thus improving the esthetic and functional outcomes of the final implant-supported restoration.

Processing of bioresorbable closed-cell Mg foam for bone implant applications

ABSTRACT Magnesium is the most promising element as a bioresorbable material in bone repairing applications. Closed-cell Mg-2Zn-2Ca foam was fabricated through melt processing route by using economical biocompatible pure dolomite+MgCO3 as dual-blowing agent with favorable advantages of uniform pore structure, improved mechanical properties and good biocompatibility. In addition, residuals of blowing agent act as biocompatible particles during degradation. Mg-2Zn-2Ca foam was characterized for its physical, mechanical, in vitro degradation properties and microstructure characterization. Mg-2Zn-2Ca foams having relative density 0.41–0.45, average uniform pore size in the range of 0.25–0.75 mm revealed plastic compression strength up-to 50.1 MPa, plateau strength up to 43.2 MPa with 56.3% densification strain and 30 MJ/m3 of energy absorption per unit volume were obtained. Moreover, Mg foam exhibited adequate compressive behavior during in vitro degradation up to 4 weeks in simulated body fluid. Despite higher amount of hydrogen release in initial stage, Mg foam observed stable degradation mechanism after 2 weeks due to formation and deposition of degradation products on cellular surfaces. Based on the processing method and results obtained, Mg-2Zn-2Ca closed-cell foam satisfied the requirement of physical, mechanical and in vitro degradation properties compared to natural bone properties and recommended as cost effective, biocompatible and bone substitution mechanical implant material.

RhBMP-2-Conjugated Three-Dimensional-Printed Poly(L-lactide) Scaffold is an Effective Bone Substitute.

Bone growth factors, particularly bone morphogenic protein-2 (BMP-2), are required for effective treatment of significant bone loss. Despite the extensive development of bone substitutes, much remains to be desired for wider application in clinical settings. The currently available bone substitutes cannot sustain prolonged BMP-2 release and are inconvenient to use. In this study, we developed a ready-to-use bone substitute by sequential conjugation of BMP to a three-dimensional (3D) poly(L-lactide) (PLLA) scaffoldusing novel molecular adhesive materials that reduced the operation time and sustained prolonged BMP release. A 3D PLLA scaffold was printed and BMP-2 was conjugated with alginate-catechol and collagen. PLLA scaffolds were conjugated with different concentrations of BMP-2 and evaluated for bone regeneration in vitro and in vivo using a mouse calvarial model. The BMP-2 release kinetics were analyzed using ELISA. Histological analysis and micro-CT image analysis were performed to evaluate new bone formation. The 3D structure of the PLLA scaffold had a pore size of 400µm and grid thickness of 187-230µm. BMP-2 was released in an initial burst, followed by a sustained release for 14days. Released BMP-2 maintained osteoinductivity in vitro and in vivo. Micro-computed tomography and histological findings demonstrate that the PLLA scaffold conjugated with 2µg/ml of BMP-2 induced optimal bone regeneration. The 3D-printed PLLA scaffold conjugated with BMP-2 enhanced bone regeneration, demonstrating its potential as a novel bone substitute.

Alternative Geometries for 3D Bioprinting of Calcium Phosphate Cement as Bone Substitute.

In the literature, many studies have described the 3D printing of ceramic-based scaffolds (e.g., printing with calcium phosphate cement) in the form of linear structures with layer rotations of 90°, although no right angles can be found in the human body. Therefore, this work focuses on the adaptation of biological shapes, including a layer rotation of only 1°. Sample shapes were printed with calcium phosphate cement using a 3D Bioplotter from EnvisionTec. Both straight and wavy spokes were printed in a round structure with 12 layers. Depending on the strand diameter (200 and 250 µm needle inner diameter) and strand arrangement, maximum failure loads of 444.86 ± 169.39 N for samples without subsequent setting in PBS up to 1280.88 ± 538.66 N after setting in PBS could be achieved.