Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Bone Substitutes”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 937 records · Page 52Linked to original sources
PubMed2004

[Structure characterization of calcium polyphosphate bioceramics during sintering process].

Calcium polyphosphate (CPP) may be a promising bone substitute with controllably-degraded ability. In this investigation, the effects of sintering temperatures on its phase transformation and structure parameters, such as crystalline size distribution and micro-strain were investigated by X-ray diffraction (XRD). The phase composition was calculated with reference intensity ratio (RIR). The crystalline size distribution and micro-strain were calculated with Warren-Averbach Fourier transfer (W-A/FT) method. The results demonstrated that at the temperature of 585 degrees C-900 degrees C, the phase transformation of amorphous CPP into crystalline gamma-CPP and then into beta-CPP occurred,and the course of such transformation was accompanied with the significant change of the mean crystalline size (D) and the mean micro-strain (epsilon).

Biocompatible Materials↗
PubMed2005

Activation of platelet-rich plasma using thrombin receptor agonist peptide.

PURPOSE: This study proposes an alternative preparation method of platelet-rich plasma (PRP). Specifically, we compare the use of thrombin receptor agonist peptide-6 (TRAP) and bovine thrombin as a clotting agent in the preparation of PRP. MATERIALS AND METHODS: PRP was prepared by centrifugation and clotted with thrombin or TRAP. In vitro clotting times were monitored as a function of TRAP concentration, and clot retraction was determined by measuring clot diameter over time. Following the optimization of TRAP concentration, experiments were repeated with the addition of several commercially available bone substitutes. The release of PRP-relevant growth factors as a function of PRP preparation was also determined. RESULTS: The most rapid polymerization of PRP takes place with the addition of thrombin, followed by TRAP/Allogro (Ceramed, Lakewood, CO), TRAP/BioGlass (Mo-Sci, Rolla, MN), TRAP/BioOss (Osteohealth, Shirley, NY), and TRAP alone. Thrombin caused considerable clot retraction (43%), whereas TRAP alone resulted in only 15% retraction. TRAP/Allogro, TRAP/BioOss, and TRAP/BioGlass all exhibited minimal retraction (8%). CONCLUSIONS: The use of TRAP to activate clot formation in the preparation of PRP may be a safe alternative to bovine thrombin. It results in an excellent working time and significantly less clot retraction than the currently available methods of PRP production.

Analysis of Variance↗
PubMed2002

A systematic review of guided tissue regeneration for periodontal infrabony defects.

OBJECTIVES: To systematically review the evidence for efficacy of guided tissue regeneration (GTR) for infrabony defects. BACKGROUND: The evidence for the efficacy of GTR has not yet been systematically appraised. METHODS: We searched for randomised controlled trials of at least 12 months' follow-up comparing GTR with open flap debridement (OFD). Data sources included electronic databases, hand-searched journals and contact with experts. Screening, data abstraction and quality assessment were conducted independently by multiple reviewers. The primary outcome measure was gain in clinical attachment. RESULTS: For attachment level change, the weighted mean difference between GTR alone and open flap debridement was 1.11 mm (95% CI: 0.63-1.59), chi-square for heterogeneity 31.4 (9 df ), P < 0.001) and for GTR + bone substitutes was 1.25 mm (95% CI: 0.89-1.61, chi-square for heterogeneity 0.01 (1 df), P = 0.91). The number of sites needed to treat (NNT) for GTR to achieve one extra site gaining 2 mm or more attachment over open flap debridement was 8 (95% CI: 4-33). Heterogeneity between studies was highly statistically significant for all principal comparisons and could not be explained satisfactorily by sensitivity analyses. CONCLUSIONS: Overall, GTR was more effective than OFD in improving attachment levels. However, there was marked variability between studies and general conclusions about the clinical benefit of GTR are limited by this heterogeneity. Future studies should aim to identify factors associated with achieving consistent benefits over open flap debridement. Open flap surgery should remain the control comparison in these studies.

Alveolar Bone Loss↗
PubMed1997

Dynamic compaction: a new process to compact therapeutic agent-loaded calcium phosphates.

The sintering stage in the classical process of preparing bone substitution materials prevents therapeutic agents from being loaded into calcium phosphate powder. However, dynamic compaction, a new process, requires no external heat, allowing the therapeutic agent to be incorporated into ceramics. This report presents the results of an in vitro study of therapeutic agents associated with calcium phosphate powder and involving this new process. A mixture of vancomycin lyophilized powder (0.15 g) and biphasic calcium phosphate (BCP) powder (1.85 g) was compacted. In addition, 2 ml of human growth hormone (1 mg ml-1) were associated with BCP powder by physical adsorption on bead surfaces before compaction. Detection by monoclonal antibodies and sodium dodecyl sulphate polyacrylamide gel electrophoresis demonstrated the structural integrity of the two therapeutic agents after consolidation. This new compaction process should be useful in developing ceramics that contain a therapeutic agent.

Adsorption↗
PubMed2002

The effect of water in inorganic microsponges of calcium phosphates on the porosity and permeability of composites made with polymethylmethacrylate.

Bone-substitute compounds were obtained by mixing pre-polymerised powders of polymethylmethacrylate and liquid methylmethacrylate monomer with two aqueous dispersions of alpha-tricalcium phosphate (alpha-TCP) grains and calcium-deficient hydroxyapatite (CDHA) powders. The final composites appeared to be porous. The total open porosity was a function of the amount of water added. The water, which was the pore-forming agent, vapourised after the polymerisation process, leaving behind empty spaces in the polymeric matrix. The inorganic powders placed inside the polymeric matrix were shown to act as local microsponges. The water capacity of these microsponges can be determined by a centrifugation step carried out on aqueous dispersion of alpha-TCP and/or CDHA powders that occur before any reaction with the organic compound. The relationship between the total open porosity of the composites and the amount of water trapped inside the inorganic agglomerates proved to be almost linear. The effect of the chemical composition of the powder on the total open porosity is not too great, provided that the two kinds of pellets are prepared with the same amount of water. Both the permeability and shape of the pores proved to be a function of the total open porosity. An increase of the latter parameter produces an increase in permeability and a decrease in tortuosity. Osteoconductivity and osteoinductivity of the final composites were tested in vivo by implantation in rabbits. Formation of new trabecular bone was observed inside the pores where the inorganic powders had been placed.

Animals↗
PubMed2006

Biodegradable porous polyurethane scaffolds for tissue repair and regeneration.

Critical-size bone defects usually require the insertion of autogenous bone graft to heal. Harvesting of bone is traumatic and results in high morbidity at the donor site. A potential alternative to bone graft may be a bone substitute with adequate biocompatibility and biological properties produced from ceramics or bioresorbable/biodegradable polymers. In the present study, new elastomeric biodegradable polyurethanes with an enhanced affinity toward cells and tissues were synthesized using aliphatic diisocyanate, poly(epsilon-caprolactone) diol, and biologically active 1,4:3,6-dianhydro-D-sorbitol (isosorbide diol) as chain extender. The polymers were processed into 3D porous scaffolds by applying a combined salt leaching-phase inverse process. The critical parameters controlling pore size and geometry were the solvents and nonsolvents used for scaffold preparation and the sizes of the solid porogen crystals. Scaffolds prepared from the polymer solution in solvents such as dimethylsulfoxide or methyl-2-pyrrolidone did not have a homogenous pore structure. Many pores were interconnected, but numerous pores were closed. Irrespective of the high pore-to-volume ratio (75%), the scaffolds showed poor water permeability. The best solvent for the preparation of scaffolds from the polyurethane used in the study was dimethylformamide (DMF). The type of nonsolvent admixed to the polymer solution in DMF strongly affected the scaffolds' pore structure. The elastomeric polyurethane scaffold prepared from the optimal solvent-nonsolvent mixture had regular interconnected pores, high water permeability, and a pore-to-volume ratio of 90%. The osteoconductive properties of the 3D porous polyurethane scaffolds can be additionally promoted by loading them with calcium phosphate salts such as hydroxyapatite or tricalcium phosphate, thus making them promising candidates for bone graft substitutes.

Absorbable Implants↗
PubMed1998

Analytical control of wollastonite for biomedical applications by use of atomic absorption spectrometry and inductively coupled plasma atomic emission spectrometry.

Preliminary in vitro experiments revealed that wollastonite (CaSiO3) is a potentially highly bioactive material that forms a hyroxyapatite (HA) surface layer on exposure to simulated body fluid with an ion concentration, pH and temperature virtually identical with those of human blood plasma. The formation of the HA layer is an essential requirement for an artificial material to be used as bioactive bone substitute. This finding opens up a wide field for biomedical applications of wollastonite. Biomaterials used as implants in the human body require strict control of trace elements and of the toxic species specified in American Society for Testing and Materials F-1185-88 (As, Cd, Hg and Pb) in ceramic hydroxyapatite for surgical implantation. In this work, two types of pseudowollastonite, the high temperature form of wollastonite, were analysed by using cold vapour atomic absorption spectrometry and hydride generation atomic absorption spectrometry, in order to determine the elements stated in the above-mentioned norm, and inductively coupled plasma atomic emission spectrometry to establish the SiO2/CaO ratio of the two materials and analyse for all other impurities introduced by the raw materials and by the processes of synthesis, sintering and grinding. Barium and Mg were especially prominent in raw materials, and Zr, Y, Mg, W, Co and Ni come mainly from the processing.

Barium↗
PubMed2006

Fabrication of biporous low-crystalline apatite based on mannitol dissolution from apatite cement.

Biporous (macro- and microporous) calcium phosphate gains much attention as a bone substitute material because of its large surface area and that it improves cell penetration. In the present study, we evaluated the feasibility of biporous, low-crystalline apatite based on dissolution of mannitol from self-setting apatite cement (Biopex). Mannitol--known as a biocompatible, easily dissolved monosaccharide alcohol--was recrystallized to obtain larger crystals. It was crushed with pestle and mortar, sieved to obtain crystals which passed through a 500-microm mesh but which remained against a 300-microm mesh, and then used as porogen. Although Biopex containing 60 wt% mannitol was not able to be taken out of the mold, addition of mannitol caused no initial setting inhibition to Biopex if the amount was 40 wt% or less. Similarly, transformation to apatitic product was confirmed when the apatite cement was immersed in 0.9% saline kept at 37 degrees C for seven days. The set mass became low-crystalline, biporous apatite with approximately 60% porosity.

Bone Substitutes↗
PubMed2006

Void filling of tibia compression fracture zones using a novel resorbable nanocrystalline hydroxyapatite paste in combination with a hydroxyapatite ceramic core: first clinical results.

INTRODUCTION: It is a generally accepted standard surgical practice to fill-in the metaphyseal defect zones resulting from the reduction of tibia compression fractures. The development of various innovative bone substitutes is also currently on the increase. MATERIALS AND METHODS: In our prospective study, we used Ostim, a novel resorbable nanocrystalline hydroxyapatite paste, together with Cerabone, a solid hydroxyapatite ceramic, in combination with angularly stable osteosynthesis to treat 24 tibia compression fractures. Types B2 and B3, as well as types C2 and C3 fractures, according to the AO classification, were included in the study. RESULTS: The mean total range of joint motion in terms of flexion and extension was improved from the immediate postoperative value of 79 +/- 14 degrees to 97 +/- 13 degrees at 6 weeks after surgery, to 109 +/- 16 degrees at 3 months, and finally to 118 +/- 17 degrees at 1 year. In three patients, a delayed wound healing was observed as a local complication. CONCLUSION: The use of the Ostim and Cerabone combination is an effective method in treating tibia compression fractures with large defect zones left after reduction.

Absorbable Implants↗
PubMed2006

Effects of sintering temperature over 1,300 degrees C on the physical and compositional properties of porous hydroxyapatite foam.

Porous hydroxyapatite (HAP) foam permits three-dimensional (3D) structure with fully interconnecting pores as well as excellent tissue response and good osteoconductivity. It is therefore thought to be a good candidate as scaffold material for bone regeneration and as a synthetic bone substitute material. To fabricate better porous HAP foam, improved physical and structural properties as well as higher osteoconductivity are desired. In the present study, the effects of sintering temperature on the physical and compositional properties of porous HAP foam were evaluated by employing high sintering temperature starting at 1,300 degrees C up to 1,550 degrees C. The mechanical strength of porous HAP foam increased with sintering temperature to reach the maximum value at 1,525 degrees C, then decreased slightly when sintering temperature was further increased to 1,550 degrees C. Alpha tricalcium phosphate (alpha-TCP) was formed, and thus the porous HAP foam became biphasic calcium phosphate. Biphasic calcium phosphate consisting of both alpha-TCP and HAP had been reported to show higher osteoconductivity than HAP alone. We therefore recommend 1,500-1,550 degrees C as the sintering temperature for porous HAP foam since this condition provided the most desirable physical properties with biphasic calcium phosphate composition.

Analysis of Variance↗
PubMed2004

Evaluations of bioactivity and mechanical properties of poly (epsilon-caprolactone)/silica nanocomposite following heat treatment.

A composite material consisting of poly(epsilon-caprolactone) (PCL) and silica was prepared and evaluated as a bioactive bone substitute. The composite was synthesized by the co-condensation of tetraethyl orthosilicate and PCL and end-capped with triethoxysilane (Si-PCL). The as-prepared specimens were subjected to an initial heat treatment of 2 days at 60 degrees C, followed by further heat-treatments at 100 degrees C, 150 degrees C, and 200 degrees C for 24 h. The tensile mechanical properties of the heat-treated specimens were determined, and additional specimens were exposed to a simulated body fluid (SBF) for different periods of time. The SBF exposure led to the deposition of a layer of apatite crystals on the surface of the composites. It was found that increasing the second heat-treatment temperature produced an increase in tensile strength and Young's modulus of the composite but a decrease in the initial rate of apatite formation. These phenomena are explained in terms of the condensation reaction that takes place between the silanol groups in the silica and Si-PCL as the heat-treatment temperature is increased.

Apatites↗
PubMed2005

Nano-composite of poly(L-lactide) and surface grafted hydroxyapatite: mechanical properties and biocompatibility.

In order to improve the bonding between hydroxyapatite (HAP) particles and poly(L-lactide) (PLLA), and hence to increase mechanical properties of the PLLA/HAP composite as potential bone substitute material, the HAP nano-particles were surface-grafted with PLLA and further blended with PLLA. The structure and properties of the composites were subsequently investigated by the mechanical property testing, the differential scanning calorimeter measurements (DSC), the scanning electron microscopy (SEM), the polarized optical microscopy (POM), and the cell culture. The PLLA molecules grafted on the HAP surfaces, as inter-tying molecules, played an important role in improving the adhesive strength between the particles and the polymer matrix. At a low content (approximately 4 wt%) of surface grafted-HAP (g-HAP), the PLLA/g-HAP nano-composites exhibited higher bending strength and impact energy than the pristine PLLA, and at a higher g-HAP content (e.g., 20 wt%), the modulus was remarkably increased. It implied that PLLA could be strengthened as well as toughened by g-HAP nano-particles. The results of biocompatibility test showed that the g-HAP existing in the PLLA composite facilitated both adhesion and proliferation of chondrocytes on the PLLA/g-HAP composite film.

Bone Substitutes↗
PubMed2005

Effect of coupling agents on the local mechanical properties of bioactive dental composites by the nano-indentation technique.

OBJECTIVES: To examine the use of nano-indentation as a method of determining the interfacial mechanics of bioactive composites for mandibular bone substitutes. METHODS: Three coupling agents (PMMA-MAA, PMMA-MA and silane) were used to treat hydroxyapatite (HA) particles before incorporation into a polymethylmethacrylate (PMMA) matrix. Nano-indentation was used to determine the hardness and Young's modulus on the HA particle surface, at the HA/PMMA interface and in the PMMA matrix region for each of the four groups. In addition bulk four-point bending tests were conducted on each of the four groups as a comparison. RESULTS: The findings resulted in significant differences in the local interfacial Young's modulus between the polymer-treated composites and the uncoupled control specimens with a marked improvement (50%) in modulus with either polymertreated group. Similarly, the bending modulus of the polymer-treated groups was significantly higher than the un-treated control group; however, these differences were not as pronounced (approximately 15%). SIGNIFICANCE: The co-polymer-treated composites resulted in improved interfacial modulus as compared to the un-treated controls and that the nano-indentation technique is a powerful tool for understanding the local interfacial mechanics of bioactive composites.

Analysis of Variance↗
PubMed2005

Composite formation from hydroxyapatite with sodium and potassium salts of polyphosphazene.

The low temperature synthesis of composites potentially suitable as bone substitutes which form in vivo, was investigated. The composites were comprised of stoichiometric hydroxyapatite (SHAp) and water-soluble poly phosphazenes. These constituents were selected because of their biocompatibility, and were mixed as powders with a phosphate buffer solution (PBS) to form the composites. The effects of poly[bis(sodium carboxylatophenoxy)phosphazene] (Na-PCPP) or poly[bis(potassium carboxylatophenoxy) phosphazene] (K-PCPP) on stoichiometric hydroxyapatite (SHAp) formation from tetracalcium phosphate and anhydrous dicalcium phosphate were assessed. The kinetics and reaction chemistries of composite formation were followed by isothermal calorimetry, X-ray diffraction, infrared spectroscopy and scanning electron microscopy. In the presence of 1% by weight of polyphosphazenes, composites comprised of SHAp and calcium cross-linked polymer salts were formed. Thus a mechanism for binding between polymer chains was established. Elevated proportions (5 and 10% by weight) of polyphosphazene, however, resulted in the inhibition of SHAp formation. This is attributed to the formation of viscous polymer solution coatings on the calcium phosphate precursors, retarding their reaction, and consequently inhibiting SHAp formation.

Biocompatible Materials↗
PubMed2004

Macroporous glass-ceramic materials with bioactive properties.

In the present research work, glass powders and three different organic starches were used to realize macroporous glass-ceramic scaffolds for bone substitutions. For this purpose, bioactive glass powders belonging to the system SiO2-CaO-Na2O-MgO were mixed in a liquid medium with the desired amount of the selected organic phase. Afterwards, by progressively raising the temperature, the water uptake of starches occurred and led to the gelling of the whole system. The resultant gel underwent two thermal treatments in order to eliminate the organic phase and to allow the sintering of the glassy phase. In this way, macroporous glass-ceramic scaffolds were successfully prepared. The samples were characterized by means of optical and scanning electron microscopy with compositional analysis. The volume and mean size of the obtained porosity were investigated by means of mercury intrusion porosimetry, whereas its morphology was assessed by means of microscopic observations. The structure of the original and the resultant materials were investigated by X-ray diffraction. In order to study the reactivity of the scaffolds towards physiological media, the samples were soaked in a simulated body fluid for various times. On their soaked surfaces, scanning electron microscopy and compositional analysis were carried out in order to assess their bioactivity.

Body Fluids↗
PubMed2005

Tape-casting technique can prepare beta-TCP sheets with uniform thickness and flexibility.

The objective of this study is to propose a new fabrication technology for bone substitutes. In this study, a tape-casting method was used to prepare flexible beta-tricalcium phosphate (beta-TCP) sheets. A beta-TCP slurry containing a binder and plasticizer was used in a doctor blade system. The beta-TCP sheet obtained by this tape-casting method was highly flexible, enabling twisting and free-form shaping. The beta-TCP sheet was approximately 0.21 mm thick. X-ray diffraction and Fourier transform infrared spectrometry revealed that the structure of the beta-TCP component in the sheet is the same as that of the original beta-TCP powder. Observation by field-emission scanning electron microscopy showed that the beta-TCP sheet had a flat, microgranular surface. During the early stages, the tensile stress-strain curves of the beta-TCP sheet showed a nonlinear behavior until reaching the point of final fracture. This result was derived from the ductile property of the prepared beta-TCP sheet. In conclusion, a flexible beta-TCP sheet was easily prepared using a tape-casting technique. Fabrication using tape casting offers the advantages of enabling the preparation of ceramic sheets with precise thickness and not requiring expensive fabrication facilities.

Biocompatible Materials↗
PubMed1998

Antibacterial effects of a bioactive glass paste on oral microorganisms.

Bioactive glasses contain oxides of calcium, sodium, phosphorus, and silicon in a proportion that provides the material with surface activity and concomitantly with the property of forming a strong bond with bone. Bioactive glasses have been tested as bone substitutes in different clinical situations. In an aqueous environment, Ca2+, Na+, PO4(3-) , and Si4+ are released from the glass, resulting in a rise in pH and in osmotic pressure in its vicinity. Since these are factors that potentially influence the viability of oral microorganisms at the dentogingival margin, we studied the effects of bioactive glass S53P4 on the oral microorganisms Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, Actinomyces naeslundii, Streptococcus mutans, and Streptococcus sanguis. This was done by incubating each microbe in a suspension, in the presence of bioactive glass S53P4 in powder form. A. naeslundii was found to lose its viability within 10 min under the experimental conditions. A. actinomycetemcomitans, P. gingivalis, and S. mutans lost their viability within 60 min. Also for S. sanguis a significant loss of viability was seen within 60 min, but it was the only microbe that had any viable cells left after 60 min. Thus, in aqueous solutions the powdered bioactive glass S53P4 appears to have a broad antimicrobial effect on microorganisms of both supra- and subgingival plaque. Consequently, it could be useful as an ingredient in tooth-care products that may have beneficial effects on oral health both from a cariologic and a periodontal point of view.

Actinomyces↗
PubMed2006

A preliminary study of the efficacy of Beta Tricalcium Phosphate as a bone expander for instrumented posterolateral lumbar fusions.

The associated morbidity of allograft(s) as bone graft expanders in spinal surgery has prompted the search for alternatives. The efficacy of Vitoss/Beta Tricalcium Phosphate (B-TCP: OrthoVita, Malvern PA, USA), an artificial bone substitute, combined with lamina autograft (50:50 mix) in 40 prospective posterolateral fusions utilizing pedicle/screw instrumentation was analyzed. Multilevel lumbar laminectomies (average 3.7 levels) were accompanied by 1 (27 patients) and 2 level (13 patients) fusions. Two neuroradiologists independently assessed fusion progression on dynamic x-rays and 2D-CT studies performed at 3, 6, and up to 12 months postoperatively. Outcomes were quantified utilizing Odom Criteria and Short-Form 36 (SF-36) questionnaires (preoperatively; and 3, 6, and 12 months postoperatively). By the sixth postoperative month, fusion was neuroradiologically confirmed on both dynamic x-rays and CT studies for 26 of 27 single level fusions (1 pseudarthrosis), and 11 of 13 two level fusions (L4-S1). Odom Criteria 3, 6, and 12 months postoperatively revealed continued improvement for all patients. SF-36 outcomes, however, revealed deterioration on 2 Health Scales (Role Physical, Role Emotional) 3 and 6 months post-operatively, and minimal to marked improvement on 6 Health Scales (PF, V, PF, V, SF, BP). Twelve months postoperatively improvement occurred on all 8 Health Scales, exceeding pre-operative baselines; minimal (RP, GH), mild (MH), moderate (PF, BP, V, SF), and marked improvement (RE). Although Vitoss/B-TCP and laminar autograft resulted in pseudarthrosis for 1 of 27 single level and 2 of 13 two level posterolateral instrumented lumbar fusions, only 1 of the latter patients required a secondary fusion.

Adult↗