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PubMed1997

Analysis of sections of implanted macroporous calcium phosphate bone substitutes by proton-induced X-emission method and energy-dispersive spectrometry.

The osseointegration of porous calcium phosphate ceramics once implanted evolves in several stages. The mechanism of integration of such material usually is evaluated by histologic analysis. The trace elements present in bone can be detected in the ceramic and help to provide a semiquantitative evaluation of osseointegration. Two different methods of microanalysis, energy-dispersive spectrometry (EDS) and proton induced x-emission (PIXE) were used in this study to determine the appearance of trace elements (Zn, Sr, and Fe) present in bone at the implantation site containing the ceramic. Porous HA-ceramic cylinders were implanted in the cortical bone of sheep femurs for periods ranging from 2 to 36 weeks. Thick sections of the implant-containing bone were made at the end of the implantation period. A scanning line with proton or electron impacts 0.5 mm apart was plotted from the edges of the cortical bone across the implanted ceramic and the resulting x-ray spectra were determined. Following EDS analysis, the sections were surface-stained, observed under a light microscope, and the pore volume occupied by bone tissue was measured. The spectra obtained by PIXE method showed two regions for each element characterising either the bone tissue or the ceramic. Zinc and strontium present in the bone tissue, but absent from the ceramic, appeared 8 and 12 weeks after implantation, respectively. The concentration of iron present in the implant decreased with time. EDS showed no significant level of either element in the bone or the ceramic. Histologic observation revealed that immature bone invaded the pores of the outer layer of the ceramic as early as 2 weeks after implantation. The ceramics were totally osseointegrated 20 weeks after implantation, although ceramic degradation continued for longer. In this experiment, the PIXE method was apparently sufficiently sensitive for monitoring the amount of trace element appearing in bone-implanted material.

Animals↗
PubMed1997

[Long-term outcome after frontal sinus obliteration with an ionomer bone substitute in the cat. I: Histological results].

BACKGROUND: Osteoplastic frontal sinus surgery in combination with sinus obliteration may occasionally be performed for indications such as severe sinus inflammations, extensive wall fractures involving the nasofrontal duct, or osteomas. The material most frequently used for this obliteration is autogenous adipose tissue. Autografts such as muscle, cartilage, and bone chips have been also recommended for this purpose. In order to avoid the surgical procedure required for harvesting an autograft from other body sites, alloplastic materials have been suggested for frontal sinus obliteration. METHODS: In an animal study using cats, the mucous lining of the frontal sinus was removed, the nasofrontal duct sealed with semifluid ionomer cement, and the cavity filled up with a solid and porous ionomer-based microimplant. RESULTS: Histological investigations were performed up to two years after surgery. Increasing obliteration of the sinus cavity by bone regeneration, starting from the sinus wall, as well as formation of connective tissue between the cement grains was detected as early as one month after implantation. Osteoblasts lining the osteoid layer were considered to be an indication of active bone regeneration. Osteogenesis inside the sinus cavity continuously progressed during the following months. Two years after implantation, osteoid and newly mineralized bone encircled the microimplants leading to an almost complete obliteration. There was no evidence for mucosal regeneration or foreign body reaction. CONCLUSIONS: Because of its osteoconductive effect, biocompatibility, and biostability the ionomer-based microimplant is a suitable alloplastic material for frontal sinus obliteration.

Animals↗
PubMed1997

[Ionomer cement as bone substitute in the middle ear of the rabbit].

Ionomer-based cements are obtained by the reaction of an aluminum-fluoro-silicate glass with a polyalcenoic acid. During setting and hardening the cement bonds closely with adjacent hard tissue. The previous implantation of this material in the baboon tibia has held great promise as a possible use in bone replacement. In the present study the cement was tested concerning its biocompatibility and biostability in the middle ears of 64 rabbits. Viscid cement paste was inserted into the epitympanic space of each animal. A preformed cement strut was then placed to serve as a columella between the eardrum and stapes footplate. During a subsequent interval of 28 days up to 2 years middle ear specimens were evaluated under a surgical microscope, following which histologic sections were studied under light microscopic conditions. Findings demonstrated that after insertion of freshly mixed cement a firm adhesion to bone developed that proved to be biocompatible and biostable over time. After 28 days the preformed and fully hardened implants were overgrown by a delicate mucosa normally present in the middle ear. No evidence for any rejection of the implants could be found. The experience available to date indicates that ionomer cement is biocompatible and biostable, easy to handle and workable without splintering. With appropriate use it represents a useful implant material in surgery of the head and neck.

Animals↗
PubMed1981

Hydroxyapatite as a bone substitute in the jaws.

Densely sintered calcium hydroxyapatite has previously been shown to be biocompatible and stable. Its possible role in jaw surgery was investigated using a clinically analogous animal model. The apatite was implanted into the mandible of twelve dogs for 12 weeks, and the healing assessed radiologically and histologically. The new bone which was deposited directly onto the surface of the implants bonded them firmly to the adjacent tissues. There was no fibrous tissue between implant and bone. This material appears to be a suitable substitute for autogenous bone when used as inert 'space filler' in maxillo-facial surgical procedures.

Animals↗
PubMed1997

[Long-term outcome after obliteration of the cat frontal sinus with ionomer bone substitute. II: Histomorphometric measurements].

BACKGROUND: Stenosis or occlusion of the nasofrontal duct with subsequent recurrent frontal sinusitis or mucocele formation may require osteoplastic surgery in combination with frontal sinus obliteration. METHODS: To study its suitability as an implant material in sinuses, granular ionomeric cement was applied for frontal sinus obliteration in 15 cats. The frontal sinus specimens were processed for histological studies after 1, 3, 6, 12, and 24 months, respectively. To obtain quantitative data from the histological sections, areas of osteoid, connective tissue, and implanted ionomeric cement were measured with a computerized digitizing pad and compared to the total area of each frontal sinus. To our knowledge, histomorphometrical analysis of mesenchymal tissue reactions in close contact to an alloplastic material inside the frontal sinus cavity has not been described to date. RESULTS: Bone regeneration, starting from the sinus wall, was detected as early as one month after implantation. The quantitative data for osteoid indicated increasing osteoneogenesis and decreasing connective tissue growth inside the sinus cavity over the period of investigation. Two years after surgery, the osteoid represented 43.5%, the connective tissue 10.7%, and the ionomeric cement 45% of the whole cavity. The implanted cement did not show a significant degradation after two years. CONCLUSION: The results of the present study demonstrated the biocompatibility and biostability of the ionomer-base microimplant.

Animals↗
PubMed2002

Calcium sulphate as a bone substitute for various osseous defects in conjunction with apicectomy.

AIM: The purpose of this study was to investigate the effect of calcium sulphate on various osseous defects when used in conjunction with apicectomy. METHODOLOGY: Mandibular third and fourth premolars of 11 beagle dogs were used. After root-canal treatment and apicectomy, three types of osseous defects were prepared on both sides of the mandible as follows: type 1, osseous defect communicating with the gingival sulcus: type 2, large osseous defect including two roots; type 3, 'through and through' osseous defect. The experimental side was allocated randomly, and the osseous defects were filled with medical grade calcium sulphate. The defects on the opposite side were left unfilled as controls. The dogs were sacrificed at 8 and 16 weeks postoperatively. Undemineralized sections were obtained and examined histomorphometrically. RESULTS: In type 1 defects, bone was not observed on the buccal side of the root on either experimental or control side at 8 and 16 weeks. In both type 2 and 3 defects, bone volume/tissue volume (BV/TV) values on the experimental side were significantly higher than those on the control side (P < 0.01), and mineral apposition rate (MAR) values on the experimental side were significantly higher than those on the control side (P < 0.01). CONCLUSIONS: The use of calcium sulphate was effective in bone regeneration on both large osseous defects and 'through and through' osseous defects. It was less effective in osseous defects communicating with the gingival sulcus.

Alveolar Bone Loss↗
PubMed2005

Preparation and in vitro investigation of chitosan/nano-hydroxyapatite composite used as bone substitute materials.

Chitosan/nano-hydroxyapatite composites with different weight ratios were prepared through a co-precipitation method using Ca(OH)(2), H(3)PO(4) and chitosan as starting materials. The properties of these composites were characterized by means of TEM, IR, XRD, burn-out test and universal matertial test machine. Additionally, in vitro tests were also conducted to investigate the biodegradability and bioactivity of the composite. The results showed that the HA synthesized here was poorly crystalline carbonated nanometer crystals and dispersed uniformly in chitosan phase and there is no phase-separation between the two phases. Because of the interactions between chitosan and n-HA, the mechanical properties of these composites were improved, and the maximum value of the compressive strength was measured about 120 MPa corresponding to the chitosan/n-HA composite with a weight ratio of 30/70. The specimens made of 30/70 chitosan/n-HA composite exhibit high biodegradability and bioactivity when being immersed in SBF solutions. The composite is appropriate to being used as scaffold materials for bone tissue engineering. (c) Springer Science + Business Media, Inc.

Biocompatible Materials↗
PubMed1998

Hydroxyapatite-polyethylene composites for bone substitution: effects of ceramic particle size and morphology.

Synthetic hydroxyapatite particles of two median sizes and different morphologies have been used to manufacture hydroxyapatite reinforced high density polyethylene composites (HAPEX) for medical applications. The effects of hydroxyapatite particle size on properties of the resultant composites were investigated using various techniques. It was found that composites with smaller hydroxyapatite particles had higher torsional modulus, tensile modulus and tensile strength, but lower strain to failure. Examination of fracture surfaces revealed that only a mechanical bond existed between the filler and the matrix. It was shown that dynamic mechanical analysis is useful in studying the viscoelastic behaviour of the composite.

Bone Substitutes↗
PubMed2005

The effect of chitosan bead encapsulating calcium sulfate as an injectable bone substitute on consolidation in the mandibular distraction osteogenesis of a dog model.

PURPOSE: The purpose of this project was to study the effect of chitosan bead encapsulating calcium sulfate, which provides a sustained release of chitosan and calcium sulfate after implantation, on early bony consolidation in distraction osteogenesis of a dog model. MATERIALS AND METHODS: Forty-five dogs were used for this study. An external distraction device was applied to the mandibular body after a vertical osteotomy and mandibular distraction was initiated 5 days after the operation at a rate of 1 mm/day up to a 10-mm distraction. The experimental group was divided into a control group (I), hyaluronic acid group (II), chitosan group (III), calcium sulfate group (IV), and chitosan bead encapsulating calcium sulfate group (V). Normal saline was injected in group I. In group II, 1 mL of hyaluronic acid solution was injected into the distracted region. In group III, 1 mL of injectable solution of chitosan mixed with hyaluronic acid was implanted. In group IV, 1 mL of injectable solution of calcium sulfate mixed with hyaluronic acid was implanted. In group V, an injectable form of powdered chitosan bead encapsulating calcium sulfate mixed with 1 mL volume of hyaluronic acid was implanted. RESULTS: Bone mineral density was 12% of the contralateral normal mandible at 3 weeks, 23.4% at 6 weeks in group I, 15% at 3 weeks, 29.1% at 6 weeks in group II, 16% at 3 weeks and 32% at 6 weeks in group III, 30.4% at 3 weeks and 52.8% at 6 weeks in group IV, and 33.6% at 3 weeks and 55% at 6 weeks in group V with statistical significance (P < .005). The mean 3-point failure load was compared with the intact contralateral mandible and noted to be 12% in the control group, 16% in group II, 18% in group III, 34.3% in group IV, and 31.7% in group V. Difference of mean percentages between one group and another was statistically significant (P < .005). In the histologic findings, new bone was generated in all groups. In groups IV and V, the formation of active woven bone was observed throughout the distracted region at 6 weeks. The amount of new bone formation in the distracted zone was in the order of group IV and V, III and II, and the control group. CONCLUSIONS: These findings suggest that chitosan bead encapsulating calcium sulfate appears to facilitate early bony consolidation in distraction osteogenesis.

Analysis of Variance↗
PubMed2001

Bone substitutes in vertebroplasty.

Vertebroplasty--percutaneous cement augmentation of vertebral bodies--is an efficient procedure for the treatment of painful vertebral fractures in osteoporosis. At the present time, polymethylmethacrylate (PMMA) is the only available cement with reports of clinical application and experience. The material is easy to handle, the radiopacity can be adapted by adding contrast dye, and it is mechanically efficient. Composite cements (acrylic cements in conjunction with ceramics) are bioactive, highly radiopaque, and feature excellent mechanical properties. One such cement, Cortoss, is currently undergoing clinical trials for vertebroplasty and has so far been shown to be a potentially valuable alternative to PMMA. Several in vitro studies with injectable calcium phosphate (CaP) cements show their feasibility and mechanical effectiveness. Animal studies confirm their biocompatibility and osteoconductivity. However, handling problems and the limited radiopacity of these cements currently preclude their clinical use.

Animals↗
PubMed2006

The effect of crystallinity on strength development of alpha-TCP bone substitutes.

Alpha phase tricalcium phosphates (alpha-TCP) were produced using a solid-state reaction method and milled for various periods of time. The resulting four materials were alpha-TCPs, ranging in crystalline content. Powders were exposed to X-ray diffraction for material identification as well as for use in crystallinity and purity calculations. Powder particle size was investigated using laser diffraction. Materials were mixed with 2.5% Na(2)HPO(4) solution to initiate the hydration of alpha-TCP to calcium-deficient hydroxyapatite (CDHA). Isothermal calorimetry was performed to observe thermal response of the powders over a period of time. During the reaction process, at various time points up to 216 h, the material was compression tested to observe strength development. Materials proved to be predominantly alpha phase, while amorphous content determined by XRD varied. Reactivity, as measured by isothermal calorimetry, varied with crystallinity of the alpha-TCP powder. Speed of strength development did not change except for the most finely ground powder. In addition, crystal size of the CDHA was changed only in the product formed from the most highly ground material. It is proposed that increasing reactivity of alpha-TCP cements does not result in a corresponding increase in rate of strength development until there is sufficient supersaturation to produce significant crystal nucleation.

Bone Substitutes↗
PubMed2006

In vitro gentamicin release from commercially available calcium-phosphate bone substitutes influence of carrier type on duration of the release profile.

BACKGROUND: Polymethyl-methacrylate (PMMA) beads releasing antibiotics are used extensively to treat osteomyelitis, but require surgical removal afterwards because they do not degrade. METHODS: As an alternative option, this report compares the in vitro gentamicin release profile from clinically used, biodegradable carrier-materials: six injectable cements and six granule-types. Cement cylinders and coated granules containing 3% gentamicin were submerged in dH2O and placed in a 48-sample parallel drug-release system. At regular intervals (30, 90, 180 min. and then every 24 h, for 21 days), the release fluid was exchanged and the gentamicin concentration was measured. The activity of released gentamicin was tested on Staphylococcus aureus. RESULTS: All combinations showed initial burst-release of active gentamicin, two cements had continuous-release (17 days). The relative release of all cements (36-85%) and granules (30-62%) was higher than previously reported for injectable PMMA-cements (up to 17%) and comparable to other biodegradable carriers. From the cements residual gentamicin could be extracted, whereas the granules released all gentamicin that had adhered to the surface. CONCLUSION: The high release achieved shows great promise for clinical application of these biodegradable drug-carriers. Using the appropriate combination, the required release profile (burst or sustained) may be achieved.

Anti-Bacterial Agents↗
PubMed1999

Biphasic synthetic bone substitute use in orthopaedic and trauma surgery: clinical, radiological and histological results.

Searching for an alternative to bone grafts in orthopedic and trauma surgery, two biphasic synthetic calcium phosphate ceramics BCP are made: the first, Eurocer 400, in granule form with a high interconnected porosity for void-filling, and the second, Eurocer 200, available in different shapes, with a good mechanical resistance in compression. Two hundred cases are reported with more than a six-month follow-up. The first 72 cases relating to hip arthroplasty revision surgery (29 involving acetabular and 43 femoral stem loosening) are exposed with some technical details. The next 71 cases concerning trauma and sequels are displayed with technical particulars. The remaining 57 other cold orthopedic indications are then enumerated. The very good biocompatibility of these ceramics is confirmed. Radiological incorporation is quickly seen in all the cases, faster with the filling substitute than with the second one, which, however, presents no mechanical failures when classical technical principles are respected. Finally, some histological studies are presented; the ceramics are progressively resorbed and bone reconstruction in and close to the substitutes is noticed. Therefore, the use of biophasic ceramics in almost all orthopedic and trauma surgery is recommended.

Journal Article↗
PubMedDate not supplied

Determination of dose enhancement in cortical bone substitute material for electron beams.

Dose measurements in Witt liquid, which simulates cortical bone, have been compared with dose in water for 6-, 9-, 12-, and 15-MeV electron beams. Measurements were made using a Farmer ionization chamber. The results of the study show dose enhancement in Witt liquid of 5%, 7%, 4%, and 0.4% for 6-, 9-, 12-, and 15 MeV electrons at shallow depths. The dose to a small mass of soft tissue in bone has also been estimated using ionization measurements. The results show a significantly higher dose in bone.

Bone and Bones↗
PubMed1992

Osteogenesis of hydroxyapatite and tricalcium phosphate used as a bone substitute.

Hydroxyapatite (HA) and tricalcium phosphate (TCP) are useful for grafting and augmentation of bone tissue. In this study, conventional and histochemical transmission electron microscopy were used to study osteogenic events at the interface between the implanted materials and adjacent tissue from 1 to 4 weeks postoperatively. The microscopic results indicated that TCP was resorbed more rapidly than HA after implantation, with a notable breakdown of material and replacement by mesenchymal cells with ultrastructural features resembling osteoprogenitor cells and collagen up to 4 weeks postoperatively. Alkaline phosphatase and acid phosphatase reactivity in the tissues helped to identify and differentiate the histologic differences observed between HA and TCP.

Acid Phosphatase↗
PubMed1991

Macroporous calcium phosphate ceramics for bone substitution: a tracer study on biodegradation with 45Ca tracer.

The value of artificial materials in bone replacement depends highly on their biocompatibility and biostability. Porous calcium phosphate ceramics have a good compatibility with natural bone. To study the biodegradation process of calcium phosphate bioceramics, labelled [45Ca]-beta-whitlockite and [45Ca]-hydroxyapatite were implanted in the femurs of dogs. The effects accompanying the ingrowth of new bone into the pores of these bioceramics and its replacement by natural bone were investigated. In vivo degradation of the implant material by biochemical dissolution processes was observed. The beta-whitlockite implants showed a conspicuous decrease in radioactive calcium, in contrast to the hydroxyapatite implants. 45Ca was absent in adjacent bones and locally newly formed bone in both beta-whitlockite and hydroxyapatite suggesting a restricted availability of the 45Ca liberated in these processes. Indications of minor mechanical degradation of the materials were also found; in the lymph nodes a very small amount of 45Ca with a high specific activity was detectable. Urine, blood or faeces contained no detectable amounts of 45Ca activity.

Animals↗