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PubMedDate not supplied

Hydroxyapatite orbital implants: indications for use and nursing considerations.

1. An orbital implant made of coralline hydroxyapatite is available as an enucleation, evisceration, or secondary orbital implant. This material is naturally occurring, nontoxic, nonallergenic, biocompatible, and resistant to infection. 2. Special nursing considerations, beginning with meticulous aseptic technique, are necessitated by the special preparation of the hydroxyapatite sphere for implantation. It is important to assess the patient's understanding of the surgical procedure, postoperative care regimen, and the importance of keeping follow-up appointments. 3. Coralline hydroxyapatite orbital implants undergo fibrovascular ingrowth, making them truly integrated orbital implants. Unique possibilities for prosthetic rehabilitation provide a significant improvement over previously available enucleation implants.

Education, Nursing, Continuing↗
PubMed1991

Histologic analysis of a retrieved hydroxyapatite-coated femoral prosthesis.

A hydroxyapatite-coated hip hemi-prosthesis was retrieved from a 98-year-old osteoporotic woman 12 weeks after implantation. Histologic analysis revealed bone and fibrous tissue almost evenly distributed around the surface of the implant circumference. Quantitative histologic analysis showed that 48% of the hydroxyapatite surface was covered by bone. Fibrous tissue covered 30% of the prosthetic surface, and 20% of the surface had no tissue coverage. Scanning electron microscopy showed direct contact without any clear boundary between the newly formed bone and the hydroxyapatite ceramic.

Aged↗
PubMed1991

Hydroxyapatite cement based drug delivery systems: drug release in vitro.

A novel approach using a self-setting hydroxyapatite (HAP) cement as a skeletal drug delivery system has been proposed to solve the problem of delivering drugs to skeletal tissue at high local concentrations for desirable therapeutic effects. Hydroxyapatite cements loaded with antibiotics can be formed in situ and can be used as bonding materials between bone and prostheses as well as for drug release devices. The cement also possesses sufficient mechanical strength to be a potential bone grafting material. Using cephalexin and norfloxacin as model drugs, the continuous in vitro release profiles of these compounds from 0.9-4.8% by weight loaded cement pellets were observed. These drug release patterns correlated well with the Higuchi model. This hydroxyapatite cement drug delivery system can be applied in the treatment of osteomyelitis and infected compound fractures.

Bone Cements↗
PubMed1992

Bone graft incorporation around titanium-alloy- and hydroxyapatite-coated implants in dogs.

To evaluate cancellous allogenic bone graft incorporation into porous-coated implants, the fixation of titanium alloy-(Ti) and hydroxyapatite-(HA) coated implants with and without bone graft was compared. An unloaded model with unilateral carragheenin-induced osteopenia of the knee was used in 12 mature dogs. Ti- and HA-coated cylinders were implanted in the distal femoral condyles and centralized in 2-mm overreamed drill holes. Allogenic, fresh-frozen (-80 degrees) cancellous bone graft was packed around the implants in six dogs. In a matched group of six other dogs, the implants were left in overreamed canals without bone graft. After six weeks the interface shear strength of grafted Ti-coated implants had significantly increased compared to the nongrafted Ti implants. However, HA coating used without bone graft was capable of enhancing the bone-implant interface shear strength to nearly the same degree. The fixation of grafted Ti- and HA-coated implants was equal. No significant difference in implant fixation was found between osteopenic and control bone. Histomorphometric evaluation of mineralizing surfaces in direct contact with the implant confirmed the results from the push-out test. Bone-implant fixation when using allogeneic fresh-frozen cancellous bone graft in osteopenic and control bone was enhanced by hydroxyapatite coating but the HA coating alone appeared to offer almost the same improvement in anchorage in 2-mm defects. Loss of bone stock around loose prosthetic implants often requires bone grafting. However, because of anatomic constraints in joint prosthetic surgery, a complete filling of defects with bone graft is difficult, and areas of gaps between bone and implant will remain. Provided mechanical stability of the prosthesis, the results reported here suggest that these areas will probably be filled early with new mineralizing bone if the prosthesis is coated with a thin layer of hydroxyapatite.

Animals↗
PubMedDate not supplied

Enucleation and the hydroxyapatite orbital implant.

Hydroxyapatite is a natural, porous material that allows the recipient's blood vessels and fibrous tissues to grow onto the implant, thus becoming a "living" portion of the orbital tissues. Natural eye movement, resistance to extrusions, rare complications, and flexibility in fitting the socket are the reasons oculoplastic surgeons are using the hydroxyapatite implant. Hydroxyapatite spheres are contraindicated in situations where other types of orbital implants are contraindicated; ie, severe trauma with possible orbital infection orbits that have poor vascularization and healing qualities, such as after irradiation, and with orbital infection.

Eye Enucleation↗
PubMed1989

Interporous hydroxyapatite as a bone graft substitute in tibial plateau fractures.

The metaphyseal defects in 40 patients with displaced tibial plateau fractures necessitating surgical repair were filled with either cancellous autograft or interporous hydroxyapatite. Roentgenographic and clinical assessments at follow-up periods averaging 15.4 months (autograft) and 34.5 months (hydroxyapatite) demonstrated no significant differences in the two groups. Interporous hydroxyapatite is a safe, effective alternative to autogenous cancellous bone for the filling of metaphyseal defects associated with tibial plateau fractures.

Adolescent↗
PubMed1989

Hydroxyapatite ceramics and the nature of the bone-ceramic interface.

Hydroxyapatite ceramics have been used as bone implants in a number of experimental systems and clinical applications. We have developed a unique experimental model that allows study of the interface between bone and implant materials. A comparison of titanium and hydroxyapatite materials, using this model, has demonstrated the osteoconductive nature of hydroxyapatite and its ability to bond directly to bone.

Animals↗
PubMed1989

Hydroxyapatite-augmented sites as receptors for replacement implants.

Implant failures can arise from a variety of conditions. Damage to the tissue structures at surgical placement, inadvertent stress distribution to the marginal bone, unfavorable arch relationships between the maxilla and mandible, occlusal trauma, inadequate prosthetic design, and improper oral hygiene are but a few of the problems that can result in ultimate damage and loss. The use of hydroxyapatite to restore bone contour and health can allow for replacement of a dental implant reconstruction. This paper will describe the use of porous hydroxyapatite to create proper bone morphology for the placement of IMZ osteointegrated dental implants in an edentulous maxilla and a mandibular distal edentulous area. Both cases are followed from the removal of previously placed blade-type implants to the reconstruction by use of the IMZ osteointegrated system within the hydroxyapatite-contoured ridges.

Aged↗
PubMed1989

Histologic evaluation of tissue response to sintered lanthanum-containing hydroxyapatites subcutaneously implanted in rats.

Hydroxyapatite, lanthanum-containing hydroxyapatite, and lanthanum- and zirconium-containing hydroxyapatite discs were implanted subcutaneously in the backs of rats. The implanted discs and surrounding tissues were removed at 5 and 12 hours, and 1, 3, 7, 14, 30 and 60 days after implantation, and fixed in paraformaldehyde. Tissue samples were dehydrated and embedded in paraffin. Paraffin sections were cut and stained with hematoxylin and eosin, van Gieson's, and Masson's trichrome. The early tissue reaction was exudative due to fibrin deposition and infiltration by polymorphonuclear leukocytes and macrophages. The later reaction was characterized by the formation of fibrous tissue without inflammatory cell infiltration. The tissue reaction to all three types of material was identical by two months after implantation.

Animals↗
PubMed1989

Effect of porous and dense hydroxyapatite implantation on periodontal tissue regeneration in monkeys.

Two different kinds of hydroxyapatite (HA) granules (size: 400-630 microns), 1) porous HA fabricated by the H2O2 bubbling method and 2) dense HA, were placed into the experimentally created, 3-wall, wide periodontal defects in two monkeys to evaluate whether the different structures of hydroxyapatite influence the periodontal response after implantation. Defects without HA implantation served as controls. The HA implant groups showed excellent biocompatibility. Both the porous HA and the dense HA showed a greater amount of "connective tissue attachment or adhesion" than the control group. The amount of the increase by the porous HA group was statistically significant when compared with the control group. However, the three groups showed a similar amount of new cementum formation. These results indicate that the improvement of tissue regeneration by hydroxyapatite implantation was probably due to the prevention of the epithelial downgrowth rather than to the acceleration of the coronal proliferation of the periodontal ligament cells. In the porous HA group, ingrowth of fibrous and osseous tissue in the HA and indefinite tissue-apatite interface were observed. These findings suggest that the porous HA granules formed a firmer attachment to the surrounding periodontal tissue.

Alveolar Process↗
PubMed1989

Porous, block hydroxyapatite as an interpositional bone graft substitute in orthognathic surgery.

Forty-six nonconsecutive patients undergoing orthognathic surgery in whom blocks of coralline, porous hydroxyapatite (Interpore-200) were used in lieu of interpositional bone grafts are the subjects of this report. Surgical procedures included inferior repositioning of the maxilla (7) and chin (12), maxillary advancements in cleft (4) and noncleft individuals (13), and transverse maxillary expansions (12). Patients included in this study were only those in whom bone grafts would have been harvested had hydroxyapatite not been available. A total of 93 anatomic sites were implanted. The complication rate attributable to the use of the implant was 4.3 percent. Follow-up period ranged from 6 to 20 months, with a mean of 9.3 months. At this time, osseous stability was confirmed cephalometrically in all but two patients undergoing maxillary expansions. The biologic behavior and mechanical properties of coralline-derived, porous, block hydroxyapatite are discussed. These implant characteristics make it a feasible bone graft substitute for interpositional use in orthognathic surgery. Proper indications for its use as well as technical details to minimize complications are stressed.

Adolescent↗
PubMed1978

An investigation of the effects of mellitic acid on hydroxyapatite.

The effects produced on the solubility and crystal growth of hydroxyapatite by the condensed phosphates and the diphosphonates are essentially physicochemical in nature. Other poly-anions, may, on this same basis, produce similar effects. Mellitic acid (benzene hexacarboxylic acid), in dilute solution, was taken up by hydroxyapatite in the presence of excess phosphate and was not significantly displaced by it. Mellitic acid treatment of hydroxyapatite inhibited its ability to "seed" metastable solutions of calcium phosphate. Mellitic acid, which has already been shown to be an effective inhibitor of dental calculus in experimental animals may also have some other properties that could be of advantage to its use in humans.

Benzoates↗
PubMed1987

[Diminution of radical surgical cavities with hydroxyapatite].

Canal wall surgery is the safest way to eradicate cholesteatoma and to prevent recurrence of the disease. On the other hand, resulting cavity problems such as a permanently discharging ear and poor functional results made the development of alternative procedures necessary. A new technique to obliterate the mastoid volume or to reduce an old cavity by means of hydroxyapatite granulate is presented. Characteristics of the material and how to manage it are demonstrated. First experiences in 30 ears are reported. Hydroxyapatite granulate enables us to establish a primarily epithelized small cavity. Since hydroxyapatite is the anorganic component of bone its biocompatibility is excellent. It is hardly resorbed, osteointegrated and induces a new formation of bone. The size of the open cavity can therefore be designed exactly during the operation and sliding and vanishing of mass as seen in soft tissue flaps (muscle and connective tissue only) can be avoided.

Cholesteatoma↗
PubMed1988

[A method of protection on out-flow of hydroxyapatite].

Attelocollagen obtained by pepsin treatment from calf skin is very poor antigen. Attelocollagen is the most promising implantable biomaterial because of its lower antigenic property and excellent tissue compatibility. The purpose of this study is to examine that attelocollagen suppress an out-flow of hydroxyapatite. The subject were 16 patients with moderate to advanced periodontal disease who visited Meika university hospital. The clinical examination were performed immediately after the surgery, 1, 2, and 4 weeks after postsurgery. The remains of hydroxyapatite were measured by the roentgenograph and an image analyzer system. As a result, the hydroxyapatite in attelocollagen treated group was remained much more than of control group in 4 weeks (p less than 0.01). In clinical finding, wound healing of attelocollagen treated group was accomplished in 4 weeks and it did not prevent the wound healing of periodontal tissue.

Collagen↗
PubMed1986

Hydroxyapatite deposition in articular cartilage by intra-articular injections of methylprednisolone. A histological, ultrastructural, and x-ray-microprobe analysis in rabbits.

The mineral deposits in rabbit articular cartilage induced by intra-articular injections of glucocorticoid were studied by light and electron microscopy, using histochemical techniques and x-ray-probe microanalysis. This study demonstrated that the mineral deposits consisted of hydroxyapatite crystals. The initial deposition of hydroxyapatite crystals was seen around degenerating chondrocytes, where a halo-like pericellular space contained a large amount of electron-dense amorphous material. The initial precipitation of the crystals with a low ratio of calcium to phosphorus and the subsequent growth of crystals were seen only on or within the electron-dense amorphous material until the crystals formed mature, calcified nodules. The electron-dense amorphous material frequently coexisted with proteoglycans and degenerated collagen fibers. Digestion studies using chondroitinase ABC, papain, or chloroform and methanol suggested that the electron-dense amorphous material consisted of some protein and a small amount of lipid. Matrix vesicles were rarely seen in the calcifying areas. In addition, there was a correlation between sulphur, calcium, and phosphorus in the calcifying areas, where the relative element concentrations were: S (estimation counts of sulphur) = -0.862 X (calcium counts) + 1.472 X (phosphorus counts) + 102.146. This study demonstrated that electron-dense amorphous material, proteoglycans, and degenerated collagen fibers are present in loci where the hydroxyapatite crystals are formed in articular cartilage.

Animals↗
PubMed1985

Scintigraphic studies to evaluate stability of ceramics (hydroxyapatite) in bone replacement.

In this study, the suitability of a radionuclide bone imaging technique was examined in cases of hydroxyapatite implants for segmental replacements of long bones. The radionuclide bone imaging technique, using [99mTc]MDP was applied to estimate osseous changes at the sites of the hydroxyapatite implants up to 2 yr after their implantation in an animal experimental model. The results were correlated with histological and radiographical findings at the same time. The radionuclide bone imaging with technetium proved to be a useful method to estimate the intensity of osseous changes after bone replacement by a hydroxyapatite implant. It proved to be more sensitive than radiography. The differences in elasticity of the implanted material and adjacent bone may cause an increase of radionuclide uptake at the site of the implant 2 yr after implantation. These osseous changes cannot be detected by standard histological and radiographical methods but could be detected by radionuclide bone imaging. It is submitted that the radionuclide bone imaging is a noninvasive, sensitive, and useful method for the estimation of osseous changes in sites of long term bone implants.

Animals↗
PubMed1986

Hydroxyapatite columns as an in vitro system to study demineralization processes.

Acetate buffers were passed through small hydroxyapatite columns and the column effluents were analysed for calcium and phosphate. Changes in the pH of the column effluents were also measured. As long as the pH of the column effluent was higher than about 5.5, only calcium was eluted from the column. However, when the pH fell below 5.5, the rate of calcium elution decreased and phosphate elution increased until calcium and phosphate elution reached constant values. Pretreating the hydroxyapatite with sodium fluoride or 1-hydroxyethylidene-1,1-bisphosphonate accelerated the drop of the pH and reduced the initial Ca/P ratio in the column effluent. We suggest that these results are due to the formation of a pH gradient along the progressing buffer fron with calcium and phosphate liberated from the hydroxyapatite reprecipitating to form calcium-poor minerals.

Calcium↗
PubMed1979

[Generalized periarthritis calcarea (generalized hydroxyapatite disease)].

The condition of generalized periarthritis calcarea (hydroxyapatite deposition disease) is characterised by multiple periarticular calcification which can be localised around practically any joint and also in proximity to the spine. This calcification consists of hydroxyapatite crystals which are responsible for the episodes of acute, subacute or chronic periarticular or articular inflammation so typical of the condition. Because of this one can classify periarthritis calcarea along with gout and chondrocalcinosis in the group of crystal deposition diseases. The actual cause of the calcification remains unknown but it is probable that, along with hereditary factors, disturbances in metabolism play an important role. The diagnosis of generalised periarthritis is made from the characteristic X-ray picture in conjunction with the clinical findings and, on occasion, the demonstration of hydroxyapatite crystals in the affected tissues. In the differential diagnosis gout, chondrocalcinosis, various inflammatory rheumatic conditions and septic arthritis must be excluded and various calcification processes, particularly interstitial calcinosis and lipocal cinogranulomatosis, must also be considered. Since the etiology of the calcification remains unknown to specific treatment is available. Symptomatic treatment with colchicine is mostly inadequate which is why one often has recourse to the use of non-steroid anti-inflammatory drugs and corticosteroids.

Calcinosis↗