Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Hydroxyapatites”

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 991 records · Page 55Linked to original sources
PubMed1989

Porous hydroxyapatite as an onlay bone-graft substitute for maxillofacial surgery.

This paper chronicles 3 years of a continuing study comparing porous hydroxyapatite to autogenous bone grafts as onlays in maxillofacial surgery. Twenty-five patients, seen from June of 1984 to May of 1985, underwent onlay augmentation on various maxillary and mandibular locations. A total of 68 onlay augmentation sites comparing Interpore porous hydroxyapatite and autogenous bone were followed for 2 years or more. This long-term study compares these substances in radiologic longevity, histologic incorporation, clinical function, and aesthetic appearance.

Adolescent↗
PubMed1990

The biologic behavior of hydroxyapatite implanted into the maxillofacial skeleton.

Eleven patients who previously had undergone elective facial osteotomy and in whom blocks of porous hydroxyapatite were implanted into osteotomy gaps later consented to open biopsy of the implant material. A total of 24 biopsies were harvested at a mean time of 10.2 months following implantation. Gross anatomic findings were recorded at the time of biopsy. Specimens were harvested from the zygomatic buttress of the maxilla (12), the piriform buttress of the maxilla (4), the maxillary interdental premolar region (2), and the anterior mandible (6). Histologic sections were examined undecalcified using a modified trichrome stain. Eight of the 11 patients were followed radiographically for a minimum of 24 months. In the absence of infection, there was rapid fibrovascular ingrowth and, provided there was contact with host bone, bone ingrowth. This was observed in 21 of 24 biopsy specimens. The extent of bone ingrowth, as judged qualitatively, was highly variable and did not correlate with the time interval from implantation, anatomic site, or surface area of bone-implant interface. A healing process involving an osteoid phase of bone maturation and suggestive of continued net bone production was consistently found. The gross anatomic, radiographic, and histologic findings are discussed and provide further insight into the biologic behavior of porous block hydroxyapatite implanted into the maxillofacial skeleton.

Adolescent↗
PubMed1991

The induction of bone by an osteogenic protein and the conduction of bone by porous hydroxyapatite: a laboratory study in the rabbit.

The influence of the addition of an osteoinductive protein, capable of inducing extraskeletal ossification, on bone ingrowth into coralline porous hydroxyapatite was evaluated in the rabbit using a calvarium onlay model. Twenty-three rabbits received hydroxyapatite implants (10 x 10 x 2 mm) prepared with and without osteoinductive protein. These were implanted on the frontal bone and secured by wire fixation after 0.25 mm of the cortical surface was abraded. The implants were harvested at 3 and 4 months and analyzed for percentage of bone ingrowth by histologic examination of decalcified H&E sections and by scanning electron microscope backscatter image analysis. The osteoinductive protein-treated implants demonstrated significantly greater amounts of bone ingrowth at both 3 (52.0 versus 10.3 percent; p less than 0.001) and 4 months (66.1 versus 39.2 percent; p less than 0.005) than the untreated implants. The type of bone found in all osteoinductive protein-treated implants was predominantly lamellar. Untreated implants contained mostly woven bone at 3 months, with increasing amounts of lamellar bone appearing at 4 months. These results suggest that the combination of a bone-inducing protein and a suitable osteoconductive matrix may provide an alternative to bone grafting.

Animals↗
PubMed1992

A study on bone induction in hydroxyapatite combined with bone morphogenetic protein.

Our present study consisted of an implantation of artificially made hydroxyapatite (HAP) ceramic pellets under the periosteum of the rabbit skull with subsequent inspection of further progress of bone formation and also of an evaluation of the effects of bone morphogenetic protein (BMP). The results revealed that the alkali phosphatase (AL-P) activity of the pellets was elevated only in those of the bone morphogenetic protein group. The results of determination of bone mineral density at the site of the pellets revealed that the increase in bone mineral density was the most remarkable in the bone morphogenetic protein group rather than the control group. The results of the histopathologic examinations revealed that marginal bone formation was found in the pores on the surface between the pellets and the skull in the control group and in the collagen group, whereas in the bone morphogenetic protein group very active bone formation was found not only on the interface in contact with the skull but also surrounding the whole pellet. It also was noted in the animals in the bone morphogenetic protein group that the pellets were corrupted from the peripheries and then absorbed into the newly formed bone. From these results, the efficacy of the hydroxyapatite-collagen-bone morphogenetic protein complex was made clear, and applications in clinical practice are expected in the near future.

Alkaline Phosphatase↗
PubMed1999

Anterior interbody fusion of the cervical spine with coralline hydroxyapatite.

STUDY DESIGN: A nonrandomized, retrospective human study of patients requiring anterior discectomy and reconstruction from C3 to T1. The pattern of incorporation, presence or absence of disc space collapse, maintenance of correction, and clinical outcomes were considered. OBJECTIVE: To determine the efficacy of coralline hydroxyapatite as a bone replacement in anterior interbody fusions of the cervical spine used in conjunction with rigid plate fixation. SUMMARY OF THE BACKGROUND DATA: Autograft is the gold standard for anterior interbody fusion of the cervical spine. Reported complication and morbidity rates with the use of autograft are as high as 21%. Using allograft instead of autograft presents numerous problems including lower rates of fusion. Other bone substitutes such as ceramics and polymethylmethacrylate are ineffective for fusion. METHODS: Twenty-six skeletally mature patients underwent anterior decompression, stabilization, microdiscectomy, and reconstruction with Pro Osteon 200 (Interpore Cross International, Irvine, CA) coralline hydroxyapatite and AO anterior cervical locking plates. Iliac crest autograft, local bone, and allograft were not used. RESULTS: The minimum follow-up period was 2 years (average, 30 months). There was no evidence of plate breakage, screw breakage, resorption of the implant, or pseudarthrosis. Two patterns of incorporation were identified. The implant incorporated totally in 100% of the disc spaces. Average hospital stay was 1.6 days. The average decrease in pain was 75.8%. There was no evidence of nonunion. CONCLUSIONS: The use of Pro Osteon 200 with rigid anterior plating seems promising as a bone replacement in the cervical spine. The incorporation rate is exceedingly high, and the complication rate nonexistent.

Adult↗
PubMed2002

Hydroxyapatite prosthesis extrusion.

OBJECTIVE: To examine the mechanism of prosthesis extrusion and evaluate preoperative and postoperative variables associated with extrusion of hydroxyapatite prostheses for ossicular reconstruction. STUDY DESIGN: Retrospective case review. SETTING: Tertiary referral, university medical center. PATIENTS: Patients undergoing ossiculoplasty with a hydroxyapatite prosthesis and having at least six months follow-up. MAIN OUTCOME MEASURE: Prosthesis extrusion, defined as loss of the tympanic membrane resulting in exposure of the prosthesis. Extrusion is further classified into early (< 2 months) and late (> 6 months). RESULTS: Early extrusion or tympanoplasty graft failure occurred in 15/195 cases (8%). Late extrusion was seen in 17/125 cases (14%). Cases exhibiting late extrusion had a significantly greater incidence of postoperative atelectasis (p < 0.0001), recurrent otitis media (p < 0.0001), and myringitis (p = 0.003) than those with retention of the prosthesis. Regression analysis found an abnormal contralateral ear increased the risk of postoperative recurrent otitis media, while staged surgery reduced the risk, odds ratios of 3.56 (95% confidence interval 2.20-9.37) and 6.84 (95% CI 4.24-17.76) respectively. There were no preoperative variables that predicted postoperative atelectasis or myringitis. CONCLUSIONS: Recurrent otitis media, myringitis, and atelectasis developing after ossiculoplasty are associated with a greater risk of prosthesis extrusion. Predicting postoperative complications from preoperative and intraoperative findings proved difficult. Measures to prevent atelectasis, such as covering the prosthesis with cartilage, are recommended at the time of ossiculoplasty.

Cartilage↗
PubMed2004

Coralline hydroxyapatite orbital implant (bio-eye): experience with 158 patients.

PURPOSE: To assess the problems seen in 158 patients with coralline hydroxyapatite (HA) orbital implants (Bio-Eye). METHODS: A consecutive case series of 170 patients receiving coralline HA implanted by two surgeons over a 5-year period were reviewed. The authors analyzed age, type of surgery, implant size, peg system, follow-up duration, time of pegging, problems encountered, and treatment. RESULTS: Twelve patients were lost to follow-up after 5 months, leaving 158 patients who were followed from 6 to 130 months (average, 39 months). Problems in unpegged implants occurred in 36 (22.8%) patients. Discharge occurred in 18 (11.4%) patients, implant exposure in 12 (7.6%), socket discomfort in 1 (0.6%), conjunctival thinning in 3 (1.9%), chronic conjunctival swelling in 2 (1.3%), and implant infection in 3 (1.9%). Problems after pegging occurred in 68 (50.7%) of 134 patients: discharge in 27 (20.1%), pyogenic granuloma in 24 (17.9%), conjunctiva overgrowing the peg in 4 (3.0%), implant exposure around the sleeve in 5 (3.7%), clicking in 6 (4.5%), peg on an angle in 2 (1.5%), loose sleeve in 1 (0.7%), peg falling out in 18 (13.4%), popping peg in 1 (0.7%), poor transfer of movement in 3 (2.2%), pain with movement in 1 (0.7%), and implant infection in 2 (1.5%). CONCLUSIONS: The Bio-Eye orbital implant represents a porous orbital implant that is biocompatible with orbital tissues and allows fibrovascular ingrowth and improved motility when coupled to the overlying artificial eye. It is more expensive than other commercially available porous orbital implants, such as synthetic FCI3 HA, porous polyethylene (Medpor), and aluminum oxide (Bioceramic) implant. Problems encountered with its use are similar to those problems seen in patients with the synthetic FCI3 hydroxyapatite and aluminum oxide orbital implants.

Adolescent↗
PubMed1983

Kinetics of adherence of Actinomyces viscosus to saliva-coated silica and hydroxyapatite beads.

Adherence of 14C-labelled strains of Actinomyces viscosus to uncoated and saliva-coated silica and hydroxyapatite beads had both loose and firm components, probably reflecting different subpopulations of bacteria within a single culture. Adherence was characterized by the proportion of bacteria available for each type of adherence and a constant (Kb) for each combination of bacterial strain and bead surface. Loose adherence, which was greater with silica than with hydroxyapatite beads, always involved many more bacteria than firm adherence. Firm adherence was greater with A. viscosus WVU627 than A. viscosus TF11. The association rate constants (Ka) for loose and firm adherence were similar, indicating simultaneous processes, but the dissociation rate constant (Kd) was lower for loose adherence than for firm adherence. Removal of loosely adhering bacteria by washing may only reflect their distance from the bead surface. Silica beads were convenient for studying bacterial adherence and formed an acceptable coating of salivary glycoprotein.

Actinomyces↗
PubMed1976

An animal model for screening drugs for antipsoriatic properties using hydroxyapatite to isolate DNA rapidly from the epidermis.

A new, rapid, simple and accurate procedure for extracting DNA from the epidermis is described involving hydroxyapatite. This compound has an unique property of high affinity for double stranded native DNA, but none for RNA and protein. The technique has been applied to a hairless mouse model for screening systemic and topical agents for cell inhibitory properties in proliferating epidermis for potential use in the therapy of psoriasis. Mitotic counts, autoradiography and a standard chloroform procedure for isolating DNA have confirmed the results obtained using hydroxyapatite column chromatography. In addition, compounds which are known to be effective in psoriasis, have been found to be effective in the system suggesting that it should be a good predictive screen for new therapies. Of several compounds screened for topical activity, cycloheximide has been found to be very effective in the system and preliminary clinical studies confirm its efficacy in psoriasis.

Animals↗
PubMed1993

Observation of the loss of the hydroxyapatite sixfold symmetry in a human fetal tooth enamel crystal.

A deviation from the hydroxyapatite hexagonal symmetry of a human tooth enamel crystal observed by high-resolution electron microscopy is reported. This symmetry deviation is characterized by: (1) 'preferential' planes that can be indexed as (100) with an intensity that differs from the (300) and the other (100) hexagonal equivalent planes; and (2) streaking of higher order reflections in the optical diffractogram of the image of the crystal. Computer simulations show that similar 'preferential' planes can also be observed at specific crystal tilt angles (and/or beam tilt and/or objective aperture misalignment) and at crystal thickness/microscope defocus values in images of hydroxyapatite crystals observed along the [0001] or [2243] zone axes. The streaking of higher order reflections in the optical diffractogram is related to a deformation of the crystal itself and does indeed show a symmetry deviation of the crystal under observation.

Crystallography↗
PubMed1992

Glucosyltransferase phase variation in Streptococcus gordonii modifies adhesion to saliva-coated hydroxyapatite surfaces in a sucrose-independent manner.

Phase variation of Streptococcus gordonii between high (Spp+) and low (Spp-) levels of glucosyltransferase (GTF) activity resulted in the greater adhesion of Spp- strains to saliva-coated hydroxyapatite (S-HA) in a washed-cell adhesion test. Specific GTF mutants did not show this response. Although washed Spp+ cells produced 5-fold or more glucan from sucrose than Spp- cells did under the conditions of the adhesion test, sucrose elevated the adhesion of both phenotypes to hydroxyapatite (HA) equally, but had no effect on adhesion to S-HA. This effect was not sucrose-specific, however, because equimolar amounts of other carbohydrates and NaCl elevated adhesion of both Spp types to levels similar to those seen with sucrose. Adhesion did not correlate with relative changes in cell hydrophobicity. These results suggest that, in addition to changes in GTF activity, other changes relevant to adhesion may occur during Spp phase variation.

Arabinose↗
PubMed1975

Improved techniques for the fractionation of non-histone proteins of chromatin on hydroxyapatite.

The effect of the dissociation medium on the fractionation of chromatin on hydroxyapatite has been studied. Optimal separations of the histones and non-histone protein are only achieved when columns are run in buffers containing high concentrations of sodium ions. We have modified our previously published method such that the chromosomal proteins can be recovered in virtually quantitative yields. Each of the hydroxyapatite fractions has been analysed with respect to nucleic acid content and the proteins have been analysed by two-dimensional gel electrophoresis.

Animals↗
PubMed1989

Ceramic hydroxyapatite high-performance liquid chromatography of complexes membrane protein and sodium dodecylsulfate.

Ceramic hydroxyapatite high-performance liquid chromatography was examined as a chromatographic method by which complexes of whole membrane proteins and sodium dodecyl sulfate could be analyzed. The chromatographic conditions were optimized using the erythrocyte membrane as a model. Whole proteins, including membrane proteins larger than 100 kDa, were eluted as sharp peaks from the column and separated well from each other under optimum conditions. This method gave better resolution of protein-SDS complexes than other chromatographic methods reported so far. The sodium dodecyl sulfate complexes of 24 well characterized proteins were analyzed by this method and their retention times were examined. The positive correlation of the retention time with log (molecular mass) and log sigma (hydrophobicity of amino acids) but not with the isoelectric point, was observed. Based on these results, the mechanism underlying the interaction of protein-SDS complexes with ceramic hydroxyapatite was discussed.

Animals↗
PubMed1979

Interaction of acid glycosaminoglycans (mucopolysaccharides) with hydroxyapatite.

Selected acidic glycosaminoglycans (GAG) have been used as a model series to study some binding properties of hydroxyapatite. The order of binding was heparin, heparin sulfate, dermatan sulfage/chondroitin-4-sulfate/chondroitin-6-sulfate (all similar) and hyaluronic acid, indicating that the negative charge on the molecules is a major determinant in the binding process. Both calcium and saliva pretreatment led to an increase in uptake of selected GAG whereas fluoride even at 1 and 3 parts/106 levels led to a graded reduction in uptake. The clinical significance of these findings may be related to the presence of certain GAG in the dental integuments and to the interaction of a chemically defined group of compounds at a specific solid surface. Such findings may also have an application in studies on endogenous mineralization. The results are in accord with the generally held view that polyanions may interact electrostatically with calcium sites present in the crystal lattice of the hydroxyapatite.

Adsorption↗
PubMed1983

Surface properties of fluoride treated hydroxyapatite as judged by interactions with albumin and lysozyme.

Hydroxyapatite treated with fluoride containing both alkali soluble fluoride (CaF2) and alkali stable fluoride (FAp) was shown to take up less albumin than hydroxyapatite but more lysozyme. The affinity of the adsorption of albumin to fluoride treated apatite was increased, whereas no difference was demonstrated in the affinity of lysozyme. Tooth surfaces in vivo contain both calcium fluoride and fluoroapatite. Protein adsorption to mixed phases may thus have clinical significance.

Adsorption↗
PubMed1993

Thermogravimetric studies on sound and carious human enamel and dentin as well as hydroxyapatite.

The present study was conducted to investigate the thermal behavior of human sound and carious enamel and dentin. The results were compared to those obtained for pure hydroxyapatite. The volatile decomposition products were identified by mass spectrometry. Solid decomposition products were analyzed by infrared (IR) spectrometry. For both normal and carious enamel, the differential thermogravimetry (DTG) curves revealed three peaks at about 90-100, 330, and 900 degrees C. Both normal and carious dentin revealed two common peaks in their DTG curves, at about 90-100 degrees C and 330 degrees C. An additional peak at 500-600 degrees C was observed in the DTG curve of carious dentin in air atmosphere. This peak completely disappeared in nitrogen (N2) atmosphere. About 11-12% of sound and carious enamel was volatilized in air. The values for sound dentin were 34% and for carious dentin 54% per weight, respectively. Enamel and dentin (apatite protein complex) decomposed at higher temperatures than pure hydroxyapatite in air. In N2 atmosphere, both enamel and dentin are more resistant to thermal decomposition than in air, because organic materials decompose easier in an oxidizing atmosphere than in an inert atmosphere.

Adolescent↗
PubMed1993

Dentine hypersensitivity: the measurement in vitro of streaming potentials with fluid flow across dentine and hydroxyapatite.

Stimulus transmission across dentine, in conditions such as dentine hypersensitivity, is considered to occur via a hydrodynamic mechanism. This fluid flow in dentine may then induce a mechanoreceptor response in pulpal nerves. However, when fluid flows through a porous structure electrical potentials are also generated. The aim of this study was to develop a reproducible model system to measure streaming potential across dentine and hydroxyapatite and determine the influence of pressure. Using an acrylic cell, with silver electrodes, streaming potentials were recorded across dimensionally standardized dentine and hydroxyapatite specimens, over a pressure range of 1-6 atmospheres. Streaming potentials were found to be directly proportional to pressure and dependent on the electrical conductivity of the saline used in the cell. The results confirm the limited existing data on streaming potentials across dentine and indicate that at these low pressures excitation of pulpal nerves would not occur. However, if, as may be the case, stimuli applied to dentine create very high pressures, the resultant potentials generated could indeed evoke a neural response. The model system is worthy of further use to study this phenomenon and the factors which may influence it.

Dentin↗