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PubMed1991

[Studies concerning the effect of sport drinks on hydroxyapatite dissolution].

The purpose of this study was to evaluate the erosive properties of sport drinks and to clarify the facts which effect these properties. We analysed the contents of 3 kinds of sport drinks and measured their capacity to dissolve hydroxyapatite in vitro under several duration times. The following results were obtained: 1) The pH Values of the sport drinks ranged from 2.91 to 4.07. 2) The total sugar concentration of the sport drinks ranged from 3.24 to 5.95%. The sugar were consisted mainly to sucrose, glucose and fructose, but their proportion in the sport drinks had different values respectively. 3) After stirring for 1 and 5 minutes, there was a negative correlation (Spearmann's rank correlation coefficient test) between the pH values of the sport drinks and the amounts of Ca2+ released into them. And after stirring for 10 and 20 minutes, there was a negative correlation between the Ca concentrations of the sport drinks and the amounts of Ca2+ released into them. 4) The addition of sugar to the sport drinks showed no effect on their capacity to dissolve hydroxyapatite. The results suggested that tooth erosion depends on the pH value of the sport drink at the early stage when the tooth contacted it, and also tooth erosion depends on the Ca concentration of the sport drink when the tooth is in contact with it for a long time.

Calcium↗
PubMed1991

Inhibition of adsorption of oral streptococci to saliva treated hydroxyapatite by chitin derivatives.

This study estimated the effects of five chitin derivatives low molecular chitosan (LMCS), ethyleneglycol chitin (PEGT), carboxymethyl chitin (PCMT), sulphated chitosan (PSSS), and phosphorylated chitin (PPPT) on the adsorption of three oral streptococci to saliva-treated hydroxyapatite (S-HA). The adsorption was evaluated by measuring the optical density of the bacterial cell suspensions released from saliva-treated hydroxyapatite by 0.5 N HCl. The adsorption of test strains to S-HA progressively decreased in proportion to each additional volume of PEGT, PPPT, or PSSS. PPPT and PSSS quite effectively inhibited the adsorption of S. mutans onto S-HA, but were less effective against S. sanguis and S. mitis. PPPT, PSSS, and PCMT all markedly promoted the desorption of S. mutans cells pre-adsorbed onto S-HA. Pretreatment of S-HA with PPPT, PSSS, or PCMT significantly decreased the subsequent adsorption of S. mutans and S. mitis. Pretreatment of these cells with PEGT also decreased their adsorption to S-HA. These findings suggest that these chitin derivatives may change the ionic natures of the S-HA and the bacterial cell surface, resulting in a less favorable interaction.

Adult↗
PubMed1991

An assessment of the interaction between human neutrophils, hydroxyapatite and dichloromethylene bisphosphonate in vitro: an electron microscopic and chemiluminescence study.

The potentially destructive effects of neutrophils, following particulate stimulus such as by hydroxyapatite (HA) crystals, may be pertinent to the progression of some inflammatory diseases, including rheumatoid arthritis. This study was designed to examine the interaction between pure hydroxyapatite particles and human neutrophil granulocytes by transmission electron microscopy and chemiluminescence (CL). The influence of dichloromethylene bisphosphonate (clodronate) in this model was investigated. Neutrophils convincingly phagocytosed HA particles within 15 min and a high CL response was elicited by the zymosan stimulated CL reaction. Clodronate alone appeared to have little effect on the cell morphology or CL. When HA was combined with clodronate, phagocytosis was more rapid, and the zymosan-stimulated CL was 50% of that of the HA group. The results demonstrate neutrophil phagocytosis of HA particles and subsequent cellular activation, which may play a role in the pathogenesis of tissue damage and suggest that the anti-inflammatory role of clodronate should be further investigated.

Adult↗
PubMed1991

Adsorption and preparation of human viruses using hydroxyapatite column.

The adsorption and chromatographic properties of hydroxyapatite sorbents for application to different viruses have been investigated. The strong adsorption of viruses was observed on macroporous hydroxyapatite with hydrophilic properties of the sorbent surface. The viruses were purified on this sorbent without loss of biological activity. The column can be used for virus vaccine production.

Adsorption↗
PubMed1991

[Histological and mechanical observations of interconnection between sintered porous hydroxyapatite and Achilles tendon in rats].

Sintered porous hydroxyapatite blocks (3 x 3 x 4 and 5 x 5 x 5) were implanted into the calcaneal tendons of 64 Wistar rats to observe tissue reaction and interconnection. Histological observations and measurements of mechanical strength of the interconnection were performed at 1 to 24 weeks after the implantation surgery. The implants were found to be surrounded by connective tissue consisting of small, round cells which infiltrated into micropores of the hydroxyapatite blocks. Neither calcifications nor inflammatory reactions were observed. The mechanical strength at the interconnection increased significantly from 1 week to 8 weeks after the implantation, which then reached the peak of 1.3 +/- 0.3 kg/cm2 at 8 weeks.

Achilles Tendon↗
PubMed1991

[Experimental study on hydroxyapatite soaked in sodium fluoride--with special reference to bone formation].

An experimental comparative study on bone formation regarding surface implantation was performed on thirty three adult mongrel dogs; using either a hydroxyapatite soaked in sodium fluoride (F-HAP) or a hydroxyapatite (HAP). F-HAP was made as follows: the HAP was soaked in 100ml of sodium fluoride solution of 5ppm., 10ppm. and 100ppm. concentration for an hour under vacuum deaeration+. Under general anesthesia, specimens were implanted into the bone immediately inferior to tibial tubercle by opening a window using a 3.5mm drill. Postoperative course was observed periodically (radiologically, macroscopically and histopathologically) from one to twelve weeks. There were no marked differences on X-rays or macroscopic findings between HAP and F-HAP. Histopathologically, there was significant new bone formation in the F-HAP specimens up until four weeks postoperatively. The 5ppm specimen especially indicated the most significant bone formation. The results of this study suggested that F-HAP was a better biomaterial (concerning new bone formation on the implant's surface) and that 5ppm was at optimal concentration for early new bone formation.

Animals↗
PubMed1991

[Histological comparison of the effect of different implanted hydroxyapatites in the animal periodontium].

The effect of various types of synthetic hydroxyapatites (HA), coated or not with collagen or human plasmatic fibrin, has been studied after 3 month implantation either in freshly extracted alveoli in miniature pigs or in experimentally induced periodontal lesions in beagle dogs. The best histological results were observed in HA without organic coating. The Bioapatite consisting in crystals with a mean size of 146 nm +/- 47 nm were well integrated in the alveolar bone. Similar results were obtained with micro-sized hydroxyapatite, with a mean crystal size of 38 nm +/- 16 nm. But at 3 months, this HA type was still actively integrated in bone with osteogenesis. When these 2 types of HA were coated with collagen or plasmatic fibrin, they were less well incorporated in alveolar bone and were even able to develop localized and moderate inflammatory reactions. The main purpose of synthetic HA is to promote alveolar bone formation in periodontal lesions. For an improved tissular regeneration, it is recommended to use simultaneously in the future synthetic HA together with resorbable biocompatible synthetic membranes.

Alveolar Bone Loss↗
PubMed1990

Use of a prefabricated splint for segmental augmentation of the mandibular alveolar ridge with hydroxyapatite.

Hydroxyapatite is a biocompatible material for augmentation of edentulous ridges to improve patient comfort and denture stability. The problems associated with hydroxyapatite are generally related to the amount of material introduced and the site of implantation. This article describes the use of a prefabricated splint that permits localization of the implant material to selected sites of the mandible and restricts the amount of material used. Fabrication of this splint under the guidance of the prosthodontist and oral surgeon permits the most effective use of this technique.

Acrylic Resins↗
PubMed1990

[Experimental development of a chitosan-bonded hydroxyapatite bone filling paste].

Chitosan, a naturally occurring high molecule or weight polymer which is stable in vivo like collagen, has proved a useful biomaterial in applications such as suture thread and artificial skin. A hydroxyapatite bone-filling material was developed with chitosan sol as a binder. Measurements were made of the solubility of chitosan, and of the setting time, compressive strength, and pH value of the material. X-ray microanalysis and diffraction analysis of the material were also conducted. Chitosan is freely soluble in malic acid and succinic acid, but insoluble in citric acid and oxalic acid. The setting time of the bone-filling material tended to decrease with increase in the amounts of its CaO and ZnO components. The setting time increased with increasing ratio of sol to other (powdered) ingredients. The pH value decreased with increasing ratios of chitosan sol to the powdered ingredients. High pH values resulted from increases in both CaO and ZnO. The time between the preparation of the chitosan sol and the onset of kneading significantly affected the compressive strength of the material when set. The strength measured roughly 50% more for times between 90 and 150 minutes than for times shorter or longer than that range. Greater compressive strength was generally observed for increases in both CaO and ZnO. The results of the X-ray microanalysis of the hardened paste showed calcium crystals other than hydroxyapatite.

Bone and Bones↗
PubMed1990

The effect of synovial fluid and serum on the growth of calcium hydroxyapatite crystals.

The presence or absence of natural crystal growth inhibitors in joint tissues and fluids may be important in the pathogenesis of several arthropathies. Synovial fluid (SF) has therefore been examined for inhibitors of seeded hydroxyapatite growth rate (Vo) using a pH stat system. Pretreatment of seed crystals with SF reduced growth (Vo = 56 +/- 5, control 117 +/- 141 mol/base/min/g hydroxyapatite, p less than 0.001). Addition of small amounts of serum or SF to the growth medium caused a dose dependent growth inhibition (0.04% SF reduced Vo by 16%). Pretreatment with protease, but not hyaluronidase, abolished this activity and gel filtration localized it to the 55-80 kDa fraction. A macromolecular factor(s) with potent inhibitory activity has therefore been detected.

Arthritis, Rheumatoid↗
PubMed1990

Radiation-induced binding of DNA from irradiated mammalian cells to hydroxyapatite columns.

In experiments designed to measure radiation-induced DNA damage using the DNA unwinding-hydroxyapatite chromatography technique, we observed that under some experimental conditions a significant proportion of the test DNA became tightly bound to the hydroxyapatite (HA) and could not be released even with a high concentration of phosphate buffer. Approximately 5-10% of DNA from unirradiated cells binds to the HA. With increasing radiation doses in air, the fraction of bound DNA increases, reaching about 30% at about 35 Gy. The binding exhibits many of the characteristics of a radiation-induced cell lesion: the proportion of DNA retained by the HA is less when cells are irradiated under hypoxic conditions or in the presence of the thiol radioprotector dithiothreitol; and the binding decreases when an incubation period is allowed between irradiation and harvest of the cells for assay. Studies to determine the nature of the lesion responsible for the binding demonstrated that lesion production requires a component found in cells since no binding was observed with irradiated isolated DNA or nuclear matrix; the binding is not a result of the production of DNA-protein crosslinks; and the bound DNA is single-stranded, based on its sensitivity to nuclease S1. Because of the dose dependence of the binding of DNA to HA, the slopes of the dose-response curves for DNA damage determined with this assay depend on the method used to calculate the fraction of double-stranded DNA. Our demonstration that the bound DNA is single-stranded guides the choice of the method for data analysis.

Animals↗
PubMed1990

Microstructure and mechanical properties of hydroxyapatite ceramics with zirconia dispersion prepared by post-sintering.

Hydroxyapatite ceramics with zirconia dispersion from fine powders synthesized hydrothermally were post-sintered at 1000-1300 degrees C under 200 MPa of argon for 1 h without capsules, after normal sintering in air at 1200 degrees C for 3 h. Densification was most significant with post-sintering at 1200 degrees C. Fracture toughness, Vickers hardness and elastic properties of these materials were investigated. Post-sintering gave twice the K1c value of transparent pure hydroxyapatite ceramics. Vickers hardness and Young's modulus of the ceramics were increased by post-sintering.

Biocompatible Materials↗
PubMed1989

Crystal growth of fluoridated hydroxyapatites inhibited in the presence of gelatin.

Three types of fluoridated hydroxyapatites were synthesized in the presence of low concentrations of gelatin solution. The crystallinity of gelatin-free fluoridated hydroxyapatites increased at high degree of fluoridation, after it showed complex behavior at lower fluoride content. However, increasing of gelatin concentration in the solution, the crystallinity decreased, especially at high fluoride content. Chemical analysis and a- and c-axis dimensions showed no significant difference among those series, and gelatin contents in the precipitates were negligible when compared with the supplied amounts. These results suggest that gelatin may inhibit the crystal growth of fluoridated apatites only as a surrounding factor, overcoming the promoting action of fluoride.

Collagen↗
PubMed1989

[Development of a slow release system of anti-cancer drugs retained in calcium-hydroxyapatite ceramic].

A new type of anticancer material with sustained release by enclosure of cisplatin (CDDP) into porous calcium hydroxyapatite ceramic (CDDP-CHA) was developed. A slow release of anticancer drug from CDDP-CHA was confirmed in in vitro experiments. When this material was implanted into normal thigh muscle of mouse, a sustained release of CDDP was observed during over 8 weeks after implantation. The diffusion of drug into blood and other organs from the implanted site was very small. CDDP-CHA placed into the implanted tumor of mouse allowed a slow release and high drug level from the material in the tumor. The concentration of the drug in other organs such as liver and kidney was very low compared with that of the tumor. These results suggest that this material has an important role for cancer chemotherapy, particularly in bone tumors for the reasons of calcium hydroxyapatite ceramic carrier having a mechanical strength.

Animals↗
PubMed1989

Isolation and characterization of three non-mucinous human salivary proteins with affinity for hydroxyapatite.

The isolation and chemical analysis of three human salivary proteins is reported. Using cation-exchange, FPLC anion-exchange chromatography and gel filtration, three human salivary proteins with affinity for hydroxyapatite were isolated, having molecular weights of 60 kD, 20 kD and 14 kD, respectively. The 60 kD protein was identified as albumin, and the 14 kD protein as a member of the cystatin family. Isoelectric focusing of the 14 kD protein revealed a single band, having an isoelectric point (pl) of 4.7. The third protein, not described yet, is appearing as a 20 kD doublet on SDS-PAGE. Isoelectric focusing resolved the 20 kD protein into four bands having pl's of 4.8, 5.0, 5.2 and 5.4, respectively. All bands were recognized by monoclonal antibodies to the 20 kD protein indicating that these four protein bands share the same epitope. The 20 kD protein is a glycoprotein with a carbohydrate content of 13% and a molar ratio of Fuc: Man: Gal: GlcNAc: NeuAc = 3.4:2.6:2.9:4.0:0.4. All three proteins bind strongly to a hydroxyapatite-based HPHT column at pH 6.0. With increasing pH, the binding diminished, especially of the 14 kD protein.

Albumins↗
PubMed1989

[Aluminum deposition and Ca-hydroxyapatite formation in frontal cortex tissue of amyotrophic lateral sclerosis].

To investigate a possible participatory role of an environmental metals in a pathogenetic process of amyotrophic lateral sclerosis (ALS), elementary and structural analyses of calcified substance in frontal cortex (percental gyrus) tissues of ALS patients were conducted using particle-induced X-ray emission (PIXE) and X-ray diffraction methods, as compared with control subjects. In the results of PIXE analysis, aluminum (Al) and calcium (Ca) contents in the frontal cortex tissues of the ALS patients were significantly increased with a high calcium (Ca)/phosphorus (P) Ca-hydroxyapatite (Ca-HAp). Although the content of peak ratio, as compared with those of control subjects. Only the Al content in the ALS patients showed significantly negative correlations with age at onset and/or at death. X-ray diffraction patterns from the sample (ashed at low temperature) of the frontal cortex tissues of the ALS patients were very similar to those from a standard sample of Ca-hydroxyapatite (Ca-HAp). Although the content of Ca-HAp in the mixed sample of frontal cortex tissues from the ten control subjects were not detectable (less than 3ppm), those of the ALS patients were markedly high, i.e., 111ppm in the mixed sample of five young patients with age under 60 and 168ppm in that of five old patients with age over 60. These results strongly indicated that Al may induce a calcifying degeneration in the CNS tissue of ALS patients, consequently leading to Ca-HAp formation as the final chemical compound.

Adult↗
PubMed1989

[Biological evaluation of new hydroxyapatite endodontic cement in vivo. Histopathological and clinico-pathological observation].

Histopathological observations of vital human and monkey dental pulp were performed to evaluate biologically a new root canal filling material APC containing hydroxyapatite. Experimental materials were divided into the following 3 groups. Group 1. Direct application to pulp wound (monkey teeth), 30 and 90 days. Group 2. Direct application to pulp wound (human teeth), 8-477 days. days. Group 3. Root canal filling on pulp stump (human teeth), 7-461 days. After extraction, the experimental teeth were fixed, demineralized, dehydrated and embedded in celloidin, they were prepared as thin sections and submitted to hematoxylin-eosin staining. Light microscopic observations were then made of them. After fixing, some specimens were embedded in resin and prepared in ultra thin sections before being triple stained with tannic acid-ethanol uranium-lead. They were submitted to observation under a HITACHI H-600 transmission electron microscope (TEM). Element analysis was performed on some unstained sections by means of energy dispersive X-ray analysis with a Kevex 7000A. Results 1. Application of APC to monkey dental pulp had no inhibiting effects on the healing progressed, the formation of regeneration hard tissue was observed. APC is believed to be biocompatible with dental pulp tissues. 2. Of the total of 50 cases in which APC was applied to human dental pulp, by the end of the experiment, 42 had occurred no symptoms of any kind. Broked down further, this means 23 (92%) of 25 cases in Group 2 and 19 (76%) of 25 cases in Group 3. Of the 25 cases in Group 2, 24 (96%) were evaluated as clinically good, none (0%) as fair, and 1 (4%) as unsatisfactory. Of the 25 cases in Group 3, 22 (88%) were evaluated as clinically good, 2 (8%) as fair, and 1 (4%) as unsatisfactory. Histopathologically, various pathological findings occurred in both groups of experimental materials. In the early stage, hyperemia, hemorrhage, round-cell infiltration, suppurative inflammation, and resorption of dentin in chamber walls were observed. By the thirtieth postoperative day, pulp cicatrization, formation of new hard tissue, and apposition of dentin on chamber walls were observed. TEM investigation of round-cell infiltration, observed in both group, revealed incursions of hydroxyapatite and bismuth in the macrophages. The tendency for hard tissue newly generated has began on 73 days in Group 2 and on 32 days in Group 3. This finding was made somewhat earlier in Group 2. Thereafter, dental pulp continued in a healthy condition.(ABSTRACT TRUNCATED AT 400 WORDS)

Animals↗
PubMed1989

[Preserving alveolar bone with submucosal hydroxyapatite].

In this article the use of hydroxyapatite granules to prevent alveolar bone loss after extraction of teeth is described. Twenty-six alveoli were treated in the mandible and the maxilla. The used method resulted in a delayed healing of the wound and loss of a part of the implants. On the account of the results it is recommended to close the extraction wound completely when using hydroxyapatite granules and to limit the indication to the mandible.

Alveolar Ridge Augmentation↗