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PubMed2005

Strengthening of calcium phosphate cement by compounding calcium carbonate whiskers.

The purpose of this study was to investigate how aragonite (calcium carbonate) whiskers influenced the strengthening and carbonating of alpha-tricalcium phosphate (alpha-TCP) based calcium phosphate cement. Aragonite whiskers of 0.95 microm width with an aspect ratio of 6.6 were prepared. The cement powder, alpha-TCP containing 0-50 mass% aragonite whisker, was mixed with 0.6 mol/L NaH2PO4 solution and incubated at 37 degrees C and 100% relative humidity. Diametral tensile strength (DTS) value increased significantly when appropriate amount of aragonaite whiskers was added. For example, DTS value of set cement containing 20 mass% aragonite whisker was 5.8 +/- 0.5 MPa, whereas DTS value of set cement containing no whiskers was 1.3 +/- 0.2 MPa after 1-week incubation. SEM observation revealed that the shape of the whiskers and the densification of the structure could have contributed to the strengthening of the set cement. Moreover, FTIR spectra implied that a bone-like carbonated apatite was precipitated in the cement. The results obtained in the present study revealed that the shape as well as any slight dissolution of aragonite whiskers could contribute to improving the properties of a-TCP based calcium phosphate cement.

Apatites↗
PubMed2006

Modification of 4-META/MMA-TBB resin for safe debonding of orthodontic brackets--influence of the addition of degradable additives or fluoride compound.

The purpose of this study was to evaluate the performance of modified 4-META/MMA-TBB resin cements (Superbond C&B) in terms of debonding orthodontic brackets easily and safely from enamel without the loss of proper bracket bond strength. Poly (DL-lactide-co-glycolide) (PLGA), calcium fluoride (CaF2), or alpha-tricalcium phosphate (alpha-TCP) was added to the polymer powder of 4-META/MMA-TBB resin, and the shear bond strength of orthodontic brackets to human enamel using modified resins was measured before and after 10,000-cycle thermal cycling test between 5 degrees C and 55 degrees C. The modified resins tended to provide lower bond strength compared with the original 4-META/MMA-TBB resin. However, alpha-TCP- or CaF2-modified resin showed no significant differences in bond strength before and after thermal cycling. Moreover, there was a tendency of more residual resin remaining on the tooth surface after debonding, thereby suggesting a lower risk of enamel fracture. In conclusion, alpha-TCP- or CaF2-modified 4-META/MMA-TBB resin seemed to allow easy and safe debonding of orthodontic brackets without loss of proper bracket bond strength.

Acid Etching, Dental↗
PubMedDate not supplied

The relationship between home smoking bans and exposure to state tobacco control efforts and smoking behaviors.

PURPOSE: To examine the relationship between home smoking bans and adult smokers' exposure to the statewide California Tobacco Control Program (TCP) and their cigarette smoking behavior. DESIGN: Cross-sectional survey that was part of the statewide Independent Evaluation of the California Tobacco Control, Prevention and Education Program. SETTING: Random telephone interviews within 18 California counties. SUBJECTS: A representative sample of 1315 adult smokers, aged 25 years and older. MEASURES: The telephone survey included questions about smoking behavior, quitting smoking, exposure to tobacco control program components, home smoking rules, and attitudes related to tobacco use and environmental tobacco smoke (ETS). RESULTS: Smokers with a home smoking ban were twice as likely (OR = 2.29; 95% CI 1.22, 4.29) to have heard of TCP community programs and three times more likely (OR = 3.18; 95% CI 1.34, 7.57) to have seen and talked about the ETS media spot than smokers with no home smoking policy. Multivariate regression models indicated that having a home smoking ban was related to smoking fewer cigarettes per day and greater interest in quitting smoking compared with smokers with no smoking rules in the home (p < .05). CONCLUSIONS: These findings suggest that smokers reporting exposure to the California TCP were more likely to have restrictive home smoking policies and that more restrictive home smoking policies were associated with reduced smoking behavior.

Adult↗
PubMed2000

The impact of delivered dose errors on local control of irradiated advanced laryngeal cancer.

On the basis of 1,015 entrance and 863 exit dose in vivo measurements, 863 calculations of midline dose were done, and the average deviation and ranges of its value were estimated. Data of 710 advanced larynx cancers were reviewed in order to achieve dose-response relationship. Patients data were fitted directly to L-Q model using maximum likelihood estimation. In 16.5% of measurements the deviation of midline dose was larger than -5.2%. A steep dose response relationship for TCP was found. Considering -5.2% deviation of 2 Gy fraction and 72 Gy of total dose, the 17% (from 48 to 31%) decrease of TCP was found. It shows that deviations of delivered dose influence the tumor control probability and that after systematic error finding during fractionated radiotherapy the value of remaining fraction size and total dose should be modified to compensate the change of TCP.

Dose-Response Relationship, Radiation↗
PubMed2001

Analysis of calcium deposits in calcific periarthritis.

OBJECTIVE: To determine if hydroxyapatite (HAP), octacalcuim phosphate (OCP), or tricalcium phosphate (TCP) can be found in the calcium deposits in calcific periarthritis. METHODS: Thirty-six specimens from 34 patients who had acute inflammation and roentgenographically recognized calcification in soft tissue were analyzed. Twenty-three patients with calcific tendinitis in the shoulder and 11 with calcific periarthritis at other sites were included. We prepared 2 kinds of samples from each specimen; a dried sample (washed and dried calcific deposit), and a sample heated to 1,000 degrees C. All were analyzed by X-ray diffraction, Raman spectroscopy, infrared absorption spectroscopy, and X-ray fluorescence spectrometry for calcium and phosphorus molar ratio. Synthetic HAP was used as the control in each analysis. RESULTS: The X-ray diffraction patterns of all dried samples were similar to those of HAP and carbonate apatite. We found no diffraction patterns of OCP or TCP. However, an OH- group at 3570cm(-1) was observed with Raman spectroscopy for samples heated to 1,000 degrees C and synthetic HAP, but not for the dried samples. Infrared absorption spectroscopy also confirmed an OH- group for samples heated to 1,000 degrees C and synthetic HAP, and confirmed that dried samples contained carbonate. CONCLUSION: Calcium deposits are composed of carbonate apatite. HAP, OCP, and TCP were not identified in any deposits.

Adult↗
PubMed1998

[Osseointegration of 2 different types of calcium phosphate materials: ceramics and ionic cements].

UNLABELLED: Different kinds of calcium phosphate biomaterials can be used as bone substitutes. Ceramics are constituted by HA or TCP grains linked by grain boundaries. Their porosity depends on the powder characteristics and the sintering temperature. It can be very low with a pore size inferior to one micron. The setting of calcium phosphate hydraulic cements results from the precipitation of a calcium phosphate phase different from the one in suspension in the paste. The strength of the cement is given by the entanglement of the growing mineral crystals. Calcium phosphate hydraulic cements and ceramics have very different physico-chemical characteristics. We have studied the histological integration of both kinds of material. The first material was constituted by macroporous ceramics composed of 75% HA and 25% beta-TCP, the cement was made of beta-TCP grains dispersed in a DCPD matrix. The sequence of events which leads to the ceramic integration is always the same: a/ ingrowth of a loose connective tissue; b/ osteoblast differentiation from fibroblast-like cells of the connective tissue in close proximity to the implant surface; c/ osteoid synthesis at the ceramic surface toward the pore center; d/ remodeling of the immature bone and the ceramic itself. The cement is differently integrated. The osteoblasts differentiate at some distance from the implant and there is a trabeculae ingrowth toward the material. CONCLUSIONS: The early stages of both materials osteointegration are different. The integration is centrifugal for ceramics and centripetal for the cement.

Animals↗
PubMed1991

Bacterial adhesion to mucosal surfaces.

Bacteria utilize one or more of several mechanisms to adhere to mucosal surfaces. Members of the enterobacteriaceae and related bacteria typically elaborate adhesive filamentous appendages from their surfaces termed fimbriae (or pili). Vibrio cholerae expresses at least three types of these structures that are likely involved in various stages of colonizing the intestine. So far one of these, termed TCP for toxin coregulated pilus, has been shown to be essential for colonization and virulence in humans and in an infant mouse model. The major pilin subunit, TcpA, is a member of the type 4 pilin class, common to a number of diverse pathogenic bacteria. To understand how these pili function at the molecular level, a transposon mutagenesis was undertaken which identified at least a dozen genes involved in TCP biogenesis, function, and regulation. Despite this complexity, passive immunization of infant mice using polyclonal and monoclonal antibodies directed against TCP suggests that the adhesive moiety lies within the major pilin subunit itself, rather than as a minor pilus adhesin protein as in the case of the PAP and type 1 fimbriae of Escherichia coli. Pilin or peptides corresponding to the epitopes recognized by the monoclonal antibodies represent possible immunogens for improved cholera vaccines.

Animals↗
PubMed2002

Durability of the dual-cure resin cement/ceramic bond with different curing strategies.

PURPOSE: To evaluate the effects of different curing strategies on the durability of the dual-cure resin cement/ceramic bond. MATERIALS AND METHODS: Machinable ceramic blanks were cut into pairs of 3-mm-thick slices, which were then polished using wet 600-grit SiC paper. The slices were silanated using one of two ceramic priming systems: (1) Tokuso Ceramic Primer (TCP), and (2) K-etchant/Clearfil Liner Bond 2V Primer (LB2V)/Porcelain Bond Activator (PBA), and bonded with one of two dual-cure resin cements (Bistite II, Panavia F), to make four experimental groups. Each group was subjected to one of three curing strategies: (1) no light, (2) 20 s light exposure from one direction, and (3) 20 s light exposure from each of six directions. After 24 h water storage at 37 degrees C, 0.7-mm-thick slabs were produced by serially sectioning perpendicular to the bonded interface. Immediately thereafter, and after one and six weeks of water storage, two slabs were randomly selected and sliced into beams for the microtensile bond strength (microTBS) test. Data were evaluated using Kruskal-Wallis and Wilcoxon rank tests (p < 0.05), and failure modes determined using a laser-scanning confocal microscope. RESULTS: After priming with TCP, microTBS of Bistite II significantly increased over time when exposed to light, whereas the microTBS of the no-light group significantly decreased over time (p < 0.05). After priming with TCP, microTBS of Panavia F increased over time, and after 6 weeks water storage, there were no significant differences in microTBS between the no-light and light-exposed groups (p > 0.05). Increases in microTBS were associated with increases in the number of cohesive failures in resin cement. After phosphoric acid treatment, priming with LB2V/PBA, and light exposure, microTBS of Bistite II remained stable, whereas that of Panavia F significantly reduced over time (p < 0.05). The microTBS of no-light LB2V/PBA groups reduced significantly over time (p < 0.05). CONCLUSION: The durability of the dual-cure resin cement/ceramic bond depends upon the multicomponent ceramic primer and the amount of light received by the resin cement.

Acid Etching, Dental↗
PubMed2003

Histologic effect of pure-phase beta-tricalcium phosphate on bone regeneration in human artificial jawbone defects.

The effect of the pure-phase beta-tricalcium phosphate (beta-TCP) Cerasorb on bone regeneration was evaluated in hollow titanium cylinders implanted in the posterior jaws of five volunteers. Beta-TCP particles were inserted inside the cylinders and harvested 6 months after placement. The density of the newly formed bone inside the bone-growing chambers measured 27.84% +/- 24.67% in test and 17.90% +/- 4.28% in control subjects, without a statistically significant difference. Analysis of the histologic specimens revealed that the density of the regenerated bone was related to the density of the surrounding bone. The present study demonstrates the spontaneous healing of infrabony artificial defects, 2.5 mm diameter, in the jaw. The pure beta-TCP was resorbed simultaneously with new bone formation, without interference with the bone matrix formation.

Absorbable Implants↗
PubMed2003

The effects of sustained delivery of glucocorticoids on the adrenal gland of male rats.

The role of stress on the structural and functional capacity of multiple organs has not been well investigated. The objective of this investigation was to morphometrically evaluate the effect of sustained delivery of corticosteroids alone or in combination with selenomethionine (SE), by tricalcium phosphate (TCP) ceramic capsule, on the adrenals of adult male rats. Nine adult male rats were randomly divided into three equal groups. Control animals were not implanted, and thus served as the control group. Group I was implanted with TCP capsules loaded with 50-mg cortisol. Group II animals were also implanted with TCP capsules loaded with both 50-mg cortisol and selenomethionine, respectively. Surgical aseptic techniques performed following standard lab protocols. At the end of the experimental phase, the animals were euthanized and the adrenal glands were collected and weights were recorded. The retrieved adrenals were fixed, processed, embedded and sectioned (5 microns) following standard laboratory procedure. The sections were subjected to qualitative and quantitative evaluation using Image Pro Digital Analysis System. Data collected expressed in mean +/- SE and analyzed for statistical significance using analysis of variance. The results indicated that Group II animals had a significant increase in body weight compared to the control group. There was a slight increase in wet adrenal weights observed in the Group II animals compared to the control animals. Histopathological evaluation of the adrenal gland revealed a decreased in the zona fasciculata lengths in Group I, a slightly decrease in Group II, compared to the control group.

Adrenal Glands↗
PubMed2003

The role of sustained delivery of corticosterone alone or in combination with antioxidants on the cardiovascular system of adult female rats.

Corticosteroids are used in the treatment of anti-inflammatory diseases, and their side effects can result in hypertension as well as effects on the cardiovascular system. Recent studies have shown the beneficial effects of anti-oxidants to delay the progression of many diseases by eliminating free radical formation. Antioxidants, such as selenium, may have an affect on the cardiovascular systems. The safety and efficiency of these over-the-counter antioxidants have not been fully investigated in vivo. The objective of this study was to supplement, the adult female rats, with the sustained release of cortisol, selenomethionine, and in combination, to evaluate its effect on the cardiovascular and reproductive systems. A total of 16 animals were randomly divided into four equal groups. A total of four animals served as naive controls. Group I animals were supplemented with a TCP capsule containing 50 mg of cortisol. Animals in Group II were supplemented with a TCP capsule containing 50 mg of selenomethionine. Group III animals were supplemented with a TCP capsule containing a combination of 50 mg of cortisol and selenomethionine. Blood and body weights were recorded weekly and at the end of 24 days, hearts were collected and analyzed morphometrically. The results indicated a slight increase in the body weights of cortisol treated animals compared to the control, selenomethionine and combination treated animals. Significant increases were observed in the heart wet weights of cortisol and combination treated animals. Further analysis of the heart showed remarkable changes in the heart apex length in the cortisol treated animals. The results suggest that cortisol caused morphological changes in the heart that may be responsible for the change in the regulation and maintenance of the normal electrical activity of the heart.

Animals↗
PubMed1992

Controlled release of hydrophilic compounds by resorbable and biodegradable ceramic drug delivery devices.

Hydroxyapatite (HA), aluminum-calcium-phosphorous oxide (ALCAP), bone meal (BM), and tricalcium phosphate (TCP) ceramic implants are biodegradable and nontoxic to the host. The purpose of this study was to investigate the capability of these ceramics to deliver the catecholamine, epinephrine (EPI) in a sustained and controlled manner. The ceramic powder (less than 38 um particle size) was prepared in our laboratory using standard procedures. Sixteen cylinders were prepared (1 g each) from each of the four ceramic materials. All cylinders were pressed at a compression load of 615 Kg and sintered for 36 hours. ALCAP (group I) and BM (group II) cylinders were sintered at 1400 degrees C and HA (group III) and TCP (group IV) ceramic capsules were sintered at 1150 degrees C. Three capsules from each group were loaded with 30 mg EPI. Capsules containing EPI and control (empty) capsules were each suspended in a serum bottle containing 100 ml of phosphate buffered saline (pH 7.4). The amount of EPI released from each capsule was determined by spectrophotometric methods. Data collected from this study showed that the rate of release of EPI from ALCAP, HA, BM and TCP was 6.14 +/- 0.3 3.55 +/- 0.29, 2.07 +/- 0.26 and 1.17 +/- 0.04 mg/day, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)

Biodegradation, Environmental↗
PubMed1992

[Mechanical principles of L-trapezoid compression plate in the fixation of trochanter fractures].

Three pairs of human cadaver femur were used for simulation electric test with load on both legs and single leg. An Evans III osteotomy was made, and stabilized with L-trapezoid compression plate (L-TCP). L-angled plate (L-AP) 95 degrees and 130 degrees respectively. The results demonstrated that the stability of fixation of L-TCP was significantly greater than L-AP. Since the cancellous screw of L-TCP can hold the proximal fragment and forms a stable triangular truss with the L end, the bony support of the medial posterior part can be reconstructed by holding the lesser trochanter with the lag screw. From June 1980 to August 1990, 68 patients with 71 trochanter fractures and osteotomies were treated with L-CTP. 54 patients with 57 fractures and osteotomies were followed up for 6-52 months. All fractures and osteotomies were healed. No bone cutting off failure was encountered. The hips and knees of 51 patients (54 limbs) (94.8%) showed excellent and good functions. Infection occurred in 3 patients (4.4%). Varus deformity developed in 2 patients with an Evans IV fracture, and plate fracture occurred in one of them.

Aged↗
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↗
PubMed2003

[Transforming the sintered ostrich cancellous bone to multiphasic calcium phosphate ceramic].

OBJECTIVE: To transform the sintered ostrich cancellous bone(ostrich true bone ceramic, OTBC) to multiphasic calcium phosphate ceramic and study its components and characterization. METHODS: The OTBC blocks were soaked in different concentration of sodium pyrophosphate (Na(4)P(2)O(7).H(2)O,NP) solution and heated to 1100 degrees C to transform its constitution from HAP into multiphasic calcium phosphate ceramics. Then the surface configuration of the material was observed by SEM and the following properties of the material:porosity,bending strength,mineral composition and element ratio were analyzed. RESULTS: The prepared material was a kind of porous calcium phosphate ceramic composed of beta-TCP, HAP and NaCaPO(4). With increase of the NP concentration,the content of HAP decreased while beta-TCP and NaCaPO(4) increased. The average bending strength of the material was (1.95+/-0.46)Mpa,the Ca/P element ratio was 1.511 and the average porosity was(60.71+/-6.9)%. The pore size was uneven. CONCLUSION: The OTBC could be transformed into beta-TCP /HAP /NaCaPO(4) multiphasic calcium phosphate ceramic by heating with NP. With characteristic porous structure, the prepared OTBC could become a new type of bone graft.

Animals↗
PubMed2004

[Preparation and degradation of poly(DL-lactide)/calcium phosphates porous scaffolds].

The porous foams were prepared by the solvent-casting and particulate-leaching technique using poly(DL-lactide) (PDLLA), poly(DL-lactide)/hydroxyapatite (PDLLA/20wt%HA), and poly(DL-lactide)/beta-tricalcium phosphate(PDLLA/20wt% beta-TCP) respectively. Observations by scanning electron microscopy indicated that the HA and beta-TCP were homogeneously dispersed in the polymer matrix, and the pores of the foams are interconnected, resulting in continuous pore structures. The porosity of PDLLA/HA and PDLLA/beta-TCP foams was lower than that of the pure PDLLA foams, but the compression strength was higher than that of the pure PDLLA foams. The results of the degradation in vitro showed that both HA and beta-TCP had significant inhibitory effects on the degradation of PDLLA, especially the HA. It is expected that the composite foams are of use as scaffolds for bone tissue engineering.

Biocompatible Materials↗
PubMed2004

The first experience with minimally invasive phlebectomy using the TriVex system.

Presented herein is the first experience gained in Russia with endoscopic transillumination phlebectomy (ETP). The aim of the study was to evaluate the clinical effectiveness and advantages of ETP versus traditional combined phlebectomy (TCP). Altogether 94 patients with different forms of lower extremity varicosis were operated on. Before operation the patients underwent Doppler ultrasound and duplex scanning. The main group included 47 patients who were operated on by ETP. The control group comprised 47 patients provided TCP. The ETP technique is based on hydraulic dissection of varicose veins which is attained by injection of a special solution under a pressure of 400-500 mm Hg, using an illumination irrigator inserted to subcutis via 2-3 mm punctures. Besides ETP is based on the effect of transillumination allowing to determine not only a precise location of varicose veins but also to control their drastic ablation by means of a special resector. To compare the above-indicated two techniques, the following parameters were studied: the time of operation, the number of incisions, the intensity of postoperative painful syndrome and the cosmetic effect according to the analog scales. The results obtained have shown that the use of ETP considerably decreased the time of operation; there was a substantial lowering of the number of incisions and punctures due to which the duration of postoperative painful syndrome decreased. Since the operation is performed via minipunctures which are closed by surgical plaster, an excellent cosmetic result is obtained. The first experience with ETP has demonstrated that this technique compares very favourably with TCP. The labor intensity of operation is minimized. Permanent visual control over vein extraction during operation makes it possible to appreciably raise the radicalness of intervention. The possibility of performing operation via minipunctures guarantees a more uneventful postoperative course and an excellent cosmetic result. So, ETP is a modern promising and a minimally invasive method for the treatment of varicose veins of the lower extremities. It requires extensive application with referral to one-day hospital.

Adult↗
PubMed1992

Design of an irreversible affinity ligand for the phencyclidine recognition site on N-methyl-D-aspartate-type glutamate receptors.

A series of 1-[1-(2-thienyl)cyclohexyl]piperidine (TCP) analogs were synthesized with the aim of developing a potent ligand for the N-methyl-D-aspartate glutamate receptor subtype. The piperidine moiety of TCP was substituted at the nitrogen position with aliphatic chains of different length or with various polar groups. A correlation between the decrease in the potency of displacement of [3H](+)-5-methyl-10,11-dihydro-5H-dibenzo-[a,d]cyclohepten-5,10-im ine maleate (MK-801) binding from bovine cortex membranes and the increase of length or polarity of the aliphatic chain was observed. Isonitrile, isothiocyanate and isoselenocyanate groups were substituted at position 4 of the thiophene ring, and the relative binding affinity and alkylating potencies of the derivatized compounds were studied. Among this set of compounds, the one carrying an isothiocyanate group at position 4 of the thiophene ring of the N-ethyl analog of TCP yielded the most efficient alkylating agent, demonstrated by its ability to irreversibly block up to 80% of the [3H]MK-801 binding sites. This affinity ligand did not significantly affect other ligand binding sites of the same N-methyl-D-aspartate receptor complex or of other receptor systems, further demonstrating its functional specificity as a potent alkylating probe for the TCP/MK-801 recognition site. Studies with a radiolabeled adduct of this isothiocyanate N-ethyl derivative, however, indicate that a substantial level of nonspecific covalent incorporation into the membranes occurs at concentrations as low as 10 nM, thereby obscuring any possibility of detecting a specifically labeled protein species.

Affinity Labels↗