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1.
J Laryngol Otol ; 127(4): 364-7, 2013 Apr.
Article in English | MEDLINE | ID: mdl-23480558

ABSTRACT

BACKGROUND: Chronic sinusitis is the most common routine presentation for a general ENT surgeon. The 2007 'Primary Care Guidelines: European Position Paper on the Primary Care Diagnosis and Management of Rhinosinusitis and Nasal Polyps' aimed to deliver evidence-based guidelines for the diagnosis and management of rhinosinusitis in specialist and primary care. OBJECTIVE: The aim of this audit was to assess the information provided in the referral letters to the ENT department regarding patients with potential rhinosinusitis, and compare this to the information required for the rhinology care pathways. METHOD: We evaluated one month of referrals to the ENT department. RESULTS: The quality of information in the referral letters was poor. Only 22 per cent of patient referrals included basic information about symptoms, duration and treatment. CONCLUSION: We plan to investigate why general practitioners are not complying with the pathway. In addition, the pathways will be more widely disseminated via the 'Map of Medicine' (an online resource for general practitioners). This should facilitate the receipt of the best evidence-based treatment for patients prior to referral to secondary care.


Subject(s)
Evidence-Based Practice/standards , General Practitioners/organization & administration , Referral and Consultation , Rhinitis/therapy , Sinusitis/therapy , Adolescent , Adult , Aged , Child , Female , General Practitioners/education , General Practitioners/standards , Humans , Male , Middle Aged , Practice Guidelines as Topic , Primary Health Care/organization & administration , Primary Health Care/standards , Referral and Consultation/standards , Young Adult
2.
Rhinology ; 51(1): 88-92, 2013 Mar.
Article in English | MEDLINE | ID: mdl-23441316

ABSTRACT

BACKGROUND: Extracorporeal septorhinoplasty (ECS) presents an important option in the surgical correction of the markedly deformed and twisted nose. However, there is a paucity of literature on the qualitative outcomes of ECS. METHODOLOGY: Retrospective telephone and postal questionnaire study of operations performed over 2 years (2008-2009) under the care of a senior rhinologist at two linked hospitals in the United Kingdom. Questionnaires were designed (i) relating to the procedure and (ii) patient perceptions of surgical success, improvements in physical health, psychosocial functioning and social interactions. For succinctness a shortened version of the Glasgow Benefit Inventory was used. RESULTS: Forty-six cases were analysed eight of which were revision cases. Two cases required revision surgery and two minor complications occurred, managed conservatively. The patients had a minimum of two to three follow-ups from seven days to one year. Questionnaire scores suggested high satisfaction in response to surgical success, with notable improvements in physical health (sleep disturbance) and in general health and well-being. Regarding psychosocial functions patients reported feeling either moderately less self-conscious or not self-conscious at all post-surgery. Improvements in social interactions were less well-defined. CONCLUSION: In this audit of cases with significant deformities, ECS appears to confer high levels of satisfaction.


Subject(s)
Nasal Septum/surgery , Outcome Assessment, Health Care , Patient Satisfaction , Rhinoplasty/methods , Female , Humans , Male , Postoperative Complications , Reoperation , Retrospective Studies , Surveys and Questionnaires , United Kingdom
3.
Med Teach ; 33(6): 491-3, 2011.
Article in English | MEDLINE | ID: mdl-21355703

ABSTRACT

PURPOSE: A personal account of learning about leadership. This article introduces the theory of power and influence, and aimed to report especially the personal reflection, emotional intelligence and learning about oneself that occurred on the way. APPROACH: Reading, group discussion and active reflection. Thoughts, reflections and learning were recorded regularly. PRACTICAL IMPLICATIONS: The concept of leadership, influence tactics and emotional intelligence all have implications in workplace relationship management and ultimately leadership qualities. The issues discussed serves as food for thought for others. ORIGINALITY: This is a genuine and very personal learning experience.


Subject(s)
Attitude of Health Personnel , Learning , Physicians/psychology , Self Concept , Emotional Intelligence , Humans , Leadership , Power, Psychological
4.
J Laryngol Otol ; 124(11): 1158-61, 2010 Nov.
Article in English | MEDLINE | ID: mdl-20441675

ABSTRACT

AIM: Meningitis is the commonest intracranial complication of suppurative otitis media, and carries the risk of death and life-changing morbidity. This study aimed to estimate the risk of an adult in the UK developing otogenic meningitis. METHODS: Adults hospitalised with meningitis in Bristol from 1997 to 2002 were identified retrospectively. Cases confirmed by positive blood culture or cerebrospinal fluid investigation were studied. A case was classified as otogenic if there was coexistent evidence of ear infection. RESULTS: Eighty-seven cases of meningitis were analysed. The overall mortality rate was 5.7 per cent. Acute and chronic suppurative otitis media accounted for 13 and three cases, respectively. The adult population of Bristol at the midpoint of the study was 635,976. CONCLUSION: In this study, the age-adjusted incidence of otogenic meningitis was 0.42 per 100,000 per year.


Subject(s)
Meningitis, Bacterial/epidemiology , Otitis Media, Suppurative/complications , Acute Disease , Adolescent , Adult , Aged , Aged, 80 and over , Child , Chronic Disease , Hospitalization/statistics & numerical data , Humans , Incidence , Meningitis, Bacterial/cerebrospinal fluid , Meningitis, Bacterial/etiology , Meningitis, Bacterial/mortality , Middle Aged , Primary Health Care , Risk Assessment , United Kingdom/epidemiology , Young Adult
5.
J Med Eng Technol ; 33(8): 628-33, 2009.
Article in English | MEDLINE | ID: mdl-19848856

ABSTRACT

This study aims to investigate arterial stiffness in selected young adults by non-invasively determining the characteristics of the photoplethysmographic dicrotic notch. A total of 15 volunteers participated in this study, divided into four groups by age and gender. Contour analysis was applied to analyse the photoplethysmographic dicrotic notch, including time-related and height-related parameters. The height of reflected wave, mirrored by the notch relative amplitude (NRA), was found to be significantly larger in the older group compared to the younger group (p = 0.016). The timing of the reflected wave, measured by three parameters, i.e. notch index (NI), notch latency (NL) and peak-to-notch latency (PTNL), significantly increased in the female group compared to the male group (all p < 0.02). The results confirm that arterial stiffness occurs in young adults, and demonstrate that a difference of arterial stiffness exists between young male and female. This study indicates that examining the characteristic notch of the PPG pulse could help in identifying differences of vascular activities.


Subject(s)
Arteries/physiology , Elasticity/physiology , Photoplethysmography/statistics & numerical data , Adult , Age Factors , Biomedical Engineering , Cardiovascular Diseases/etiology , Female , Fingers/blood supply , Humans , Male , Pulsatile Flow/physiology , Pulse , Risk Factors , Signal Processing, Computer-Assisted , Young Adult
6.
Surgeon ; 7(6): 340-4, 2009 Dec.
Article in English | MEDLINE | ID: mdl-20681376

ABSTRACT

BACKGROUND: There has been a plethora of new job titles emerging in the NHS. While the term 'nurse practitioner' was fairly well received, and offers a pretty clear indication of the background of the person working, other new titles can be misleading. Since 2003, when the NHS Modernisation Agency proposed its 'Changing Workforce Programme', nurses and other allied health professionals were recruited and trained to perform 'simple operations'. The surgical care practitioner is being developed along with other practitioners. OBJECTIVE: To find out whether patients are able to identify healthcare professionals by their title and what do patients think about a non-medically qualified person carrying out their operations. METHODS: A cross-sectional survey of ENT patients using a questionnaire. MAIN FINDINGS: Titles similar to those of medically qualified professionals--anaesthetic practitioner, consultant nurse and surgical care practitioners--can lead patients to think that they are doctors. Fifty-three per cent of the respondents agreed that not all hospital visits need to be attended by a doctor, but if an operation is needed, 92% of respondents thought it should be carried out by someone who is medically trained. Ninety-four per cent stated that they should be informed if this is not the case. Seventy-nine per cent of the respondents stated that they would rather wait longer to be operated on by a doctor than being operated on earlier by someone who is not medically qualified but trained to perform the operation only. This result is significant, p<0.001). CONCLUSION: Patients do find the different titles confusing, with many preferring a more transparent approach in knowing who their surgeon is. The majority would prefer to wait longer for their operation if this means it is carried out by a doctor.


Subject(s)
Clinical Competence , General Surgery/standards , Physician Assistants , Terminology as Topic , Adolescent , Adult , Aged , Aged, 80 and over , Cross-Sectional Studies , Female , Humans , Male , Middle Aged , Patient Care Team/standards , Patient Satisfaction , Physician Assistants/standards , Physician Assistants/statistics & numerical data , State Medicine/organization & administration , State Medicine/standards , United Kingdom , Young Adult
7.
Cancer Gene Ther ; 15(9): 553-62, 2008 Sep.
Article in English | MEDLINE | ID: mdl-18535622

ABSTRACT

Human bone marrow-derived mesenchymal stem cells (BM-hMSCs) are nonhematopoietic stem cells that have the potential to differentiate into adipocytes, osteocytes and chondrocytes. Because of its propensity to migrate to the sites of injury and the ability to expand them rapidly, BM-hMSCs have been exploited as potential gene transfer vehicles to deliver therapeutic genes. Herein, we evaluated the feasibility of employing herpes simplex virus type I (HSV-1) amplicon viral vector as a gene delivery vector to BM-hMSCs. High transduction efficiencies were consistently observed in different isolates of BM-hMSCs following infection with HSV-1 amplicon viral vectors. Furthermore, we demonstrated that transduction with HSV-1 amplicon viral vector did not alter the intrinsic properties of the BM-hMSCs. The morphology and cellular proliferation of the transduced BM-hMSCs were not altered. Chromosomal stability, as confirmed by karyotyping and soft agar colony assays, of the transduced BM-hMSCs was not affected. Similarly, transduction with HSV-1 amplicon viral vectors has no effect on the pluripotent differentiation potential and the tumor tropism of BM-hMSCs. Taken together, these results demonstrated that BM-hMSCs could be transduced efficiently by HSV-1 amplicon viral vector in an 'inert' manner and thus enable strategies to express potential therapeutic genes in BM-hMSCs.


Subject(s)
Bone Marrow Cells , Gene Transfer Techniques , Genetic Vectors , Herpesvirus 1, Human/genetics , Mesenchymal Stem Cells , Bone Marrow Cells/cytology , Cell Differentiation , Cell Line, Tumor , Cell Lineage , Cells, Cultured , Genetic Therapy/methods , Humans , Karyotyping , Mesenchymal Stem Cells/cytology , Transduction, Genetic
9.
J Laryngol Otol ; 122(10): 1042-6, 2008 Oct.
Article in English | MEDLINE | ID: mdl-18346290

ABSTRACT

OBJECTIVE: To compare hearing results in patients undergoing myringostapediopexy or myringolenticulopexy in canal wall down mastoidectomy. STUDY DESIGN: Case series of one surgeon. A retrospective review of 83 consecutive mastoid cavity operations for primary cholesteatoma. Only those patients who had undergone either myringostapediopexy or myringolenticulopexy were included. SETTING: District general hospital. PATIENTS: Forty-two procedures were performed in 40 patients. The mean age was 42 years old. The average follow up was 5.9 years. INTERVENTION: Seventeen patients underwent myringolenticulopexy (the incus head was excised, leaving the lenticular process attached to the stapes prior to graft placement) and 25 underwent myringostapediopexy (type III tympanoplasty). MAIN OUTCOME MEASURES: Audiometry three to six months after surgery, and status of mastoid cavity after a minimum follow up of one year. RESULTS: Comparison of post-operative hearing results for the two groups showed a statistically significant hearing advantage for myringolenticulopexy (p = 0.029). In the myringolenticulopexy group, 92 per cent achieved a post-operative air-bone gap of less than 30 dB, compared with 62 per cent in the myringostapediopexy group. The mean post-operative air-bone gaps in the two groups were 17.5 and 24.7 dB, respectively. CONCLUSION: When surgically feasible, the technique of myringolenticulopexy is a useful method of preserving serviceable hearing in single-stage mastoid cavity surgery.


Subject(s)
Cholesteatoma, Middle Ear/surgery , Incus/surgery , Mastoid/surgery , Myringoplasty/methods , Adult , Audiometry , Cholesteatoma, Middle Ear/pathology , Female , Hearing , Humans , Male , Middle Aged , Retrospective Studies , Treatment Outcome
11.
J R Soc Interface ; 5(21): 427-39, 2008 Apr 06.
Article in English | MEDLINE | ID: mdl-17698476

ABSTRACT

The synthesis and subsequent assembly of nearly spherical nano-hydroxyapatite (nHA) particles in the presence of trace amounts of the polysaccharide chitosan was carried out employing a wet chemical approach. Chitosan addition during synthesis not only modulated HA crystallization but also aided in the assembly of nHA particles onto itself. Solvent extraction from these suspensions formed iridescent films, of which the bottom few layers were rich in self-assembled nHA particle arrays. The cross-section of these hybrid films revealed compositional and hence structural grading of the two phases and exhibited a unique morphology in which assembled nHA particles gradually gave way to chitosan-rich top layers. Transmission electron microscope and selected area electron diffraction studies suggested that the basal plane of HA had interacted with chitosan, and scanning electron microscope studies of the hybrid films revealed multi-length scale hierarchical architecture composed of HA and chitosan. Phase identification was carried out by X-ray diffraction (XRD) and Rietveld analysis of digitized XRD data showed that the basic apatite structure was preserved, but chitosan inclusion induced subtle changes to the HA unit cell. The refinement of crystallite shape using the Popa method clearly indicated a distinct change in the growth direction of HA crystallites from [001] to [100] with increasing chitosan concentration. The paper also discusses the likelihood of chitosan phosphorylation during synthesis, which we believe to be a pathway, by which chitosan molecules chemically interact with calcium phosphate precursor compounds and orchestrate the crystallization of nHA particles. Additionally, the paper suggests several interesting biomedical applications for graded nHA-chitosan nanostructured films.


Subject(s)
Chitosan/chemistry , Durapatite/chemistry , Nanostructures/chemistry , Crystallization , Membranes, Artificial , Nanostructures/ultrastructure
13.
J Laryngol Otol ; 121(12): 1129-34, 2007 Dec.
Article in English | MEDLINE | ID: mdl-17708777

ABSTRACT

BACKGROUND: Secondary or referred otalgia can represent a diagnostic challenge to the otolaryngologist. Collectively, dental disorders are the most common causes of secondary otalgia presenting to the ENT clinic, and may account for up to 50 per cent of referred otalgia. Temporomandibular joint dysfunction syndrome represents the most common dental cause of referred otalgia. Decay and pulpal inflammation of posterior teeth can also frequently present as otalgia. The common embryological developmental origin of both oral and dental structures and the ear is responsible for their overlapping sensory nerve supplies, and this explains referred otalgia secondary to dental and temporomandibular joint disorders. These disorders can be easily overlooked, resulting in unnecessary and costly investigations. AIMS: This review aims to give a succinct overview of common dental causes of otalgia, and to provide ENT clinicians with guidelines for performing a rapid and simple dental and temporomandibular joint examination, which will reliably diagnose or exclude dental otalgia.


Subject(s)
Earache/etiology , Mouth Diseases/complications , Pain, Referred/etiology , Temporomandibular Joint Dysfunction Syndrome/complications , Humans , Mouth Diseases/diagnosis , Periodontitis/complications , Periodontitis/diagnosis , Temporomandibular Joint Dysfunction Syndrome/diagnosis , Tooth Diseases/complications , Tooth Diseases/diagnosis
14.
Gene Ther ; 14(10): 828-35, 2007 May.
Article in English | MEDLINE | ID: mdl-17344903

ABSTRACT

We have compared the ability of several nanosized bioceramic particles including negatively charged silica (SiO(2)), neutrally charged hydroxyapatite (HA) and positively charged zirconia (ZrO(2)) nanoparticles as non-viral vectors for efficient in vivo gene delivery. A mixture of highly monodispersed aqueous suspension of HA or SiO(2) nanoparticles, coated with protamine sulfate (PS), complexed efficiently with plasmid DNA and significantly enhanced transgene expression in vitro. In comparison, ZrO(2) nanoparticles gave poor transfection efficiency under similar conditions tested. It was also determined that, under the same conditions, PS-SiO(2)-DNA, but not PS-HA-DNA-nanoplexes, were able to mediate efficient transgene expression in vitro in the presence of 50% serum. Intraperitoneal injections of PS-SiO(2)-luciferase DNA nanoplexes targeted the highest level of transgene expression in the spleen of recipient mice that lasted for more than 48 h. Injection of PS-SiO(2)-pNGVL-hFLex-MUC-1 nanoplexes was able to mediate the production of Flt-3L in the sera of recipient mice. Simultaneously, the production of Flt-3L was accompanied by the stimulation of IL-2 and interferon-gamma (IFN-gamma). Most importantly, the injection of PS-SiO(2)-pNGVL-hFLex-MUC-1 nanoplexes could mount potent anti-tumour specific immune responses that led to the subsequent regression of parental tumor cells containing the muc-1 determinant.


Subject(s)
Genetic Therapy/methods , Nanoparticles , Neoplasms/therapy , Spleen/metabolism , Transfection/methods , Animals , Biocompatible Materials , Cell Line, Tumor , Female , Gene Expression , Humans , Interferon-gamma/blood , Interleukin-2/blood , Liposomes , Luciferases/genetics , Melanoma, Experimental , Membrane Proteins/blood , Mice , Mice, Inbred BALB C , Microscopy, Confocal , Microscopy, Electron , Neoplasms/immunology , Neoplasms/metabolism
15.
J Biomed Mater Res A ; 82(2): 296-303, 2007 Aug.
Article in English | MEDLINE | ID: mdl-17274029

ABSTRACT

This study aimed to fabricate bulk nanostructured hydroxyapatite (HA) pellets with improved properties using spark plasma sintering (SPS) for orthopedic applications. Spray-dried nanostructured HA (nSD-HA) powders were consolidated using the rapid SPS processing. The SPS processed nSD-HA was characterized using Raman spectroscopy and field emission scanning electron microscopy (FESEM). Mechanical properties of the consolidates were also evaluated through indentation approach. The nanostructures ( approximately 80 nm in grain size) of the starting powders were successfully retained after the SPS processing operated at 950 degrees C with <15 min holding time. The SPS consolidated nSD-HA showed promising mechanical properties, approximately 118 GPa for Young's modulus, and up to 2.22 MPa m(0.5) for fracture toughness. SPS holding time showed minor influence on the phases of the pellets. Furthermore, the spheroidized nanostructured HA retained the HA structure after the SPS consolidation. Preliminary cytotoxicity and cell attachment studies were also carried out using a human osteoblast cell line hFOB 1.19. Enhanced cell attachment and proliferation on the nanostructured pellets were revealed. The presence of the nanostructures accounts mainly for the enhanced mechanical properties and promoted proliferation of the osteoblast cells. This study suggests that the SPS technique is an appropriate process for fabrication of bulk nSD-HA from nanostructured powder.


Subject(s)
Biocompatible Materials/pharmacology , Durapatite/pharmacology , Osteoblasts/cytology , Osteoblasts/drug effects , Biocompatible Materials/chemistry , Biomechanical Phenomena , Cell Line , Durapatite/chemistry , Humans , Materials Testing , Microscopy, Electron, Scanning , Nanostructures/ultrastructure , Nanotechnology , Powder Diffraction
16.
J Phys Chem B ; 110(48): 24457-62, 2006 Dec 07.
Article in English | MEDLINE | ID: mdl-17134201

ABSTRACT

Conductometry was employed to study the phase evolution of calcium phosphate compounds during the wet-chemical synthesis of hydroxyapatite (HA). Calcium hydroxide and orthophosphoric acid were used to prepare HA at various temperatures ranging from 30 to 95 degrees C. The electrical conductivity and pH of the reaction mixture were measured at regular intervals of time during acid addition, and the rate of change of conductivity was used to decipher the end point of the reaction. Our previous studies have shown that the end product of this reaction route yields mildly carbonated crystalline HA. The trend of the change in conductivity with time was similar at all temperatures. The conductivity curves were divided into three regions based on the variation in slope of the curves. The slope of the curves decreased with increasing temperatures in the first two regions, and the slope is greater in the second region than in the first. From the conductivity and pH measurement results, the possible precursor phase was identified and it had the composition Ca(3)(PO(4))(2). The kinetics of phase transformation was also analyzed and compared to previous work. The similarities between this work and the traditionally adapted experimental work for phase formation and transformation kinetics are highlighted, and the novelty in the current work is discussed.


Subject(s)
Durapatite/chemical synthesis , Nanostructures/chemistry , Acids/chemistry , Crystallization , Durapatite/chemistry , Hydrogen-Ion Concentration , Ions/chemistry , Solubility , Suspensions , Temperature
17.
Langmuir ; 22(26): 11002-8, 2006 Dec 19.
Article in English | MEDLINE | ID: mdl-17154577

ABSTRACT

Two differing wet-chemical synthesis routes, Ca(OH)2 + H3PO4 and CaCl2 + Na3PO4/NaOH, were used to prepare hydroxyapatite (HA) at various temperatures ranging from 30 to 95 degrees C. The electrical conductivity of the solution was measured at regular intervals of time during H3PO4 and Na3PO4 addition to the suspension/solution containing Ca2+ ions. The rate of change of conductivity is used to note the end point of the reaction. X-ray diffraction of the dried, precipitated particles revealed HA as the predominant phase, and the FTIR spectroscopy studies indicated the presence of CO3(2-) groups which substituted PO4(3-) groups in the HA lattice (B-type). FESEM observations revealed that the aspect ratio of the particles decreased with increasing precipitation reaction temperature in one system [Ca(OH)2 + H3PO4] and in the other system it increased with increasing temperature. The changes in the morphology with temperature were analyzed through conductivity measurements and the thermochemical properties of the reaction systems. Conductivity measurements showed that the concentration of dissolved ions at the end point of the reaction between Ca(OH)2 and H3PO4 increased, indicating an increased apparent solubility of HA with increasing temperature, whereas the end-point conductivity did not increase noticeably in the other reaction system.


Subject(s)
Durapatite/chemistry , Nanostructures/chemistry , Chemical Precipitation , Crystallization , Durapatite/chemical synthesis , Materials Testing , Nanostructures/ultrastructure , Solubility , Spectroscopy, Fourier Transform Infrared/methods , Temperature , X-Ray Diffraction/methods
18.
Langmuir ; 22(1): 269-76, 2006 Jan 03.
Article in English | MEDLINE | ID: mdl-16378431

ABSTRACT

Derived from reaction kinetics, a simple but useful method, based on "apatite forming capacity" or AFC of solutions mimicking blood plasma, is proposed to decipher the rate of calcium phosphate mineralization. Apatite growth rate constants were calculated using this method for a model composite surface varying the volume fraction of synthetic hydroxyapatite (HA) in a polymer matrix. Previously reported data for mineralized surfaces on Ta, Ti, and its alloys are also analyzed similarly and compared. Utilizing the growth rate constant, the bioactivity of the materials was indexed in vitro. Complementarily, semiempirical quantum mechanical calculation (ZINDO method) showed that the interaction of cations with TRIS-hydroxymethyl aminomethane molecules in the solution is stronger than that with the polymer substrate considered, but weaker than hydrated Ti and TiO(2) surfaces. This analysis then quantifies for example the extent of polymer inertness and the "bioactivity" of alkali treated Ti. The growth rate constants for the model materials prepared in this work are explained on the basis of localized dissolution of HA, the amount of which simply increases with increasing volume fraction of HA in the composite.


Subject(s)
Apatites/chemistry , Biocompatible Materials/chemistry , Body Fluids/chemistry , Coated Materials, Biocompatible , Humans , In Vitro Techniques , Kinetics , Quantum Theory , Surface Properties
19.
Biomaterials ; 26(15): 2197-207, 2005 May.
Article in English | MEDLINE | ID: mdl-15585221

ABSTRACT

The present study describes the synthesis of spheroidized hydroxyapatite (HA) powders using a radio frequency (rf) inductively coupled plasma (ICP) torch. The spheroidized powders were consolidated through a spark plasma sintering (SPS) system. The microstructure and crystallographic phases in the synthesized powders were characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Raman spectrometry. Results showed that the HA feedstock decomposed after rf plasma processing. Crystalline HA, alpha-tri-calcium phosphate (alpha-TCP), tetra-calcium phosphate (TTCP) and calcium oxide (CaO) were detected in the plasma-spheroidized powders. Raman spectra results indicated strong presence of amorphous calcium phosphate (ACP) in the spheroidized powders. The particle size distribution and specific surface area were influenced through the rf plasma working plate power levels. The sintering behavior of the rf plasma synthesized powders was analyzed through the SPS process and the results indicated that the spheroidized powders commence sintering at approximately 900 degrees C and through to 1150 degrees C. After sintering above 1100 degrees C for 3min, the relative densities of the SPS compacts reached 96% of the theoretical value. The SPS compacts were immersed in simulated body fluids (SBF) for different durations and the results confirmed their bioactivities.


Subject(s)
Body Fluids/chemistry , Crystallization/methods , Durapatite/chemistry , Durapatite/radiation effects , Hot Temperature , Radio Waves , Biocompatible Materials/analysis , Biocompatible Materials/chemistry , Biocompatible Materials/radiation effects , Calcium Phosphates , Durapatite/analysis , Elasticity , Electromagnetic Fields , Hardness , Materials Testing , Microspheres , Particle Size , Phase Transition , Powders , Temperature
20.
Biomaterials ; 26(7): 713-20, 2005 Mar.
Article in English | MEDLINE | ID: mdl-15350775

ABSTRACT

Glass ionomer cements (GICs) are a class of bioactive cements that bond directly to bone. In this paper, a new bioactive hydroxyapatite (HA)/zirconia (ZrO(2))-filled GIC composite was developed to improve the biocompatibility and bioactivity of the GICs with the surrounding bone and connective tissues. Nano-sized HA/30 wt% ZrO(2) powders were heat treated at 700 degrees Celsius and 800 degrees Celsius for 3 h to elucidate the influence of the crystallinity of composite powders on the performance of HA/ZrO(2)-GICs. The effects of different volume percentages of HA/ZrO(2) powders (4, 12, 28 and 40 vol%) substituted within GICs were investigated based on their microhardness, compressive strength and diametral tensile strength. The HA/ZrO(2)-GICs composite was soaked in distilled water for 1 day and 1 week before subjecting the samples to mechanical testing. Results showed that the glass and HA/ZrO(2) particles were distributed uniformly in the GIC matrix. The substitution of highly crystalline HA/ZrO(2) improved the mechanical properties of the HA/ZrO(2)-GICs due to the slow resorption rate for highly crystalline powders in distilled water. The mechanical properties of HA/ZrO(2)-GICs increased with increasing soak time due to the continuous formation of aluminium salt bridges, which improved the final strength of the cements. The compositions 4 and 12 vol% HA/ZrO(2)-GICs exhibited superior mechanical properties than the original GICs. The mechanical properties of HA/ZrO(2)-GICs were found to be much better than those of HA-GICs because ZrO(2) has the attributes of high strength, high modulus, and is significantly harder than glass and HA particles. Furthermore, ZrO(2) does not dissolve with increasing soaking time.


Subject(s)
Bone Cements/chemistry , Durapatite/chemistry , Glass Ionomer Cements/chemistry , Zirconium/chemistry , Bone Cements/chemical synthesis , Compressive Strength , Hardness , Materials Testing , Particle Size , Powders , Surface Properties , Tensile Strength
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