Impact of early clinical exposure on the learning experience of undergraduate dental students.

AIMS: The aim of this research was to evaluate the impact of early clinical exposure on the learning experiences of undergraduate dental students. METHODS: This study was based on mixed methods. The first phase involved administering a purposely designed questionnaire consisting of 16 items, grouped into three subscales. The second phase of the research was conducted using qualitative semi-structured interviews to explore the perceptions and experiences of stakeholders regarding early clinical exposure. RESULTS: In total, 134 undergraduate dental students and eight clinical supervisors responded to the questionnaire and reported positive perceptions regarding the learning experiences, professional relationship and learning environment. Qualitative interviews were conducted with 12 participants, and early clinical exposure was perceived to be useful in providing a context to theoretical learning and development of interpersonal skills. Curriculum overload and further need for consolidation were highlighted as the main challenges. CONCLUSIONS: This study provided insights into the clinical training model in an undergraduate dental programme and highlights the benefits and challenges of early clinical exposure in the study population. The study served as a vehicle for engagement with a range of stakeholders using a mixed methods approach to inform further development of the training model.

A surprisingly poor correlation between in vitro and in vivo testing of biomaterials for bone regeneration: results of a multicentre analysis.

New regenerative materials and approaches need to be assessed through reliable and comparable methods for rapid translation to the clinic. There is a considerable need for proven in vitro assays that are able to reduce the burden on animal testing, by allowing assessment of biomaterial utility predictive of the results currently obtained through in vivo studies. The purpose of this multicentre review was to investigate the correlation between existing in vitro results with in vivo outcomes observed for a range of biomaterials. Members from the European consortium BioDesign, comprising 8 universities in a European multicentre study, provided data from 36 in vivo studies and 47 in vitro assays testing 93 different biomaterials. The outcomes of the in vitro and in vivo experiments were scored according to commonly recognised measures of success relevant to each experiment. The correlation of in vitro with in vivo scores for each assay alone and in combination was assessed. A surprisingly poor correlation between in vitro and in vivo assessments of biomaterials was revealed indicating a clear need for further development of relevant in vitro assays. There was no significant overall correlation between in vitro and in vivo outcome. The mean in vitro scores revealed a trend of covariance to in vivo score with 58 %. The inadequacies of the current in vitro assessments highlighted here further stress the need for the development of novel approaches to in vitro biomaterial testing and validated pre-clinical pipelines.

Single-step electrochemical deposition of antimicrobial orthopaedic coatings based on a bioactive glass/chitosan/nano-silver composite system.

Composite orthopaedic coatings with antibacterial capability containing chitosan, Bioglass® particles (9.8µm) and silver nanoparticles (Ag-np) were fabricated using a single-step electrophoretic deposition (EPD) technique, and their structural and preliminary in vitro bactericidal and cellular properties were investigated. Stainless steel 316 was used as a standard metallic orthopaedic substrate. The coatings were compared with EPD coatings of chitosan and chitosan/Bioglass®. The ability of chitosan as both a complexing and stabilizing agent was utilized to form uniformly deposited Ag-np. Due to the presence of Bioglass® particles, the coatings were bioactive in terms of forming carbonated hydroxyapatite in simulated body fluid (SBF). Less than 7wt.% of the incorporated silver was released over the course of 28days in SBF and the possibility of manipulating the release rate by varying the deposition order of coating layers was shown. The low released concentration of Ag ions (<2.5ppm) was efficiently antibacterial against Staphyloccocus aureus up to 10days. Although chitosan and chitosan/Bioglass® coating supported proliferation of MG-63 osteoblast-like cells up to 7days of culture, chitosan/Bioglass®/Ag-np coatings containing 342 µg of Ag-np showed cytotoxic effects. This was attributed to the relatively high concentration of Ag-np incorporated in the coatings.

Stratified scaffolds for osteochondral tissue engineering applications: electrospun PDLLA nanofibre coated Bioglass®-derived foams.

This work focuses on designing bilayered constructs by combining electrospun poly-DL-Lactide (PDLLA) fibers and Bioglass®-derived scaffolds for development of osteochondral tissue replacement materials. Electrospinning was carried out using a solution of 5 wt/v% PDLLA in dimethyl carbonate. The PDLLA layer thickness increased from 2 to 150 µm with varying electrospinning time. Bioactivity studies in simulated body fluid showed that HA mineralization decreased as the thickness of the PDLLA layer increased. A preliminary in vitro study using chondrocyte cells (ATDC5) showed that cells attached, proliferated and migrated into the fibrous network, confirming the potential applicability of the bilayered scaffolds in osteochondral defect regeneration.

Titanium-containing bioactive phosphate glasses.

The use of biomaterials has revolutionized the biomedical field and has received substantial attention in the last two decades. Among the various types of biomaterials, phosphate glasses have generated great interest on account of their remarkable bioactivity and favourable physical properties for various biomedical applications relating to both hard and soft tissue regeneration. This review paper focuses mainly on the development of titanium-containing phosphate-based glasses and presents an overview of the structural and physical properties. The effect of titanium incorporation on the glassy network is to introduce favourable properties. The biocompatibility of these glasses is described along with recent developments in processing methodologies, and the potential of Ti-containing phosphate-based glasses as a bone substitute material is explored.

The enhanced modulation of key bone matrix components by modified Titanium implant surfaces.

Modifications to Titanium (Ti) implant surfaces enhance osseointegration by promoting bone-implant contact and peri-implant bone accrual; which in vitro analyses of osteoblastic cells suggest is due to an enhancement in cellular phenotypic maturation and function. To evaluate these effects on uncommitted cells, this study examined the osteogenic mineralisation and phenotypic marker expression of human marrow derived stromal cells (hBMSCs) from three unrelated donors cultured on tissue culture plastic (TCP), polished (P), rough-hydrophobic (SLA) and rough-hydrophilic (modSLA) Ti surfaces over the course of 21 days. Transcriptional analyses indicated a significant early up-regulation of both Runx2 (p<0.05) and Osteopontin (OP) (p<0.05) but not Bone Sialoprotein 2 (BSP2) (p<0.05) by rough surfaces 1 day post seeding. The phenotypic analyses showed that whilst cellular proliferation was relatively restricted and slower on the rough substrates; osteogenic mineralisation, assessed by quantifying extracellular matrix calcium deposition, collagen formation and the ratio of collagen to mineral deposited were significantly higher (p<0.05); as was alkaline phosphatase (ALP) activity (p<0.05). The rough surfaces caused an increase of secreted osteoblastic markers Osteoprotegrin (OPG) (p<0.05), growth differentiation factor 15 (GDF-15) (p<0.05) and Osteocalcin (OC) (p<0.05). These findings suggest that modified Ti surfaces induce an enhancement in osteogenic commitment and differentiation, which likely underlie the deposition of more stable bone matrix early in the healing process in vivo.

Effect of deposition parameters and post-deposition annealing on the morphology and cellular response of electrosprayed TiO2 films.

Titania films (TiO(2)) were deposited on Ti alloy substrates by electrohydrodynamic atomization (EHDA), also called electrospraying, and the morphology and phase composition of the coatings were evaluated. A range of TiO(2) sols (2-8 wt%) were prepared via the hydrolysis of polymeric precursors using isopropanol (prOH) as a solvent carrier. Stable cone-jet formation during the EHDA process was greatly influenced by varying the liquid physical properties. Deposition parameters such as sol concentration, needle-to-substrate distance and spray time were found to affect film morphology. Dense and continuous films were obtained under optimized conditions whereby a 2 wt% TiO(2) sol was atomized at a flow rate of 5 µl min(-1) by a needle of 300 µm inner diameter, kept at a distance of 20 mm from the grounded substrate and operating at an applied voltage of 3.5-4.2 kV. The films were then crystallized by heating to 300-600 °C. Annealing increased the hydrophilicity of the films but did not significantly affect the surface roughness of the films. In vitro cellular response was determined by studying the interaction between MG63 cells and the films annealed at the various temperatures. MG63 cells were able to grow and proliferate on all the TiO(2) films, while the highest proliferation rate was found on the TiO(2) films annealed at 600 °C. Our results indicate that electrosprayed TiO(2) films possess great potential for biomedical applications.

Single incision endoscopic surgery for gynaecomastia.

INTRODUCTION: Surgical excision has been an effective treatment for gynaecomastia. Recently, there has been a shift from the open approach to minimally invasive techniques. In this report we describe our technique which includes endoscopic excision and/or liposuction of gynaecomastia via a single lateral chest wall incision. METHODS: Between May 2007 and April 2010, a total of 12 gynaecomastia patients were treated with liposuction and/or endoscopic excision. Patients were divided into 3 groups: group I; liposuction only, group II; endoscopic excision plus liposuction and group III; endoscopic excision only. One 15 mm incision was made laterally at the anterior axillary line. A vacuum assisted liposuction removing the fatty tissue was performed. Then endoscopic excision of the remaining fibroglandular tissue was done under vision through the same incision. The parynchyma was then dissected into small pieces and pulled out. RESULTS: Group I had liposuction only (n = 4), group II had liposuction combined with endoscopic excision (n = 7) (58%) while group III had endoscopic excision only (n = 1). The mean operative time for liposuction and endoscopic excision was 58 min for each side. Mean hospital stay was 1.4 days. Postoperative complications included infection with abscess formation and one patient had seroma. Mean follow-up was 56 weeks. Eleven out of twelve patients (92%) were satisfied with their results. Long-term follow-up showed that results were stable over time, and no revisions were necessary. CONCLUSION: Endoscopic excision of gynaecomastia through a single lateral chest wall incision is a minimally invasive effective and safe technique for the management of gynaecomastia, with excellent aesthetic results and an acceptable complication rate.

In vitro antibacterial efficacy of tetracycline hydrochloride adsorbed onto Bio-Oss bone graft.

Local delivery of antibiotics may provide the advantage of reducing the potential side effects associated with their systemic administration. This study assessed, in vitro, the antimicrobial efficacy of tetracycline hydrochloride (TCH) adsorbed onto Bio-Oss bone grafts against a range of pathogenic bacteria. Various levels of TCH were adsorbed onto Bio-Oss granules by immersing in TCH aqueous solutions of different initial concentrations for 48 h at room temperature. TCH release was assessed in phosphate buffered saline at 37 degrees C, and its antimicrobial efficacy, up to 96 h, was tested against two Gram-negative bacteria associated with periodontal diseases: Aggregatibacter (formerly Actinobacillus) actinomycetemcomitans, and Porphyromonas gingivalis, and one Gram-positive bacterium associated with soft-tissue and bone infections: Staphylococcus aureus. The range of TCH concentrations studied was also assessed for cytotoxicity against osteoblast-like human osteosarcoma cell lines. The amount of TCH adsorbed and released from Bio-Oss was concentration dependent. All TCH adsorbed Bio-Oss resulted in a reduction of A. actinomycetemcomitans, P. gingivalis, and S. aureus and higher concentrations were generally more effective in reducing or eliminating bacterial growth. The proliferation of HOS cells was not substantially reduced except for the maximum concentration of TCH. In addition to its osteoconductive role, TCH adsorbed Bio-Oss could also be functional in negating systemically antibiotic prophylactic treatment in the prevention of implant or biomaterial related infections.

Chemical, modulus and cell attachment studies of reactive calcium phosphate filler-containing fast photo-curing, surface-degrading, polymeric bone adhesives.

The initial structure, setting and degradation processes of a poly(lactide-co-propylene glycol-co-lactide) dimethacrylate adhesive filled with 50, 60 or 70 wt.% reactive calcium phosphates (monocalcium phosphate monohydrate (MCPM)/beta-tricalcium phosphate (beta-TCP)) have been assessed using nuclear magnetic resonance, Fourier transform infrared spectroscopy, Raman, X-ray powder diffraction and gravimetric studies. Filler incorporation reduced the rapid light-activated monomer polymerization rates slightly, but not the final levels. Upon immersion in water for 24h, the set composite mass and volume increased due to water sorption. This promoted initial soluble MCPM loss from the composite surfaces, but also its reaction and monetite precipitation within the specimen bulk. After 48 h, composite gravimetric and chemical studies were consistent with surface erosion of polymer with reacted/remaining filler. The filled formulations exhibited more rapid early water sorption and subsequent surface erosion than the unfilled polymer. Calcium and phosphate release profiles and solution pH measurements confirmed early loss of surface MCPM with protons from polymer degradation products. At later times, the slower release of monetite/beta-TCP buffered composite storage solutions at approximately 5 instead of 3.2 for the unfilled polymer. Incorporation of filler increased both the early and later time material modulus. At intermediate times this effect was lost, presumably as a result of enhanced water sorption. The early modulus values obtained fell within the range reported for cancellous bone. Despite surface degradation, initial human mesenchymal cell attachment to both composites and polymer could be comparable with a non-degrading positive Thermanox control. These studies indicate that the filled formulations may be good candidates for bone repair. Release of calcium and phosphate ions provides components essential for such repair.

Strontium oxide doped quaternary glasses: effect on structure, degradation and cytocompatibility.

This preliminary study focuses on the effect of adding SrO to a Ti-containing quaternary phosphate glass system denoted by P(2)O(5)-Na(2)O-CaO-TiO(2). The following four different glass compositions were manufactured: 0.5P(2)O(5)-0.17Na(2)O-0.03TiO(2)-(0.3-x)CaO-xSrO where x = 0, 0.01, 0.03 and 0.05. Structural characterisation revealed glass transition temperatures in the range 427-437 degrees C and the presence of sodium calcium phosphate as the dominant phase in all the glasses. Degradation and ion release studies conducted over a 15-day period revealed that the Sr-containing glasses showed significantly higher degradation and ion release rates than the Sr-free glass. Cytocompatibility studies performed over a 7-day period using MG63 cells showed that the addition of 5 mol% SrO yielded glasses with cell viability nearly equivalent to that observed for quaternary TiO(2) glasses.

RNA interference of the BMPR-IB gene blocks BMP-2-induced osteogenic gene expression in human bone cells.

We have previously shown that human bone cells express bone morphogenetic protein receptor-IB (BMPR-IB). However, little is known about the precise role of this receptor in the response of osteoblastic genes to the BMP in these cells. To determine BMPR-IB-dependent osteoblastic gene expression, the present study examined the effects of BMPR-IB knockdown on BMP-induced osteoblast-associated genes. BMPR-IB mRNA and protein were markedly suppressed by transfection of cells with BMPR-IB siRNA. Using three different bone cell samples, BMP-2 stimulation of alkaline phosphatase (ALP), osteocalcin (OC), distal-less homeobox-5 (Dlx5) and core binding factor alpha-1 (Cbfa1) was found to be specifically and significantly reduced in the BMPR-IB siRNA-transfected cultures compared with that of control cultures. Our study has provided evidence that BMPR-IB-dependent signaling plays a crucial role in BMP-2 up-regulation of the ALP, OC, Dlx5 and Cbfa1 genes in bone cells, suggesting a pivotal role of this receptor in BMP-2-induced osteoblast differentiation in vitro. These findings thus suggest the possibility that BMPR-IB could be a therapeutic target for enhancing bone regeneration in vivo.

Bioglass-derived glass-ceramic scaffolds: study of cell proliferation and scaffold degradation in vitro.

Cell support function as well as cell proliferation on highly porous Bioglass(R)-derived glass-ceramic scaffolds (designed for bone tissue engineering) have been assessed in vitro using osteoblast-like cells (MG 63) cultured for up to 6 days. The biodegradation and mechanical stability of the scaffolds in the cell-culture medium have also been investigated. It was found that the scaffolds had excellent cell supporting ability, with cells effectively infiltrating into and surviving at the center of the scaffolds. A quantitative study using the AlamarBlue assay revealed that the proliferation of cells on the glass-ceramic materials was comparable to that on the noncrystallized Bioglass. While the crystalline phase in the glass-ceramic scaffolds transformed into a biodegradable amorphous calcium phosphate phase during cell culture, the mechanical strength of the scaffolds was maintained when compared with that of scaffolds incubated in simulated body fluid or immersed in cell-free culture medium. It is believed that the attached cells and collagen secreted by cells could fill the micropores and microcracks on the surface of the foam struts, thus contributing to the mechanical stability of the degrading scaffolds. In summary, the developed glass-ceramic scaffolds possess the most essential features of a scaffold for bone tissue engineering: they are capable to support and foster relevant cells, able to provide temporary mechanical function, and biodegradable.

Zinc-containing phosphate-based glasses for tissue engineering.

It has been shown that the addition of zinc to hydroxyapatite promotes osteoblast cell adhesion (Ishaug et al 1994 J. Biomed. Mater. Res. A 28 1445-53). Therefore, this study presents a series of phosphate-based glass compositions that contain varying amounts of zinc in order to promote osteoblast cell adhesion. The compositions investigated were P(50)Ca((40-x))Na(10) where x = 0, 1, 2, 3, 4 and 5 mol%. The dissolution rate and effect on pH of glass discs were investigated and ion release from the glass discs was examined in distilled water at 37 degrees C after 1, 2, 3, 4 and 7 days. The attachment of osteoblast-like cells (HOB) was observed by SEM on the glass discs. A linear decrease in the %mass of the glass discs was observed for all compositions for the duration of the study. The dissolution rates were similar for all the compositions. After 7 days, a mass loss of 3-6% was observed for all the compositions. The pH of distilled water decreased to a range of pH 4.5-5.5 from pH 7 after 1 day, and remained in this range for the duration of the study. The composition containing 0 mol% Zn reduced the pH to a lesser extent than the composition containing the highest amount of Zn. Furthermore, Zn(2+) ion release was observed from all the Zn-containing compositions. These glass compositions may therefore be suitable for tissue engineering applications.

Photodynamic therapy down-regulates the invasion promoting factors in human oral cancer.

Squamous cell carcinomas of the head and neck are characterized by their high tendency for invasion and metastasis. Several studies have identified the roles of matrix metalloproteinases (MMPs), vascular endothelial growth factors (VEGF) and urokinase plasminogen activators (uPA) in this process. Photodynamic Therapy (PDT) is an emerging treatment currently in clinical practice for the treatment of early cancer. Here we evaluate, in vitro, the influence of PDT on the expression of these molecules. A series of human keratinocyte cell lines derived from human oral squamous cell carcinomas (OSCC) were used as the PDT 'targets' in this study. Each cell line was subjected to sublethal dose of PDT. Activity of MMP-2, MMP-9, MMP-13, uPA and VEGF were evaluated at protein levels using zymography and ELISA on culture medium. For uPA, a chromogenic assay was performed. Gelatin zymography results revealed that, in control medium, MMP-9 and MMP-2 were secreted in proform. MMP-2 was highly expressed by H376 cells while VB6 and UP cells relatively show similar MMP-2 with comparatively low expression. For MMP-9, the latent type was highly expressed by VB6 cells and only slightly by H376, while active-MMP-9 was expressed by VB6 cell line only. Following PDT, both active and latent MMP-2 and MMP-9 were down regulated by UP and VB6 cells (p<0.001), while H376 showed an increase in active-MMP-2. These observations were supported by ELISA. This study has demonstrated that, PDT causes the suppression of factors responsible for tumour invasion which may be of therapeutic value.

Bone morphogenetic protein receptors and bone morphogenetic protein signaling are controlled by tumor necrosis factor-alpha in human bone cells.

Bone morphogenetic proteins (BMP) stimulate osteoblast differentiation by signal transduction via three BMP receptors (BMPR-IA, -IB and -II), whereas the inflammatory cytokine tumor necrosis factor-alpha (TNF-alpha) has been shown to suppress osteoblast differentiation. Although the mechanisms which regulate the BMPR are not yet known, it is possible that they may be negatively controlled by TNF-alpha, thereby inhibiting BMP-induced osteoblast differentiation. To test this hypothesis, we have examined the effects of TNF-alpha on BMPR-IA, -IB and -II expression and the functional consequences of this cytokine on BMPR-mediated functions in human bone cells. The results showed that although TNF-alpha down-regulated BMPR-IA and -II transcripts, it increased the level of BMPR-IB mRNA via a MAPK-dependent pathway. In marked contrast, however, TNF-alpha nevertheless caused marked down-regulation of the expression of the BMPR-IB surface antigen specifically. Moreover, the cytokine-induced decrease in BMPR-IB expression was found to be associated with the concurrent presence of a 'soluble' form of this antigen in supernatants of TNF-alpha-treated cultures. Furthermore, the TNF-alpha-induced loss of BMPR-IB was found to ablate BMP-2-stimulated bone cell functions, including phosphorylation of Smad1/5/8, alkaline phosphatase activity and osteocalcin expression. In conclusion, our study has provided evidence, for the first time, that BMPR can be differentially modulated by TNF-alpha at both the post-transcriptional and post-translational levels, with the TNF-alpha-induced shedding of the BMPR-IB antigen associated with a significantly diminished response to BMP-2 in vitro.

Shedding of a soluble form of BMP receptor-IB controls bone cell responses to BMP.

Bone morphogenetic proteins (BMP) are members of the transforming growth factor beta (TGF-beta) superfamily and are involved in a wide variety of biological processes, including osteoblast differentiation and bone healing. The activities of the BMP are mediated by signal transduction via three BMP receptors (BMPR-IA, -IB and -II), which are thus essential for the biological actions of the BMP. Although the precise mechanisms which control the BMPR are not yet known, it is possible that post-translational regulation of these cell surface antigens by shedding could modulate their expression and thereby at least partly determine the response of the cells to the BMP. To test this possibility, the present study has examined whether soluble forms of the BMPR are produced by shedding from primary human bone cells in vitro. The results showed that human bone cells expressed both mRNA transcripts and antigens corresponding to BMPR-IA, -IB and -II. Incubation of the cells with phorbol 12-myristate 13-acetate (PMA), a potent inducer of proteolytic shedding, resulted in a pronounced decrease in cell surface expression of all three BMPR and, concurrently, the presence of "soluble" forms of these antigens in culture supernatants. Moreover, PMA treatment significantly reduced the level of BMP-2-induced Smad1/5 phosphorylation, a major early activation step in signal transduction initiated by BMP/BMPR interaction. It is notable that, while treatment of bone cells with interleukin-1beta (IL-1beta) also reduced the level of surface BMPR-IB, this inflammatory cytokine had no effect on BMPR-IA or -II levels, hence only the soluble form of BMPR-IB was detected. Furthermore, in addition to down-regulating BMP-2-induced Smad1/5 phosphorylation, IL-1beta also caused a reduction in the level of BMP-2-induced alkaline phosphatase activity and osteocalcin expression, both closely associated with bone cell differentiation. In conclusion, our study has provided evidence, for the first time, that BMPR can be modulated at the cell surface by the shedding of a soluble form of the antigen, resulting in a markedly diminished response to BMP-2 in vitro.

Fluorescence spectroscopy combined with 5-aminolevulinic acid-induced protoporphyrin IX fluorescence in detecting oral premalignancy.

BACKGROUND: Early detection of premalignant/malignant lesions in the oral cavity can certainly improve the patient's prognosis. This study presents fluorescence imaging with the topical application of 5-aminolevulinic as a way to improve detection of various oral tissue pathologies. This procedure depends mainly on comparing the intensity of red and green fluorescence emitted from tissues during examination. MATERIALS AND METHODS: Seventy-one patients who presented with clinically suspicious oral leukoplakia were recruited for this study. Each of the patients was required to have 5-aminolevulinic acid in the form of mouth rinse prior to fluorescence imaging. Following this a surgical biopsy was acquired from the exact examination site. The results of the fluorescence spectroscopy have been compared with histopathology. RESULTS: A Student's t-test was applied to test the viability of the ratio between red and green fluorescence. The red-to-green ratio was found to increase significantly when the lesion was identified as dysplastic or carcinoma in situ. By applying a threshold line to discriminate between normal and dysplastic lesions; a sensitivity of 83-90% and specificity of 79-89% were obtained. CONCLUSION: Fluorescence spectroscopy combined with 5-aminolevulinic acid-induced protoporphyrin IX was found as a valuable tool in the diagnosis of oral premalignancy. This technique offers the potential to be advantageous over other non-optical techniques in terms of providing real-time diagnosis, in situ monitoring, cost effectiveness and more tolerated by patient compared to surgical biopsy.

Assessment of oral premalignancy using elastic scattering spectroscopy.

Optical spectroscopy systems have been involved in various clinical fields; however the main interest is still in the diagnosis of premalignant/malignant lesions. The aim of this study was to compare findings of Elastic Scattering Spectroscopy (ESS) with histopathology of oral tissues to see if this technique could be used as an adjunct or alternative to histopathology in identifying dysplasia. The technique involves the use of Mie scattering and is a simple non-invasive method of tissue interrogation. Twenty-five oral sites from 25 patients who presented with oral leukoplakia were examined by ESS using a pulsed xenon-arc lamp. Surgical biopsies were acquired from each of the examination sites. The results of the acquired spectra were then compared with histopathology. Two sets of spectra were obtained, and by using a linear discriminant analysis, a sensitivity of 72% and a specificity of 75% were obtained. These results are promising and could suggest that ESS may be able to identify dysplasia in oral tissues. To prove the usefulness of the ESS in dysplasia detection in oral tissues conclusively, a larger body of data is needed. We aim to continue this study to obtain more data in an attempt to increase the accuracy of the technique. Large, multi-centre trails are needed for each anatomical site, in order to gather more information about the differences between normal and dysplastic tissue.

Effects of ultrasound on transforming growth factor-beta genes in bone cells.

Therapeutic ultrasound (US) is a widely used form of biophysical stimulation that is increasingly applied to promote fracture healing. Transforming growth factor-beta (TGF-beta), which is encoded by three related but different genes, is known to play a major part in bone growth and repair. However, the effects of US on the expression of the TGF-beta genes and the physical acoustic mechanisms involved in initiating changes in gene expression in vitro, are not yet known. The present study demonstrates that US had a differential effect on these TGF-beta isoforms in a human osteoblast cell line, with the highest dose eliciting the most pronounced up-regulation of both TGF-beta1 and TGF-beta3 at 1 hour after treatment and thereafter declining. In contrast, US had no effect on TGF-beta2 expression. Fluid streaming rather than thermal effects or cavitation was found to be the most likely explanation for the gene responses observed in vitro.