Development of dental composites with reactive fillers that promote precipitation of antibacterial-hydroxyapatite layers.

The study aim was to develop light-curable, high strength dental composites that would release calcium phosphate and chlorhexidine (CHX) but additionally promote surface hydroxyapatite/CHX co-precipitation in simulated body fluid (SBF). 80wt.% urethane dimethacrylate based liquid was mixed with glass fillers containing 10wt.% CHX and 0, 10, 20 or 40wt.% reactive mono- and tricalcium phosphate (CaP). Surface hydroxyapatite layer thickness/coverage from SEM images, Ca/Si ratio from EDX and hydroxyapatite Raman peak intensities were all proportional to both time in SBF and CaP wt.% in the filler. Hydroxyapatite was, however, difficult to detect by XRD until 4weeks. XRD peak width and SEM images suggested this was due to the very small size (~10nm) of the hydroxyapatite crystallites. Precipitate mass at 12weeks was 22wt.% of the sample CaP total mass irrespective of CaP wt.% and up to 7wt.% of the specimen. Early diffusion controlled CHX release, assessed by UV spectrometry, was proportional to CaP and twice as fast in water compared with SBF. After 1week, CHX continued to diffuse into water but in SBF, became entrapped within the precipitating hydroxyapatite layer. At 12weeks CHX formed 5 to 15% of the HA layer with 10 to 40wt.% CaP respectively. Despite linear decline of strength and modulus in 4weeks from 160 to 101MPa and 4 to 2.4GPa, respectively, upon raising CaP content, all values were still within the range expected for commercial composites. The high strength, hydroxyapatite precipitation and surface antibacterial accumulation should reduce tooth restoration failure due to fracture, aid demineralised dentine repair and prevent subsurface carious disease respectively

Hydroxyapatite, fluor-hydroxyapatite and fluorapatite produced via the sol-gel method: dissolution behaviour and biological properties after crystallisation.

Hydroxyapatite (HA), fluor-hydroxyapatite (FHA) with varying levels of fluoride ion substitution and fluorapatite (FA) were synthesised by the sol-gel method as possible implant coating or bone-grafting materials. Calcium nitrate and triethyl phosphite were used as precursors under an ethanol-water based solution. Different amounts of ammonium fluoride were incorporated for the preparation of the FHA and FA sol-gels. After heating and powdering the sol-gels, dissolution behaviour was assessed using ion chromatography to measure Ca(2+) and PO4 (3-) ion release. Biological behaviour was assessed using cellular proliferation with human osteosarcoma cells and alamarBlue™ assay. Statistical analysis was performed with a two way analysis of variance and post hoc testing with a Bonferroni correction. Increasing fluoride substitution into an apatite structure decreased the dissolution rate. Increasing the firing temperature of the HA, FHA and FA sol-gels up to 1,000 °C decreased the dissolution rate. There was significantly higher cellular proliferation on highly substituted FHA and FA than on HA or Titanium. The properties of an implant coating or bone grafting material can be tailored to meet specific requirements by altering the amount of fluoride that is incorporated into the original apatite structure. The dissolution behaviour can further be altered by the temperature at which the sol-gel is fired

Nanotechnology in dentistry: prevention, diagnosis, and therapy

Ensanya Ali Abou Neel,1–3 Laurent Bozec,3 Roman A Perez,4,5 Hae-Won Kim,4–6 Jonathan C Knowles3,5 1Division of Biomaterials, Operative Dentistry Department, Faculty of Dentistry, King Abdulaziz University, Jeddah, Saudi Arabia; 2Biomaterials Department, Faculty of Dentistry, Tanta University, Tanta, Egypt; 3UCL Eastman Dental Institute, Biomaterials and Tissue Engineering, London, UK; 4Institute of Tissue Regenerative Engineering (ITREN), 5Department of Nanobiomedical Science and BK21 Plus NBM Global Research Center for Regenerative Medicine, 6Department of Biomaterials Science, College of Dentistry, Dankook University, Cheonan, Republic of Korea Abstract: Nanotechnology has rapidly expanded into all areas of science; it offers significant alternative ways to solve scientific and medical questions and problems. In dentistry, nanotechnology has been exploited in the development of restorative materials with some significant success. This review discusses nanointerfaces that could compromise the longevity of dental restorations, and how nanotechnolgy has been employed to modify them for providing long-term successful restorations. It also focuses on some challenging areas in dentistry, eg, oral biofilm and cancers, and how nanotechnology overcomes these challenges. The recent advances in nanodentistry and innovations in oral health-related diagnostic, preventive, and therapeutic methods required to maintain and obtain perfect oral health, have been discussed. The recent advances in nanotechnology could hold promise in bringing a paradigm shift in dental field. Although there are numerous complex therapies being developed to treat many diseases, their clinical use requires careful consideration of the expense of synthesis and implementation. Keywords: nanotechnology, nanointerfaces, biofilm-related oral diseases, tissue engineering, drug delivery, toxicit

Physical activity and associations with clinical outcome measures in adults with cystic fibrosis; A systematic review

Background: Physical activity (PA) is important in the management of Cystic Fibrosis (CF) and is associated with a number of beneficial effects. PA assessment is not commonplace or consistent clinical practice, therefore understanding of PA in adults with CF remains limited. The purpose of this review was to evaluate PA levels in this population and compare PA to global recommendations and non-CF peers. Methods: The Preferred Reporting Items for Systematic Reviews and Meta-analyses guidelines were utilised to inform the review process. Original research was identified and screened against inclusion/exclusion criteria. Quality was assessed, data extracted and a narrative synthesis undertaken to describe the findings. Results: Adults with CF did not achieve recommended PA guidelines and step count targets in 5/8 studies where assessment was possible. No significant differences in PA were found between CF and non-CF peers in 3/5 studies. Associations between PA and improved lung function were inconsistent with 4/9 studies finding a positive association. Evidence for an association between PA and higher exercise capacity was stronger with all 4 studies reviewed reporting a positive association. Quality ratings were low across all studies. Conclusions: PA in adults with CF is largely comparable to their non-CF peers, despite being insufficiently active to achieve PA recommendations. Assessment tools used and outcomes reported are variable, many of which do not provide sufficient information to assess relevant components of PA. There is a requirement for high quality studies designed specifically to explore PA in adults with CF, ideally employing standardised PA assessment methods

Genetic variation associated with hypersensitivity to mercury

OBJECTIVES: Very little is known about mechanisms of idiosyncratic sensitivity to the damaging effects of mercury (Hg); however, there is likely a genetic component. The aim of the present study was to search for genetic variation in genes thought to be involved in Hg metabolism and transport in a group of individuals identified as having elevated Hg sensitivity compared to a normal control group. MATERIALS AND METHODS: Survivors of pink disease (PD; infantile acrodynia) are a population of clinically identifiable individuals who are Hg sensitive. In the present study, single nucleotide polymorphisms in genes thought to be involved in Hg transport and metabolism were compared across two groups: (i) PD survivors (n = 25); and (ii) age- and sex-matched healthy controls (n = 25). RESULTS: Analyses revealed significant differences between groups in genotype frequencies for rs662 in the gene encoding paraoxanase 1 (PON1) and rs1801131 in the gene encoding methylenetetrahydrofolate reductase (MTHFR). CONCLUSIONS: We have identified two genetic polymorphisms associated with increased sensitivity to Hg. Genetic variation in MTHFR and PON1 significantly differentiated a group formerly diagnosed with PD (a condition of Hg hypersensitivity) with age- and gender-matched healthy controls

Biological performance of titania containing phosphate-based glasses for bone tissue engineering applications

The interplay between glass chemistry, structure, degradation kinetics, and biological activity provides flexibility for the development of scaffolds with highly specific cellular response. The aim of this study was therefore to investigate the role of titania inclusion into the phosphate-based glass on its ability to stimulate osteoblast-like human osteosarcoma (HOS) cells to adhere, proliferate and differentiate. In depth morphological and biochemical characterisation was performed on HOS cells cultured on the surface of glass discs. Cell proliferation was also studied in the presence of the glass extract. Cell differentiation, through osteoblast phenotype genes, alkaline phosphatase (ALP) activity and osteocalcin production, was carried out using normal or osteogenic media. Both Thermanox® and titania free glass were used as controls. The data demonstrated that titania inclusion provides desired cytocompatible surface that supported initial cell attachment, sustained viability, and increased cell proliferation similar or significantly higher than Thermanox®. The modified glasses regulated osteoblastic cell differentiation as detected by osteoblast phenotype gene transcription and upregulated ALP and osteocalcin expression. Using osteogenic media had no significant effect on ALP activity and osteocalcin expression. Therefore, titania modified phosphate glasses may have future use as bone tissue engineering scaffolds

Tissue Engineering in Dentistry.

Objectives of this review is to inform practitioners with the most updated information on tissue engineering and its potential applications in dentistry. Data The authors used “PUBMED” to find relevant literature written in English and published from the beginning of tissue engineering until today. A combination of keywords was used as the search terms e.g., “tissue engineering”, “approaches”, “strategies” “dentistry”, “dental stem cells”, “dentino-pulp complex”, “guided tissue regeneration”, “whole tooth”, “TMJ”, “condyle”, “salivary glands”, and “oral mucosa”. Sources Abstracts and full text articles were used to identify causes of craniofacial tissue loss, different approaches for craniofacial reconstructions, how the tissue engineering emerges, different strategies of tissue engineering, biomaterials employed for this purpose, the major attempts to engineer different dental structures, finally challenges and future of tissue engineering in dentistry. Study selection Only those articles that dealt with the tissue engineering in dentistry were selected. Conclusions There have been a recent surge in guided tissue engineering methods to manage periodontal diseases beyond the traditional approaches. However, the predictable reconstruction of the innate organisation and function of whole teeth as well as their periodontal structures remains challenging. Despite some limited progress and minor successes, there remain distinct and important challenges in the development of reproducible and clinically safe approaches for oral tissue repair and regeneration. Clearly, there is a convincing body of evidence which confirms the need for this type of treatment, and public health data worldwide indicates a more than adequate patient resource. The future of these therapies involving more biological approaches and the use of dental tissue stem cells is promising and advancing. Also there may be a significant interest of their application and wider potential to treat disorders beyond the craniofacial region. Clinical Significance Considering the interests of the patients who could possibly be helped by applying stem cell-based therapies should be carefully assessed against current ethical concerns regarding the moral status of the early embryo

In vitro biocompatibility and mechanical performance of titanium doped high calcium oxide metaphosphate-based glasses

This study challenged to produce phosphate-based glasses (PBG) for the treatment of osseous defects. The glasses contained, among other components, 40 mol% CaO and 1-5 mol% TiO(2). The mechanical performance and in vitro biocompatibility using both human osteosarcoma and primary osteoblasts were carried out. Incorporation of TiO(2) into PBG had no significant effect on strength and modulus. These glasses encouraged attachment and maintained high viability of osteosarcoma cells similar to the positive control surface. Cells grown directly (on glasses) or indirectly (in the presence of glass extracts) showed similar proliferation pattern to the positive control cells with no significant effect of TiO(2) detected. Increasing TiO(2) content, however, has a profound effect on cytoskeleton organization and spreading and maturation of primary osteoblasts. It is believed that TiO(2) might have acted as a chemical cue-modulating cells response, and hence the substrates supported maturation/mineralization of the primary osteoblasts

Development of conical soluble phosphate glass fibres for directional generation of microchannels in dense collagen implants

Successful integration of the tissue engineered construct depends greatly on the ability of host tissues to innervate and vascularise the implant. To achieve this goal we proposed using dissoluble phosphate-based glass fibres to create microchannels in the plastic compressed collagen gel. To make the ingrowth dynamic we hypothesized that fibres should be conically shaped, so that after implantation the microchannel will open in the direction of increasing diametre. PC collagen is a novel technique for the rapid fabrication of dense collagen bio-mimetic tissues by rapid expulsion of the liquid from hyperhydrated collagen gel.1 Dissolution of phosphate glass (PG) fibres compressed into collagen gels, produce microchannels2 but products from fast dissolving glasses may be detrimental to the seeded cells.3 In this study we tested the viability of Schwann cells (SC) and human bone marrow stromal cells (hBMSC) in the PCC-PGF system and possibility of fabrication of the conically shaped fibres

Patients' Experience of therapeutic footwear whilst living at risk of neuropathic diabetic foot ulceration: an interpretative phenomenological analysis (IPA).

BACKGROUND: Previous work has found that people with diabetes do not wear their therapeutic footwear as directed, but the thinking behind this behaviour is unclear. Adherence to therapeutic footwear advice must improve in order to reduce foot ulceration and amputation risk in people with diabetes and neuropathy. Therefore this study aimed to explore the psychological influences and personal experiences behind the daily footwear selection of individuals with diabetes and neuropathy. METHODS: An interpretative phenomenological analysis (IPA) approach was used to explore the understanding and experience of therapeutic footwear use in people living at risk of diabetic neuropathic foot ulceration. This study benefited from the purposive selection of a small sample of four people and used in-depth semi structured interviews because it facilitated the deep and detailed examination of personal thoughts and feelings behind footwear selection. FINDINGS: Four overlapping themes that interact to regulate footwear choice emerged from the analyses: a) Self-perception dilemma; resolving the balance of risk experienced by people with diabetes and neuropathy day to day, between choosing to wear footwear to look and feel normal and choosing footwear to protect their feet from foot ulceration; b) Reflective adaption; The modification and individualisation of a set of values about footwear usage created in the minds of people with diabetes and neuropathy; c) Adherence response; The realignment of footwear choice with personal values, to reinforce the decision not to change behaviour or bring about increased footwear adherence, with or without appearance management; d) Reality appraisal; A here and now appraisal of the personal benefit of footwear choice on emotional and physical wellbeing, with additional consideration to the preservation of therapeutic footwear. CONCLUSION: For some people living at risk of diabetic neuropathic foot ulceration, the decision whether or not to wear therapeutic footwear is driven by the individual 'here and now', risks and benefits, of footwear choice on emotional and physical well-being for a given social context