St John Crean

Delayed osteoblast differentiation and altered inflammatory response around implants placed in incisor sockets of type 2 diabetic rats

OBJECTIVE Central to the process of osseointegration is the recruitment of mesenchymal progenitor cells to the healing site, their proliferation and differentiation to bone synthesising osteoblasts. The process is under the control of pro-inflammatory cytokines and growth factors. The aim of this study was to monitor these key stages of osseointegration and the signalling milieu during bone healing around implants placed in healthy and diabetic bone. METHODS Implants were placed into the sockets of incisors extracted from the mandibles of normal Wistar and diabetic Goto-Kakizaki rats. Mandibles 1-12 weeks post-insertion of the implant were examined by histochemistry and immunocytochemistry to localise the presence of Stro-1- positive mesenchymal progenitor cells, proliferating cellular nuclear antigen proliferative cells, osteopontin and osteocalcin, macrophages, pro-inflammatory cytokines interleukin (IL)-1β, IL-6, tumour necrosis factor (TNF)-α and tumour growth factor (TGF)-β1. Image analysis provided a semi-quantification of positively expressing cells. RESULTS Histological staining identified a delay in the formation of mineralised bone around implants placed in diabetic animals. Within the diabetic bone, the migration of Stro-1 mesenchymal cells in the healing tissue appeared to be unaffected. However, in the diabetic healing bone, the onset of cell proliferation and osteoblast differentiation were delayed and subsequently prolonged compared with normal bone. Similar patterns of change were observed in diabetic bone for the presence of IL-1β, TNF-α, macrophages and TGF-β1. CONCLUSION The observed alterations in the extracellular presence of pro-inflammatory cytokines, macrophages and growth factors within diabetic tissues that correlate to changes in the signalling milieu, may affect the proliferation and differentiation of mesenchymal progenitor cells in the osseointegration process.

Stability of parenteral nanoemulsions loaded with paclitaxel: the influence of lipid phase composition, drug concentration and storage temperature

Abstract Paclitaxel was loaded into licensed parenteral nutrition nanoemulsions (Clinoleic® and Intralipid®) using bath sonication, and the stability of the formulations was investigated following storage for two weeks at room temperature or at 4 °C. In general, Clinoleic droplets were smaller than Intralipid droplets, being around 255 and 285 nm, respectively, for blank and freshly loaded emulsions. Regardless of storage temperature, the Clinoleic exhibited a very slight or no increase in droplet size upon storage, whilst the droplet size of the Intralipid emulsion increased significantly. The droplet size of both emulsions was minimally affected by paclitaxel concentration within the range of 0, 1, 3 and 6 mg/ml. The pH of both emulsions markedly decreased upon storage at room temperature, which was possibly attributed to the production of fatty acids resulting from phospholipid hydrolysis. However, at 4 °C, the pH of Clinoleic emulsion was unaffected by storage or paclitaxel concentration while the Intralipid emulsion demonstrated a trend for pH reduction. Both nanoemulsions had a negative zeta potential, with the Clinoleic formulations having the highest charge, possibly explaining the better size stability of this emulsion. Overall, this study has shown that paclitaxel was successfully loaded into clinically licensed parenteral emulsions and that Clinoleic showed greater stability than the Intralipid.

Emerging evidence for associations between periodontitis and the development of Alzheimer’s disease

Periodontal disease (PD) is an inflammatory disease affecting tooth-supporting tissues in which interaction of specific bacteria and the host’s immune responses play a pivotal role. The pathogenic bacteria associated with PD are a source of systemic inflammation as they have the ability to enter systemic circulation during everyday tasks such as brushing teeth and chewing food. Alzheimer’s disease (AD) is a form of dementia whereby inflammation is thought to play a key role in its pathogenesis and the risk of developing the disease increasing with age. The exact aetiology of the late-onset AD is unknown but peripheral infections are being considered as a potential risk factor.

Migration medicine in dentistry: educational challenges for the future?

The patient population of the UK is changing due to the influx of a significant number of international migrants.The impact this will have and is having upon the changing face of our patient base should be viewed as a manifestation of the globalisation process. For those charged with providing healthcare, there remains a need to maintain a contemporary awareness of the additional health challenges this group may pose.The dental profession, as part of that care provision service, faces the same demands.

Diamond Synthesis, Properties and Applications

Diamond is an ideal material for numerous applications such as cutting tools such as dental burs and drills due to its unique combination of chemical, mechanical and thermal properties. The most widely used method of growth diamond is chemical vapour deposition (CVD) namely hot filament and microwave plasma processes. The use of vertical filament chemical vapour deposition (VFCVD) process has been developed to uniformly coat complex shaped tools and is described in detail. The growth characteristics and film properties are described for use on dental burs and drills.

Sinus membrane perforation and its impact on implant survival – a mini-systematic review

&NA; Sinus membrane perforation is the most common complication of sinus augmentation procedures. Their relevance to implant survival, however, is less clear. A mini‐systematic literature review was conducted to determine whether membrane perforations have a detrimental effect on implant survival.

Developing an ecologically relevant heterogeneous biofilm model for dental-unit waterlines

Abstract This study monitored the biodiversity of microbes cultured from a heterogeneous biofilm which had formed on the lumen of a section of dental waterline tubing over a period of 910 days. By day 2 bacterial counts on the outlet-water showed that contamination of the system had occurred. After 14 days, a biofilm comparable to that of clinical waterlines, consisting of bacteria, fungi and amoebae had formed. This showed that the proprietary silver coating applied to the luminal surface of the commercial waterline tubing failed to prevent biofilm formation. Molecular barcoding of isolated culturable microorganisms showed some degree of the diversity of taxa in the biofilm, including the opportunistic pathogen Legionella pneumophila. Whilst the system used for isolation and identification of contaminating microorganisms may underestimate the diversity of organisms in the biofilm, their similarity to those found in the clinical environment makes this a promising test-bed for future biocide testing.

Controlling structure and morphology

The performance of the burs and tools coated with diamond depend on the properties of the films deposited including the structure, morphology and adhesion onto the substrate material. These film characteristics are in turn controlled by a number of factors including the VFCVD reactor parameters such as substrate temperature, substrate bias, pressure, methane concentration, plasma characteristics and affinity of the substrate for diamond nucleation. In this chapter the effects of process parameters on the structure and morphology of the films deposited and therefore control of the film properties.

Chemical Vapour Deposition of Diamond for Dental Tools and Burs

The depostition of diamond films using VFCVD onto tungsten carbide dental burs has been described. To enchance nucleation, growth and adhesion of the diamond substrate was pre-treated using a Murakami etch.The structure and morphology of the diamond coated bursa and uncoated burs have been compared.

Diamond Deposition on Tungsten Carbide Burs Using VFCVD

The deposition of diamond films using VFCVD onto tungsten carbide dental burs has been described. To enhance nucleation, growth and adhesion of diamond substrate was pre-treated using a Murakami etch. The structure and morphology of the diamond coated burs and uncoated burs have been compared.