A bilayered tissue engineered in vitro model simulating the tooth periodontium.

Due to the complexity of the structure of the tooth periodontium, regeneration of the full tooth attachment is not a trivial task. There is also a gap in models that can represent human tooth attachment in vitro and in vivo. The aim of this study was to develop a bilayered in vitro construct that simulated the tooth periodontal ligament and attached alveolar bone, for the purpose of tissue regeneration and investigation of physiological and orthodontic loading. Two types of materials were used to develop this construct: sol-gel 60S10Mg derived scaffold, representing the hard tissue component of the periodontium, and commercially available Geistlich Bio-Gide® collagen membrane, representing the soft tissue component of the tooth attachment. Each scaffold was dynamically seeded with human periodontal ligament cells (HPDLCs). Scaffolds were either cultured separately, or combined in a bilayered construct, for 2 weeks. Characterisation of the individual scaffolds and the bilayered constructs included biological characterisation (cell viability, scanning electron microscopy to confirm cell attachment, gene expression of periodontium regeneration markers), and mechanical characterisation of scaffolds and constructs. HPDLCs enjoyed a biocompatible 3-dimensional environment within the bilayered construct components. There was no drop in cellular gene expression in the bilayered construct, compared to the separate scaffolds.

What the future holds for regenerative endodontics: novel antimicrobials and regenerative strategies.

Regenerative/revitalisation endodontic techniques are increasingly used as a treatment approach for the management of immature permanent teeth with necrotic pulps. Different chemical irrigants and medicaments are routinely used clinically for intra-canal disinfection. However, despite remarkable progress in this field, coronal discolouration, cell cytotoxicity, difficulty of removal of organic biofilm from the root canal, development of sensitisation and antimicrobial resistance are still challenges to this line of treatment. This review critically discusses and challenges the current status quo of antimicrobials used in regenerative endodontics and sheds the light on future alternative antimicrobial materials with regenerative potential.

The role of the insulin­like growth factor (IGF) axis in osteogenic and odontogenic differentiation.

The insulin-like growth factor (IGF) axis is a multicomponent molecular network which has important biological functions in the development and maintenance of differentiated tissue function(s). One of the most important functions of the IGF axis is the control of skeletal tissue metabolism by the finely tuned regulation of the process of osteogenesis. To achieve this, the IGF axis controls the activity of several cell types­osteoprogenitor cells, osteoblasts, osteocytes and osteoclasts to achieve the co-ordinated development of appropriate hard tissue structure and associated matrix deposition. In addition, there is an increasing awareness that the IGF axis also plays a role in the process of odontogenesis (tooth formation). In this review, we highlight some of the key findings in both of these areas. A further understanding of the role of the IGF axis in hard tissue biology may contribute to tissue regeneration strategies in cases of skeletal tissue trauma.

Ag-doped 45S5 Bioglass®-based bone scaffolds by molten salt ion exchange: processing and characterisation.

There is increasing interest in developing scaffolds with therapeutic and antibacterial potential for bone tissue engineering. Silver is a proven antibacterial agent which bacteria such as MRSA have little or no defense against. Using an ion exchange method, silver ions have been introduced into 45S5 Bioglass(®) based scaffolds that were fabricated using the foam replication technique. This technique allows the introduction of Ag(+) ions onto the surface of the scaffold without compromising the scaffold bioactivity and other physical properties such as porosity. Controlling the amount of Ag(+) ions introduced onto the surface of the scaffold was achieved by tailoring the ion exchange parameters to fabricate samples with repeatable and predictable Ag(+) ion release behavior. In vitro studies in simulated body fluid were carried out to ensure that the scaffolds maintained their bioactivity after the introduction of Ag(+) ions. It was also shown that the addition of low concentrations (2000:1 w/w) of silver ions supported the attachment and viability of human periodontal ligament stromal cells on the 3D scaffolds. This work has thus confirmed ion exchange as an effective technique to introduce Ag(+) ions into 45S5 Bioglass(®) scaffolds without compromising the basic properties of 45S5 Bioglass(®) which are required for applications in bone tissue engineering.

The burden of trachoma in the rural Nile Delta of Egypt: a survey of Menofiya governorate.

BACKGROUND: Evidence of widespread distribution of trachoma in Egypt had not been clarified as previous surveys were limited to individual communities which may not have been representative of the general population. The Nile Delta of Egypt presents a unique environment for trachoma to persist. Economic improvements in the past decade have affected even the poorest rural environments; availability of electricity is now found in many rural communities. Availability of water in Nile Delta has always been good but poor hygienic conditions have been the primary factor in trachoma transmission. A survey of trachoma was undertaken in Menofiya governorate to determine if Egypt should be identified as trachoma endemic and targeted for trachoma control efforts. METHODS: A multistage random cluster study design was used with the target population defined as adults aged 50 and over and children aged 2-6 years from throughout the governorate. Among preschool children only trachoma was graded while among adults presenting visual acuity and cause of vision loss or blindness were also recorded. Adults were interviewed regarding past trichiasis surgery; those currently with trichiasis or a history of trichiasis surgery were also interviewed regarding outcome of surgery. RESULTS: A total of 3272 children aged 2-6 and 3322 adults age 50+ were enumerated. Among the children 81.3% were examined and among the adults 73.0% were examined. Active trachoma (follicles (TF) and/or intense inflammation (TI)) was found among 36.5% (95% confidence interval (CI) 34.7-38.3%) of the children. TI was 1.89 (95% CI 1.22-2.94) times more common in rural children compared to urban children. The prevalence of trichiasis (TT) in adults was 6.5%; women had an age adjusted odds of trichiasis of 1.68 (95% CI 1.18-2.39) compared to men. Trichiasis was 2.11 times (95% CI 1.33-3.37) more common in rural Menofiya compared to urban Menofiya. TT accounts for blindness (presenting vision <3/60) in 8% of patients and accounts for 13.2% of visual impairment. Overall, trichiasis surgical coverage was 34.4%, slightly higher among men than women. The outcome of trichiasis surgery was poor in 44.4% of cases. CONCLUSION: Trachoma is a serious public health problem in Menofiya governorate and a significant contributor to vision loss. These findings would suggest that continued poor hygienic conditions in rural Egypt have limited the reduction of active trachoma even in the face of significant improvements in socioeconomic status. Furthermore, the high proportion of trichiasis surgery cases with a poor outcome would indicate a need to reassess current surgical practices in Egypt and improve training and monitoring.