Basic and Applied Oral Biosciences
(i) Cell Biology of Oral Tissues
The primary focus of this research theme is to understand the molecular regulation of cellular events within oral tissues. These include an investigation into the role of inflammation in the progression of oral cancer and understanding the mechanism of pain transmission and modulation. Additional studies currently ongoing include the role of periodontitis in systemic disease, the utilization of dental pulp stem cells in neuron-protection and tissue engineering to generate bone tissue on titanium.
Staff: Dr. Jeff O’Sullivan, Dr. Michael O’Sullivan, Dr. Hal Duncan and Dr. Brendan Grufferty
(ii) Materials Science
The Dental Materials Science Research Unit undertakes research into a variety of dental materials routinely employed in clinical practice.
The projects currently under investigation include:
- Research into developing an ideal posterior filling material to replace dental amalgam. Recent research investigations have included gallium-based alloys and conventional methacrylate resin and oxirane resin based composites (RBCs). More recently research has focused on RBC research in particular nano-composites and low shrink organically modified ceramics as well as reinforced glass-ionomer restoratives as possible aesthetic alternatives to dental amalgams.
- The unit also undertakes research on the performance of all-ceramic restorations including porcelain laminate veneers, crowns and bridges. The unit has employed an in-vitro mechanical test to examine the clinical failure mode and fracture origin of dentine bonded crowns and the connector area of fixed partial dentures produced by different laboratory and machined fabrication processes. Recent research has focused on a novel profilometric technique to determine stressing patterns throughout the thickness of a dentine bonded crown material induced by pre-cementation and cementation operative techniques. The deflection test has proved to be a reliable method that enabled quantification of the stresses induced in dentine bonded crown materials and offers a further complimentary tool to the ceramicists’ armoury as a non-destructive test.
- Research within the unit also include the performance of dental cements when employed in conjunction with dental ceramics and include investigations into the corrosive potential of acid-base cements and the apparent strengthening mechanism of resin cements on controlled porcelain surfaces.
- Investigations into the potential toxicity effects of Nickel containing dental alloys routinely used in metal-ceramic crowns are also ongoing in the unit. Biocompatibility studies employed include the assessment of cell density, cell morphology, and cell viability. Cellular proliferation analysis includes using an XTT metabolic assay techniques, cellular toxicity levels with LDH assay techniques and metal ion release by ICP-MS techniques are regularly performed. Immunological cytokine profiles with a sandwich ELISA method specific for inflammatory molecules IL-1α, IL-8, PGE2 and TNF-α are also employed for biocompatibility studies.
Staff: Dr. Garry Fleming
(iii) Oral and Applied Microbiology
Microbes are responsible for a wide range of oral diseases. The Microbiology Research Unit in the Division of Oral Biosciences currently conducts research in four areas.
The oral cavity is home to many microbial species, including fungi such as Candida albicans. While these yeasts are usually innocuous, in certain circumstances (such as immune deficiency) they can overgrow and cause oral thrush. DDUH staff were the first to identify the new species Candida dubliniensis in 1995. Current research in this area is directed towards investigating the epidemiology, drug resistance and molecular pathogenesis of Candida species.
Staff: Prof. Derek Sullivan, Dr. Gary Moran and Prof. David Coleman.
Methicillin Resistant Staphylococcus aureus (MRSA) are bacteria that cause serious hospital-acquired infections in many countries. More recently Community-Acquired MRSA have also emerged as a significant cause of infection. Current research on MRSA focuses on the application of high-throughput DNA-based screening technologies to rapidly identify particular clones and strains of MRSA in order to identify sources and routes of transmission. Other research focuses on the evolution and emergence of new MRSA strains by transfer of genetic elements from a range of staphylococcal species.
Staff: Prof. David Coleman, Dr. Anna Shore and Prof. Derek Sullivan
Biofilm control in waterlines:
Dental chairs are complex medical devices that integrate a variety of equipment systems and services in a compact arrangement. Many of the instruments attached to dental units, such as ultrasonic scalers and drills are supplied with water for instrument cooling and tooth irrigation during dental treatment. Water to these instruments is provided by a network of narrow-bore plastic waterlines that are prone to contamination with microorganisms, especially bacterial species, present in low numbers in supply water. These microbes form slimy biofilms within the waterlines where they multiply rapidly resulting in heavily contaminated output water. Since 2000 research by the DDUH on dental waterlines has focused on the successful development of novel dental chairs equipped with integrated and automated waterline cleaning systems. Current research involves the development of large-scale automated centralised water treatment systems for minimising microbial contamination in water systems throughout healthcare facilities.
Staff: Prof. David Coleman, Dr. Mary O’Donnell and Dr. Maria Boyle
Periodontal disease is an infection of the tissues supporting teeth and is the major cause of tooth loss in adults. Several species of anaerobic bacteria have been implicated, including Porphyromonas gingivalis. This research theme is focused on investigating the pathogenic mechanisms of P. gingivalis and novel strategies to eradicate biofilms of these organisms.
Staff: Dr. Gary Moran