Title: Re-mineralising, antibacterial composites and adhesives for more durable, conservative and pain less tooth restoration
Funder: Engineering and Physical Sciences Research Council

Abstract: Dental caries is caused by specific acid producing bacteria that demineralise enamel and dentine. If left unchecked, infection of the dentine pulp complex and associated pain occurs. Treatment costs then escalate several folds, particularly if root canal procedures or tooth replacement with implants is ultimately required. Dental caries is the most common disease in humans. Almost 40% of UK adults have at least one untreated carious tooth. This rises to 60-90% for children or across the whole population in deprived nations. Pain and tooth loss from dental caries is associated with significant adverse impact on quality of life. Damaged or infected tooth structure must be partially or totally replaced in order to halt disease progression, preserve function and improve aesthetics. Tooth restoration treatments have enabled the UK population to keep its teeth for longer. The financial cost of restoration maintenance, however, is high due to their limited lifetime expectancy. Amalgam restorations are increasingly being replaced by more aesthetic white composites. Composites have good strength and wear resistance but the procedures used to bond them to teeth are complex and require a skilled dentist. The main reason for composite replacement is adhesive failure due to combined bacterial and enzyme action. This failure enables microgap formation between the tooth and restoration through which more bacteria and enzymes can penetrate. As composites have no antibacterial action re-infection subsequently occurs. An alternative method of treatment is the ART approach. The atraumatic restorative technique (ART) was originally developed for regions of the world with limited electricity supply and no access to dentists and the associated infrastructure eg dental chair, compressed air etc. It is also favoured, however, by children due to reduced use of local anaesthetics / drills and greater procedure simplicity. It uses hand instruments to remove the bulk of the carious tissue and then a glass ionomer cement (GIC) to seal the cavity. Sealing halts the spread of any remaining infection. The good durability of the GIC / dentine bond has enabled this method to succeed in small cavities but failure in larger restorations is common due poor GIC strength. The aim of this study is therefore to develop new materials that are simpler to place, have the high strength of composites but the dentine adherence durability of GICs. These new materials contain a combination of components from dental composites and GICs but also calcium phosphate bone cements. In addition they contain antibacterial agents used in mouth washes and food preservatives. Effective antibacterial properties will enable the materials to be placed without the need for total removal of infected dental tissue. Furthermore the materials will release calcium phosphates that can undo the demineralisation damage caused by bacteria and thereby stabilise dentine against enzymes. This will enable a higher percentage of the original tooth structure to be preserved. Further smart features of the new materials will include their increase in antibacterial and calcium phosphate release in the presence of bacteria. Moreover, they will have the ability to self repair after any damage caused by chewing or large temperature variations (for example upon drinking hot drinks or eating ice cream). The conclusion will be increased restoration longevity and reduced pain and cost associated with dental caries.


Research activity codes: 5.3 MEDICAL DEVICES
Health categories: INFECTION;ORAL AND GASTROINTESTINAL