Research at UCL Eastman is investigating how new ‘smart’ composite resin filling materials could make filling placement easier and less susceptible to bacterial contamination due to self-sealing, antibacterial and remineralizing properties.
These composites have the potential to reduce the need for complete caries removal and encourage a shift toward less invasive tooth restoration procedures that will allow for greater natural restoration under a filling. In addition, they could reduce the risk of long-term recurrent decay under fillings which is the main cause of restoration failure.
New study findings, published in Journal of Functional Biomaterialssuggest that dental composites, with higher early release of an antimicrobial substance called polylysine (PLS), are more effective in reducing the growth of harmful bacteria.
Dental caries is caused by specific oral bacteria (eg, streptococcus mutans and lactobacillus) that produce acids that deionize tooth enamel and then the underlying dentin. With the continued elimination of amalgam, composite fillings are the mainstay of dental treatment. Composite materials, however, have higher failure rates because, unlike amalgam fillings, they do not have antibacterial activity.
In addition, composite materials are difficult and time-consuming to place in very young children or other patients with special care needs in general dental practices. Consequently, the majority of young children are not hospitalized and have to wait many months for a hospital appointment. Materials that are self-sealing, antibacterial, and reversible have the potential for much easier placement that could help address this problem. An optimized formulation – known as Renewal MI – developed by the UCL research team, led by Professors Anne Young and Paul Ashley, is currently in phase II clinical trials at the Eastman Dental Institute.
“Renewal MI is a new type of dental filling material designed to fight bacteria and help teeth repair. Unlike regular fillings, these new composites contain special ingredients that may reduce the risk of recurrent caries and improve the long-term success of dental treatments,” says Lampis Petridis (UCL Eastman), Professor of Prosthodontics and co-author of the most recent experimental study.
Lead researcher Anne Young (UCL Eastman) Professor of Biomaterials and corresponding author of the study notes: “MI regeneration composites are made with reactive fillers including polylysine (PLS) and calcium phosphate monohydrate (MCPM). Both are widely used in food and are generally recognized as safe. These components contribute to the unique properties of composites. For this study, we mixed different compound formulations – with increasing levels of PLS - to assess the effect it had on oral bacteria. Overall, we found that increasing PLS content in dental composites led to a reduction in the early development of oral streptococcus mutans biofilms on the composite surfaces. This could be achieved with only a minimal reduction in the long-term strength of the composite.”
Professor Young adds: “While these findings offer promising insights into the development of advanced dental materials, it is important to note that additional research and clinical trials are needed to determine the long-term efficacy and safety of smart composites in caries prevention in clinical practice.” . Phase I clinical trials of an optimized formulation – Renewal MI – demonstrated that it could be placed in less than five minutes directly into minimally excavated caries. Phase II clinical trials to assess the longevity of the rehabilitation are underway at UCL Eastman’s Department of Paediatrics with Professor Paul Ashley.
Professors Anne Young and Paul Ashley described this work in a public presentation on Tuesday 16 January 2024. View the recording:
