Plastic restorative materials as potential environmental pollutants

Grantham Scholar Steven Mulligan is investigating ways dentistry can be made more sustainable as well as wider issues in healthcare. 

Background to the project

I am a general dentist working in primary care and also a clinical academic in the School of Clinical Dentistry, TUoS.

My research started with looking at the environmental impact of dental filling materials. Basically, silver amalgam restorations (fillings) are made with 50% by weight inorganic mercury. Through the use of this material, it gets into the environment and mercury is bad in lots of ways. To that end, the Minamata Treaty was ratified to reduce the anthropogenic release of mercury into the environment and dental amalgam fell under the auspices of this international agreement.

As a result, dentistry has to phase-down and hopefully stop using dental amalgam, but what will we use instead? The answer is that the current most suitable alternative is a material called resin-based composite (RBC). This is a tooth coloured material that bonds to tooth structure. It is made of glass and resin monomers (plastic).

The project

So the question is, if we stop using amalgam and replace it with RBC, is RBC a potential environmental issue? And the answer is, of course it is. The amount of single use plastic, energy and other environmental burdens (these materials leach bisphenol-A, a nasty chemical and when they are removed, or polished they generate microparticulate waste – a bit like microplastics!) make it a great topic for a PhD. This is my project, looking into the environmental impacts of RBC.

Further, my research has expanded to include sustainability in healthcare in general and I have been involved in research into the circular economy of healthcare’s single use plastics (I was a co-I on Plastics: Redefining Single-use), various clinical trials, the attitudes and opinions of the public regarding sustainability in dentistry and analysis of micro-particulate RBC waste.

In addition I was asked to be a founding member of the FDI World Dental Federation Sustainability in Dentistry Task Team. One of the Task Team’s roles is working alongside major dental industry companies to map out strategies and implement solutions to help reduce the environmental impact of dentistry and the dental industry in the supply chain. The intention of this is the development and future publication of an FDI Sustainability Code of Practice that provides guidelines and objectives for sustainable procurement and supply procedures, which will be signed and adopted by co-signatories across the supply chain. More information can be found here.

Steven Mulligan’s publications

Lucy Smith, Mustafa Ali, Manon Agrissais, Steven Mulligan, Lenny Koh, Nicolas Martin, A comparative life cycle assessment of dental restorative materials, Dental Materials, 2022, ISSN 0109-5641,

Martin, N., & Mulligan, S. (2021). Environmental sustainability through good-quality oral healthcare. International Dental Journal. doi:10.1016/j.identj.2021.06.005

Mulligan, S., Ojeda, J. J., Kakonyi, G., Thornton, S. F., Moharamzadeh, K., & Martin, N. ( 2021). Characterisation of microparticle waste from dental resin-based composites. Materials, 14(16). doi:10.3390/ma14164440

Kakonyi, G., Mulligan, S., Fairburn, A. W., Moharamzadeh, K., Thornton, S. F., Walker, H. J., . . . Martin, N. (2021). Simultaneous detection of monomers associated with resin- based dental composites using SPME and HPLC. Dental Materials Journal, 40(4), 1007-1013. doi:10.4012/dmj.2020-240

Martin, N., Smith, L., & Mulligan, S. (2021). Sustainable oral healthcare and the environment : mitigation strategies. Dental Update, 48(7). doi:10.12968/denu.2021.48.7.524

Martin, N., Sheppard, M., Gorasia, G., Arora, P., Cooper, M., & Mulligan, S. (2021). Drivers, opportunities and best practice for sustainability in dentistry: A scoping review. Journal of Dentistry. doi:10.1016/j.jdent.2021.103737

Martin, N., Sheppard, M., Gorasia, G., Arora, P., Cooper, M., & Mulligan, S. (2021). Awareness and barriers to sustainability in dentistry: A scoping review. Journal of Dentistry. doi:10.1016/j.jdent.2021.103735

Mulligan, S., Smith, L., & Martin, N. (2021). Sustainable oral healthcare and the environment : challenges. Dental Update, 48(6), 493-501. doi:10.12968/denu.2021.48.6.493

Falyouna, O., Kakonyi, G., Mulligan, S., Fairburn, A., Moharamzadeh, K., Martin, N., & Thornton, S. (2018). Behavior of dental composite materials in sterilized and non- sterilized landfill leachate. doi:10.15017/1961288

Mulligan, S., Kakonyi, G., Moharamzadeh, K., & Martin, N. (2018). The environmental impact of dental amalgam and resin-based composite materials. British Dental Journal , 224, 542-548. doi:10.1038/sj.bdj.2018.229


Professor Nicolas Martin

School of Clinical Dentistry


Professor Barry Gibson

School of Clinical Dentistry