Dental caries amongst children is a significant dental public health problem as it is highly prevalent globally [1]. Dental caries can have social, psychological, environmental and economic impacts on children and broader societies despite being preventable [2,3]. Dental caries can be prevented and controlled effectively by targeting younger children with evidence-based oral health improvement programmes [4], [5], [6]. In Scotland, the government funded a nationwide supervised toothbrushing in early years childcare called the Childsmile programme. Since its implementation in 2001, this programme has successfully reduced inequalities in dental health amongst 5-year-old children and improved their access to dental services [6]. In Childsmile, every 3- to 4-year-old child attending early years childcare (whether local authority, non-profit or private early years childcare) is provided with free, daily toothbrushing under teacher supervision with support from dental services [7].

From a global health perspective, it is essential to evaluate the effectiveness of a healthcare intervention by using the triple bottom line of sustainability framework in terms of clinical, cost and environmental sustainability. An analysis of the nationwide Childsmile programme revealed a significant decrease in the prevalence of decayed, missing and filled teeth (dmft) in primary dentition amongst children. This reduction has effectively alleviated the financial burden of dental treatment on healthcare institutions [6,8]. However, more research needs to be done on its environmental impact with the use of the life cycle assessment (LCA).

LCA is a systematic methodology used in industry and healthcare to understand the environmental impact of specific healthcare products or services, from raw material extraction to disposal or recycling. LCA has been utilised in dentistry to assess the environmental impact of prevention programmes, including water fluoridation, early years childcare toothbrushing programme, fluoride varnish application and provisions of toothbrushes and toothpaste [9], [10], [11], [12], [13]. Research has shown that community water fluoridation had the lowest annual carbon footprint amongst these programmes, followed by supervised toothbrushing and fluoride varnish. Additionally, supervised toothbrushing emitted 1.5 times less CO2e than providing toothbrushes and toothpaste to children in the UK [11]. In Wales, the Designed to Smile (D2S) programmes, which comprise of supervised toothbrushing and fluoride varnish for nursery and infant schools, resulted in an estimated 388 tonnes of CO2e emissions in 2016/17 [13]. While these studies have predominantly focused on assessing the environmental effects of various caries prevention programmes and their relative comparisons, there has been no investigation into the quantification of CO2e emissions associated with the implementation of an early years childcare supervised toothbrushing programme, as opposed to the potential CO2e emissions savings resulting from investing in such a programme. This study, therefore, aims to assess the environmental impact of providing Childsmile programme for 5-year-old children in Scotland.