Introduction

One of the major challenges of the twenty-first century has been global warming induced climate change, proven unequivocally as the cause of unprecedented drastic weather events across the globe, not observed over the past decades or millennia.1 The first climate change risk assessments (CCRA) carried out for the UK in 2012 predicted drier summers with heat-waves, winters with greater rainfall leading to flooding, and higher air pollution.2,3 Human activity is said to be the dominant cause of this observed warming since the mid-twentieth century. Exponentially increasing energy demands are met by progressively burning greater amounts of fossil fuels, which release greenhouse gases in amounts greater than what can be neutralised by the natural eco-systems of earth. These are in turn being depleted, consequent to excessive exploitation, in the process of creating products for human consumption and degraded by the toxic pollutants released in them, thus rendering them unable to arrest the vicious cycle of global warming.1

Heightened environmental awareness or eco-consciousness in recent times, has translated into a gradual global movement to mitigate environmental damage, leading to 'green' transformations, where 'green' is defined as 'having positive environmental attributes or objectives.'4 In the UK the government has legally binding requirements to reduce carbon emissions by 80% by 2050 compared to 1990 levels.5 The healthcare sector through the NHS aims to contribute to this target, by reducing its emissions by 34% by 2020.6 The Sustainable Development Unit (SDU) of NHS England and Public Health England facilitates achieving this by developing tools, policy and research for sustainable practices which reduce carbon emissions, minimise waste and pollution and make best use of scarce natural resources.6 Dentistry lacks such information, evidence or even studies on sustainable practices7 which is why efforts on greening practices have been scant and mostly been founded on compiled lists of general suggestions.8 Therefore, the aim of this paper is to describe a broad range of areas where dentistry has an impact on the environment and where interventions could be targeted to incorporate sustainability principles.

'Green dentistry' also described as eco-friendly dentistry, has been described by Dr Ali Farhani as an:

'approach to dentistry that implements sustainable practices by keeping resource consumption in line with nature's economy, by safeguarding the external environment by virtue of eliminating or reducing outgoing wastes and by promoting the well-being of all those in the clinical environment by conscious reduction of the chemicals in the breathable air.'9

The term 'eco-friendly dentistry' was patented and trademarked by Dr Goran Kralj, Dr Steven Koos, and Mladen Kralj, the founders of ORA Dental Studio, a green group dental practice.10 They describe that 'eco-friendly dentistry, through green design and operations, protects the immediate health of patients and team members, protects the health of the surrounding community, and protects the health of the global community and natural resources.'10 These concepts are based on the principle of sustainable development which is defined as development that 'meets the needs of the present without compromising the ability of future generations to meet their own needs.'11

The main document on sustainable health practices in the UK is the Sustainable Development Strategy for the Health, Public Health and Social Care System 2014-2020.12 It highlights eight key areas for implementing sustainability in healthcare which are: i) Carbon hotspots; ii) Commissioning and procurement; iii) Sustainable clinical and care models; iv) Healthy, sustainable and resilient communities; v) Metrics; vi) Innovation, technology and R&D; vii) Creating social value; and viii) Leadership, engagement and development.12,13 The underlying principles of sustainability in these eight key areas will be used to outline the action plan for a sustainable practice customised to dentistry.

Carbon hotspots

These are sources with a high level of carbon emissions, which in healthcare, have been identified as: 1) Pharmaceuticals, medical devices and gases; 2) Energy; 3) Travel and transport; 4) Waste; and 5) Anaesthetic gases.14 By targeting these domains, significant reductions in the carbon footprint can be achieved through strategies, which are discussed below.

1. Pharmaceuticals, medical devices and gases

In dentistry biomaterials are the equivalent of medical pharmaceuticals, and these fall in one of the three categories of polymers, metals or chemicals. Their environmental impact includes emissions generated by businesses in manufacturing the products and transporting them, their impact during clinical use and post-usage end-of-life disposal. The three Rs, 'Reduce, Reuse, and Recycle', apply to sustainable biomaterial usage. In recent times, 'energy recovery' and 'molecular redesigning' have also been added to make up the five Rs.15

Polymer products are integral to the practice of dentistry, be it as a bonding agent or impression material or the plastic packaging in which materials are supplied. Table 1 shows their impact and environmentally-friendly use. Metals in the form of instruments and wires are also the mainstay of dentistry. Toxic by-products released while mining and refining the natural resources to obtain metals in usable form, and their continued leaching into the environment after their disposal, are their environmental hazards.18 Instruments being amenable to sterilisation are constantly reused, however, reusing or recycling orthodontic appliances like brackets, bands and wires remains a contentious issue due to the significant clinical, financial, ethical and legal issues associated with it.19 A survey of British Orthodontic Society members revealed that 47.5% of respondents recycled metal brackets, with 96% of consultants and 92% of specialist practitioners not informing their patients that they used recycled brackets.19 Patients have a highly negative psychological reaction towards reuse with 33–57% being unwilling to permit the use of recycled brackets and 85% stating there should be a reduction in fees for those who are treated with recycled brackets.20 Hence, while reusing orthodontic brackets in other patients, clinicians should keep themselves updated with new studies, evidence, legislation or guidelines with respect to the use of reconditioned appliances, maintain documented records for quality checks and using recycling services, limit the number of reuses, obtain informed consent from patients and offer a reduction in fees. Chemicals, radiation, indoor air quality, dental operatory environment, paper and electronic usage contribute to significant environmental impact in dental practices and measures to mitigate the same are discussed in Tables 2 and 3.

Table 1 Biomaterials used in dentistry: environmental impact and mitigation measures
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Table 2 Air quality: environmental impact and mitigation measures
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Table 3 Paper and general electronics: environmental impact and mitigation measures
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2. Energy

In the healthcare system, energy usage contributes to 15% of the carbon footprint, with a significant component attributed to buildings.35 This can be reduced by increasing energy efficiency, reducing unnecessary usage and using low carbon energy. 'Green buildings' incorporate design features which enhance energy and resource efficiency by 40–45%, and consequently reduce energy demand, energy bills and emissions, compared to traditional buildings.36 Without green features, buildings contribute to 24% of the total healthcare system carbon footprint by consuming more than £410 million worth of energy.37 The UK Climates Impact Programme has published information for construction of new healthcare buildings.38 The UK government has set a target for new public sector buildings to be zero carbon from 2018 onwards, and the NHS healthcare buildings aimed to be low carbon by 2015.39,40

At the core of dental practice, is the use of various electronic equipment for diagnosis and treatment, which by virtue of being indispensable make the practice of dentistry highly energy intensive. Hence, a cost-benefit analysis while purchasing or replacing any equipment, should also include energy efficiency assessment. Energy audit and monitoring can help reduce overall energy consumption, the steps for which consist of studying the energy usage, identifying areas of energy wastage and implementing actions to plug the leaks. Plugging can involve fixing issues like air gaps in the building envelope, energy inefficient electronic equipment, leaking taps and faucets or keeping lights and HVAC on at all times, even in areas of low usage etc. Power consumption over at least one week is recorded to obtain a base figure against which energy improvements are measured. Several online websites provide simple step-by-step instructions for carrying out energy audits. Real-time electricity measuring devices can also be used to track energy flow in specific areas.41

In large set-ups the Building Energy Management System (BEMS), which consists of a real-time monitoring network to control and regulate the building service performances including HVAC, compressors, air handling units, water pumps, fans etc, can be employed. BEMS is estimated to reduce 10% or more of total energy costs.42 Great Ormond Street Hospital has implemented the Smart metering system and publishes real-time information on their website regarding energy use in kilowatt, hours, cost and carbon emissions, thus providing accessible feedback to users, stakeholders and the public.43 Energy management is a continuous process and has to be continually appraised and repeated in cycles to accrue major and lasting environmental and economic gains from the same. Switching over to cleaner, low-carbon fuels and other strategies to reduce energy-related emissions are discussed in Table 4.

Table 4 Sustainable energy management strategies: increase efficiency, reduce usage, alternative low carbon sources
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3. Travel and transport

Travel and transport form 13% of the health, public health and social care carbon footprint, which can be reduced by employing alternative sustainable options like:35

  • Increasing active travel by cycling or walking, carpooling, using mass transit systems

  • Switching over to vehicles which reduce fossil fuel usage or run on alternate energy sources, by staff, service users

  • Selecting location of services close to public transit systems

  • Choosing manufacturers and disposal services closer to end user to reduce carbon emissions resulting from transportation of goods and long supply chains52

  • Employing technology for communication and professional interactions to reduce travel-related emissions. Teledentistry is the use of information technology and telecommunications. It greatly increases access and communication between practitioners, peers and patients, while totally eliminating the need to travel and meet in person to discuss the same.53 Similarly, using digital intra-oral scanners, 3D models, digital images, and transmitting them electronically instead of shipping their physical counterparts to the lab or professionals, eliminates emissions resulting from the transportation.

4. Waste

The British Dental Association guidance requires that dentists should identify each waste product as hazardous (including clinical waste), non-hazardous or offensive and document how each of them are handled in the practice.7 Mercury has always raised great concerns in dentistry. Although its use in dental fillings poses no hazards for intra-oral application, its post-use disposal in dental operatory and crematorial emissions create grave environmental issues.54,55 The European Union has adopted phase-down of the use of dental amalgam driven by these environmental reasons.56

Green waste management additionally advocates reduction of waste at source referred to as 'waste minimisation' by: a) material elimination, change or product substitution – for example, substituting a hazardous cleaning solution with non-toxic biodegradable cleaner; using multiple-use instead of single-use products; b) Technology or process change, for example, using non-mercury alternatives; using ultrasonic or steam cleaning instead of chemical-based cleaners; c) Good operating practice, for example, improving inventory control; covering disinfecting solution trays to prevent evaporative losses; d) Preferential purchasing such as selecting vendors with reduced packaging.57

Final disposal of hazardous medical waste by incineration has serious environmental concerns due to production of noxious emissions containing dioxins, furans, fly ash with heavy metals, etc. Alternative non-incineration technologies, like autoclave, dry heat, electrothermal deactivation, reverse polymerisation, plasma pyrolysis, biological enzyme-based reduction, etc, reduce hazardous medical waste to unrecognisable remnants which can then be discarded safely in a sanitary landfill.57 Waste management companies which generate electricity or heat from waste and sometimes even recycling the waste streams where possible, are accredited and provide a suitable sustainable option for dentists.8

5. Anaesthetic gases

Use of nitrous oxide combined with oxygen as an anaesthetic in dentistry contributes to some environmental concerns, since nitrous oxide is estimated to contribute about five percent to the greenhouse effect.58,59 However, only 0.35–2%, is actually attributed to combined medical and dental applications of nitrous oxide gas.59 SDU statistics reveal that desflurane and nitrous oxide caused the most global warming and sevoflurane the least.60 Hence, using sevoflurane, which was found to be a safe and effective alternative to nitrous oxide for dental application would make practice more environment-friendly.61

Commissioning and procurement

The procurement of goods and services represents 72% of the NHS, public health and social care carbon footprint and over £40 billion each year is spent on procuring large amounts of goods, services and infrastructure.62 This offers a great impetus for healthcare systems to ask for, and the suppliers of goods and services to offer, more sustainable, environmentally-friendly and socially responsible practices. For dental product companies in the UK, the British Dental Industry Association (BDIA) requires member companies to 'demonstrate a commitment to environmentally sound procedures' by having an environmental policy in place,8 which includes reducing the requirement for fresh natural resources by making efficient use of existing resources, minimising production of toxic, hazardous waste and emissions released during production and recycling and reusing waste materials, prioritising local procurement and production factors, making up for the natural resources consumed by implementing measures like reforestation, rain-water harvesting, etc.63

Sustainable clinical/care models

Delivering the highest quality of care is the core value and intent of every dental health service provider. Adoption of environmentally-friendly measures should not be allowed to undermine the core value, hence the sustainable clinical care model should be built by adding the following elements (Fig. 1):

  • Effective care: consisting of the delivery of the right evidence-based intervention at the right time and in the right place.

  • Positive experience: by customising treatment to patient needs while treating them with compassion, respect and dignity

  • Safe care: where people are protected from physical, psychological or emotional harm.

Figure 1
figure 1

Elements of a sustainable clinical care model

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In short, clinical care delivery can minimise embedded carbon emissions, mainly by considering the environmental impact and toxicity of products and pharmaceuticals, appropriately identificatying and eliminating waste and conserving existing resources, all of which have been discussed in detail in the previous section.64

Communities

Dental practices, organisations and boards, by embracing sustainable practices and policies, can contribute to the health and resilience of their local community network, through both simple interventions adopted in day-to-day practice, to system-wide long-term strategies to mitigate environmental damage. Being aligned with their local authorities, they can also be of help in developing cross agency partnerships and responding to emergencies and extreme events at the local level by extending coordinated collaborative working.65

Metrics

Sustainable development in dentistry has to be measured to improve understanding, recognise effective actions and areas needing improvement, foster accountability and monitor long-term progress. Examples of metrics include measuring the amount of carbon dioxide reduction, energy and water efficiency, recycling and waste volumes, emissions and mileage.66 Scotland's NHS is probably the first in the world to quantify emissions from dental services, which amounted to 0.16 mega tonne (Mt) CO2eq and contributed to 4% of the total Scottish NHS carbon footprint. Procurement gave rise to 36% of the carbon footprint and 18% was attributed to building energy, with nearly half of the carbon emissions relating to patient and staff travel.67

Although measurements can be carried out and monitored at individual practice levels or on smaller scales, standardisation of metrics and sustainability impact assessments for quantification across the breadth and depth of all processes and actions in healthcare is required. This is still in its infancy and much needs to be developed. The Sustainable Development Unit's metrics steering group intends to address the issue by developing core measures, indicators and measurement mechanisms in healthcare.66

Innovation, technology and R&D

The key to maximising sustainability in dentistry lies in the innovation of green dental products and processes, refining available or developing newer technologies and initiating research in the area of sustainable practice to generate data where none exists so far, to guide future actions. Currently, very few green products, for example Earth-friendly High Volume Evacuator paper tips or non-toxic, non-corrosive, environment-friendly waterline treatment systems, exist in the market.68 Demand from the dental fraternity can spur the manufacturers to innovate, design and supply more 'green' products and adopt measures like reduced packaging.69

The emerging field of 'green chemistry', aims to design fully effective chemical products which have little or no toxicity or endocrine-disrupting activity, and break down into innocuous substances if released into the environment after use.15 'Bioplastics' are environment-friendly organic plastics derived from renewable biomass sources, such as vegetable oil, corn starch, microbiota, etc. However, their lower emissions and higher green quotient notwithstanding, these products pose a threat to global food security due to deforestation and diversion of agricultural land for alternate purposes.70 Thus, the challenge in innovating 'green' products, lies in balancing eco-friendly attributes with practicality, usability and biocompatibility. Research and development in the hitherto unexplored field of green dental biomaterial research offers new opportunities, possibilities and scope for the sustainable future of dentistry, based on green chemistry.

Creating social value

The three domains of sustainable health delivery are environmental, financial and social. Social value is created not only by local commissioning and procurement but also through the non-investment positive value that is added to the community by adopting ecologically valuable traits. An Environmental Impact Assessment (EIA) aids in measuring the effects of a practice or organisation on its locality and its resources to identify opportunities and initiate action to add more social value.8 Dental professionals by virtue of their services which engage individuals, families and communities in a day-to-day manner, have a privileged position to make a big impact by practically, ideologically and economically supporting the green movement. Thus, the practice not only provides mere dental services, but also adds positive value to the community and environment they are rooted in.

Leadership and development

Engagement of stakeholders including staff, patients and community for sustainable care delivery is essential so that they understand the value of measures being implemented and enthusiastically participate to ensure success. Training NHS staff to implement energy efficiency measures with the intent to improve patient experience resulted in estimated savings of up to £800,000 on energy bills across the trust's £12m energy bill. In England some Royal colleges and professional bodies have clinical sustainability fellows, and trade unions of the NHS have 'green workplace' initiatives. Clinical services are being delivered on models of sustainable care and junior staff have also organised themselves into a sustainable development training network.71

However, bringing a shift in thinking and practice to adopt newer changes has never been easy, and barriers are posed by lack of information, attitudinal issues and perceptions that sustainable practice is financially burdensome, or increases costs.8 In reality, adopting energy efficiency measures cuts down on energy costs, mitigation measures to ensure a healthier environment reduce expenses incurred due to poor health, lost economic output and cleaning up of toxic waste generated, sound procurement policies strengthen economy and green energy usage minimises effects of fluctuating global oil prices. Working in a sustainably designed environment has shown to bring about a 3–18% increase in individual productivity and 40% increase in organisational sales.72 Low-cost energy efficiency measures have been proven to be equally if not more effective than high-cost technological applications.73 As refinements in green technologies and infrastructure continue, the cost of green products and associated green services is bound to come down, thus automatically rationalising the financials involved. Additionally, as the momentum for environmentally-responsible actions picks up, and governments across the world increasingly make environmental abuse unviable by imposing green taxes, carbon taxes, or fines on polluters, going green remains the only financially advantageous option in the long run.

Removal of barriers and adoption of guidance are shown to be more successful when there is strong professional support, the professionals involved are not isolated and the evidence base is stable and convincing.74 Restructuring and reinforcing new practice norms by opinion leaders, educational outreach, educational meetings and materials/guidelines, and associating them with peer and reference group behaviours by emphasising the expectations of an external reference group through reminders, audit and feedback are more likely to lead to behaviour change.75 Dental bodies having failed to recognise this critical aspect of the profession thus far, have zero guidance, targets or framework for sustainable dentistry. Developing the plan and providing support and leadership to implement the same has never been more important, since, all this while, sustainable initiatives have been at a small scale and adopted voluntarily by groups or professionals as an ethical duty and practical requirement, in the absence of comprehensive standards or guidelines. Efforts can begin with initiatives like consistent data collection in practice to enhance understanding and identify opportunities for action, developing green dentistry benchmarks, teaching sustainability principles by including them in training curriculums, initiating research and creating awareness.

Dentistry is a profession with serious environmental concerns by virtue of the materials used, waste generated and high electricity and water consumption involved. Practising environmentally sound and socially responsible dentistry may entail a recalibration in our understanding of the concept of 'value for money' by not only thinking about value in terms of equivalent revenue savings, but also by taking into account the investments to save the planet.76 A survey of the general public found that 89% think it is important for the healthcare system to become more sustainable and 36% said sustainability should be adopted in the healthcare system even if it costs more money.77 Often, patients equate the quality of a dental office with the quality of care, hence the adoption of sustainability definitely helps foster a positive practice image and values.78 Sustainable practice is beneficial not only for practitioners, patients and local communities but also for global health and wellbeing; a reason good enough to inspire systematic efforts towards greening dentistry.