This website uses cookies to help us understand the way visitors use our website. We can't identify you with them and we don't share the data with anyone else. If you click Reject we will set a single cookie to remember your preference. Find out more in our privacy policy.

Innovating to reduce nitrous oxide waste in dentistry

In 2025, a team at the Royal National ENT and Eastman Dental Hospital (part of University College Hospitals London NHS Foundation Trust) ran a pilot to reduce nitrous oxide waste in dental settings, leading them to make changes which reduced not only the waste, but also the clinical demand of nitrous oxide.

Nitrous oxide waste

Nitrous oxide is used in dentistry for sedation and to support safe, effective care. It is delivered either via small, portable cylinders or via medical gas pipeline systems. In most dental settings portable cylinders are used but medical gas pipeline systems are used in large dental hospitals.

It is widely recognised that up to 99% of nitrous oxide delivered via these medical gas pipeline systems is wasted. In 24/25, NHS England launched a programme to reduce this, saving 80 ktCO₂e & £2.3 million in avoided costs.

However, previous national efforts have focused on areas such as anaesthetics and emergency departments, as opposed to dental settings that present a different challenge.

In dentistry, nitrous oxide is mixed with oxygen at a level determined by a clinician. This mixed gas is then typically delivered to the patient at a steady rate manually set by the clinician. This is known as continuous flow (or free flow). The exact flow rate is tailored to each patient based on their breathing. Dentists monitor and adjust the flow rate by checking the reservoir bag remains sufficiently inflated (a bag that stores gas connected to the sedation equipment).

The gas travels through tubing to a nasal mask for a patient to inhale. Because the gas is being supplied continuously, much is not inhaled, and is wasted. The graphic depicts how sedation was typically delivered at the Eastman Dental Hospital before the pilot.


Findings from the pilot suggest that the continuous flow gas system delivered more gas than necessary for successful treatment , highlighting a previously under-recognised opportunity to reduce waste in dental sedation.

The pilot

The Eastman Dental Hospital, part of University College Hospitals London NHS Foundation Trust, provides specialist dental care for both adult and paediatric patients. It sees approximately 800 cases each year where nitrous oxide may be required for sedation.

The Eastman dental hospital relies on a medical gas pipeline of nitrous oxide. The manifold (where multiple large cylinders are plugged in to supply the medical gas pipeline) represents the single largest source of nitrous oxide use across the Trust, accounting for approximately 61% of all nitrous oxide cylinders procured annually (around 54,000 litres), costing £1,700 annually to maintain .

Teams at the Eastman Dental Hospital sedated patients using the continuous flow method. They wanted to test new approaches to reducing nitrous oxide waste:

  • To reduce continuous flow waste
  • Without compromising patient experience or clinical outcomes
  • And to enable them to remove their large medical gas pipeline system that was oversized for their clinical demand

They did this across three dental specialties: Paediatric Dentistry, Special Care Dentistry and Oral Surgery.

The team’s findings have wide applicability across the NHS due to their identification and mitigation of continuous flow waste.

The innovations

The team tested two innovations these were eAdvantage™ and Silhouette™ – coupled with a low flow protocol. Each innovation addressed continuous flow waste in different ways. Both had positive results. eAdvantage™ achieved a 70% reduction in nitrous oxide use per patient. Silhouette™ coupled with a low flow protocol achieved a 58% reduction in nitrous oxide use per patient.

More information can be found in the downloadable case studies:

The impact

The Eastman Dental Hospital has decided to adopt the eAdvantage™ system as its primary approach to nitrous oxide delivery. Seven have been procured to meet clinical demand across the site. This will deliver the greatest reduction in nitrous oxide use while maintaining high levels of clinical and patient acceptability.

Alongside this, the trust is now exploring decommissioning the nitrous oxide manifold (which previously was not possible), to help further reduce waste.

The team also plans to maintain a supply of Silhouette™ nasal masks coupled with a low flow protocol specifically for its advanced sedation clinics, which treat around 40 patients per year.

This pilot has allowed initial insights into two possible approaches and insights into nitrous oxide waste in dental settings. However, given the small sample sizes, results should be treated as indicative rather than conclusive. Services considering this approach should review their own local context, clinical needs and existing equipment before deciding whether to adopt any innovation.

Further resources and information on this trial will include the Eastman Dental Hospital team’s forthcoming publication and project report.

UCLPartners supported this pilot by brokering the introduction to the UK supplier of eAdvantage™ and providing guidance in our capacity as a health innovation network.

For more information, contact sustainablility@uclh.nhs.uk  

References

  • Lyne, A., Muirhead, L., Angus, K. and Ale-Gurung, L. (2026) ‘The environmental impact of free flow vs on-demand gas release for dental inhalation sedation’, British Dental Journal. (corresponding author alexandra.lyne@nhs.net)