Author Name/s: Lyne, A., Muirhead, L., Angus, K. and Ale-Gurung, L.
Journal Reference: Lyne, A., Muirhead, L., Angus, K. and Ale-Gurung, L. (2026) ‘The environmental impact of free-flow versus on-demand gas release for dental inhalation sedation’, British Dental Journal. Available at: https://doi.org/10.1038/s41415-026-9882-5 (Accessed: 7 October 2026)
Background:
Nitrous oxide (N₂O) is widely used for inhalation sedation in dentistry and is an effective conscious sedation technique. However, N₂O is a potent greenhouse gas and contributes to the environmental impact of healthcare. Current UK dental practice commonly uses a continuous free-flow of N₂O and oxygen, with flow rates determined by the clinical team. Previous national quality improvement data found that N₂O use during an individual sedation episode was associated with an average carbon footprint of 28.62 kg CO₂e.
Aims:
This quality improvement project aimed to determine whether two alternative inhalation sedation techniques could reduce the volume of N₂O required while maintaining effective patient care. The techniques investigated were Silhouette, using a low continuous flow rate, and eAdvantage, which delivers gas on demand.
Methodology:
The study was conducted at Eastman Dental Hospital, London, using a Plan-Do-Study-Act quality improvement methodology. Data were collected over six weeks between September and November 2025. Ninety-eight inhalation sedation episodes were observed across paediatric dentistry, special care dentistry and oral surgery. Patients received either current practice, Silhouette or eAdvantage. The primary outcome was the volume of N₂O used per sedation episode. Secondary outcomes included sedation success rates and feedback from patients, dentists and dental nurses.
Results:
Both alternative techniques substantially reduced N₂O consumption compared with current practice. Silhouette reduced N₂O use by 58%, while eAdvantage achieved a 70% reduction. Success rates were 97% for both current practice and eAdvantage, compared with 86% for Silhouette. Patient feedback was generally positive, while both dentists and dental nurses expressed a preference for eAdvantage.
Discussion:
The findings suggest that continuous free-flow delivery may provide more N₂O than is necessary for effective sedation. The 70% reduction achieved with eAdvantage could provide substantial environmental benefits; the authors estimated that this could save approximately 20.4 tonnes of CO₂ annually based on the hospital’s current procurement. However, the study’s small sample size, single-centre design and convenience sampling limit the ability to generalise the findings.
Conclusion:
Reducing or eliminating continuous N₂O flow during dental inhalation sedation appears to offer significant environmental benefits while maintaining effective patient care. eAdvantage demonstrated the greatest reduction in N₂O use without compromising the success rate, suggesting that on-demand delivery could be a promising approach for more sustainable dental sedation.
Research summary written by: Nour Al-arbi
University of Manchester- BDS4