Assertion: nitrous oxide | /r/ObjectUse | used for year
Facets:
value: in the practice of dentistry
type: LOCATION
Source sentences:
text: Nitrous Oxide (NO2)-commonly referred to as ‘ gas' was used for years in the practice of dentistry.
text: Nitrous oxide (N 2 O) has been used for years as an essential part of general anaesthesia.