title: An in vitro evaluation of the efficiency of an air-abrasion system using helium as a propellant.
abstract: OBJECTIVE
  Helium is currently used as a propellant gas for air-abrasion with manufacturer claims that this affords greater cutting efficiency compared to the use of air as a propellant. Higher cutting rates, when desired, can reduce operative times. This study set out to investigate these claims by comparing the rate at which helium propelled air-abrasion cut a standard enamel analogue, Macor, versus that of standard air propelled air-abrasion at different propellant pressures.
  
  
  METHODS
  An enamel substitute, Macor, was used as the substrate in order to enable a greater control of physical variables. Powder flow rate, air abrasion nozzle distance and angle to the enamel substitute were constant throughout the experiments. The cutting efficiency of air and helium with propellant pressures of 20, 40, 60, 80 and 100PSI were dynamically investigated, attempting to replicate clinical use.
  
  
  RESULTS
  Helium air-abrasion was significantly more efficient in cutting the enamel analogue at all pressures, with a 40% increase for 100PSI propellant pressure.
  
  
  CONCLUSIONS
  This finding suggests that air-abrasion units using helium as a propellant will be able to cut enamel more quickly in the clinical setting.
authors.affiliation: Departments of Biomaterials and Conservative Dentistry, King's College London Dental Institute at Guy's Hospital, KCL, London, UK.
authors.forename: George
authors.initials: G
authors.lastname: Paolinelis
authors.forename: Avijit
authors.initials: A
authors.lastname: Banerjee
authors.forename: Timothy F
authors.initials: TF
authors.lastname: Watson
mesh_terms: D000335:Aerosol Propellants / Q000008:administration & dosage*; D000388:Air; D020906:Air Abrasion, Dental / Q000295:instrumentation / Q000379:methods*; D000537:Aluminum Oxide / Q000008:administration & dosage; D002516:Ceramics / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D006371:Helium / Q000008:administration & dosage*; D006801:Humans; D008422:Materials Testing; D011208:Powders; D011312:Pressure; D012212:Rheology; D013499:Surface Properties
chemical_list: D000335:Aerosol Propellants; D003764:Dental Materials; D011208:Powders; D006371:Helium; C023506:Glass ceramics; D000537:Aluminum Oxide