title: Effectiveness of battery powered light activation units.
abstract: OBJECTIVE
  To investigate the effectiveness of chargeable light curing units and their ability to sustain a high radiant output following successive discharge cycles.
  
  
  METHODS
  University based research investigation assessing the output intensity of three battery powered light activation units and the effect of successive discharge cycles, without intervening periods of recharging, on light output and depth of cure of resin composite.
  
  
  METHODS
  Mean light intensity (mW/cm2), through a 4 mm aperture, was measured with a computer based radiometer. Two commercially available resin composites (one hybrid and one microfilled resin) were used for the depth of cure determinations using a digital penetrometer.
  
  
  RESULTS
  Depths of cure were significantly greater for the hybrid resin composite. Output intensity diminished over the period of battery discharge for two of the three units and this finding was paralleled in the depth of cure results. The battery light units tested varied significantly with regard to their length of discharge cycle and recharge times from complete discharge.
  
  
  CONCLUSIONS
  Output intensity diminishes over the period of battery discharge for some makes of battery light units. However, many other factors including handpiece size and weight and unit cost and reliability are important considerations when choosing a unit.
authors.affiliation: University of Birmingham, School of Dentistry, St Chad's, Queensway, Birmingham.
authors.forename: A C
authors.initials: AC
authors.lastname: Shortall
authors.forename: E
authors.initials: E
authors.lastname: Harrington
mesh_terms: D003188:Composite Resins / Q000737:chemistry*; D003199:Computer Systems; D003365:Costs and Cost Analysis; D003764:Dental Materials / Q000737:chemistry*; D003793:Dental Restoration, Permanent / Q000295:instrumentation*; D011211:Electric Power Supplies / Q000191:economics; D004867:Equipment Design; D006801:Humans; D008027:Light; D008029:Lighting; D008422:Materials Testing; D011874:Radiometry / Q000295:instrumentation; D015203:Reproducibility of Results; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials