title: Assessing the irradiance delivered from light-curing units in private dental offices in Jordan.
abstract: BACKGROUND
  The authors conducted a study to examine the irradiance from light-curing units (LCUs) used in dental offices in Jordan.
  
  
  METHODS
  Two of the authors visited 295 private dental offices (15 percent) in Jordan and collected the following information about the LCUs: age, type (quartz-tungsten-halogen or light-emitting diode), date of last maintenance, type of maintenance, last date of use, number of times used during the day, availability of a radiometer, exposure time for each resin-based composite increment, size of light-curing tips and presence of resin-based composite on the tips. The authors used a radiometer to measure the irradiance from the LCUs. They used linear regression with stepwise correlation for the statistical analysis. The authors set the minimum acceptable irradiance at 300 milliwatts/square centimeter.
  
  
  RESULTS
  The mean irradiance of the 295 LCUs examined was 361 mW/cm(2), and 136 LCUs (46.1 percent) delivered an irradiance of less than 300 mW/cm(2). The unit's age, type and presence of resin-based composite on the light-curing tips had a significant effect on the irradiance (P ≤ .001).
  
  
  CONCLUSIONS
  Only 37 of the 141 quartz-tungsten-halogen units (26.2 percent) and 122 of the 154 light-emitting diode units (79.2 percent) delivered at least 300 mW/cm(2). Resin contamination on the light-curing tips had a significant effect on the irradiance delivered. The irradiance from the LCUs decreased with use. Practical Implications. The irradiance from many of the units in this study was less than 300 mW/cm(2), which may affect the quality of resin-based composite restorations. Dentists should monitor the performance of the LCUs in their offices weekly.
authors.affiliation: Department of Conservative Dentistry, Jordan University of Science and Technology, P.O. Box 3030, Irbid-22110, Jordan. gmaghair@just.edu.jo
authors.forename: Ghada A
authors.initials: GA
authors.lastname: Maghaireh
authors.forename: Hanan
authors.initials: H
authors.lastname: Alzraikat
authors.forename: Nessrin A
authors.initials: NA
authors.lastname: Taha
mesh_terms: D003188:Composite Resins / Q000528:radiation effects; D055117:Curing Lights, Dental / Q000145:classification / Q000592:standards / Q000706:statistics & numerical data*; D003764:Dental Materials / Q000528:radiation effects; D003770:Dental Offices; D004866:Equipment Contamination; D004867:Equipment Design; D006801:Humans; D007597:Jordan; D008283:Maintenance; D011331:Private Practice; D011829:Radiation Dosage; D011874:Radiometry / Q000295:instrumentation; D013499:Surface Properties; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003764:Dental Materials
keywords: Resin-based composites; dental offices; irradiance; light output; light-curing units; survey