title: Light curing in orthodontics; should we be concerned?
abstract: OBJECTIVE
  Light cured materials are increasingly used in orthodontic clinical practice and concurrent with developments in materials have been developments in light curing unit technology. In recent years the irradiances of these units have increased. The aim of this study was to determine the safe exposure times to both direct and reflected light.
  
  
  METHODS
  The weighted irradiance and safe exposure times of 11 dental curing lights (1 plasma arc, 2 halogen and 8 LED lights) were determined at 6 distances (2-60 cm) from the light guide tip using a spectroradiometer. In addition, using the single most powerful light, the same two parameters were determined for reflected light. This was done at a distance of 10 cm from the reflected light, but during simulated bonding of 8 different orthodontic brackets of three material types, namely stainless steel, ceramic and composite.
  
  
  RESULTS
  The results indicate that the LED Fusion lamp had the highest weighted irradiance and the shortest safe exposure time. With this light the maximum safe exposure time without additional eye protection for the patient (at 10 cm), the operator (at 30 cm) and the assistant (at 60 cm) ranged from 2.5 min, 22.1 min and 88.8 min respectively. This indicates a relatively low short term risk during normal operation of dental curing lights. For reflected light at a distance of 10 cm the risk was even lower, but was affected by the material and shape of the orthodontic bracket under test.
  
  
  CONCLUSIONS
  The short term risks associated with the use of dental curing lights, halogen, LED or plasma, appear to be low, particularly if as is the case adequate safety precautions are employed. The same is true for reflected light from orthodontic brackets during bonding. What is still unclear is the potential long term ocular effects of prolonged exposure to the blue light generated from dental curing lights.
authors.affiliation: Child Dental Health, School of Oral and Dental Science, University of Bristol, Bristol, UK.
authors.forename: Neil
authors.initials: N
authors.lastname: McCusker
authors.forename: Siu Man
authors.initials: SM
authors.lastname: Lee
authors.forename: Stephen
authors.initials: S
authors.lastname: Robinson
authors.forename: Naresh
authors.initials: N
authors.lastname: Patel
authors.forename: Jonathan R
authors.initials: JR
authors.lastname: Sandy
authors.forename: Anthony J
authors.initials: AJ
authors.lastname: Ireland
mesh_terms: D002516:Ceramics / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D055117:Curing Lights, Dental / Q000145:classification / Q000592:standards*; D003722:Dental Alloys / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D005135:Eye Protective Devices; D006801:Humans; D055115:Light-Curing of Dental Adhesives / Q000295:instrumentation*; D008452:Maximum Allowable Concentration; D016910:Orthodontic Brackets; D009970:Orthodontics; D011829:Radiation Dosage; D011835:Radiation Protection / Q000295:instrumentation; D011874:Radiometry / Q000379:methods; D012307:Risk Factors; D012449:Safety; D013193:Stainless Steel / Q000737:chemistry; D013997:Time Factors
chemical_list: D003188:Composite Resins; D003722:Dental Alloys; D003764:Dental Materials; D013193:Stainless Steel