title: Transmission of violet and blue light through conventional (layered) and bulk cured resin-based composites.
abstract: This study measured the transmission of light in the 'violet' (350≤λ≤425nm) and 'blue' (425<λ≤550nm) spectral ranges from a polywave(®) LED curing light through different thicknesses of four commercial, resin-based composites (RBCs).
  
  
  
  Samples of conventional layered RBCs (Tetric EvoCeram A2, Filtek Supreme Ultra A2B), and bulk-curing resins (Tetric EvoCeram Bulk Fill IVA, and SureFil SDR Flow U) were prepared. Three samples of each RBC were made at thicknesses of 0.1, 0.7, 1, 2, and 4-mm. The uncured RBC specimens were affixed at the entrance aperture of a 6-inch integrating sphere and light-cured once for 20s using a polywave(®) LED curing light (Bluephase G2) on its high power setting. The spectral radiant power transmitted through each RBC in the 'violet' and 'blue' regions was measured using a fiberoptic spectrometer.
  
  
  
  As RBC thickness increased, an exponential attenuation of transmitted light was measured (R(2)>0.98). Attenuation was greater for the 'violet' than for the 'blue' spectral regions. At the light tip, the violet light component represented 15.4% of the light output. After passing through 4-mm of RBC, the violet light represented only between 1.2-3.1% of the transmitted light depending on the RBC. Depending on RBC, approximately 100mW from the Bluephase G2 was transmitted through 0.1-mm of RBC in the 'violet' range, falling at most to 11mW after passing through 2-mm of RBC, and to only 2mW at 4-mm depth.
  
  
  
  Increasing RBC thickness results in an exponential decrease in light transmission. This attenuation is RBC-dependent with shorter wavelengths (violet) attenuated to a greater extent than longer wavelengths (blue).
  
  
  
  Despite the increased translucency of bulk curing RBCs, spectral radiant power shorter than 425nm from a curing light is unlikely to be effective at a depth of 4-mm or more.
authors.affiliation: Dental Clinical Sciences, Dalhousie University, P.O. BOX 15000, Halifax (NS), B3H 4R2, Canada. Electronic address: Jessie.Harlow@Dal.Ca.
authors.forename: J E
authors.initials: JE
authors.lastname: Harlow
authors.affiliation: Department of Oral Rehabilitation, Section of Dental Materials, Dental College of Georgia, Augusta University, Augusta, GA, United States. Electronic address: frueggeb@augusta.edu.
authors.forename: F A
authors.initials: FA
authors.lastname: Rueggeberg
authors.affiliation: Department of Physics and Atmospheric Science, Dalhousie University, P.O. BOX 15000, Halifax (NS), B3H 4R2, Canada. Electronic address: daniel.labrie@dal.ca.
authors.forename: D
authors.initials: D
authors.lastname: Labrie
authors.affiliation: Dental Clinical Sciences, Dalhousie University, P.O. BOX 15000, Halifax (NS), B3H 4R2, Canada. Electronic address: Braden.Sullivan@Dal.Ca.
authors.forename: B
authors.initials: B
authors.lastname: Sullivan
authors.affiliation: Dental Clinical Sciences, Dalhousie University, P.O. BOX 15000, Halifax (NS), B3H 4R2, Canada. Electronic address: rbprice@dal.ca.
authors.forename: R B
authors.initials: RB
authors.lastname: Price
mesh_terms: D003116:Color; D003188:Composite Resins; D055117:Curing Lights, Dental; D003764:Dental Materials; D008027:Light; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing
chemical_list: D003188:Composite Resins; D003764:Dental Materials
keywords: Emission spectrum; Incremental (layered) vs. bulk filling and bulk curing resins; LED curing lights; Light transmission through dental resins; Product design; Restorative dentistry