TY - JOUR
T1 - Localised irradiance distribution found in dental light curing units
AU - Michaud, Pierre Luc
AU - Price, Richard B.T.
AU - Labrie, Daniel
AU - Rueggeberg, Frederick A.
AU - Sullivan, Braden
PY - 2014/2/1
Y1 - 2014/2/1
N2 - Objective To measure the localised irradiance and wavelength distributions from dental light curing units (LCUs) and establish a method to characterise their output. Methods Using a laboratory grade integrating sphere spectrometer system (Labsphere and Ocean Optics) the power, irradiance, and spectral emission were measured at the light tips of four LCUs: one plasma-arc (PAC) unit, one single peak blue light-emitting diode (blue-LED) unit, and two polywave LED (poly-LED) units. A beam profiler camera (Ophir Spiricon) was used to record the localised irradiance across the face of the light tips. The irradiance-calibrated beam profile images were then divided into 45 squares, each 1 mm2. Each square contained the irradiance information received from approximately 3200 pixels. The mean irradiance value within each square was calculated, and the distribution of irradiance values among these 45 squares across the tip-ends was examined. Additionally, the spectral emission was recorded at various regions across each light tip using the integrating sphere with a 4-mm diameter entrance aperture. Results The localised irradiance distribution was inhomogeneous in all four lights. The irradiance distribution was most uniformly distributed across the PAC tip. Both the irradiance and spectral emission from the poly-LED units were very unevenly distributed. Conclusions Reporting a single irradiance value or a single spectral range to describe the output from a curing light is both imprecise and inappropriate. Instead, an image of both the irradiance distribution and the distribution of the spectral emission across the light tip should be provided. Clinical significance The localised beam irradiance profile at the tip of dental LCUs is not uniform. Poly-LED units may deliver spectrally inhomogeneous irradiance profiles. Depending on the photoinitiator used in the RBC and the orientation of the LCU over the tooth, this non-uniformity may cause inadequate and inhomogeneous resin polymerisation, leading to poor physical properties, and premature failure of the restoration.
AB - Objective To measure the localised irradiance and wavelength distributions from dental light curing units (LCUs) and establish a method to characterise their output. Methods Using a laboratory grade integrating sphere spectrometer system (Labsphere and Ocean Optics) the power, irradiance, and spectral emission were measured at the light tips of four LCUs: one plasma-arc (PAC) unit, one single peak blue light-emitting diode (blue-LED) unit, and two polywave LED (poly-LED) units. A beam profiler camera (Ophir Spiricon) was used to record the localised irradiance across the face of the light tips. The irradiance-calibrated beam profile images were then divided into 45 squares, each 1 mm2. Each square contained the irradiance information received from approximately 3200 pixels. The mean irradiance value within each square was calculated, and the distribution of irradiance values among these 45 squares across the tip-ends was examined. Additionally, the spectral emission was recorded at various regions across each light tip using the integrating sphere with a 4-mm diameter entrance aperture. Results The localised irradiance distribution was inhomogeneous in all four lights. The irradiance distribution was most uniformly distributed across the PAC tip. Both the irradiance and spectral emission from the poly-LED units were very unevenly distributed. Conclusions Reporting a single irradiance value or a single spectral range to describe the output from a curing light is both imprecise and inappropriate. Instead, an image of both the irradiance distribution and the distribution of the spectral emission across the light tip should be provided. Clinical significance The localised beam irradiance profile at the tip of dental LCUs is not uniform. Poly-LED units may deliver spectrally inhomogeneous irradiance profiles. Depending on the photoinitiator used in the RBC and the orientation of the LCU over the tooth, this non-uniformity may cause inadequate and inhomogeneous resin polymerisation, leading to poor physical properties, and premature failure of the restoration.
KW - Beam uniformity
KW - Irradiance beam profile
KW - Light curing units
KW - Localised spectral emission
KW - Resin photopolymerisation
UR - http://www.scopus.com/inward/record.url?scp=84892366189&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84892366189&partnerID=8YFLogxK
U2 - 10.1016/j.jdent.2013.11.014
DO - 10.1016/j.jdent.2013.11.014
M3 - Article
C2 - 24287255
AN - SCOPUS:84892366189
SN - 0300-5712
VL - 42
SP - 129
EP - 139
JO - Journal of Dentistry
JF - Journal of Dentistry
IS - 2
ER -