684 Quantifying clinical implications of ISO standards used in light curing

Thursday, March 21, 2013: 2 p.m. - 3:15 p.m.
Location: Hall 4 (Washington State Convention Center)
Presentation Type: Poster Session
H. STRASSLER, University of Maryland, Baltimore, MD, and C. FELIX, BlueLight analytics inc, Halifax, NS, Canada
Objective: To identify clinically relevant differences between the light curing unit (LCU) manufacturer stated (MS) irradiance defined under ISO 10650-2, and the irradiance received by a ISO 4049-2009 Depth of Cure Mould (ISO-DOC) sized restoration.  

Method: The lateral and vertical beam homogeneity of three narrow spectrum LED LCUs was examined and compared. Three irradiance measurements were made to confirm the average irradiance at the LCU tip using an integrating sphere (Labsphere), and to measure the irradiance delivered to the MARC® Resin Calibrator (BlueLight) 4 mm diameter sensors at different distances and positions. Both sets of measurements used a calibrated spectrometer (Ocean Optics). A beam profiler (Spiricon) was used to capture each LCU’s beam profile . Three beam profile images were calibrated to identify hot and cold spots within the beam of light exiting the LCU tip and within a 10 mm diameter area, which is the size of an average adult molar.  Each LCU was fixed with a stabilizing arm (benchMARC™, BlueLight).

Result: The MS irradiance and the mean irradiance received by the 4 mm diameter sensor, when the LCU tip was moved across and away from the surface of the sensor, differed depending the LCU’s lateral or vertical position (Table 1). The specific brands and models of LCUs were not reported to focus attention on the clinical limitations of the current ISO standards.

Table 1:

Distance from Light Tip to Sensor 

 

Irradiance (mW/cm²)

Measurement

LED LCU#1  

LED LCU#2  

LED LCU#3

0 mm (ISO 10650-2)

Manufacturer stated

1,000

1,500

3,000

0 mm

Average

1,100 ± 03

1,226 ± 03

2,947 ± 8

0 mm

Center (4 mm ø)

1,012 ± 02

2,758 ± 07

6,467 ± 118

 

Hot (4 mm ø)

1,086 ± 06

2,780 ± 15

6,467 ± 35

 

Cold (4 mm ø)

536 ± 03

527 ± 08

1,054 ± 15

4 mm

Center (4 mm ø)

864 ± 04

806 ± 20

2,306 ± 28

 

Hot (4 mm ø)

864 ± 04

806 ± 10

2,306 ± 22

 

Cold (4 mm ø)

326 ± 02

175 ± 04

371 ± 07

 Conclusion: : Each LCU demonstrated differences between the MS irradiance and the mean irradiance delivered to an ISO-DOC sized restoration. There are differences in the delivery of irradiance both across and away from the LCU tip. Depending on the curing time and technique used by the clinician, and the restoration location on the tooth, these differences could result in composite not receiving minimum energy required for adequate curing even when the LCU is positioned over the tooth.


Keywords: Biomaterials, Composites, Curing lights and Polymerization