Composite depth of cure and LED dental curing lamp characteristics

Depth of cure measurements were performed at NIOM according to ISO 4049.
Test materials were Tetric EvoCeram (Ivoclar Vivadent) and Filtek Z250 (3M ESPE) colour A3.

These composites were cured with 30 LED lamps using various curing methods and -times. The data were collected from 2005 to 2011.

Procedure for depth of cure.
Procedure for lamp measurement.

 

Depth of cure of Tetric EvoCeram and Filtek Z250

Table 1: Depth of cure of Tetric EvoCeram and Filtek Z250 using a range of curing duration and curing methods depending on the recommendations of the composite- and lamp manufacturers.

Tetric EvoCeram recommendations: 2 mm depth of cure layer is obtained after 20 seconds of light curing. When lamp intensity (irradiance) of at least 1100 mW/cm2 is used, curing time can be reduced to 10 seconds.

Filtek Z250 recommendations: 2.5 mm depth of cure is obtained after 20 seconds of light curing.According to ISO 4049, depth of cure should be no less than 0.5 mm of the value recommended by the manufacturer.

Comments Table 1: Depth of cure values lower than those given by the manufacturers and according to the ISO 4049 requirement are indicated in red. Depth of cure values lower than those given by the manufacturers, but within the limits of the ISO 4049 requirement, are indicated in blue. According to the standard the composite is cured by “direct contact” between the material and the light emission area of the lamp. This situation will, in many cases, differ from a clinical situation in which the distance between the light emission area and material surface is considerably larger, resulting in a decreased depth of cure. The measured light emission area diameters are given in Table 2.

LED curing lamp spectral characteristics

Table 2: LED curing lamp spectral characteristics: Measured and according to manufacturers.

Comments Table 2: According to the curing lamp standard ISO 10650-2, the measured irradiance value should be no less than that given by the manufacturer. Measured irradiance values (± 9%) that are higher or lower than the corresponding values given by the manufacturer are indicated. Light emission area diameters given by the manufacturers are presented in Table 1.

 

Other curing lamp information

Table 3: Lamp battery and light meter information as given by the manufacturers

Tabel 4: Lamp manufacturers, serial/identification numbers and year of testing

 


Responsible
Hanne Wellendorf, chief engineer, and Ellen Bruzell, senior scientist

Funding
The testing was performed on assignment of the Swedish National Board on Health and Welfare, Stockholm, Sweden. The data (2005 to 2007) was previously published as a report (2008-126-8).