Ability of short exposures from laser and quad-wave curing lights to photo-cure bulk-fill resin-based composites

ElsevierVolume 39, Issue 3, March 2023, Pages 275-292Dental MaterialsAuthor links open overlay panel, , , , Highlights•

The spectral radiant powers and the radiant exposures delivered to the RBCs from the LCUs ranged from 5.3 J/cm2 to 32.1 J/cm2.

The effect of high irradiance and short exposure times was material dependant.

There was an excellent correlation (r > 0.98) between both the DC and the VH at the bottom and the radiant exposure.

There was little correlation between the irradiance and the DC or the VH.

AbstractObjective

This study investigated the ability of a laser, and a ‘quad-wave’ LCU, to photo-cure paste and flowable bulk-fill resin-based composites (RBCs).

Methods

Five LCUs and nine exposure conditions were used. The laser LCU (Monet) used for 1 s and 3 s, the quad-wave LCU (PinkWave) used for 3 s in the Boost and 20 s in the Standard modes, the the multi-peak LCU (Valo X) used for 5 s in the Xtra and 20 s in the Standard modes, were compared to the polywave PowerCure used in the 3 s mode and for 20 s in the Standard mode, and to the mono-peak SmartLite Pro used for 20 s. Two paste consistency bulk-fill RBCs: Filtek One Bulk Fill Shade A2 (3 M), Tetric PowerFill Shade IVA (Ivoclar Vivadent), and two flowable RBCs: Filtek Bulk Fill Flowable Shade A2 (3 M), Tetric PowerFlow Shade IVA (Ivoclar Vivadent) were photo-cured in 4-mm deep x 4-mm diameter metal molds. The light received by these specimens was measured using a spectrometer (Flame-T, Ocean Insight), and the radiant exposure delivered to the top surface of the RBCs was mapped. The immediate degree of conversion (DC) at the bottom, and the 24-hour Vickers Hardness (VH) at the top and bottom of the RBCs were measured and compared.

Results

The irradiance received by the 4-mm diameter specimens ranged from 1035 mW/cm2 (SmartLite Pro) to 5303 mW/cm2 (Monet). The radiant exposures between 350 and 500 nm delivered to the top surface of the RBCs ranged from 5.3 J/cm2 (Monet in 1 s) to 26.4 J/cm2 (Valo X), although the PinkWave delivered 32.1 J/cm2 in 20 s 350 to 900 nm. All four RBCs achieved their maximum DC and VH values at the bottom when photo-cured for 20 s. The Monet used for 1 s and the PinkWave used for 3 s on the Boost setting delivered the lowest radiant exposures between 420 and 500 nm (5.3 J/cm2 and 3.5 J/cm2 respectively), and they produced the lowest DC and VH values.

Conclusions

Despite delivering a high irradiance, the short 1 or 3-s exposures delivered less energy to the RBC than 20-s exposures from LCUs that deliver> 1000 mW/cm2. There was an excellent linear correlation (r > 0.98) between the DC and the VH at the bottom. There was a logarithmic relationship between the DC and the radiant exposure (Pearson's r = 0.87-97) and between the VH and the radiant exposure (Pearson's r = 0.92–0.96) delivered in the 420-500 nm range.

Keywords

Dental curing lights

Dental laser

Resin-based composites

Photo-curing

Degree of conversion

Vickers hardness

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© 2023 The Academy of Dental Materials. Published by Elsevier Inc. All rights reserved.

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