Influence of light-curing units on the activation potential of bulk-fill composites

Luis Felipe Jochims Schneider, Ana Carolina Carmello, Leonardo Duarte Eiras Pereira, Mário Pereira Couto Neto, Rodrigo Antonio Modena e Larissa Maria Cavalcante.

Objectives: To determine: (a) the influence of the light-curing unit (LCU) type (“monowave” vs. “polywave”) on the degree of conversion (GC) as a function of depth, for different formulations of bulk-fill composites; (b) which light evaluation parameter is able to predict photoactivation as a function of depth of bulk-fill composites; and (c) verify whether these param- eters are related to the cost of the light source. Methods: Four LED-based sources were used (Poly Wireless/ Kavo; Radii-Cal/SDI; Bluephase G2/Ivoclar; and Valo Cordless/Ultradent) and three bulk-fill composites (Aura BF/SDI, regular viscosity and conventional initiator; Tetric N-Ceram BF/Ivoclar, regular viscosity and alternative initiator; and Surefill SDR /Dentsply, flowable viscosity). For each material, the activation time was that indicated by the manufacturer and GC (%) was determined by FTIR spectroscopy (n = 5) at the subsurface (0.1mm) and 4mm depth. The results were submitted to analysis of variance and Tukey test (95%). Pearsons’ correlation analyzes were performed (a) between the light source irradiance data and the degree of conversion and (b) among the irradiance values and the cost of the light sources. Results: For Aura BF the light source did not influence the subsurface GC, but the use of the RadiCall reduced GC at 4mm. For Tetric BF, Bluephase G2 and Valo polywave devices produced higher values than Poly Wireless and Radii-Cal. For SDR, the conversion was uniform across the mate- rial’s depth, regardless of the apparatus used. There was a positive correlation between the irradiance values and the activation capacity when considering the data obtained with the tip of the curing device distanced from the analysis sensor. There was a positive correlation between the LCUs’ cost and its collimation capacity. Conclusions: The LCU had little influence on the DC at the subsurface. The GC was dependent on the LCU at a depth of 4 mm for regular-viscosity bulk-fill composites, and the behavior of the SDR resin was homogeneous as a function of depth and not dependent on the light source employed. A positive correlation was observed (a) between activation capacity and light source collimation and (b) collimation capacity and LCU cost.

Keywords: Photoactivator. Photoinitiator. Degree of conversion. Bulk-fill resin.

How to cite: Schneider LFJ, Carmello AC, Pereira LDE, Couto Neto MP, Modena RA, Cavalcante LM. Influence of light-curing units on the activation potential of bulk-fill composites. J Clin Dent Res. 2019 Sep-Dec;16(3):128-41.

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