Effect of preheating and light-curing unit on physicochemical properties of a bulk fill composite

Abstract

ObjectiveThe aim of this study is to evaluate the effect of composite preheating and polymerization mode on degree of conversion (DC), microhardness (KHN), plasticization (P), and depth of polymerization (DP) of a bulk fill composite.MethodsForty disc-shaped samples (n = 5) of a bulk fill composite were prepared (5 × 4 mm thick) and randomly divided into 4 groups according to light-curing unit (quartz–tungsten–halogen [QTH] or light-emitting diode [LED]) and preheating temperature (23 or 54 °C). A control group was prepared with a flowable composite at room temperature. DC was determined using a Fourier transform infrared spectrometer, KHN was measured with a Knoop indenter, P was evaluated by percentage reduction of hardness after 24 h of ethanol storage, and DP was obtained by bottom/top ratio. Data were statistically analyzed by analysis of variance and Tukey’s test (α = 0.05).ResultsRegardless of light-curing, the highest preheating temperature increased DC compared to room temperature on bottom surface. LED showed a higher DC compared to QTH. Overall, DC was higher on top surface than bottom. KHN, P, and DP were not affected by curing mode and temperature, and flowable composite showed similar KHN, and lower DC and P, compared to bulk fill.ConclusionComposite preheating increased the polymerization degree of 4-mm-increment bulk fill, but it led to a higher plasticization compared to the conventional flowable composite evaluated.

The effect of preheating resin composites on surface hardness: a systematic review and meta-analysis

“…Two studies (15%) evaluated the microhardness of the Filtek Silorane resin composite (3M ESPE) [2729], and 2 other studies (15%) evaluated the microhardness of the TPH Spectra microhybrid resin composite (Dentsply Caulk, Milford, DE, USA) [816]. The remaining studies evaluated other resin composites: Charisma (Heraeus-Kulzer, Hanau, Germany) [21], Enamel Plus HFO (Micerium SpA, Avegno, Italy), Opallis (FGM Produtos Odontologicos, Joinville, Brazil), Ceram X Duo (Dentsply DeTrey GmbH, Konstanz, Germany) [22], Grandio (Voco, Cuxhaven, Germany), Simile (Jeneric Pentron, Wallingford, CT, USA), Tetric N-Ceram (Ivoclar Vivadent, Schaan, Liechtenstein) [23], Microhybrid Esthet-X (Dentsply Caulk) [16], light-cured low-stress posterior bulk fill flowable base composites, Surefil SDR (Dentsply Caulk) [24], Vit-l-escence (microhybrid, Ultradent, Salt Lake City, UT, USA), Tetric Ceram HB (Ivoclar Vivadent), Filtek Supreme Ultra (3M ESPE), Filtek LS Low Shrink Posterior Restorative System (3M ESPE) [25], and a nanofilled composite (Filtek Supreme Plus, 3M ESPE) [19].…”

“…Moreover, most of the reviewed articles were recently published. Two studies were published in 2017 [1924], 1 was published in 2016 [27], 3 were published in 2015 [222330], 1 was published in 2014 [25], and 1 was published in 2013 [21]. The rest of the studies were published between 2007 and 2011 [8161928].…”

“…Of the remaining 112 manuscripts, 1 clinical trial and 1 review article were excluded, and 97 other studies were excluded because they evaluated the effect of preheating a composite on microleakage and other viscoelastic and mechanical properties of composites than microhardness. Finally, 13 studies were selected [8161921222324252627282930]. The detailed study selection procedures are illustrated in a flowchart (Figure 1).…”

Color Stability of Ceramic Veneers Luted With Resin Cements and Pre-Heated Composites: 12 Months Follow-Up

“…There are several methods described in the literature to pre-heat resin-based materials, such as the Calset and Therma-Flo composite warmers, ovens, light of the dental unit chair, hand holding, thermocycling machines, and wax warmers (31,32). The present study used an oven to pre-heat the composite resins, as has been previously described in the literature (12,33). This method is simple, the temperature can be easily controlled, and it is commonly available in the dental clinics.…”

“…The literature reports, in some cases, an increase in DC with pre-heating of resins (33), as high temperatures increase the mobility of monomers, the collision between molecules, and the amount of bonds (34). The increase in DC would cause the polymer matrix to absorb less solvent and to lose fewer components to the external environment, slowing down its degradation (34).…”