Effect of Rapid Polymerization on Water Sorption and Solubility of Bulk-fill Composites

Evaluation of colour stability, water sorption and solubility of no-cap flowable bulk fill resin composites

BACKGROUND

The aim of this study is to investigate the colour stability, water absorption, and solubility values of low viscosity bulk fill resin composites that do not require an additional layer in comparison with high viscosity and low viscosity bulk fill resin composites used as a base.

METHODS

In the present study, four different bulk fill resin composites were used: Charisma Bulk Flow One (Kulzer), Estelite Bulk Fill Flowable (Tokuyama), X-tra Base (VOCO), Filtek One Bulk Fill (3M ESPE). The resin composites were prepared as disc-shaped samples with a diameter of 5 mm and a thickness of 4 mm, then polymerized using a LED light device (Elipar DeepCureS, 3M ESPE). The samples were kept in artificial saliva and coffee solution for 28 days to determine water absorption, solubility levels and ∆E values, with measurements taken on days 7, 14, 21 and 28. Water absorption and solubility levels were calculated based on ISO4049:2009 specification, and mean colour change values were calculated based on CIEDE2000 formula. Repeated Measures ANOVA, along with post hoc Bonferroni, Tamhane, and Adjusted Bonferroni tests, were used for the statistical evaluation of the data (p < 0.05).

RESULTS

Among all composite groups at all time intervals, Charisma Bulk Flow One composite showed the highest water absorption, solubility, and discolouration values.

CONCLUSION

The water absorption, solubility and discolouration values of the resin composites used in this study were affected by the amount of filler in the resin structure. The clinical applicability of low-viscosity bulk-fill resin composites that do not require an additional capping layer should be carefully reassessed.

Comparison of Water Sorption and Water Solubility Properties of Current Restorative Materials with Different Contents

OBJECTIVES

 This study aimed to investigate and compare water sorption and solubility properties of current restorative materials with different contents.

MATERIALS AND METHODS

 Alkasite, self-adhesive restorative material (Cention N, Ivoclar Vivadent AG, Schaan, Liechtenstein), bulk-fill glass hybrid restorative material (EQUIA Forte HT, GC Corp., Tokyo, Japan), nanohybrid universal composite material (OptiShade, Kerr Dental, United States), and bulk-fill composite material (Filtek One Bulk Fill Restorative, 3M ESPE, St. Paul, Minnesota, United States) were used. Samples (n = 6) were prepared (2 × 10 mm) according to the ISO 4049 standards. Water sorption and solubility values were calculated according to the ISO 4049 standards.

STATISTICAL ANALYSIS

 One-way ANOVA, Tukey's post-hoc, Tamhane's T2 post-hoc, Pearson's correlation, and independent samples t-tests were used for statistical analysis (p < 0.05).

RESULTS

 Group EQUIA Forte HT significantly showed the highest water sorption values (57.278 ± 3.174), while Group Filtek One Bulk Fill Restorative exhibited the lowest (4.429 ± 0.174; p < 0.05). The water sorption values for Group Cention N were 5.000 ± 0.542. Group EQUIA Forte HT significantly had the lowest water solubility values (-99.799 ± 1.909), while Group Cention N (-2.966 ± 0.402) significantly exhibited the highest (p < 0.05). There was no significant correlation between water sorption and solubility values for each material (p > 0.05).

CONCLUSION

 The bulk-fill nano-filled composite resin material was successful in terms of water sorption while the bulk-fill glass hybrid restorative system in terms of water solubility. Alkasite can be recommended to be used as a base material due to its high solubility feature. Monomer, filler type, and amount had an impact on the water sorption and solubility properties of the tested materials.

Effect of ultra-fast high-intensity light-curing on the properties of a new bulk-fill restorative resin composite system: A Scoping Review

Background

This scoping review aims to analyze the impact of rapid high-intensity light-curing on a new bulk-fill resin-based composites (RBCs) designed for this type of polymerization.

Material and Methods

This scoping review was reported according to the Preferred Reporting Items for Systematic reviews and Meta-Analyses extension for Scoping Reviews (PRISMA-ScR) and Joanna Briggs Institute Manual of Evidence Synthesis. The methods were registered on the Open Science Framework (). The literature search was conducted in PubMed/MEDLINE, Embase, Web of Science, Scopus and Cochrane Library databases. Eligibility was considered for in vitro and clinical studies evaluating the effects of ultra-fast high-intensity light-curing on a new system of bulk-fill RBCs.

Results

Of 1.688 articles identified, 27 were included in the qualitative synthesis. All studies were conducted in vitro. A total of 2.432 specimens were evaluated. The studies have shown that shortness light-curing may result in similar properties (stress generated by polymerization shrinkage, marginal integrity, and bond strength to dental interface) for the new bulk-fill RBCs.

Conclusions

Therefore, the new bulk-fill RBCs can be light-cured with a short exposure time and high intensity, providing a time-saving benefit in clinical practice, with similar results to standard light-curing in conventional composites, although, its use should be approached with caution in the flowable composite. Key words:Resin composites, polymerization, dental materials, review.

Effect of polymerisation protocols on water sorption, solubility and hygroscopic expansion of fast-cure bulk-fill composite

OBJECTIVE

This study examines the effect of two light-curing protocols from a LED polywave light curing unit (LCU) on water sorption, solubility, and hygroscopic expansion of fast and conventional bulk-fill resin-based composites (RBCs) aged in distilled water for 120 d.

METHODS

Three bulk-fill RBCs materials were studied: Tetric PowerFill® (fast photo-polymerised composite) (TPF), Tetric EvoCeram bulk-fill (EVO), and GrandioSo x-tra bulk-fill (GSO) (conventional photo-polymerised composites). Specimens were prepared within a 3D-printed resin mold (8-mm diameter x 4-mm height) and light-cured from one side only with 2 modes of polywave LCU (Bluephase® PowerCure): 3 s mode and for 20 s in "Standard" mode. Water sorption and solubility were measured at fixed time intervals for 120 d of distilled water storage, then reconditioned to dry to measure desorption for 75 d, all at 37 ± 1 °C. Hygroscopic (volumetric) expansion was recorded at the same time intervals up to 120 d. Data were analysed through SPSS using Two-way ANOVA, One-way ANOVA, independent t-tests, and Tukey's post-hoc correction tests (p < 0.05).

RESULTS

TPF, when irradiated for 3 s demonstrated minimal water sorption (0.83%), solubility (1.01 μg/mm3), and least volumetric expansion (1.64%) compared to EVO and GSO. While EVO showed the highest water sorption (1.03%) and solubility (1.95 μg/mm3) at 3 s. GSO had the lowest sorption (0.67%) and (0.56%) in 3 s and 20 s protocols, respectively. Nevertheless, all the sorption and solubility data were within the ISO 4049 limits.

SIGNIFICANCE

For TPF, fast (3 s) polymerisation did not increase either water sorption or solubility, compared with 20 s irradiation. However, with the two comparative bulk-fill composites, fast cure increased water sorption by 15-25% and more than doubled solubility. These findings were consistent with the lesser volumetric expansions observed for Tetric PowerFill at both the fast and standard protocols, indicating its relative stability across polymerisation protocols.

One-Year Evaluation of High-Power Rapid Curing on Dentin Bond Strength

This study investigated the effect of 3 s light-curing with a high-power LED curing unit on the shear bond strength of bulk-fill composites. Four bulk-fill composites were bonded to dentin with a universal adhesive (Scotchbond Universal Plus): two materials designed for rapid curing (Tetric PowerFill and Tetric PowerFlow) and two controls (Filtek One Bulk Fill Restorative and SDR Plus Bulk Fill Flowable). The 4 mm composite layer was light-cured with Bluephase PowerCure for 20 s at 1000 mW/cm2 ("20 s") or for 3 s at 3000 mW/cm2 ("3 s"). The samples were stored at 37 °C in distilled water and tested after 1, 6 and 12 months. The samples polymerised in the "3 s" mode had statistically similar or higher bond strength than the samples cured in "20 s" mode, except for the Tetric PowerFlow (1 month) and SDR+ (6 month). The flowable materials Tetric PowerFlow and SDR Plus initially showed the highest values in the "3 s" and "20 s" groups, which decreased after 12 months. The bond strength was statistically similar for all materials and curing protocols after 12 months, except for Tetric PowerFill cured with the "3 s" protocol (21.22 ± 5.0 MPa), which showed the highest value. Tetric PowerFill showed the highest long-term bond strength. While "3 s" curing resulted in equal or better shear bond strength, its use can only be recommended for a material with an AFCT agent such as Tetric PowerFill.

Monowave vs. Polywave Light - Curing Units: Effect on Light Transmission of Composite without Alternative Photoinitiators

Objective

The aim of this study was to compare the light transmission of monowave and polywave-curing devices by a bulk-fill composite containing only camphorquinone as a photoinitiator.

Materials and methods

Three light-curing devices were used to cure bulk-fill composite QuiXfil: one monowave (Translux® Wave) and two polywave (VALO Cordless and Bluephase® PowerCure. The NIST-calibrated spectrometer (MARC Resin Calibrator, BlueLight Analytics Inc.) was used to measure the incident and transmitted light through a 2-mm composite specimen over 20 s. Light transmittance was calculated from the ratio of the amount of transmitted and incident light. For data analysis (ANOVA, α = 0.05), total irradiation of the entire spectrum, irradiation with wavelengths of 360-420 nm for the violet spectrum, and 420-540 nm for the blue spectrum were selected.

Results

Monowave curing unit Translux® Wave had the lowest light transmission (13.78 ± 0.5%), similar to the violet light transmission of polywave devices (12.02 ± 0.94% and 13.81 ± 1.72% for Valo Cordless and Bluephase PowerCure, respectively). Blue light transmittance (32.15-23.70%) was more than twofold higher than for the wavelengths in the violet region of the spectrum (13.81-12.02%) for the two polywave devices. VALO Cordless showed the highest total and blue light transmission (p<0.001). There was no significant difference in the transmission of the violet part of the spectrum between VALO Cordless and Bluephase® PowerCure (p = 0.465).

Conclusion

Within the limitations of this study, we could conclude that polywave curing devices can be used for the polymerization of the bulk-fill composite with camphorquinone as the sole photoinitiator.

Blue Laser for Polymerization of Bulk-Fill Composites: Influence on Polymerization Kinetics

The objective of this study was to compare the polymerization kinetics of bulk-fill resin composites cured with a LED-curing device and a diode laser (449 nm). Three bulk-fill composites were light-cured with constant radiation exposure at 10 J/cm² by varying radiant exitance and curing time. The following three light-curing protocols were used: (I) 3300 mW/cm² for 3 s; (II) 2000 mW/cm² for 5 s; and (III) 1000 mW/cm² for 10 s. The degree of conversion (DC) was monitored in real time at a data acquisition rate of 2 spectra/s over a 5-min period and again after seven days using Fourier transform infrared spectroscopy. DC amounted to 30.9-61.7% at 4-mm depth after 5 min. DC values of two sculptable composites were significantly higher with the laser, regardless of the curing protocol used, but not for the flowable composite. The maximum polymerization rate (2.0-22.1%/s) was less affected by the type of curing device for one of the composites, while the other two composites achieved significantly higher values when cured with the laser. Laser curing generally increased the DC and the maximum polymerization rate while it shortened the onset of the maximum reaction rate. New handheld laser devices with adjustable power have the potential to be used as a photopolymerization light source for new generations of bulk-fill composites.