Direct and indirect eluates from bulk fill resin-based-composites

Long-term effect of exposure to triethylene glycol dimethacrylate (TEGDMA) on male mouse reproduction

Our study investigated the impact on male mouse fertility and reproduction of long-term (14 weeks) exposure to triethylene glycol dimethacrylate (TEGDMA), a co-monomer of resin-based compounds, at doses of 0.01, 0.1, 1, and 10 ppm. Test and control mice were then paired with sexually mature untreated female mice and their fertility evaluated. Females paired with males exposed to all TEGDMA doses exhibited a significant decline in pregnancy rates, and significant increases in the total embryonic resorption-to-implantation ratio, except for males exposed to 0.01 ppm TEGDMA. Males in the highest dose group (10 ppm) showed significant increases in seminal vesicle and preputial gland weights. They also had significantly higher serum levels of luteinizing hormone (LH) and follicle stimulating hormone (FSH) than the controls, and the 0.01 ppm dosage group for FSH levels. TEGDMA exposure resulted in notable histopathological alterations in the testis, with detachment of germ cells and shedding of germinal epithelium into the tubule lumen. These results strongly indicate that TEGDMA exposure has detrimental consequences on the reproductive abilities and functions in male mice through disruption of the standard hormonal regulation of the reproductive system, leading to changes in spermatogenesis and ultimately leading to decreased fertility.

A Blinded Comparative Study of Four Commercially Available LEDs and a Laser Light Curing Device

OBJECTIVE

 This study determined the effectiveness of five light-curing units (LCUs; four light-emitting diode [LED] and one laser) used on different settings to photo-activate four conventional resin-based composites (RBCs).

MATERIALS AND METHODS

 A total of 108 RBC specimens were photo-activated in a white Delrin mold representing a mesial-occlusal-distal (MOD) class II restoration in a molar tooth. The proximal boxes were 5 mm deep, and the mesial-distal length was 12 mm. Immediately after photo-curing, the RBC specimens were immersed in a solvent to remove the uncured materials, after which they were photographed and deidentified. A Research Electronic Data Capture survey was created using these images and sent to respondents who blindly assessed the ability of the various LCUs to photo-cure the MOD restorations.

RESULTS

 There were significant differences in how the five curing lights had cured RBCs. One-way analysis of variance (ANOVA), pairwise t-test, Welch's one-way ANOVA, and Kruskal-Wallis rank test in the blinded survey data showed significant differences between the LED curing lights used for two 10-second cures and the laser curing light used for 1 second, and LED lights at lower settings.

CONCLUSION

 There was a significant difference in how the curing lights could photo-cure the RBCs used in this study. The laser curing light used for 1 second produced the worst results in all four RBCs.

Light-curing dental resin-based composites: How it works and how you can make it work

Aim

Clinicians may become quite familiar with the rapid transformation of composite pastes to rigid solids, as a routine phenomenon in operative dentistry. But they may still lack scientific understanding of how and why this happens. Efforts to learn scientifically about the interaction between light beams and resin-composites can significantly promote effective clinical placement of restorations. Neglect of such study can result in practical procedures of light-curing that are inadequate or even seriously defective.

Method

This review addresses the underlying science and technology to elucidate how light curing works, for dental resin-based composites, including—but not limited to—bulk fill types. This involves questions concerning: (a) the particle-wave understanding of light; (b) how photons can penetrate sufficiently deeply into bulk fill composites; (c) the necessary technology of LED light-curing units (LCUs); (d) the criteria for absorption of photons by photo initiators to initiate free-radical addition polymerisation.

Conclusions

The implications for clinical practice are surveyed. These include design variables and selection criteria for LED-LCUs and guidelines on their use. This is to guide practitioners towards safe and effective light-curing procedures so that they can achieve optimal result for their patients.

Effects of Sr/F-Bioactive Glass Nanoparticles and Calcium Phosphate on Monomer Conversion, Biaxial Flexural Strength, Surface Microhardness, Mass/Volume Changes, and Color Stability of Dual-Cured Dental Composites for Core Build-Up Materials

This study prepared composites for core build-up containing Sr/F bioactive glass nanoparticles (Sr/F-BGNPs) and monocalcium phosphate monohydrate (MCPM) to prevent dental caries. The effect of the additives on the physical/mechanical properties of the materials was examined. Dual-cured resin composites were prepared using dimethacrylate monomers with added Sr/F-BGNPs (5 or 10 wt%) and MCPM (3 or 6 wt%). The additives reduced the light-activated monomer conversion by ~10%, but their effect on the conversion upon self-curing was negligible. The conversions of light-curing or self-curing polymerization of the experimental materials were greater than that of the commercial material. The additives reduced biaxial flexural strength (191 to 155 MPa), modulus (4.4 to 3.3), and surface microhardness (53 to 45 VHN). These values were comparable to that of the commercial material or within the acceptable range of the standard. The changes in the experimental composites’ mass and volume (~1%) were similar to that of the commercial comparison. The color change of the commercial material (1.0) was lower than that of the experimental composites (1.5–5.8). The addition of Sr/F-BGNPs and MCPM negatively affected the physical/mechanical properties of the composites, but the results were satisfactory except for color stability.

Monomer Release from Dental Resins: The Current Status on Study Setup, Detection and Quantification for In Vitro Testing

Improvements in mechanical properties and a shift of focus towards esthetic dentistry led to the application of dental resins in various areas of dentistry. However, dental resins are not inert in the oral environment and may release monomers and other substances such as Bisphenol-A (BPA) due to incomplete polymerization and intraoral degradation. Current research shows that various monomers present cytotoxic, genotoxic, proinflammatory, and even mutagenic effects. Of these eluting substances, the elution of BPA in the oral environment is of particular interest due to its role as an endocrine disruptor. For this reason, the release of residual monomers and especially BPA from dental resins has been a cause for public concern. The assessment of patient exposure and potential health risks of dental monomers require a reliable experimental and analytical setup. However, the heterogeneous study design applied in current research hinders biocompatibility testing by impeding comparative analysis of different studies and transfer to the clinical situation. Therefore, this review aims to provide information on each step of a robust experimental and analytical in vitro setup that allows the collection of clinically relevant data and future meta-analytical evaluations.

Influence of curing modes on monomer elution, sorption and solubility of dual-cure resin-cements

OBJECTIVE

To explore the effect of two curing modes, for dual-cure resin cements, on their monomer elution, water sorption and solubility after 30 d water storage and 30 d dry reconditioning.

METHODS

Eight dual-cure resin-cements were investigated (Bifix SE, Nexus Third Generation, PANAVIA SA, PANAVIA V5, RelyX Ultimate Universal, RelyX Unicem 2, RelyX Universal and SpeedCEM Plus). Six disk-shaped specimens were made per curing mode: light-cure (LC) versus self-cure (SC) to measure amounts of eluted monomers after 30 d of water storage at 37 °C. Ultra-high performance liquid chromatography tandem mass spectrometry (UHPLC MS/MS) was performed to identify and quantify three eluted monomers (Bis-GMA, UDMA and TEGDMA). Water sorption/ solubility specimens were prepared according to ISO 4049. Specimens from each curing mode (LC/SC) were immersed separately in distilled water for 30 d and then reconditioned for 30 d; all at 37 °C. Mass change was measured at different time intervals. Data were analyzed via one-way ANOVA, Tukey post-hoc tests and independent sample t-tests (α = 0.05).

RESULTS

After 30 d of water storage, the three monomers Bis-GMA, UDMA and TEGDMA were detected in water. All monomers showed a variable extent of elution into water and were significantly higher (p < 0.0001) with SC compared to LC curing modes. BSE had the highest quantity of eluted monomers. After 30 d of water sorption (μg/mm³), all rein-cements showed significantly higher sorption (p < 0.05) of SC compared to LC curing modes except for PV5, RXU and CEM (p > 0.05). After 30 d of water solubility (μg/mm³), all resin-cements showed significantly higher solubility (p < 0.0001) of SC compared to LC curing mode. BSE had the highest water sorption and solubility. The total amounts of eluted monomers correlated positively with solubility: r² = 0.95 for LC and r² = 0.93 for SC.

SIGNIFICANCE

Whenever light access is possible, light curing remains beneficial to reduce the extent of resin degradation and related properties of dual-cure resin cements. BSE showed statistically the highest extent of eluted monomers, sorption and solubility.