The Influence of Various Photoinitiators on the Properties of Commercial Dental Composites

The aim of this article was to compare the biomechanical properties of commercial composites containing different photoinitiators: Filtek Ultimate (3M ESPE) containing camphorquinone (CQ); Estelite Σ Quick (Tokuyama Dental) with CQ in RAP Technology®; Tetric EvoCeram Bleach BLXL (Ivoclar Vivadent AG) with CQ and Lucirin TPO; and Tetric Evoceram Powerfill IVB (Ivoclar Vivadent AG) with CQ and Ivocerin TPO. All samples were cured with a polywave Valo Lamp (Ultradent Products Inc.) with 1450 mW/cm2. The microhardness, hardness by Vicker’s method, diametral tensile strength, flexural strength and contraction stress with photoelastic analysis were tested. The highest hardness and microhardness were observed for Filtek Ultimate (93.82 ± 17.44 HV), but other composites also displayed sufficient values (from 52 ± 3.92 to 58,82 ± 7.33 HV). Filtek Ultimate not only demonstrated the highest DTS (48.03 ± 5.97 MPa) and FS (87.32 ± 19.03 MPa) but also the highest contraction stress (13.7 ± 0.4 MPa) during polymerization. The TetricEvoCeram Powerfill has optimal microhardness (54.27 ± 4.1 HV), DTS (32.5 ± 5.29 MPa) and FS (79.3 ± 14.37 MPa) and the lowest contraction stress (7.4 ± 1 MPa) during photopolymerization. To summarize, Filtek Ultimate demonstrated the highest microhardness, FS and DTS values; however, composites with additional photoinitiators such as Lucirin TPO and Ivocerin have the lowest polymerization shrinkage. These composites also have higher FS and DTS and microhardness than material containing CQ in Rap Technology.

A Comparative Study of the Mechanical Properties of Selected Dental Composites with a Dual-Curing System with Light-Curing Composites

Dual-curing composites have a wide spectrum of use in practice (rebuilding, reconstruction, and luting). The characterization of this type of material and comparative study of selected mechanical properties with light-cured materials were carried out for this paper. In this study, we used six materials with a dual-cure system—Bulk EZ, Fill-Up!, StarFill 2B, Rebilda DC, MultiCore Flow, Activa Bioactive-Restorative—and three light-cured materials—Filtek Bulk Fill Posterior, Charisma Classic, and G-aenial Universal Flo. The materials were conditioned for 24 h in water at 37 °C before testing. Selected material properties were determined: three-point bending flexural strength, diametral tensile strength, hardness, microhardness, and shrinkage stress. The highest three-point bending flexural strength (TPB) was 137.0 MPa (G-aenial Universal Flo), while the lowest amounted to 86.5 MPa (Activa Bioactive). The diametral tensile strength (DTS) values were in a range from 39.2 MPa (Rebilda DC) to 54.1 MPa (Charisma Classic). The lowest hardness (HV) value of 26 was obtained by the Activa Bioactive material, while the highest values were recorded for Filtek Bulk Fill Posterior and Charisma Classic-53. The shrinkage stress of the tested materials ranged from 6.3 MPa (Charisma Classic) to 13.2 MPa (G-aenial Universal Flo). Dual-curing composites were found to have similar properties to light-cured composites.

An Evaluation of the Properties of Urethane Dimethacrylate-Based Dental Resins

Most of the dental materials available on the market are still based on traditional monomers such as bisphenol A-glycidyl methacrylate (Bis-GMA), urethane dimethacrylate (UDMA), triethyleneglycol dimethacrylate (TEGDMA), and ethoxylated bisphenol-A dimethacrylate (Bis-EMA). The interactions that arise in the monomer mixture and the characteristics of the resulting polymer network are the most important factors, which define the final properties of dental materials. The use of three different monomers in proper proportions may create a strong polymer matrix. In this paper, fourteen resin materials, based on urethane dimethacrylate with different co-monomers such as Bis-GMA or Bis-EMA, were evaluated. TEGDMA was used as the diluting monomer. The flexural strength (FS), diametral tensile strength (DTS), and hardness (HV) were determined. The impacts of material composition on the water absorption and dissolution were evaluated as well. The highest FS was 89.5 MPa, while the lowest was 69.7 MPa. The median DTS for the tested materials was found to range from 20 to 30 MPa. The hardness of the tested materials ranged from 14 to 16 HV. UDMA/TEGDMA matrices were characterized by the highest adsorption values. The overall results indicated that changes in the materials’ properties are not strictly proportional to the material’s compositional changes. The matrices showed good properties when the composite contained an equal mixture of Bis-GMA/Bis-EMA and UDMA or the content of the UDMA monomer was higher.

EFFECT OF WATER-SETTABLE GIC IMMERSION IN RIVER WATER AND PDAM WATER ON DIAMETRAL TENSILE STRENGTH

ABSTRACTBackground: Dental and oral health problems according to Riskesdas (2018) in Indonesia is 57.6% and South Borneo is almost 60%. High level of damage in South Borneo is caused by the people still consumption of river water as a source of clean water. Caries can be treated by restoration of tooth, one of them is water settable GIC.. Objective: Knowing the effect of water settable GIC immersion in river water and PDAM water to diametric tensile strength. Method: This study used a true experimental laboratory research method with a post test only design with a control group design on 27 samples which were divided into 3 groups immersion. Result: This research shows that the mean of diametric tensile strength in group 1 (7.15 MPa), group 2 (8.42 MPa), and group 3 (10.54 MPa). The One Way Anova statistical test shows the value of (P <0.05) which means that there is a significant difference in the value of the diametric tensile strength of each treatment group. Conclusion: There is an effect on the decrease in the value of the diametric tensile strength after immersion of water settable GIC in river water and PDAM water.Keyword: Diametral Tensile Strength, GIC Immersion, River Water.

COMPARATIVE EVALUATION OF EFFECT OF TWO LIGHT CURING UNITS ON MECHANICAL PROPERTIES OF FILTEK BULK FILL COMPOSITE

Context:The quality of light curing units can profoundly influence mechanical properties of dental composite materials. Aim: To compare effect of Woodpecker RTA Mini-S and Elipar Deep Cure-L curing units onmechanical properties (compressive strength, diametral tensile strength and microhardness) of Filtek Bulk-Fill. Methods and Materials: A total of 32 samples of Filtek Bulk Fill composite were divided into 2 equal groups (n=16). 12 samples in each group were fabricated using a tooth shaped mold and 4 in circular rings to test compressive strength, microhardness and diametral tensile strength, respectively. Theblocks were evaluated for the above parameters using Universal Testing Machine and Vickers Microhardness Tester.Independent sample-t test was used in this study (p< 0.05). Results: The results of this study showed that the group of composites cured using Elipar Deep Cure-L curing unit showed better mechanical properties and the difference between the groups was statistically significant for compressive strength and diametral tensile strength (p < 0.05) Conclusion: It was concluded that a curing unit of higher intensity and quality of output used in conjugation with bulk fill composites are likely to give better results.

Antimicrobial properties, mechanics, and fluoride release of ionomeric cements modified by red propolis

ABSTRACT Objectives To evaluate the antimicrobial activity, mechanical properties, and fluoride release capacity of glass ionomer cement (GIC) used for cementing orthodontic bands and modified by ethanolic extract of red propolis (EERP) in different concentrations. Materials and Methods Two orthodontic GICs containing EERP at 10%, 25%, and 50%, were used. The following assays were carried out: cell viability tests against Streptococcus mutans and Candida albicans, diametral tensile strength, compressive strength, shear bond strength, microhardness, and fluoride release capacity. The statistical analyses of the antimicrobial tests, fluoride release, diametral tensile strength, compressive strength, and microhardness were performed using two-way analysis of variance and Tukey test (P &lt; .05). Shear bond strength data were analyzed using one-way analysis of variance followed by Tukey test (P &lt; .05). Results At the concentrations of 25% and 50%, EERP was shown to be a promising antimicrobial agent incorporated into GICs against C albicans (P &lt; .001) and S mutans (P &lt; .001). The fluoride release capacity of the GICs was not affected, and the EERP concentration of 25% was the one that least affected the mechanical properties of the cements (P &gt; .05). Conclusions The GICs containing EERP at 25% showed a significant increase in their antimicrobial activity against S mutans and C albicans, while mechanical properties and fluoride release remained without significant changes.

Effect of Streptococcus mutans on surface-topography, microhardness, and mechanical properties of contemporary resin composites

Objective: Dental caries is the most prevalent disease globally, and Streptococcus mutans ( S. mutans) is a common associated oral bacteria. Additionally, S. mutans possess esterase activity capable of degrading resin composites (RC). However, the effect of degradation on the physical-mechanical properties of the RC has not been extensively studied. We evaluated the flexure strength (FS), the diametral tensile strength (DTS), the modulus of elasticity (ME), and the microhardness of three contemporary RC to establish if S. mutans could affect them. Methods: One hundred thirty-eight bar-shaped and 276 disc-shaped specimens were fabricated with Enamel Plus HRi, IPS Empress Direct, and Clearfil AP-X, and physical-mechanical testing was done after been incubated during 30 and 60 days in culture media with or without S. mutans. Also, a scanning electron microscope was used to identify surface changes. Results: None of the tested RC were affected in their mechanical properties (FS, ME, and DTS). However, Clearfil AP-X and Enamel Plus HRI showed eroded surfaces and a decreased microhardness after 30 and 60 days S. mutans incubation. IPS Empress Direct presented the lowest values in all the tests, but its physical-mechanical features and surface were not affected by bacteria’s exposure. Conclusions: Exposure to S. mutans could affect some contemporary RC; however, the effect seems superficial since its mechanical features were not affected.