The effect of preheating of nano-filler composite resins on their degree of conversion and microfiltration in dental fillings

Abstract Objectives This study aimed to compare the polymerization shrinkage and degree of conversion of new zirconia-reinforced rice husk nanohybrid composite with commercialized microhybrid and nanofilled composites. Materials and Methods Overall, 180 samples were used for polymerization shrinkage (buoyancy and optical methods) and degree of conversion tests in which they were divided into Group 1, nanofilled composite (Filtek-Z350- XT; 3M ESPE, St Paul, MN 55144-1000, USA), Group 2, microhybrid composite (Zmack-Comp), and Group 3, nanohybrid composite (Zr-Hybrid). Polymerization shrinkage test was performed using buoyancy and optical methods. For buoyancy method, samples were weighed in air and water to calculate the shrinkage value, whereas, for optical method, images of nonpolymerized samples were captured under a digital microscope and recaptured again after light-cured to calculate the percentage of shrinkage. Degree of conversion was tested using Fourier-transform infrared spectroscopy spectrometer. Statistical Analysis Data were analyzed using one-way analysis of variance complemented by post hoc Dunnett’s T3 test for polymerization shrinkage and Tukey’s honestly significant difference test for degree of conversion. Level of significance was set at p < 0.05. Results Group 3 demonstrated similar polymerization shrinkage with Group 1, but lower shrinkage (p < 0.05) than Group 2 based on buoyancy method. However, optical method (p < 0.05) showed that Group 3 had the lowest shrinkage, followed by Group 1 and lastly Group 2. Besides, Group 3 showed a significantly higher degree of conversion (p < 0.05) than Group 1 and comparable conversion value with Group 2. Conclusions Zirconia-reinforced rice husk nanohybrid composite showed excellent shrinkage and conversion values, hence can be considered as an alternative to commercially available composite resins.

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Influence of Different Cordless Light-emitting-diode Units and Battery Levels on Chemical, Mechanical, and Physical Properties of Composite Resin

Operative Dentistry ◽

10.2341/19-095-l ◽

2019 ◽

Vol 45 (4) ◽

pp. 377-386 ◽

Cited By ~ 1

Author(s):

IO Cardoso ◽

AC Machado ◽

DNR Teixeira ◽

FC Basílio ◽

A Marletta ◽

...

Keyword(s):

Tensile Strength ◽

Physical Properties ◽

Composite Resin ◽

Light Emitting Diode ◽

Pearson Correlation ◽

Composite Resins ◽

Degree Of Conversion ◽

Light Emitting ◽

Mechanical And Physical Properties ◽

Diametral Tensile Strength

Clinical Relevance Irradiance may decrease as the light-emitting diode (LED) is discharged. Therefore, the LED must be charged carefully to prevent the possibility of influencing the chemical, mechanical, and physical properties of composite resin. SUMMARY The aim of this study was to evaluate the influence of different light-emitting diode (LED) curing units and battery levels on the chemical, mechanical, and physical properties of composite resins. The irradiance for each cycle from full to completely discharged battery level was evaluated, for five different new cordless LED units: Optilight Color (Gnatus), Bluephase (Ivoclar), Valo (Ultradent), Radii Plus (SDI), and Radii Xpert (SDI). After the irradiance evaluation, composite resin specimens were prepared and light cured, while varying the battery level for each LED unit: high level (HL, 100%), medium level (ML, 50%), and low level (LL, 10%). The degree of conversion, diametral tensile strength, sorption, and solubility were also evaluated. Data were checked for homoscedasticity and submitted to two-way and three-way analysis of variance, depending on the test performed, followed by the Tukey test with a significance level of 95%. A negative correlation was found between irradiance and cycles of light curing, which was checked by the Pearson correlation test. Valo and Radii Xpert were not influenced by the battery level in any test performed. However, different battery levels for some LED units can influence the degree of conversion, diametral tensile strength, sorption, and solubility of composite resins.

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Influence of Pre-curing warming on micro-leakage, micro-hardness and degree of conversion of high viscosity bulk fill composite resins: An in vitro study

Egyptian Dental Journal ◽

10.21608/edj.2018.77269 ◽

2018 ◽

Vol 64 (3) ◽

pp. 2717-2735

Author(s):

Eman Elbahrawy ◽

Reham Attia

Keyword(s):

In Vitro Study ◽

High Viscosity ◽

Composite Resins ◽

Degree Of Conversion ◽

Vitro Study ◽

Micro Hardness

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Correlation between degree of conversion, filler concentration and mechanical properties of posterior composite resins

Journal of Oral Rehabilitation ◽

10.1111/j.1365-2842.1990.tb01419.x ◽

1990 ◽

Vol 17 (5) ◽

pp. 487-494 ◽

Cited By ~ 131

Author(s):

K.-H. CHUNG ◽

E. H. GREENER

Keyword(s):

Mechanical Properties ◽

Composite Resins ◽

Degree Of Conversion ◽

Filler Concentration

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Analysis of transmittance and degree of conversion of composite resins

Microscopy Research and Technique ◽

10.1002/jemt.23364 ◽

2019 ◽

Author(s):

Elisa do Carmo Agostini Balbinot ◽

Marta Fávaro Costa Cesário Pereira ◽

Jovito Adiel Skupien ◽

Carlos Eduardo Agostini Balbinot ◽

Grazielli da Rocha ◽

...

Keyword(s):

Composite Resins ◽

Degree Of Conversion

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Influence of Battery Level of a Cordless LED Unit on the Properties of a Nanofilled Composite Resin

Operative Dentistry ◽

10.2341/15-200-l ◽

2016 ◽

Vol 41 (4) ◽

pp. 409-416 ◽

Cited By ~ 2

Author(s):

AG Pereira ◽

LHA Raposo ◽

DNR Teixeira ◽

RCQ Gonzaga ◽

IO Cardoso ◽

...

Keyword(s):

Tensile Strength ◽

Light Intensity ◽

Composite Resin ◽

Light Emitting Diode ◽

Pearson Correlation ◽

Composite Resins ◽

Degree Of Conversion ◽

Battery Voltage ◽

Significant Difference ◽

Diametral Tensile Strength

SUMMARY The properties of composite resins can be influenced by light activation, depending primarily on the performance of the curing unit. The aim of this study was to evaluate how different battery levels of a cordless light-emitting diode (LED) unit influence the properties of a nanofilled composite resin. First, the battery voltage and light intensity of the cordless LED unit were individually checked for all light-curing cycles. Then, composite resin discs were prepared and light-cured at different battery levels: high level (HL, 100%), medium level (ML, 50%), and low level (LL, 10%). The degree of conversion, diametral tensile strength, sorption, and solubility of the specimens were tested. Data were checked for homoscedasticity and submitted to one-way analysis of variance followed by Tukey honestly significant difference and Pearson correlation tests (p<0.05). The battery voltage and light intensity varied significantly among the groups (p<0.001). The LL group presented a lower degree of conversion than the HL and ML groups (p<0.001), which shower similar results (p=0.182). Lower diametral tensile strength was also verified for the LL group when compared with the HL and ML groups (p<0.001), which presented no difference (p=0.052). Positive correlation was observed between the light intensity and the parameters studied, with the exception of sorption and solubility (p<0.001). The ML and LL groups showed higher sorption than the HL group (p <0.001), but no difference was verified between the first two groups (p=0.535). No significant differences were found for solubility between the ML and LL groups (p=0.104), but the HL group presented lower values (p<0.001). The different battery levels of the cordless LED curing unit influenced all the properties of the nanofilled composite resin evaluated.

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Oxygen Inhibition of Surface Composites and Its Correlation with Degree of Conversion and Color Stability

Brazilian Dental Journal ◽

10.1590/0103-6440202103641 ◽

2021 ◽

Vol 32 (1) ◽

pp. 91-97

Author(s):

Marcela Gonçalves Borges ◽

Gisele Rodrigues Silva ◽

Fernanda Teodoro Neves ◽

Carlos José Soares ◽

André Luís Faria-e-Silva ◽

...

Keyword(s):

Repeated Measures ◽

Composite Resin ◽

Color Stability ◽

Composite Resins ◽

Degree Of Conversion ◽

Oxygen Inhibition ◽

Fourier Transformed Infrared Spectroscopy ◽

Surface Composites ◽

Cielab System ◽

Polishing Procedures

Abstract This study investigated the effects of oxygen inhibition and finishing/polishing procedures on the composite resin properties. One bulk-fill and two conventional composite resins (nanoparticle and microhybrid) were evaluated. Specimens were prepared using 4 surface treatments: control, no treatment; Gly, oxygen inhibition with glycerin; FP, finishing and polishing; Gly + FP, glycerin followed by finishing and polishing. The degree of conversion (DC) was measured using Fourier Transformed Infrared Spectroscopy (FTIR) immediately and after 15 days (n=5). Color stability (ΔEab, and ΔE00) and opacity were evaluated using a spectrophotometer after 15 days of immersion in coffee, using the CIELAB system (n=5). Data were analyzed by two-way ANOVA and Tukey tests (α=0.05) and opacity by two-way repeated-measures ANOVA. Glycerin usage increased significantly the DC however had no influence on the ΔEab, ΔE00 and, opacity values. Finishing and polishing reduced ΔEab and ΔE00 values, regardless of composite resins. Microhybrid showed higher opacity, followed by the nanoparticle and bulk fill, regardless of surface treatment. Post-polymerization polishing procedures resulted in lower conversion than using an oxygen inhibitor agent (Gly condition), but similar staining caused by coffee.

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Influence of alternative photoinitiators in composite resins: A literature review

Research Society and Development ◽

10.33448/rsd-v9i12.11128 ◽

2020 ◽

Vol 9 (12) ◽

pp. e32091211128

Author(s):

Nathalie Murielly Rolim de Abreu ◽

Ruth Venâncio Fernandes Dantas ◽

Hugo Ramalho Sarmento ◽

Robinsom Viégas Montenegro ◽

Heloísa Helena Pinho Veloso ◽

...

Keyword(s):

Search Strategy ◽

Color Stability ◽

Composite Resins ◽

Degree Of Conversion ◽

Exclusion Criteria ◽

Light Emitting ◽

Electronic Search ◽

Light Curing ◽

Knoop Microhardness

Objective: To evaluate the influence of alternative photoinitiators present in composite resins related to yellowing, color stability, photosensitivity, light-curing efficiency, degree of conversion, and microhardness. Materials and methods: The literature was reviewed by two independent reviewers at PubMed. The search strategy was carried out using the following descriptors: (Photoinitiators, dental) AND (Curing lights, dental) AND (Composite Resins) NOT (Case report). The electronic search was carried out until March 2019, without language restrictions, and inclusion and exclusion criteria were applied in the selection. Results: Thirteen articles met the previously established criteria, and all were included. Of these, most were in vitro studies. After the aging of the composite, all systems suffered yellowing, however the isolates with camphorquinone were the most affected and, although there is a greater tendency to yellowing, this does not directly affect color stability. However, the literature is still conflicting about which system has significant color stability. Regarding photosensitivity, all photoinitiators have different absorption peaks. In this sense, the photopolymerization must be chosen with caution, as the conversion of monomers and microhardness proved to be directly linked to the correct combination of photoactivator and photopolymerizing unit. Conclusion: Alternative photoinitiators have a lower yellowing rate and good color stability. They can be up to five times more sensitive than systems containing isolated camphorquinone. Only third-generation light-emitting diodes photopolymerize satisfactorily composite resins that have alternative photoinitiators in their composition, ensuring a good degree of conversion and acceptable Knoop microhardness values.

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