The Effect of Soft-start Polymerization by Second Generation LEDs on the Degree of Conversion of Resin Composite

Clinical Relevance Photo-polymerization using second generation LED and halogen light in the soft-start mode of curing was able to produce an adequate degree of conversion in resin composites. The lower degree of conversion produced by low power LED in the soft-start mode could lead to restoration failure, degradation of the organic matrix and recurrent caries.

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Post-gel Shrinkage Strain and Degree of Conversion of Preheated Resin Composite Cured Using Different Regimens

Operative Dentistry ◽

10.2341/09-072-l ◽

2010 ◽

Vol 35 (2) ◽

pp. 172-179 ◽

Cited By ~ 22

Author(s):

D. I. El-Korashy

Keyword(s):

Clinical Relevance ◽

Negative Impact ◽

Resin Composite ◽

Shrinkage Strain ◽

Degree Of Conversion ◽

Soft Start

Clinical Relevance The preheating of resin composite prior to curing yielded a better degree of conversion but had a negative impact on the induced post-gel shrinkage strain; soft-start mode is recommended, as it reduces the post-gel shrinkage strain without affecting the degree of conversion.

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Influence of curing duration and mixing techniques of bulk fill resin composites on bi-axial flexural strength and degree of conversion

Journal of Applied Biomaterials & Functional Materials ◽

10.1177/2280800020975721 ◽

2020 ◽

Vol 18 ◽

pp. 228080002097572

Author(s):

Thamer Almohareb ◽

Abdulaziz A Alayed ◽

Khalid M. Alzahrani ◽

Ahmed M Maawadh ◽

Basil Almutairi ◽

...

Keyword(s):

Fourier Transform ◽

Flexural Strength ◽

Statistical Data ◽

Resin Composite ◽

Degree Of Conversion ◽

Resin Composites ◽

Photo Polymerization ◽

Biaxial Flexural Strength ◽

Curing Methods ◽

Mixing Techniques

Objectives: The aim was to assess the influence of polymerization duration, method and resin manipulation techniques on the biaxial flexural strength (BFS) and degree of conversion (DC) of bulk fill resin composites (BFRC). Methods: One hundred and eighty disc specimens were fabricated using MultiCore (MC) and Core-It (CI) bulk fill resin composite. Each material group, specimens were divided into nine subgroups based on curing methods (Light cure for 10 and 20 s; and auto-cure) and mixing techniques (first auto-mix, second automix, and hand mix). BFS was tested with a ball indenter at a crosshead speed of 0.50 mm/min. DC was assessed for MC and CI materials for 10 s and 20 s light cure; and auto cure specimens using Fourier Transform-Infrared Spectroscopy (FTIR). Statistical data comparisons were performed using ANOVA, Bonferroni and Tukey-Kramer tests. Results: For MC and CI, BFS was highest in 10 s light cure specimens, however comparable to specimens cured for 20 s ( p > 0.05). Auto cure specimens showed lower BFS than light cured samples for both materials ( p < 0.05). Hand mixed specimens showed significantly compromised BFS compared to automix technique for MC and CI. DC % was comparable for 10 s and 20 s light cure methods for both materials ( p > 0.05), which was higher than DC % of auto cure bulk fill resins ( p < 0.05). CI showed higher DC % and BFS compared to MC bulk fill resin composite. Conclusion: Photo-polymerization duration of 10 and 20 s showed similar outcomes for BFS and DC %; and BFS for auto-mixed resins (MC and CI) was significantly higher than hand mixed resin. BFS and DC was higher in photopolymerized groups as compared to auto-cured resin regardless of the manipulation technique for both materials (MultiCore and Core it).

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Development of Chlorhexidine Loaded Halloysite Nanotube Based Experimental Resin Composite with Enhanced Physico-Mechanical and Biological Properties for Dental Applications

Journal of Composites Science ◽

10.3390/jcs4020081 ◽

2020 ◽

Vol 4 (2) ◽

pp. 81 ◽

Cited By ~ 1

Author(s):

Tejas Barot ◽

Deepak Rawtani ◽

Pratik Kulkarni

Keyword(s):

Mechanical Properties ◽

Resin Composite ◽

Biological Properties ◽

Degree Of Conversion ◽

Dental Composites ◽

Resin Composites ◽

Dental Resin ◽

Dental Resin Composites ◽

Mass Fractions ◽

Nih 3T3

Objective: The objective of this study was to explore the effect of Chlorhexidine-loaded Halloysite nanotubes (HNT/CHX) fillers (diverse mass fractions from 1 to 10 wt.%) on physicochemical, morphological and biological properties of newly developed experimental dental resin composite, in order to compare with the properties of composites composed of conventional glass fillers. Methods: The dental resin composites were prepared by incorporating various proportions of HNT/CHX. Six different groups of specimens: control group and five groups composed of varied mass fractions of HNT/CHX (e.g., 1.0, 2.5, 5.0, 7.5 and 10 wt.%) as fillers in each group were fabricated. Mechanical properties of the composites were monitored, using UTM. The degree of conversion of dental resin composites and their depth of cure were also evaluated. Antimicrobial properties of dental composites were studied in vitro by applying agar diffusion test on strain Streptococcus mutans and cytotoxicity were studied using NIH-3T3 cell line. Results: The incorporation of varied mass fractions (1.0 to 5.0 wt.%) of HNT/CHX in dental resins composites enhanced mechanical properties considerably with significant antibacterial activity. The slight decrease in curing depth and degree of conversion values of composites indicates its durability. No cytotoxicity was noticed on NIH-3T3 cell lines. Significance: Consistent distribution of HNT/CHX as a filler into dental composites could substantially improve not only mechanical properties but also biological properties of dental composites.

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Thermal Variations in the Pulp Chamber Associated with Composite Insertion Techniques and Light-curing Methods

The Journal of Contemporary Dental Practice ◽

10.5005/jcdp-10-1-17 ◽

2009 ◽

Vol 10 (1) ◽

pp. 17-24 ◽

Cited By ~ 7

Author(s):

Mário Alexandre Coelho Sinhoreti ◽

Ricardo Danil Guiraldo ◽

Simonides Consani ◽

Lourenço Correr-Sobrinho ◽

Luis Felipe Jochims Schneider

Keyword(s):

Light Exposure ◽

Resin Composite ◽

Continuous Light ◽

Pulp Chamber ◽

Pulp Tissue ◽

Soft Start ◽

Halogen Light ◽

Curing Methods ◽

Light Curing ◽

Insertion Techniques

Abstract Aim The aim of this study was to investigate the effect of different incremental insertion techniques, photoactivation, and restorative phases on thermal variations occurring during the polymerization of Filtek Z250 composite resin. Methods and Materials The experiment was conducted using 90 bovine incisor teeth. The teeth were randomly assigned to three groups according to the technique used for photoactivation with a halogen light (continuous, soft-start, or intermittent). The groups were further separated into three subgroups according to method of increment placement (bulk, oblique, or horizontal/vertical) for a total of nine groups (n=10). Restorations were placed in a controlled environment (37°C and 50±10% RU) and the temperature recorded using a digital thermometer coupled to a Type-K thermocouple inserted in the pulp chamber through the root canal in contact with the dentin. Data were analyzed using an analysis of variance (ANOVA) and the Tukey's test. Results Higher temperature values were found for continuous light photoactivation in combination with the placement of horizontal/vertical composite increments and photoactivation of the adhesive using a continuous light exposure. Conclusion The light source is the most important factor producing temperature changes during photoactivation of resin composite. Clinical Significance Temperature increases in the pulp chamber due to light curing should be considered to avoid harming the delicate pulp tissue when large restorations or inlays/onlays require several consecutive light curing exposures for a complete cure. Citation Guiraldo RD, Consani S, Sinhoreti MAC, Correr-Sobrinho L, Schneider LFJ. Thermal Variations in the Pulp Chamber Associated with Composite Insertion Techniques and Light-curing Methods. J Contemp Dent Pract 2009 January; (10)1:017-024.

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Effect of 4-(N,N-dimethylamino)phenethyl Alcohol on Degree of Conversion and Cytotoxicity of Photo-Polymerized CQ-Based Resin Composites

Brazilian Dental Journal ◽

10.1590/0103-6440201300113 ◽

2014 ◽

Vol 25 (6) ◽

pp. 538-542 ◽

Cited By ~ 5

Author(s):

Dayane Carvalho Ramos Salles de Oliveira ◽

Camila Batista da Silva ◽

Bruno Vilela Muniz ◽

Maria C. Volpato ◽

Ana Rosa Costa ◽

...

Keyword(s):

Organic Matrix ◽

Human Keratinocytes ◽

Filler Loading ◽

Degree Of Conversion ◽

Control Group ◽

Resin Composites ◽

Cytotoxic Effects ◽

Phenethyl Alcohol ◽

Significant Difference ◽

Post Hoc

The aim of this study was to evaluate the degree of conversion (DC) and the cytotoxicity of photo-cured experimental resin composites containing 4-(N,N-dimethylamino)phenethyl alcohol (DMPOH) combined to the camphorquinone (CQ) compared with ethylamine benzoate (EDAB). The resin composites were mechanically blended using 35 wt% of an organic matrix and 65 wt% of filler loading. To this matrix was added 0.2 wt% of CQ and 0.2 wt% of one of the reducing agents tested. 5x1 mm samples (n=5) were previously submitted to DC measurement and then pre-immersed in complete culture medium without 10% (v/v) bovine serum for 1 h or 24 h at 37 °C in a humidifier incubator with 5% CO2 and 95% humidity to evaluate the cytotoxic effects of experimental resin composites using the MTT assay on immortalized human keratinocytes cells. As a result of absence of normal distribution, the statistical analysis was performed using the nonparametric Kruskal-Wallis to evaluate the cytotoxicity and one-way analysis of variance to evaluate the DC. For multiple comparisons, cytotoxicity statistical analyses were submitted to Student-Newman-Keuls and DC analysis to Tukey's HSD post-hoc test (=0.05). No significant differences were found between the DC of DMPOH (49.9%) and EDAB (50.7%). 1 h outcomes showed no significant difference of the cell viability between EDAB (99.26%), DMPOH (94.85%) and the control group (100%). After 24 h no significant difference were found between EDAB (48.44%) and DMPOH (38.06%), but significant difference was found compared with the control group (p>0.05). DMPOH presented similar DC and cytotoxicity compared with EDAB when associated with CQ.

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Influence of the Internal Conditioning of Indirect Restorations of Resin Composite in Relation to Microleakage Using LEDs and QTH Units

Operative Dentistry ◽

10.2341/08-83 ◽

2009 ◽

Vol 34 (3) ◽

pp. 293-298 ◽

Cited By ~ 3

Author(s):

S. Calabrez-Filho ◽

V. C. N. Calabrez ◽

E. G. Reston ◽

M. F. Andrade ◽

L. H. Borges

Keyword(s):

Clinical Relevance ◽

Resin Composite ◽

Resin Composites ◽

Composite Inlays

Clinical Relevance An efficient polymerization of resin composite inlays associated with treatment of the surface and luting with dual resinous cement and flowable resin composites presents better longevity of restorations.

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The Influence of C-factor, Flexural Modulus and Viscous Flow on Gap Formation in Resin Composite Restorations

Operative Dentistry ◽

10.2341/06-104 ◽

2007 ◽

Vol 32 (4) ◽

pp. 356-362 ◽

Cited By ~ 29

Author(s):

E. Moreira da Silva ◽

G. O. dos Santos ◽

J. G. A. Guimarães ◽

A. A. L. Barcellos ◽

E. M. Sampaio

Keyword(s):

Viscous Flow ◽

Clinical Relevance ◽

Resin Composite ◽

Flexural Modulus ◽

Resin Composites ◽

Gap Formation ◽

Composite Restorations

Clinical Relevance Resin composites with high viscous flow and low flexural modulus may reduce gap formation in resin composite restorations.

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The effect of radiation exposure and storage time on the degree of conversion and flexural strength of different resin composites

Bulletin of the National Research Centre ◽

10.1186/s42269-021-00605-y ◽

2021 ◽

Vol 45 (1) ◽

Author(s):

Ragia M. Taher ◽

Lamiaa M. Moharam ◽

Amin E. Amin ◽

Mohamed H. Zaazou ◽

Farid S. El-Askary ◽

...

Keyword(s):

Flexural Strength ◽

Radiation Exposure ◽

Storage Time ◽

Resin Composite ◽

Degree Of Conversion ◽

Bending Test ◽

Resin Composites ◽

Significant Difference ◽

Infrared Spectrometer ◽

And Storage

Abstract Background This study was conducted to evaluate the effect of radiation exposure and storage time on the degree of conversion (DC%) and flexural strength (FS) of three different resin composites. In total, 90 disk-shaped, and 360 rod-shaped composite specimens were prepared to evaluate the DC% and FS, respectively. Specimens were divided into 18 groups (DC%: n = 5 and FS: n = 20) according to the three experimental factors of the study: 1—Radiation (no-exposure and exposure), 2—Resin composite material (Herculite XRV Ultra, Z250 XT and Grandio), and 3—Storage time (24 h in distilled water, 3-m and 6-m in 70% ethanol). Fourier transform infrared spectrometer (FTIR) was used to determine the DC%. For FS, the specimens were subjected to a three-point bending test at 1 mm/min crosshead speed. Data were analyzed using three-way ANOVA/Tukey HSD test. Significant level was set at P = 0.05. Results For DC%, there was no significant difference between no-radiation exposure and radiation exposure (P > 0.05). Herculite XRV Ultra revealed the highest statistically significant DC% (P < 0.05). The 24-h storage time revealed the least significant DC% (P < 0.05). For FS, radiation exposure showed a statistically significant higher value compared to no-radiation exposure (P < 0.05). Herculite XRV Ultra showed the least FS value (P < 0.05). The 24-h storage time showed the highest significant value (P < 0.05). Conclusions Radiation exposure has no significant impact on the DC% of the different resin composites, but it has a significant positive effect on the FS. Storage time had a significant effect on both DC% and FS.

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Shrinkage Stress and Temperature Variation in Resin Composites Cured via Different Photoactivation Methods: Insights for Standardisation of the Photopolymerisation

Polymers ◽

10.3390/polym13132065 ◽

2021 ◽

Vol 13 (13) ◽

pp. 2065

Author(s):

Guilherme dos Santos Sousa ◽

Gabriel Felipe Guimarães ◽

Edilmar Marcelino ◽

José Eduardo Petit Rodokas ◽

Arilson José de Oliveira Júnior ◽

...

Keyword(s):

Factor Analysis ◽

Temperature Variation ◽

Resin Composite ◽

Smartphone App ◽

Shrinkage Stress ◽

Resin Composites ◽

Pulse Delay ◽

Depth Of Cure ◽

Practical Applications ◽

Soft Start

The literature has shown that there is no consensus regarding the best resin composite photoactivation protocol. This study evaluated the efficiency of the conventional, soft-start, pulse-delay and exponential protocols for photoactivation of resin composites in reducing the shrinkage stress and temperature variation during the photopolymerisation. The photoactivation processes were performed using a photocuring unit and a smartphone app developed to control the irradiance according each photoactivation protocol. These photoactivation methods were evaluated applying photoactivation energies recommended by the resins manufactures. Three brands of resin composites were analysed: Z-250, Charisma and Ultrafill. The cure effectiveness was evaluated through depth of cure experiments. All results were statistically evaluated using one-way and multi-factor analysis of variance (ANOVA). The use of exponential and pulse-delay methods resulted in a significant reduction of the shrinkage stress for all evaluated resins; however, the pulse-delay method required too long a photoactivation time. The increases on the temperature were lower when the exponential photoactivation was applied; however, the temperature variation for all photoactivation protocols was not enough to cause damage in the restoration area. The evaluation of the depth of cure showed that all photoactivation protocols resulted in cured resins with equivalent hardness, indicating that the choice of an alternative photoactivation protocol did not harm the polymerisation. In this way, the results showed the exponential protocol as the best photoactivation technique for practical applications.

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