Influence of photoactivation method on conversion, mechanical properties, degradation in ethanol and contraction stress of resin-based materials

Witzel, Marcelo Ferreira; Calheiros, Fernanda Calabró; Gonçalves, Flávio de Oliveira; Kawano, Yoshio; Braga, Roberto Ruggiero

doi:10.1016/j.jdent.2005.02.005

Cited by 84 publications

(91 citation statements)

References 32 publications

(54 reference statements)

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“…These results indicate that all the tested photo-activation methods were able to cure appropriately the Filtek TM Z-250 and Filtek TM Supreme XT (both 3M Espe) composites, despite the differences (e.g., PD) among them. These results are similar to those found by other studies [2,6,13,26,34,54,55].…”

Section: Resultssupporting

confidence: 93%

“…Studies have shown that PD and photo-activation methods of cure influence the degree of conversion [20,23,24,[34][35][36], volume shrinkage [37,38], elastic modulus, and T g [17], among other properties of composite resins. Thereby, in this study, microhybrid (Filtek TM Z-250) and nanocomposite (Filtek TM Supreme XT) resins were light cured according to two photo-activation methods: continuous and gradual provided by two LED LCUs (Elipar Freelight 2 TM and Bluephase Ò C8).…”

Section: Resultsmentioning

confidence: 99%

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Continuous and gradual photo-activation methods: influence on degree of conversion and crosslink density of composite resins

Costa

Galvão

Jacomassi

et al. 2010

J Therm Anal Calorim

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Thermal properties and degree of conversion (DC%) of two composite resins (microhybrid and nanocomposite) and two photo-activation methods (continuous and gradual) displayed by the light-emitting diode (LED) light-curing units (LCUs) were investigated in this study. Differential scanning calorimetry (DSC) thermal analysis technique was used to investigate the glass transition temperature (T g ) and degradation temperature. The DC% was determined by Fourier transform infrared spectroscopy (FT-IR). The results showed that the microhybrid composite resin presented the highest T g and degradation temperature values, i.e., the best thermal stability. Gradual photo-activation methods showed higher or similar T g and degradation temperature values when compared to continuous method. The Elipar Freelight 2 TM LCU showed the lowest T g values. With respect to the DC%, the photoactivation method did not influence the final conversion of composite resins. However, Elipar Freelight 2 TM LCU and microhybrid resin showed the lowest DC% values. Thus, the presented results suggest that gradual method photoactivation with LED LCUs provides adequate degree of conversion without promoting changes in the polymer chain of composite resins. However, the thermal properties and final conversion of composite resins can be influenced by the kind of composite resin and LCU.

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Section: Resultssupporting

confidence: 93%

Section: Resultsmentioning

confidence: 99%

Continuous and gradual photo-activation methods: influence on degree of conversion and crosslink density of composite resins

Costa

Galvão

Jacomassi

et al. 2010

J Therm Anal Calorim

View full text Add to dashboard Cite

show abstract

“…However, such evaluations require complex tests and special equipment. On the other hand, some studies have used the softening test as an alternative method of evaluation 3,30,39,40) , in which measurement is based on repeated hardness tests after the samples have been softened in organic solvents. It is generally accepted that highly cross-linked polymers are more resistant to degradation and to solvent molecules diffusing within their structure 14) .…”

Section: Discussionmentioning

confidence: 99%

Light Energy Transmission through Composite Influenced by Material Shades

Guiraldo¹,

Consani

Berger

et al. 2009

Bull. Tokyo Dent. Coll.

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This study investigated the influence of different composite resin shades on light energy transmission through the composite, hardness and cross-link density (CLD). The composite Filtek Z250 was used in shades A1, A2, A3, A3.5 and A4. A quartz tungsten halogen light curing unit was used at an irradiance of 900mW/cm 2 . Thirty specimens were made for each shade. Light energy transmission that passed through the composite was calculated (n‫.)01ס‬ Differences in Knoop hardness between the top and bottom (DKH) of the same specimen were calculated (n‫.)01ס‬ The Knoop hardness value for each surface was recorded as the average of three indentations (KHN 1 ). Thereafter, the specimens were soaked in absolute ethanol for 24hr at room temperature, and hardness was again determined (KHN 2 ). The CLD was estimated by the softening effect produced by ethanol, i.e., by decrease in hardness. The percentage of decrease in KHN 2 compared with KHN 1 (PD) in the same specimen was then calculated for both surfaces (n‫.)01ס‬ The data were submitted to an ANOVA in different tests (Light energy transmission, Knoop hardness and CLD). The irradiance of light that passed through composite shade A1 (408mW/cm 2 ) was statistically greater than that through shade A2 (376mW/cm 2 ), and was greater through A2 than A3 (359 mW/cm 2 ) and through A3 than A3.5 (327 mW/cm 2 ); A3.5 showed no statistical difference when compared to A4 (324mW/cm 2 ). The DKH of A4 (20.56%) was not statistically higher than that of A3.5 (20.14%), which was greater than that of A3 (14.08%), A2 (11.65%) and A1 (9.06%). There was no statistical difference in CLD. Darker shades had a significant influence on light energy transmission through dental resin composite and its hardness. However, CLD was not affected by darker dental composite shades.

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“…[14][15][16][17] It is assumed that improved marginal fidelity in prior studies is a result of lower shrinkage stress, and several studies have found that soft-start light curing can reduce the polymerization contraction stresses transferred to the tooth-restoration interface. 5,[18][19][20][21] Another factor that may play a role in the development of contraction stresses and, thus, the adaptation of the resin composite to the bonded cavity walls, is the C-factor, which is the ratio of the bonded to unbonded surface area. 3 Increasing the C-factor has been associated with an increase in the development of shrinkage stresses 3 and, subsequently, an adverse effect on bond strength.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Energy Application Sequence on the Microtensile Bond Strength of Different C-factor Cavity Preparations

Maghaireh

Bouschlicher²,

Qian³

et al. 2007

Operative Dentistry

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Influence of photoactivation method on conversion, mechanical properties, degradation in ethanol and contraction stress of resin-based materials

Cited by 84 publications

References 32 publications

Continuous and gradual photo-activation methods: influence on degree of conversion and crosslink density of composite resins

Continuous and gradual photo-activation methods: influence on degree of conversion and crosslink density of composite resins

Light Energy Transmission through Composite Influenced by Material Shades

The Effect of Energy Application Sequence on the Microtensile Bond Strength of Different C-factor Cavity Preparations

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