scholarly journals Pulse-delay Curing: Influence of Initial Irradiance and Delay Time on Shrinkage Stress and Microhardness of Restorative Composites

2006 ◽  
Vol 31 (5) ◽  
pp. 610-615 ◽  
Author(s):  
C. S. C. Pfeifer ◽  
R. R. Braga ◽  
J. L. Ferracane
Keyword(s):  
Network Structure ◽  
Delay Time ◽  
Clinical Relevance ◽  
Polymer Network ◽  
Degree Of Conversion ◽  
Shrinkage Stress ◽  
Clinical Use ◽  
Pulse Delay ◽  
Polymerization Shrinkage ◽  
Restorative Composites

Clinical Relevance New photoactivation protocols need to be tested before being recommended for clinical use. This study suggests that pulse-delay curing may be an efficient way to reduce polymerization shrinkage stress without compromising degree of conversion or polymer network structure.

scholarly journals Influence of Modulated Photo-Activation on Shrinkage Stress and Degree of Conversion of Bulk-Fill Composites

2019 ◽  
Vol 30 (6) ◽  
pp. 592-598 ◽  
Author(s):  
Marilia Mattar de Amoêdo Campos Velo ◽  
Linda Wang ◽  
Adilson Yoshio Furuse ◽  
Letícia Ferreira de Freitas Brianezzi ◽  
Cassiana Koch Scotti ◽  
...  
Keyword(s):  
Testing Machine ◽  
Continuous Light ◽  
High Viscosity ◽  
Degree Of Conversion ◽  
Steel Plates ◽  
Attenuated Total Reflectance ◽  
Shrinkage Stress ◽  
Polymerization Shrinkage ◽  
Low Viscosity ◽  
Universal Testing

Abstract This study aimed to evaluate the polymerization properties of bulk-fill materials (low and high-viscosity) by using high-intensity continuous light and intermittent photo-activation in terms of polymerization shrinkage stress and degree of conversion (DC). The following Bulk-fill and Conventional nanofilled resin composites were evaluated: Filtek Z350XT Flow (3M/ESPE), SureFil SDR Flow (Dentsply), Filtek Bulk Fill Flow (3M/ESPE), Filtek Z350XT (3M/ESPE) and Filtek Bulk Fill Posterior (3M/ESPE). A LED device (DB 685, Dabi Atlante) was used for both protocols: continuous uniform and intermittent photo-activation (light-on and light-off cycles) with identical radiant exposure (14 J/cm2). The polymerization shrinkage stress (n=6) was evaluated by inserting a single increment of 12 mm3 between two stainless steel plates (6×2 mm) adapted to a Universal Testing Machine (UTM), at different times. Measurements were recorded after photo-activation. The degree of conversion was evaluated by Fourier transformed infrared spectroscope (FTIR) with an attenuated total reflectance (ATR) accessory (n=5). Data were analyzed by three-way ANOVA and Tukey’s HSD (α=0.05) tests. Bulk Fill Posterior presented higher shrinkage stress values when photo-activated with the intermittent technique (p<0.05). The intermittent photo-activation increased the degree of conversion for the low-viscosity bulk-fills (p<0.05). Therefore, the use of modulated photo-activation (intermittent) must be indicated with caution since its use can influence the shrinkage stress and degree of conversion of composites, which varies according to the resin formulations.

scholarly journals Polymerization Shrinkage, Shrinkage Stress, and Degree of Conversion in Bulk-Fill Resin Composites After Different Photo-Activation Methods

2020 ◽  
Vol 11 (1) ◽  
pp. 4
Author(s):  
Fatemeh Namdar ◽  
Sara Majidinia ◽  
Hossein Bagheri ◽  
Shadi Ramezani ◽  
MohammadJafari Giv ◽  
...  
Keyword(s):  
Degree Of Conversion ◽  
Shrinkage Stress ◽  
Resin Composites ◽  
Polymerization Shrinkage

scholarly journals Polymerization shrinkage behaviour of resin composites functionalized with unsilanized bioactive glass fillers

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Matej Par ◽  
Dirk Mohn ◽  
Thomas Attin ◽  
Zrinka Tarle ◽  
Tobias T. Tauböck
Keyword(s):  
Bioactive Glass ◽  
Degree Of Conversion ◽  
Stress Rate ◽  
Partial Replacement ◽  
Shrinkage Stress ◽  
Resin Composites ◽  
Dental Resin ◽  
Polymerization Shrinkage ◽  
Reinforcing Fillers ◽  
Shrinkage Behaviour

Abstract Previous work has shown that partial replacement of reinforcing fillers with unsilanized silica particles can diminish polymerization shrinkage stress of dental resin composites. The aim of the present study was to investigate whether such an effect can be attained by using unsilanized bioactive glass (BG). Incorporating BG fillers into resin composites is interesting due to their potential for exerting caries-preventive effects. Experimental light-curable composites with a total filler load of 77 wt% were prepared. Reinforcing fillers were partially replaced with 0–60 wt% of BG 45S5 and an experimental low-sodium fluoride-containing BG. The following properties were investigated: linear shrinkage, degree of conversion, shrinkage stress, maximum shrinkage stress rate, and time to achieve maximum shrinkage stress rate. The diminishing effect of BG 45S5 on shrinkage stress was mediated by a decrease in degree of conversion caused by this BG type. In contrast, as the degree of conversion remained unaffected by the experimental BG, the resulting shrinkage behaviour was governed by the effect of varying amounts of silanized and unsilanized fillers on material’s viscoelastic properties. The replacement of silanized reinforcing fillers with unsilanized BG did not reduce polymerization shrinkage stress unless the reduction was attained indirectly through a diminished degree of conversion.

The Combination of CQ-amine and TPO Increases the Polymerization Shrinkage Stress and Does Not Improve the Depth of Cure of Bulk-fill Composites

2019 ◽  
Vol 44 (5) ◽  
pp. 499-509
Author(s):  
MG Rocha ◽  
DCRS de Oliveira ◽  
MAC Sinhoreti ◽  
JF Roulet ◽  
AB Correr
Keyword(s):  
Near Infrared ◽  
Light Emitting Diode ◽  
Flexural Modulus ◽  
Degree Of Conversion ◽  
Light Transmittance ◽  
Volumetric Shrinkage ◽  
Shrinkage Stress ◽  
Polymerization Shrinkage ◽  
Depth Of Cure ◽  
Three Point Bend Test

SUMMARY Objectives: To evaluate the effect of combining camphorquinone (CQ) and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO) on the depth of cure and polymerization shrinkage stress of bulk-fill composites. Methods and Materials: Experimental bulk-fill composites were produced containing equal molar concentrations of either CQ-amine or CQ-amine/TPO. The degree of in-depth conversion through each millimeter of a 4-mm-thick bulk-fill increment was evaluated by Fourier transform near-infrared microspectroscopy using a central longitudinal cross section of the increment of each bulk-fill composite (n=3). Light-transmittance of the multi-wave light-emitting diode (LED) emittance used for photoactivation (Bluephase G2, Ivoclar Vivadent) was recorded through every millimeter of each bulk-fill composite using spectrophotometry. The volumetric shrinkage and polymerization shrinkage stress were assessed using a mercury dilatometer and the Bioman, respectively. The flexural modulus was also assessed by a three-point bend test as a complementary test. Data were analyzed according to the different experimental designs (α=0.05 and β=0.2). Results: Up to 1 mm in depth, adding TPO to CQ-based bulk-fill composites increased the degree of conversion, but beyond 1 mm no differences were found. The light-transmittance of either wavelengths emitted from the multi-wave LED (blue or violet) through the bulk-fill composites were only different up to 1 mm in depth, regardless of the photoinitiator system. Adding TPO to CQ-based bulk-fill composites did not affect volumetric shrinkage but did increase the flexural modulus and polymerization shrinkage stress. Conclusion: Adding TPO to CQ-based bulk-fill composites did not increase the depth of cure. However, it did increase the degree of conversion on the top of the restoration, increasing the polymerization shrinkage stress.

Effect of Layering Techniques on Polymerization Shrinkage Stress of High- and Low-viscosity Bulk-fill Resins

2020 ◽  
Vol 45 (6) ◽  
pp. 655-663
Author(s):  
A Tsujimoto ◽  
CA Jurado ◽  
WW Barkmeier ◽  
ME Sayed ◽  
T Takamizawa ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Clinical Relevance ◽  
High Viscosity ◽  
Shrinkage Stress ◽  
Polymerization Shrinkage ◽  
Low Viscosity ◽  
Aluminum Block ◽  
Scanning Electron

Clinical Relevance The use of layering techniques is still advisable with many bulk-fill resins and should be the default unless a particular resin is known to not need it. SUMMARY Objective: The purpose of this study was to investigate how layering techniques affect polymerization shrinkage stresses of high-and low-viscosity bulk-fill resins. Method: Six high-viscosity and six low-viscosity bulk-fill resins were evaluated. Aluminum blocks with a mesial-occlusal-distal (MOD) cavity were machined and randomly divided into groups for different filling techniques (bulk-fill vs horizontal layering vs oblique layering) and further subdivided according to type of resin (high- vs low-viscosity). The cuspal deflection resulting from the polymerization of bulk-fill resin bonded to a MOD cavity within an aluminum block was measured with a digimatic micrometer. Scanning electron microscopy analyses of tested resins were also conducted. Results: In the high-viscosity bulk-fill resins, cuspal deflection of the MOD cavity ranged from 11.2 to 18.2 μm with the bulk-filling technique, from 10.7 to 15.5 μm with the horizontal layering technique, and from 10.9 to 15.2 μm with the oblique layering technique. In the low-viscosity bulk-fill resins, cuspal deflection of the material ranged from 9.2 to 19.8 μm with the bulk-filling technique, from 8.2 to 15.7 μm with the horizontal layering technique, and from 8.4 to 16.4 μm with the oblique layering technique. Conclusion: Cuspal deflections for some high-and low-viscosity bulk-fill resins were significantly reduced by using layering techniques, but the resultant improvement of layering techniques was not applicable to all the bulk-fill resins used in this study.

Effect of LED Light-Curing Spectral Emission Profile on Light-Cured Resin Cement Degree of Conversion

2020 ◽  
Author(s):  
RQ Ramos ◽  
RR Moraes ◽  
GC Lopes
Keyword(s):  
Clinical Relevance ◽  
Degree Of Conversion ◽  
Resin Cement ◽  
Light Activation ◽  
Spectral Emission ◽  
Led Light ◽  
Emission Profile ◽  
Light Curing

Clinical Relevance The use of multipeak LED light-curing guarantees efficiency on light activation of Ivocerin-containing light-cured resin cement.

scholarly journals Photoelastic evaluation of the effect of composite formulation on polymerization shrinkage stress

2012 ◽  
Vol 26 (3) ◽  
pp. 202-208 ◽  
Author(s):  
Karla Mychellyne Costa Oliveira ◽  
Simonides Consani ◽  
Luciano Souza Gonçalves ◽  
William Cunha Brandt ◽  
Renzo Alberto Ccahuana-Vásquez
Keyword(s):  
Shrinkage Stress ◽  
Polymerization Shrinkage

scholarly journals THE COMPARISON OF RESIN-BASED COMPOSITES PHYSICAL PROPERTIES BETWEEN BULK-FILL TECHNIQUE AND INCREMENTAL TECHNIQUE

2021 ◽  
Vol 6 (1) ◽  
pp. 85
Author(s):  
Rahmi Khairani Aulia
Keyword(s):  
Physical Properties ◽  
Composite Resin ◽  
Color Stability ◽  
Composite Resins ◽  
Shrinkage Stress ◽  
Restorative Material ◽  
Polymerization Shrinkage ◽  
Advantages And Disadvantages ◽  
Restoration Technique ◽  
Restoration Failure

ABSTRACT:Composite resins are currently the most popular restorative material in dentistry. This is due to good aesthetics and maximum conservation ability. Behind these advantages, there are disbenefits of composite resin materials, such as polymerization shrinkage, which can lead to restoration failure. Various attempts have been investigated to reduce the shrinkage incidence of composite resins, one of which is the technique of placing the restorative material into the cavity. The restoration filling technique is recognized as a significant factor in shrinkage stress. By using a special filling technique, the polymerization shrinkage damage stress can be reduced. There are several techniques in performing composite resin fillings, including bulk and incremental techniques. These techniques have their respective advantages and disadvantages. The aim of this literature review was to compare the physical properties of composite resin restorations with bulk filling and incremental techniques. Physical properties that being studied include polymerization shrinkage, stress shrinkage, degree of conversion, bonding strength, water resorption, color stability, and temperature increase. Comparing the two techniques, composite resin with incremental filling technique has superior physical properties compared to bulk technique. From the comparison of the two techniques, the composite resin with incremental filling technique has superior physical properties compared to the bulk technique, especially in higher conversion which causes lower shrinkage stress. This situation makes the incremental technique provide better bond strength, water resorption, color stability, and lower temperature rise.Keywords: Bulk, Composite Resin, Incremental,  Physical Properties, Restoration, Restoration Technique

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