Influence of light-curing protocols on polymerization shrinkage and shrinkage force of a dual-cured core build-up resin composite

2010 ◽  
Vol 118 (4) ◽  
pp. 423-429 ◽  
Author(s):  
Tobias T. Tauböck ◽  
Tissiana Bortolotto ◽  
Wolfgang Buchalla ◽  
Thomas Attin ◽  
Ivo Krejci
2018 ◽  
Vol 43 (6) ◽  
pp. 619-630 ◽  
Author(s):  
N Rohr ◽  
JA Müller ◽  
J Fischer

ABSTRACT Objective: The purpose of this study was to establish a clinically appropriate light-curing moment for resin composite cements while achieving the highest indirect tensile strength and lowest polymerization shrinkage. Methods and Materials: Polymerization shrinkage of seven resin composite cements (Multilink Automix, Multilink Speed Cem, RelyX Ultimate, RelyX Unicem 2 Automix, Panavia V5, Panavia SA plus, VITA Adiva F-Cem) was measured at ambient temperatures of 23°C and 37°C. Testing was done for autopolymerized and light-cured specimens after light application at either 1, 5, or 10 minutes after mixing. Indirect tensile strength of all cements was measured after 24 hours of storage at temperatures of 23°C and 37°C, for autopolymerized and light-cured specimens after light application 1, 5, or 10 minutes after mixing. To illustrate filler size and microstructures, SEM images of all cements were captured. Statistical analysis was performed with one-way ANOVA followed by post hoc Fisher LSD test (α=0.05). Results: Final polymerization shrinkage of the resin composite cements ranged from 3.2% to 7.0%. An increase in temperature from 23°C to 37°C as well as the light-curing moment resulted in material dependent effects on the polymerization shrinkage and indirect tensile strength of the cements. Polymerization shrinkage of the cements did not correlate with the indirect tensile strength of the cement in the respective groups. Highest indirect tensile strengths were observed for the materials containing a homogeneous distribution of fillers with a size of about 1 μm (Multilink Automix, Panavia V5, VITA Adiva F-Cem). Conclusion: The magnitude of the effect of light-curing moment and temperature increase on polymerization shrinkage and indirect tensile strength of resin composite cements is material dependent and cannot be generalized.


2007 ◽  
Vol 86 (3) ◽  
pp. 227-231 ◽  
Author(s):  
E. Cabrera ◽  
J.C. de la Macorra

Shrinkage results from a complex spatial strain network, producing movements within materials. The purpose of this study was to test whether microtensile bond strength (μTBS) of a light-curing resin composite to enamel depends on distance to the center of the curing mass. Labial surfaces of bovine incisors were ground flat, divided into 2 groups (n = 8), acid-etched, and coated with an unfilled resin bond. A resin-based composite was placed in one increment (group A) or separately at gingival, central, and incisal sites (group B), and light-cured. Teeth were sectioned, yielding stick-shaped specimens assigned to one of 9 groups according to distance to incisal edge of restoration (NDistanc). Microtensile bond strength was transformed to percentages of its maximum values within each tooth (PMPa). Comparisons within groups showed (group A) that mean PMPa decreased from central to gingival and from central to incisal (p < 0.01). Comparisons between groups showed that mean PMPa was significantly lower in group A compared with group B, only at gingival and incisal sites. Microtensile bond strength significantly decreased as the distance increased to the center of the curing mass.


2020 ◽  
Vol 45 (5) ◽  
pp. 496-505
Author(s):  
CS Sampaio ◽  
PG Pizarro ◽  
PJ Atria ◽  
R Hirata ◽  
M Giannini ◽  
...  

Clinical Relevance Shortened light curing does not affect volumetric polymerization shrinkage or cohesive tensile strength but negatively affects the shear bond strength of some bulk-fill resin composites. When performing shortened light curing, clinicians should be aware of the light output of their light-curing units. SUMMARY Purpose: To evaluate volumetric polymerization shrinkage (VPS), shear bond strength (SBS) to dentin, and cohesive tensile strength (CTS) of bulk-fill resin composites (BFRCs) light activated by different modes. Methods and Materials: Six groups were evaluated: Tetric EvoCeram bulk fill + high mode (10 seconds; TEC H10), Tetric EvoFlow bulk fill + high mode (TEF H10), experimental bulk fill + high mode (TEE H10), Tetric EvoCeram bulk fill + turbo mode (five seconds; TEC T5), Tetric EvoFlow bulk fill + turbo mode (TEF T5), and experimental bulk fill + turbo mode (TEE T5). Bluephase Style 20i and Adhese Universal Vivapen were used for all groups. All BFRC samples were built up on human molar bur-prepared occlusal cavities. VPS% and location were evaluated through micro–computed tomography. SBS and CTS tests were performed 24 hours after storage or after 5000 thermal cycles; fracture mode was analyzed for SBS. Results: Both TEC H10 and TEE H10 presented lower VPS% than TEF H10. However, no significant differences were observed with the turbo-curing mode. No differences were observed for the same BFRC within curing modes. Occlusal shrinkage was mostly observed. Regarding SBS, thermal cycling (TC) affected all groups. Without TC, all groups showed higher SBS values for high mode than turbo mode, while with TC, only TEC showed decreased SBS from high mode to turbo modes; modes of fracture were predominantly adhesive. For CTS, TC affected all groups except TEE H10. In general, no differences were observed between groups when comparing the curing modes. Conclusions: Increased light output with a shortened curing time did not jeopardize the VPS and SBS properties of the BFRCs, although a decreased SBS was observed in some groups. TEE generally showed similar or improved values for the tested properties in a shortened light-curing time. The VPS was mostly affected by the materials tested, whereas the SBS was affected by the materials, curing modes, and TC. The CTS was not affected by the curing modes.


2017 ◽  
Vol 25 (2) ◽  
pp. 140-146 ◽  
Author(s):  
Kelly Antonieta Oliveira Rodrigues de Faria CARDOSO ◽  
Driellen Christine ZARPELLON ◽  
Camila Ferreira Leite MADRUGA ◽  
José Augusto RODRIGUES ◽  
Cesar Augusto Galvão ARRAIS

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6849
Author(s):  
Francesco De Angelis ◽  
Mirco Vadini ◽  
Mario Capogreco ◽  
Camillo D’Arcangelo ◽  
Maurizio D’Amario

The aim of this study was to compare three different light-curing-units (LCUs) and determine their effectiveness in the adhesive cementation of indirect composite restorations when a light-curing resin cement is used. Two resin composites were selected: Enamel Plus HRI (Micerium) and AURA (SDI). Three thicknesses (3 mm, 4 mm and 5 mm) were produced and applied as overlays and underlays for each resin composite. A standardized composite layer was placed between underlay and overlay surfaces. Light curing of the resin-based luting composites was attained through the overlay filters using LCUs for different exposure times. All specimens were allocated to experimental groups according to the overlay thickness, curing unit and curing time. Vickers Hardness (VH) notches were carried out on each specimen. Data were statistically evaluated. The curing unit, curing time and overlay thickness were significant factors capable of influencing VH values. The results showed significantly decreased VH values with increasing specimen thickness (p < 0.05). Significant differences in VH values were found amongst the LCUs for the various exposure times (p < 0.05). According to the results, a time of cure shorter than 80 s (with a conventional quartz–tungsten–halogen LCU) or shorter than 40 s (with a high-power light-emitting diode (LED) LCU) is not recommended. The only subgroup achieving clinically acceptable VH values after a short 20 s curing time included the 3 mm-thick overlays made out of the AURA composite, when the high-power LED LCU unit was used (VH 51.0). Composite thickness has an intense effect on polymerization. In clinical practice, light-cured resin cements may result in insufficient polymerization for high thickness and inadequate times. High-intensity curing lights can attain the sufficient polymerization of resin cements through overlays in a significantly shorter time than conventional halogen light.


2018 ◽  
Vol 29 (3) ◽  
pp. 282-289 ◽  
Author(s):  
Carlos José Soares ◽  
Gabriel Felipe de Bragança ◽  
Renata Afonso da Silva Pereira ◽  
Monise de Paula Rodrigues ◽  
Stella Sueli Lourenço Braga ◽  
...  

Abstract The combination of the restoration location, the hand preference of the operator using the light-curing unit (LCU), and the design of the LCU all can have an impact on the amount of the light delivered to the restoration. To evaluate the effect of left-handed or right-handed users, the position of the operator (dentist or assistant), and the LCU design on the irradiance, radiant exposure and emission spectrum delivered to the same posterior tooth. Two light emitting diode (LED) LCUs were tested: an angulated monowave LCU Radii-Cal (SDI, Victoria, Australia) and a straight aligned multi-peak LCU Valo Cordless (Ultradent, South Jordan, UT, USA). The irradiance values (mW/cm2), radiant exposure (J/cm2) and emission spectrum were measured using a sensor in maxillary left second molar tooth. The irradiance and radiant exposure were analyzed using three-way ANOVA followed by Tukey test (a=0.05). The emission spectra (nm) were analyzed descriptively. The interaction between LCU design, operator position, and hand preference significantly influenced the irradiance and radiant exposure (P<0.001). In all cases, Valo delivered significantly higher irradiance than Radii-Cal. The handedness and the operator position affected the irradiance and radiant exposure delivered from Valo. Operator position and access affect the irradiance and radiant exposure delivered to the maxillary left second molar. The irradiance and radiant exposure can be greater when a right-hand operator is positioned on the right side of the chair and a left-hand operator is positioned on the left side of the chair. This may result in better resin composite polymerization.


2006 ◽  
Vol 20 (4) ◽  
pp. 342-346 ◽  
Author(s):  
Daniela Francisca Gigo Cefaly ◽  
Linda Wang ◽  
Liliam Lucia Carrara Paes de Mello ◽  
Janaína Lima dos Santos ◽  
Jean Rodrigo dos Santos ◽  
...  

The Light Emitting Diodes (LED) technology has been used to photoactivate composite resins and there is a great number of published studies in this area. However, there are no studies regarding resin-modified glass-ionomer cements (RMGIC), which also need photoactivation. Therefore, the aim of this study was to evaluate water sorption of two RMGIC photoactivated with LED and to compare this property to that obtained with a halogen light curing unit. A resin composite was used as control. Five specimens of 15.0 mm in diameter x 1.0 mm in height were prepared for each combination of material (Fuji II LC Improved, Vitremer, and Filtek Z250) and curing unit (Radii and Optilight Plus) and transferred to desiccators until a constant mass was obtained. Then the specimens were immersed into deionized water for 7 days, weighed and reconditioned to a constant mass in desiccators. Water sorption was calculated based on weight and volume of specimens. The data were analyzed by two-way ANOVA and Tukey test (p < 0.05). Specimens photocured with LED presented significantly more water sorption than those photocured with halogen light. The RMGIC absorbed statistically significant more water than the resin composite. The type of light curing unit affected water sorption characteristics of the RMGIC.


2016 ◽  
Vol 27 (4) ◽  
pp. 430-435 ◽  
Author(s):  
Adriana Corrêa de Lima ◽  
Fuad Jacob Rached-Junior ◽  
Natália Spadini de Faria ◽  
Danielle Cristine Messias ◽  
Carolina de Andrade Lima Chaves ◽  
...  

Abstract The aim of this study was to assess the influence of sealer and light-curing unit on regional bond strength of resin composite to the weakened roots. Ninety roots of incisors were experimentally weakened, subjected to biomechanical preparation and filled with either Endofill, AH Plus or MTA Fillapex The roots were desobturated e reinforced with resin composite and fiber post light-activated with one of the light sources: halogen at 600 mW/ cm2 (QTH-600), LED at 800 mW/ cm2 (LED-800) and LED at 1500 mW/ cm2 (LED-1500). The roots were sectioned in slices from cervical, middle and apical root-reinforcement regions and analyzed by push out test, scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). Bond strength data were analyzed using three-way ANOVA and Tukey´s test (α=0.05). Specimens filled with AH Plus had higher bond strength, followed by MTA Fillapex and Endofill (p<0.05). For light-curing unit, LED-1500 presented superior bond strength than LED-800, which was higher than QTH-600 (p<0.05). The cervical region had the greatest mean values (p<0.05) while apical part showed the lowest bond strength (p<0.05). CLMS revealed remaining filling material in the dentinal tubules for all groups. The eugenol-containing sealer (Endofill) compromised the push-out bond strength of composite resin to the root dentin. Bond strength was favored in the cervical region, and when LED-1500 was used.


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