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

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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Bonding Interaction and Shrinkage Stress of Low-viscosity Bulk Fill Resin Composites With High-viscosity Bulk Fill or Conventional Resin Composites

Operative Dentistry ◽

10.2341/18-163-l ◽

2019 ◽

Vol 44 (6) ◽

pp. 625-636 ◽

Cited By ~ 3

Author(s):

ER Cerda-Rizo ◽

M de Paula Rodrigues ◽

ABF Vilela ◽

SSL Braga ◽

LRS Oliveira ◽

...

Keyword(s):

Failure Mode ◽

Resin Composite ◽

High Viscosity ◽

Shrinkage Stress ◽

Resin Composites ◽

Posterior Teeth ◽

Low Viscosity ◽

Bonding Interaction ◽

Significant Difference ◽

Chi Square Analysis

SUMMARY Objective: To analyze the shrinkage stress, bonding interaction, and failure modes between different low-viscosity bulk fill resin composites and conventional resin composites produced by the same manufacturer or a high-viscosity bulk fill resin composite used to restore the occlusal layer in posterior teeth. Methods & Materials: Three low-viscosity bulk fill resin composites were associated with the conventional resin composites made by the same manufacturers or with a high-viscosity bulk fill resin composite, resulting in six groups (n=10). The bonding interaction between resin composites was tested by assessing the microshear bond strength (μSBS). The samples were thermocycled and were tested with 1-mm/min crosshead speed, and the failure mode was evaluated. The post-gel shrinkage (Shr) of all the resin composites was measured using a strain gauge (n=10). The modulus of elasticity (E) and the hardness (KHN) were measured using the Knoop hardness test. Two-dimensional finite element models were created for analyzing the stress caused by shrinkage and contact loading. The μSBS, Shr, E, and KHN data were analyzed using the Student t-test and one-way analysis of variance. The failure mode data were subjected to chi-square analysis (α=0.05). The stress distribution was analyzed qualitatively. Results: No significant difference was verified for μSBS between low-viscosity bulk fill resin composites and conventional or high-viscosity bulk fill composites in terms of restoring the occlusal layer (p=0.349). Cohesive failure of the low-viscosity bulk fill resin composites was the most frequent failure mode. The Shr, E, and KHN varied between low-viscosity and high-viscosity resin composites. The use of high-viscosity bulk fill resin composites on the occlusal layer reduced the stress at the enamel interface on the occlusal surface. Conclusions: The use of high-viscosity bulk fill resin composites as an occlusal layer for low-viscosity bulk fill resin composites to restore the posterior teeth can be a viable alternative, as it shows a similar bonding interaction to conventional resin composites as well as lower shrinkage stress at the enamel margin.

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Polymerization Shrinkage and Depth of Cure of Bulk-Fill Resin Composites and Highly Filled Flowable Resin

Operative Dentistry ◽

10.2341/13-307-l ◽

2015 ◽

Vol 40 (2) ◽

pp. 172-180 ◽

Cited By ~ 87

Author(s):

J-H Jang ◽

S-H Park ◽

I-N Hwang

Keyword(s):

Surface Hardness ◽

Bottom Surface ◽

Shrinkage Stress ◽

Internal Diameter ◽

Resin Composites ◽

Polymerization Shrinkage ◽

Depth Of Cure ◽

Custom Made ◽

Polymerization Behavior ◽

The Mean

SUMMARY The aim of this study was to evaluate the polymerization behavior and depth of cure (DOC) of recently introduced resin composites for posterior use: highly filled flowable composite and composites for bulk fill. A highly filled flowable (G-aenial Universal Flo [GUF]), two bulk-fill flowables (Surefil SDR Flow [SDR] and Venus Bulk fill [VBF]), and a bulk-fill nonflowable composite (Tetric N-Ceram Bulk fill [TBF]) were compared with two conventional composites (Tetric Flow [TF], Filtek Supreme Ultra [FS]). Linear polymerization shrinkage and polymerization shrinkage stress were each measured with custom-made devices. To evaluate DOC, the composite specimen was prepared using a mold with a hole of 4 mm depth and 4 mm internal diameter. The hole was bulk filled with each of the six composites and light cured for 20 seconds, followed by 24 hours of water storage. The surface hardness was measured on the top and the bottom using a Vickers microhardness (HV) indenter. The linear polymerization shrinkage of the composite specimens after photo-initiation decreased in the following order: TF and GUF > VBF > SDR > FS and TBF (p<0.05). The polymerization shrinkage stress of the six composite groups decreased in the following order: GUF > TF and VBF > SDR > FS and TBF (p<0.05). The mean bottom surface HV of SDR and VBF exceeded 80% of the top surface HV (HV-80%). However, the bottom of GUF and TBF failed to reach HV-80%. A highly filled flowable (GUF) revealed limitations in polymerization shrinkage and DOC. Bulk-fill flowables (SDR and VBF) were properly cured in 4-mm bulk, but they shrank more than the conventional nonflowable composite. A bulk-fill nonflowable (TBF) showed comparable shrinkage to the conventional nonflowable composite, but it was not sufficiently cured in the 4-mm bulk.

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Dental Resin Composites with Enhanced Properties Bycommercial Silica Particles as Fillers

Materials Science Forum ◽

10.4028/www.scientific.net/msf.815.336 ◽

2015 ◽

Vol 815 ◽

pp. 336-341

Author(s):

Shuang Bao ◽

Rui Li Wang ◽

Bin Sun ◽

Xiao Ze Jiang ◽

Mei Fang Zhu

Keyword(s):

Mechanical Properties ◽

Resin Composite ◽

Flexural Modulus ◽

Silica Particles ◽

Component Ratio ◽

Resin Composites ◽

Dental Resin ◽

Depth Of Cure ◽

Dental Resin Composites ◽

Enhanced Properties

To explore the preparation of novel dental resin composites with enhanced properties, two commercial silica particles with sizes of around 1μm and 40 nm were chosen as inorganic fillers, and firstly surface functionalized by 3-methacryloxypropyltrimethoxysilane (γ-MPS) to incorporate cross-linkable vinyl groups onto the surface of fillers. Then the modified fillers were blended with organic monomers, bisphenolAdiglycidyldimethacrylate (Bis-GMA) and triethylene glycol dimethacrylate (TEGDMA), to fabricate the resin compositeswith a three-roll mixer.Resin composites with various weight percentage of fillers and component ratio of microparticle and nanoparticle were prepared. Surface functionalization of silica particles was characterized by fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA), and mechanical properties degree of conversion, and depth of cure of the resultant resin composites were investigated byuniversal testing machineand FTIR. The results indicated that surface modification of silica particles was successful and the surface organic contents were 3.29% and 4.34%, respectively. Among the studied resin composites, the resin composite with 75 wt.% silica particles (59 wt.% microparticles and 16 wt.% nanoparticles) presented the highest value of depth of cure (5.52 ± 0.07 mm), and optimum mechanical properties such as flexural strength (149.8 ± 3.3 MPa), flexural modulus (13.8 ± 0.06 GPa), compressive strength (340.6 ± 8.3 MPa) and Vicker’smicrohardness (78.26 ± 2.45 HV). The study of dental resin composites fabricated from commercial silica particles with excellent properties might provide a new sight for realizing the preparation of this kind of dental resin composites in an industrial scale.

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Effect of Dentin Bonding Agents, Various Resin Composites and Curing Modes on Bond Strength to Human Dentin

Materials ◽

10.3390/ma12203395 ◽

2019 ◽

Vol 12 (20) ◽

pp. 3395

Author(s):

Rene Steiner ◽

Daniel Edelhoff ◽

Bogna Stawarczyk ◽

Herbert Dumfahrt ◽

Isabel Lente

Keyword(s):

Bond Strength ◽

Resin Composite ◽

Adhesive System ◽

Resin Composites ◽

Adhesive Systems ◽

Bonding Agents ◽

Soft Start ◽

Human Dentin ◽

One Step ◽

Push Out

This study investigated the influence of several dentin bonding agents, resin composites and curing modes on push-out bond strength to human dentin. 360 extracted caries-free third molars were prepared, cut into slices, embedded in epoxy resin and perforated centrally. One half of the specimens (180) were treated by using one-step adhesive systems and the other half (180) with multi-step adhesive systems. Subsequently, the cavities were filled with either universal, flowable or bulk-fill resin composite according to the manufactures’ product line and cured with either turbo or soft start program. After storage the push-out test was performed. The data was analyzed using Kolmogorov-Smirnov, three- and one-way ANOVA followed by the Scheffé post-hoc test, unpaired two-sample t-test (p < 0.05). The strongest influence on push-out bond strength was exerted by the resin composite type (partial eta squared ηP2 = 0.505, p < 0.001), followed by the adhesive system (ηP2 = 0.138, p < 0.001), while the choice of the curing intensity was not significant (p = 0.465). The effect of the binary or ternary combinations of the three parameters was significant for the combinations resin composite type coupled adhesive system (ηP2 = 0.054, p < 0.001), only. The flowable resin composites showed predominantly mixed, while the universal and bulk-fill resin composite showed adhesive failure types. Cohesive failure types were not observed in any group. Multi-step adhesive systems are preferable to one-step adhesive systems due to their higher bond strength to dentin. Flowable resin composites showed the highest bond strength and should become more important as restoration material especially in cavity lining. The use of a soft start modus for polymerization of resin composites does not enhance the bond strength to dentin.

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

Operative Dentistry ◽

10.2341/06-45 ◽

2007 ◽

Vol 32 (2) ◽

pp. 160-165 ◽

Cited By ~ 27

Author(s):

L. E. S. Soares ◽

P. C. S. Liporoni ◽

A. A. Martin

Keyword(s):

Clinical Relevance ◽

Second Generation ◽

Resin Composite ◽

Organic Matrix ◽

Degree Of Conversion ◽

Resin Composites ◽

Photo Polymerization ◽

Soft Start ◽

Halogen Light ◽

Restoration Failure

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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Bulk-Fill Resin Composites: Polymerization Contraction, Depth of Cure, and Gap Formation

Operative Dentistry ◽

10.2341/13-324-l ◽

2015 ◽

Vol 40 (2) ◽

pp. 190-200 ◽

Cited By ~ 86

Author(s):

AR Benetti ◽

C Havndrup-Pedersen ◽

D Honoré ◽

MK Pedersen ◽

U Pallesen

Keyword(s):

Resin Composite ◽

Class Ii ◽

High Viscosity ◽

International Organization ◽

Resin Composites ◽

Gap Formation ◽

Depth Of Cure ◽

Low Viscosity ◽

Dental Cavities ◽

Fill Materials

SUMMARY The bulk-filling of deep, wide dental cavities is faster and easier than traditional incremental restoration. However, the extent of cure at the bottom of the restoration should be carefully examined in combination with the polymerization contraction and gap formation that occur during the restorative procedure. The aim of this study, therefore, was to compare the depth of cure, polymerization contraction, and gap formation in bulk-fill resin composites with those of a conventional resin composite. To achieve this, the depth of cure was assessed in accordance with the International Organization for Standardization 4049 standard, and the polymerization contraction was determined using the bonded-disc method. The gap formation was measured at the dentin margin of Class II cavities. Five bulk-fill resin composites were investigated: two high-viscosity (Tetric EvoCeram Bulk Fill, SonicFill) and three low-viscosity (x-tra base, Venus Bulk Fill, SDR) materials. Compared with the conventional resin composite, the high-viscosity bulk-fill materials exhibited only a small increase (but significant for Tetric EvoCeram Bulk Fill) in depth of cure and polymerization contraction, whereas the low-viscosity bulk-fill materials produced a significantly larger depth of cure and polymerization contraction. Although most of the bulk-fill materials exhibited a gap formation similar to that of the conventional resin composite, two of the low-viscosity bulk-fill resin composites, x-tra base and Venus Bulk Fill, produced larger gaps.

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Depth of Cure of Dental Resin Composites: ISO 4049 Depth and Microhardness of Types of Materials and Shades

Operative Dentistry ◽

10.2341/07-104 ◽

2008 ◽

Vol 33 (4) ◽

pp. 408-412 ◽

Cited By ~ 78

Author(s):

B. K. Moore ◽

J. A. Platt ◽

G. Borges ◽

T-M. G. Chu ◽

I. Katsilieri

Keyword(s):

Clinical Relevance ◽

Resin Composite ◽

Resin Composites ◽

Dental Resin ◽

Degree Of Cure ◽

Depth Of Cure ◽

Dental Resin Composites ◽

High Degree

Clinical Relevance Achieving a high degree of cure throughout a 2 mm thickness of light-activated resin composite did not occur for many types and shades of resin composite. Clinicians should check the depth of cure by using the scraping method.

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Effect of Polymerization Time and Shade on the Depth of Cure of Nano-Hybrid Resin Composites

European Dental Research and Biomaterials Journal ◽

10.1055/s-0041-1726169 ◽

2021 ◽

Vol 2 (01) ◽

pp. 28-33

Author(s):

Noha Abdullah Bin Jabr ◽

Wacim Nassouh Al-Saidi ◽

Ibtessam Abdullah Bin Jabr ◽

Roula Safouh Al-Bounni

Keyword(s):

Resin Composite ◽

Multiple Comparisons ◽

Descriptive Statistics ◽

Resin Composites ◽

Polymerization Time ◽

Depth Of Cure ◽

Hybrid Resin ◽

The Mean ◽

Spss Software ◽

Post Hoc

Abstract Objective The effect of polymerization time and resin shade on the depth of cure (DOC) of two nano-hybrid resin composites (Filtek Z250 XT and IPS Empress Direct) was evaluated and compared. Materials and Methods Sixty specimens were prepared from two shades (A1 and A3) of the resin composites. The specimens were allocated into two groups that were further divided into three subgroups depending on the polymerization time (20, 40, and 60 sec; n = 5). After that, the DOC was evaluated by calculating the polymerized part of the specimen’s thickness to the nearest (0.01 mm) using a high-accuracy micrometer. Each specimen was measured three times, and the corresponding mean reading (in mm) was divided by two to obtain the DOC. The data were analyzed using SPSS software, version 20. Descriptive statistics followed by three-way analysis of variance was applied. Multiple comparisons were made using Scheffe post hoc tests (α = 0.05). Results Filtek Z250 XT-A1-60sec presented with the greatest DOC (7.42 ± 0.47 mm), and the lowest DOC was obtained with IPS Empress-A3-20sec (2.31 ± 0.21 mm). The mean DOC of Filtek Z250 XT and IPS Empress Direct resin composites were 6.18 mm and 3.59 mm, respectively. Statistically significant (p < 0.05) difference was observed between the resin composites. The interaction between independent factors, namely composites, resin shade, and polymerization time, revealed that interaction between them contributed significantly to the DOC (p ≤0.05). However, the interaction between resin shade and the polymerization time was insignificant (p = 0.148). Conclusion Filtek Z250 XT demonstrated greater DOC than IPS Empress Direct resin composite. An increase in polymerization time significantly enhanced the DOC of the resin composites irrespective of the resin shade. Regardless of the resin composite tested, DOC was lower for darker shades (A3).

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Curing Depth of Light-activated Nanofiller containing Resin Composites

World Journal of Dentistry ◽

10.5005/jp-journals-10015-1141 ◽

2012 ◽

Vol 3 (2) ◽

pp. 119-125 ◽

Cited By ~ 2

Author(s):

Werner J Finger ◽

Masafumi Kanehira ◽

Yasuyuki Araki ◽

Takehiko Wada ◽

Andreas Utterodt ◽

...

Keyword(s):

Crosslink Density ◽

Mechanical Characteristics ◽

Polynomial Regression ◽

Knoop Hardness ◽

Resin Composites ◽

Depth Level ◽

Depth Of Cure ◽

Micro Raman Spectroscopy ◽

Parallel Lines ◽

Order Polynomial

ABSTRACT Objective To compare the depth of cure of nanofiller containing with conventional resin composites. Materials and methods Five nanofilled and nanohybrid composites were investigated and compared with a microfilled and a microhybrid reference, using the ISO 4049 scraping test, Knoop hardness (KHN) and DC profiling. Specimens from all materials (shade A3) were activated with the same LED light source for 20s. KHN (0.25N/15s) of three specimens each, produced in split molds was measured after 24 hours dark storage on sections perpendicular to the irradiated surface at 250 µm distance along the center line and two parallel lines, 0.5 mm apart, to a depth of 3 mm. Mean KHNs of the three neighboring indentations at each level were calculated. Degree of conversion (DC) was determined on specimens as mentioned above using micro-Raman spectroscopy at 125 µm distance with three measurements at each depth level. Results The depth of cure of all materials was >2 mm when determined according to the ISO test. KHN and DC data followed second order polynomial regression lines (r2 > 0.70; p < 0.001). At 2 mm depth, the KHN of six resin composites was ≤80% of the top KHN whereas the DC of all materials was ≥86% of the maximum DC at the irradiated surface. Conclusion The ISO scraping test overemphasizes the attainable depth of cure, when compared with 80% of top KHN as arbitrarily defined curing depth. KHNs reflect the crosslink density of the polymer, whereas DC additionally includes double bond conversions not contributing to enhancement of mechanical characteristics. How to cite this article Kanehira M, Araki Y, Finger WJ, Wada T, Utterodt A, Komatsu M. Curing Depth of Light-activated Nanofiller containing Resin Composites. World J Dent 2012;3(2): 119-125.

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