Effects of wall compliance and light-curing protocol on wall deflection of simulated cavities in bulk-fill composite restoration

SUMMARY Objectives: To analyze the effect of pulp-capping materials and resin composite light activation on strain and temperature development in the pulp and on the interfacial integrity at the pulpal floor/pulp-capping materials in large molar class II cavities. Methods: Forty extracted molars received large mesio-occlusal-distal (MOD) cavity bur preparation with 1.0 mm of dentin remaining at the pulp floor. Four pulp-capping materials (self-etching adhesive system, Clearfil SE Bond [CLE], Kuraray), two light-curing calcium hydroxide cements (BioCal [BIO], Biodinâmica, and Ultra-Blend Plus [ULT], Ultradent), and a resin-modified glass ionomer cement– (Vitrebond [VIT], 3M ESPE) were applied on the pulpal floor. The cavities were incrementally restored with resin composite (Filtek Z350 XT, 3M ESPE). Thermocouple (n=10) and strain gauge (n=10) were placed inside the pulp chamber in contact with the top of the pulpal floor to detect temperature changes and dentin strain during light curing of the pulp-capping materials and during resin composite restoration. Exotherm was calculated by subtracting postcure from polymerization temperature (n=10). Interface integrity at the pulpal floor was investigated using micro-CT (SkyScan 1272, Bruker). The degree of cure of capping materials was calculated using the Fourier transform infrared and attenuated total reflectance cell. Data were analyzed using one-way analysis of variance followed by the Tukey test (α=0.05). Results: Pulpal dentin strains (μs) during light curing of CLE were higher than for other pulp-capping materials (p<0.001). During resin composite light activation, the pulpal dentin strain increased for ULT, VIT, and CLE and decreased for BIO. The pulpal dentin strain was significantly higher during pulp-capping light activation. The temperature inside the pulp chamber increased approximately 3.5°C after light curing the pulp-capping materials and approximately 2.1°C after final restoration. Pulp-capping material type had no influence temperature increase. The micro-CT showed perfect interfacial integrity after restoration for CLE and ULT; however, gaps were found between BIO and pulpal floor in all specimens. BIO had a significantly lower degree of conversion than ULT, VIT, and CLE. Conclusions: Light curing of pulp-capping materials caused deformation of pulpal dentin and increased pulpal temperature in large MOD cavities. Shrinkage of the resin composite restoration caused debonding of BIO from the pulpal floor.

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Application of different light sources for polymerization of restorative resins

Stomatoloski glasnik Srbije ◽

10.2298/sgs0204095b ◽

2002 ◽

Vol 49 (3-4) ◽

pp. 95-100 ◽

Cited By ~ 4

Author(s):

Larisa Blazic ◽

Slavoljub Zivkovic ◽

Ivana Stojsin

Keyword(s):

Blue Light ◽

Composite Resin ◽

Argon Laser ◽

Light Sources ◽

Plasma Arc ◽

Light Curing ◽

Long Life ◽

Basic Characteristics ◽

Resin Curing ◽

Composite Restoration

The aim of this work was the introduction of the basic characteristics of contemporary polymerization light sources for composite resin curing. Two basic groups of available curing technologies are introduced. First are those that produce white light (conventional halogen lamps and plasma arc polymerization units). The second group comprises "blue light" curing devices that produce blue light at the origin of the light source. Lights belonging to this group include the blue LEDs and argon laser. Information about main characteristics of light sources (irradiance, wavelength range) and their proper choice could have a significant impact on polymerization quality and on long-life of composite restoration.

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Evaluation of Microleakage in Class V Composite Restoration using Different Techniques of Polymerization

International Journal of Prosthodontics and Restorative Dentistry ◽

10.5005/jp-journals-10019-1039 ◽

2012 ◽

Vol 2 (1) ◽

pp. 10-15 ◽

Cited By ~ 1

Author(s):

Anshu Milind Chandurkar ◽

Sandeep S Metgud ◽

Shaikh S Yakub ◽

Vaishali J Kalburge

Keyword(s):

High Intensity ◽

Resin Composite ◽

Nitrate Solution ◽

Silver Nitrate Solution ◽

The Other ◽

Class V ◽

Soft Start ◽

Light Curing ◽

Qth Light ◽

Composite Restoration

ABSTRACT Aims The purpose of this study was to evaluate the effect of light intensity and curing cycle of quartz tungsten halogen (QTH) and plasma arc curing (PAC) lights on the microleakage of class V composite restorations. Materials and methods A total of 60 freshly extracted human maxillary premolars were used for this study. Standardized class V cavities were prepared and restored with microhybrid resin composite. According to the curing protocol, the teeth were then divided into three groups (n = 20): QTH curing (standard and soft start mode) and PAC high intensity irradiation. The microleakage was evaluated by immersion of the samples in 50% silver nitrate solution. The samples were then sectioned, evaluated under a stereomicroscope and scored for microleakage. Statistical analysis used Dye leakage scores were obtained, and analysis was done using Student's t-test. Results Light curing with QTH light in the soft start mode, showed the least leakage in the composite restoration, which was highly significant when compared with the other groups (p < 0.01). Light curing with QTH light in the standard mode, showed moderate microleakage, which was statistically significant (p < 0.05), when compared with the PAC high intensity curing. Curing with PAC light in high intensity mode resulted in severe microleakage along the cavity margins. Conclusion Within the limitations of the study, it may be concluded that: 1. The high intensity PAC light resulted in maximum leakage, when compared to the other groups in the study. 2. The soft start polymerization mode offers a distinctive advantage over the standard curing protocol, in terms of microleakage, for the QTH curing lights. Clinical significance In the clinical scenario, soft start curing regimen offers a distinctive advantage over the conventional mode of the QTH curing and the high intensity rapid curing offered by the PAC light. How to cite this article Chandurkar AM, Metgud SS, Yakub SS, Kalburge VJ. Evaluation of Microleakage in Class V Composite Restoration using Different Techniques of Polymerization. Int J Prosthodont Restor Dent 2012;2(1): 10-15.

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Optimization of Photopolymerization Process of Dental Composites

Processes ◽

10.3390/pr9050779 ◽

2021 ◽

Vol 9 (5) ◽

pp. 779

Author(s):

Tsanka Dikova ◽

Jordan Maximov ◽

Vladimir Todorov ◽

Georgi Georgiev ◽

Vladimir Panov

Keyword(s):

Light Intensity ◽

Regression Models ◽

Irradiation Time ◽

Composite Layer ◽

High Hardness ◽

Dental Composites ◽

Light Curing ◽

Dental Offices ◽

Curing Regimes ◽

Composite Restoration

The aim of this paper is to perform optimization of photopolymerization process of dental composites in order to obtain maximum hardness. Samples (5 mm diameter; 2, 3 and 4 mm thickness) were made of Universal Composite (UC), Bulk fill Composite (BC) and Flowable Composite (FC). Light curing of specimens was performed with 600, 1000 and 1500 mW/cm2 light intensity and an irradiation time of 20, 40 and 60 s. Vickers microhardness on the top and bottom surfaces of samples was measured. Optimization was carried out via regression analysis using QStatLab software. Photopolymerization process parameters were calculated using a specially designed MatLab software-based algorithm. For all composites, regression models for hardness on top and bottom surfaces of composite layer were established. Layer thickness as well as hardness on top and bottom surfaces of each composite was calculated for 21 curing modes varying with light intensity and irradiation time. It was established that photopolymerization guidelines only of FC manufacturer guarantee the required hardness, while recommended regimes for UC and BC did not satisfy this requirement. Tables, containing recommended light curing regimes, were developed for three composite types, guaranteeing high hardness of composite restoration. They were designed to facilitate work of dentists in dental offices.

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Effects of flowable liners on the shrinkage vectors of bulk-fill composites

Clinical Oral Investigations ◽

10.1007/s00784-021-03801-2 ◽

2021 ◽

Author(s):

Dalia Kaisarly ◽

D. Meierhofer ◽

M. El Gezawi ◽

P. Rösch ◽

K.H. Kunzelmann

Keyword(s):

Thin Layers ◽

Filling Material ◽

Micro Computed Tomography ◽

Stress Relieving ◽

Before And After ◽

Light Curing ◽

Cylindrical Cavities ◽

Flowable Composites ◽

Self Etch ◽

Composite Restoration

Abstract Objectives This investigation evaluated the effect of flowable liners beneath a composite restoration applied via different methods on the pattern of shrinkage vectors. Methods Forty molars were divided into five groups (n = 8), and cylindrical cavities were prepared and bonded with a self-etch adhesive (AdheSe). Tetric EvoCeram Bulk Fill (TBF) was used as the filling material in all cavities. The flowable liners Tetric EvoFlow Bulk Fill (TEF) and SDR were used to line the cavity floor. In gp1-TBF, the flowable composite was not used. TEF was applied in a thin layer in gp2-fl/TEF + TBF and gp3-fl/TEF + TBFincremental. Two flowable composites with a layer thickness of 2 mm were compared in gp4-fl/TEF + TBF and gp5-fl/SDR + TBF. TEF and SDR were mixed with radiolucent glass beads, while air bubbles inherently present in TBF served as markers. Each material application was scanned twice by micro-computed tomography before and after light curing. Scans were subjected to image segmentation for calculation of the shrinkage vectors. Results The absence of a flowable liner resulted in the greatest shrinkage vectors. A thin flowable liner (gp2-fl/TEF + TBFbulk) resulted in larger overall shrinkage vectors for the whole restoration than a thick flowable liner (gp4-fl/TEF + TBF). A thin flowable liner and incremental application (gp3-fl/TEF + TBFincremental) yielded the smallest shrinkage vectors. SDR yielded slightly smaller shrinkage vectors for the whole restoration than that observed in gp4-fl/TEF + TBF. Conclusions Thick flowable liner layers had a more pronounced stress-relieving effect than thin layers regardless of the flowable liner type. Clinical relevance It is recommended to apply a flowable liner (thin or thick) beneath bulk-fill composites, preferably incrementally.

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Effect of dispensing method and curing modes on the microleakage of composite resins

Journal of Baghdad College of Dentistry ◽

10.26477/jbcd.v32i1.2752 ◽

2020 ◽

Vol 32 (1) ◽

pp. 9-15

Author(s):

Bahar J Selivany ◽

Muhand A Khadim ◽

Dara H Saeed ◽

Abdulhaq A Suliman

Keyword(s):

Composite Resin ◽

Conventional Technique ◽

Composite Resins ◽

Conventional Group ◽

Class V ◽

Dye Penetration ◽

Light Curing ◽

Blue Solution ◽

Nail Varnish ◽

Composite Restoration

Background: Vibration decreases the viscosity of composite, making it flow and readily fit the walls of the cavity. This study is initiated to see how this improved adaptation of the composite resin to the cavity walls will affect microleakage using different curing modes Materials and methods: Standard Class V cavities were prepared on the buccal surface of sixty extracted premolars. Teeth were randomly assigned into two groups (n=30) according to the composite condensation (vibration and conventional) technique, then subdivided into three subgroups (n=10) according to light curing modes (LED-Ramp, LED-Fast and Halogen Continuous modes). Cavities were etched and bonded with Single Bond Universal then restored with Filtek® Z350 (3M ESPE, USA). In the vibration group, condensation was done using CompothixoTM (Kerr, Switzerland). In the conventional group, condensation was done with hand plugger. Curing modes for all groups were LED-Ramp, LED-Fast and halogen continuous modes, respectively. Samples stored in distilled water at 37°C for seven days, and painted completely with two layers of nail varnish with only 1 mm around the composite restoration left. Samples were thermocycled, immersed in 2% methylene blue solution for 3 hours, and sectioned longitudinally. Dye penetration was assessed under a stereomicroscope. Data were analyzed by Kruskal-Wallis and Mann-Whitney U tests with p <0.05 considered significant. Results: Vibration group showed less microleakage (P=0.028). In the conventional group there were no differences by using different curing modes (P=0.277). In the vibration group no differences were found between LED-Ramp and LED-Fast mode (P=0.989). However, there were significant differences between LED-Fast and halogen (P=0.05) and between LED-Ramp and halogen group (P=0.001). Microleakage scores of all cervical walls were higher than the occlusal walls (P=0.001). Occlusal walls leakage for conventional and vibration groups were not different (P=0.475), while there were significant differences between them at cervical walls (P=0.001). Conclusion: Vibration with LED-Ramp curing mode may decrease marginal leakage of composite restoration placed in Standard Class V tooth preparations. Keywords: Composite resin, Vibration, Condensation, Compothixo, Microleakage,

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Temperature Rise at the Pulp-Dentin Junction for a Multi-Layered Composite Restoration using the Finite Element Method

The Open Dentistry Journal ◽

10.2174/1874210602115010487 ◽

2021 ◽

Vol 15 (1) ◽

pp. 487-494

Author(s):

Ali Mohammed Ridha ◽

Konstantinos Aidinis ◽

Abdul Haq Suliman

Keyword(s):

Finite Element Method ◽

Finite Element ◽

Temperature Rise ◽

Temperature Increase ◽

Thermal Injury ◽

Layered Composite ◽

Curing Process ◽

Light Curing ◽

Composite Restoration ◽

Element Method

Objectives: During the light-curing process of composite restoration, excessive heat can be produced, which can potentially lead to pulp necrosis (death). In this study, we aimed, based on the Finite Element Method (FEM), to assess the risk of pulp damage during the light-curing process by investigating the influence of light-curing devices, under various irradiation regimes, on the temperature increase at the pulp-dentin junction, during a one-layer or multi-layered deep composite restoration. Methods: A Three-dimensional finite element method model of typical geometry and material properties, as commonly reported in the literature, was employed in COMSOL Multiphysics simulations in order to determine the temperature increase in the pulp. Various combinations of light intensities, durations, and irradiation regimes were investigated for the two cases, of shallow and deep multi-layered composite restoration. Results: Results of light-curing composite resins within enamel; indicate that the temperature rise during the curing process was within the safety margins. Results of light-curing composite resin restorations closer to the pulp with thin remaining dentin, indicate a temperature increase that could be sufficient to cause thermal injury in the pulp. Modulating the light output marginally, reduced the temperature rise while reducing the intensity and increasing the curing duration which was consistently more effective in this respect. Conclusion: The results clearly demonstrate that with currently adopted standard procedures, there exists a risk of thermal injury during multi-layered composite restorations with thin remaining dentin; it is thus important to establish appropriate curing regimes that would lead to minimal temperature increase during deep composite restorations and hence reduce the risk of thermal injury to the pulp.

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Influence of the Compliance and Layering Method on the Wall Deflection of Simulated Cavities in Bulk-fill Composite Restoration

Operative Dentistry ◽

10.2341/15-260-l ◽

2016 ◽

Vol 41 (6) ◽

pp. e183-e194 ◽

Cited By ~ 18

Author(s):

Y-J Kim ◽

R Kim ◽

JL Ferracane ◽

I-B Lee

Keyword(s):

Wall Thickness ◽

Mold Wall ◽

Flexural Modulus ◽

The Other ◽

Shrinkage Stress ◽

Linear Variable Differential Transformer ◽

Polymerization Shrinkage ◽

Wall Deflection ◽

Composite Restorations ◽

Composite Restoration

SUMMARY The aim of this study was to investigate the effects of the layering method and compliance on the wall deflection of simulated cavities in bulk-fill and conventional composite restorations and to examine the relationships between the wall deflection and the polymerization shrinkage, flexural modulus, and polymerization shrinkage stress of composites. Six light-cured composites were used in this study. Two of these were conventional methacrylate-based composites (Filtek Z250 and Filtek Z350 XT Flowable [Z350F]), whereas four were bulk-fill composites (SonicFill, Tetric N-Ceram Bulk-Fill, SureFil SDR Flow [SDR], and Filtek Bulk-Fill). One hundred eighty aluminum molds simulating a mesio-occluso-distal cavity (6 W×8 L×4 D mm) were prepared and classified into three groups with mold wall thicknesses of 1, 2, and 3 mm. Each group was further subdivided according to the composite layering method (bulk or incremental layering). Linear variable differential transformer probes were used to measure the mold wall deflection of each composite (n=5) over a period of 2000 seconds (33.3 minutes). The polymerization shrinkage, flexural modulus, and polymerization shrinkage stress of the six composites were also measured. All groups with bulk filling exhibited significantly higher deflection compared with groups with incremental layering. The deflection decreased as mold wall thickness increased. The highest and lowest polymerization shrinkage stresses were recorded for Z350F (5.07 MPa) and SDR (1.70 MPa), respectively. The correlation between polymerization shrinkage and the mold wall deflection decreased with increasing wall thickness. On the other hand, the correlation between flexural modulus and the mold wall deflection increased with increasing wall thickness. For all groups, wall deflection correlated strongly with polymerization shrinkage stress.

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Influences of Different Air-Inhibition Coatings on Monomer Release, Microhardness, and Color Stability of Two Composite Materials

BioMed Research International ◽

10.1155/2019/4240264 ◽

2019 ◽

Vol 2019 ◽

pp. 1-8 ◽

Cited By ~ 2

Author(s):

Luca Marigo ◽

Giuseppina Nocca ◽

Giulia Fiorenzano ◽

Cinzia Callà ◽

Raffaella Castagnola ◽

...

Keyword(s):

Red Wine ◽

Color Stability ◽

Multiple Comparisons ◽

Storage Conditions ◽

Resin Composites ◽

Surface Microhardness ◽

Argon Gas ◽

Light Curing ◽

Effect Of Light ◽

Composite Restoration

The aim of this study was to evaluate the effect of light-curing protocols on two modern resin composites using different air-inhibition coating strategies. This was accomplished by assessing the amount of monomer elution, surface microhardness, and composite discoloration in different storage conditions. A total of 120 specimens were prepared using Filtek Supreme XTE (3M ESPE, Seefeld, Germany) and CeramX Universal (Dentsply DeTrey, Konstanz, Germany). Specimens were light-cured in air as per manufacturer’s instructions or in the absence of oxygen. This latter condition was achieved using three different approaches: (i) transparent polyester strip; (ii) glycerin; (iii) argon gas. Specimens were assessed for release of monomers, Vickers hardness, and discoloration after storage in different solutions. The results were analyzed with ANOVA one-way test followed by Student-Newman-Keuls test. Moreover, multiple comparisons of means were performed using the Student t-test (p<0.05). The amount of monomers released from the tested specimens was very low in all conditions. The presence of oxygen induced some decrease in microhardness. The highest discoloration values, for both materials, were obtained after ageing in red wine. In case finish and polish procedures are awkward to achieve in posteriors composite restoration, light-curing in the absence of oxygen should be considered, especially when performing composite restoration in esthetic areas.

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Effect of Curing Mode on Microtensile Bond Strength to Dentin of Two Dual-cured Adhesive Systems in Combination with Resin Luting Cements for Indirect Restorations

Operative Dentistry ◽

10.2341/06-4 ◽

2007 ◽

Vol 32 (1) ◽

pp. 37-44 ◽

Cited By ~ 16

Author(s):

C. A. G. Arrais ◽

M. Giannini ◽

F. A. Rueggeberg ◽

D. H. Pashley

Keyword(s):

Bond Strength ◽

Resin Composite ◽

Adhesive Systems ◽

Microtensile Bond Strength ◽

Adhesive Resin ◽

Luting Cements ◽

Fifth Generation ◽

Light Curing ◽

Separate Step ◽

Composite Restoration

Clinical Relevance The separate step of light curing the adhesive resin component of some fourth and fifth generation dual-cured adhesive systems may be eliminated prior to cementation of an indirect resin composite restoration without deterioration in microtensile bond strength.

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