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D C Watts - One of the best experts on this subject based on the ideXlab platform.
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Polymerization Shrinkage and Shrinkage stress development in ultra rapid photo polymerized bulk fill resin composites
Dental Materials, 2021Co-Authors: Hamad Algamaiah, Nikolaos Silikas, D C WattsAbstract:Abstract Objective To determine the Polymerization Shrinkage (%) and Shrinkage stress (MPa) characteristics of ultra-rapid photo-polymerized bulk fill resin composites. Methods Two ultra-rapid photo-polymerized bulk fill (URPBF) materials: PFill and PFlow were studied, along with their comparators ECeram and EFlow. PFill contains an addition fragmentation chain transfer (AFCT) agent. The URPBR materials were irradiated using two different 3 s high irradiance protocols (3000 and 3200 mW/cm2 based on Bluephase PowerCure and VALO LCUs, respectively) and one 10 s standard protocol (1200 mW/cm2 based on a Bluephase PowerCure LCU). Bonded disk and Bioman II instruments were used to measure Polymerization Shrinkage % and Shrinkage stress MPa, respectively, for 60 min at 23 ± 1 °C (n = 5). Maximum Shrinkage-rate and maximum Shrinkage stress-rate were also calculated for 15 s via numerical differentiation. The data were analyzed via multiple One-way ANOVA and Tukey post-hoc tests (α = 0.05). Results PFill groups, regardless of their irradiance protocol, showed significantly lower PS than the comparator, ECeram (p 0.05). PFill consistently produced stress results which were significantly lower than ECeram (p 0.05). PFlow only exhibited significantly higher Shrinkage stress when polymerized with the 3 sVALO protocol (p The maximum Shrinkage strain-rate (%/s) was significantly lower in PFill-10s and PFill-3s groups (using PowerCure LCU) compared to ECeram. However, no differences were seen between PFlow and EFlow (p > 0.05). The maximum Shrinkage stress-rate of PFill and PFlow was comparable between different irradiation protocols, as well as to their comparator ECeram (p > 0.05). Significance High irradiation protocols over ultra-short periods led to slightly lower Shrinkage strain but slightly higher stress, possibly due to reduced network mobility. The AFCT agent incorporated in PFill composite seemed to reduce Shrinkage stress development, even with high irradiance protocols.
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Polymerization Shrinkage kinetics of dimethacrylate resin cements
Dental Materials, 2009Co-Authors: Thomas Spinell, Andreas Schedle, D C WattsAbstract:OBJECTIVES: To determine Polymerization Shrinkage-strain (S(Y)) and Shrinkage-stress (S(Z)) of six resin-cements and to compare their performance with the aid of degree of conversion (DC) data. METHODS: Variolink 2 (VL2), Multilink Automix (MA), Multilink Sprint (MS, all Ivoclar-Vivadent), Nexus 2 (NX2), Maxcem (MX, both Kerr) and RelyX Unicem (RX, 3M-Espe) were investigated. MS, MX and RX were self-adhesive; others require a bonding-agent. All measurements were conducted at 23 degrees C for 60min (n=5), except 80min for RX, with materials self-cured only (sc) and dual-cured (dc); NX2 and VL2 were additionally light-cured only (lc). S(Y) was measured by the bonded-disk method [Watts DC, Cash AJ. Determination of Polymerization Shrinkage kinetics in visible-light-cured materials: methods development. Dent Mater 1991;7(4):281-7; Watts DC, Marouf AS. Optimal specimen geometry in bonded-disk Shrinkage-strain measurements on light-cured biomaterials. Dent Mater 2000;16(6):447-51]; S(Z) by the Bioman instrument [Watts DC, Satterthwaite JD. Axial Shrinkage-stress depends upon both C-factor and composite mass. Dent Mater 2008;24(1):1-8 [Epub October 24, 2007]; Watts DC, Marouf AS, Al-Hindi AM. Photo-Polymerization Shrinkage-stress kinetics in resin-composites: methods development. Dent Mater 2003;19(1):1-11]. Light-cure was achieved by QTH at 500mW/cm(2). The respective DCs were measured under the same conditions by FTIR-ATR spectroscopy. Data were analyzed by One-Way ANOVA plus Bonferroni test, and by t-test, at p<0.05. RESULTS: DC by self-curing was less than the DC by dual-curing, for all cements. Shrinkage-strain ranged from 1.77 to 5.29% and Shrinkage-stress from 3.36 to 10.37MPa. NX2 and VL2 were not significantly different, when light-cured only. Except for RX, sc and dc Shrinkage-strain varied maximally by 0.4%. MX showed the highest S(Y), RX the lowest. When sc, RX initially expanded by <0.5% (t approximately 5min). For most materials, S(Y) correlated with their filler loading. The highest stress with sc was exerted by MX, and when dc by MS, which was not statistically different from MX. SIGNIFICANCE: Shrinkage data of resin-cements are of intrinsic clinical importance. Self-cure, despite a lower DC, did not necessarily result in a lower S(Y) compared to dual-cure. S(Y)-rate and S(Z) development depend upon cure mode and S(Y) upon filler fraction.
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measurement of the full field Polymerization Shrinkage and depth of cure of dental composites using digital image correlation
Dental Materials, 2009Co-Authors: Alex Fok, Julian D Satterthwaite, D C WattsAbstract:OBJECTIVES: The aim of this study was to measure the full-field Polymerization Shrinkage of dental composites using optical image correlation method. METHODS: Bar specimens of cross-section 4mm x 2mm and length 10mm approximately were light cured with two irradiances, 450 mW/cm(2) and 180 mW/cm(2), respectively. The curing light was generated with Optilux 501 (Kerr) and the two different irradiances were achieved by adjusting the distance between the light tip and the specimen. A single-camera 2D measuring system was used to record the deformation of the composite specimen for 30 min at a frequency of 0.1 Hz. The specimen surface under observation was sprayed with paint to produce sufficient contrast to allow tracking of individual points on the surface. The curing light was applied to one end of the specimen for 40s during which the painted surface was fully covered. After curing, the cover was removed immediately so that deformation of the painted surface could be recorded by the camera. The images were then analyzed with specialist software and the volumetric Shrinkage determined along the beam length. RESULTS: A typical Shrinkage strain field obtained on a specimen surface was highly non-uniform, even at positions of constant distance from the irradiation surface, indicating possible heterogeneity in material composition and Shrinkage behavior in the composite. The maximum volumetric Shrinkage strain of approximately 1.5% occurred at a subsurface distance of about 1mm, instead of at the irradiation surface. After reaching its peak value, the Shrinkage strain then gradually decreased with increasing distance along the beam length, before leveling off to a value of approximately 0.2% at a distance of 4-5mm. The maximum volumetric Shrinkage obtained agreed well with the value of 1.6% reported by the manufacturer for the composite examined in this work. Using irradiance of 180 mW/cm(2) resulted in only slightly less Polymerization Shrinkage than using irradiance of 450 mW/cm(2). SIGNIFICANCE: Compared to the other measurement methods, the image correlation method is capable of producing full-field information about the Polymerization Shrinkage behavior of dental composites.
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measurement of the full field Polymerization Shrinkage and depth of cure of dental composites using digital image correlation
Dental Materials, 2009Co-Authors: Jianying Li, Julian D Satterthwaite, D C WattsAbstract:OBJECTIVES: The aim of this study was to measure the full-field Polymerization Shrinkage of dental composites using optical image correlation method. METHODS: Bar specimens of cross-section 4mm x 2mm and length 10mm approximately were light cured with two irradiances, 450 mW/cm(2) and 180 mW/cm(2), respectively. The curing light was generated with Optilux 501 (Kerr) and the two different irradiances were achieved by adjusting the distance between the light tip and the specimen. A single-camera 2D measuring system was used to record the deformation of the composite specimen for 30 min at a frequency of 0.1 Hz. The specimen surface under observation was sprayed with paint to produce sufficient contrast to allow tracking of individual points on the surface. The curing light was applied to one end of the specimen for 40s during which the painted surface was fully covered. After curing, the cover was removed immediately so that deformation of the painted surface could be recorded by the camera. The images were then analyzed with specialist software and the volumetric Shrinkage determined along the beam length. RESULTS: A typical Shrinkage strain field obtained on a specimen surface was highly non-uniform, even at positions of constant distance from the irradiation surface, indicating possible heterogeneity in material composition and Shrinkage behavior in the composite. The maximum volumetric Shrinkage strain of approximately 1.5% occurred at a subsurface distance of about 1mm, instead of at the irradiation surface. After reaching its peak value, the Shrinkage strain then gradually decreased with increasing distance along the beam length, before leveling off to a value of approximately 0.2% at a distance of 4-5mm. The maximum volumetric Shrinkage obtained agreed well with the value of 1.6% reported by the manufacturer for the composite examined in this work. Using irradiance of 180 mW/cm(2) resulted in only slightly less Polymerization Shrinkage than using irradiance of 450 mW/cm(2). SIGNIFICANCE: Compared to the other measurement methods, the image correlation method is capable of producing full-field information about the Polymerization Shrinkage behavior of dental composites.
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Polymerization Shrinkage of experimental short glass fiber reinforced composite with semi inter penetrating polymer network matrix
Dental Materials, 2008Co-Authors: Sufyan Garoushi, D C Watts, Lippo V J LassilaAbstract:OBJECTIVES: The aim of this study was to determine the magnitude of short fiber-reinforced composite resin, with a semi-IPN-polymer matrix, on Polymerization resin Shrinkage-strain, Shrinkage stress and marginal microleakage of the restoration. MATERIALS AND METHODS: Experimental composite FC resin was prepared by mixing 22.5 wt.% of short E-glass fibers, 22.5 wt.% of IPN-resin and 55 wt.% of silane treated silica fillers using a high speed mixing machine. As control material, commercial particulate filler composite resin (PFC) was used. Polymerization Shrinkage-strain and stress of the specimens (n=5) were measured using the bonded-disc technique and tensilometer, respectively with respect to time. FC composite and PFC were placed incrementally in class II cavities sized 4 mm x 4 mm x 6 mm (n=8/group) using total-etch adhesive system according to manufacturer's instructions. After the class II restorations were completed, the specimens were finished and polished, thermocycled, stained, sectioned, and viewed under a stereo-microscope for leakage at occlusal/enamel and gingival/dentin margins. The data were analyzed using ANOVA. RESULTS: ANOVA revealed that restorations made from experimental FC composite had a significantly lower Shrinkage stress and microleakage than those made from PFC (p<0.05). The data show that gingival margins had higher microleakage than that obtained from occlusal margins of restorations (p<0.05). CONCLUSIONS: The use of short fiber filler with semi-IPN polymer matrix reduced Polymerization Shrinkage stress and microleakage compared to a conventional restorative composite.
Lippo V J Lassila - One of the best experts on this subject based on the ideXlab platform.
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evaluation of Polymerization Shrinkage and hydroscopic expansion of fiber reinforced biocomposites using optical fiber bragg grating sensors
Dental Materials, 2008Co-Authors: Emilia J Anttila, Pekka K Vallittu, Lippo V J Lassila, Outi H Krintila, Toni Laurila, Rolf HernbergAbstract:Abstract Objectives Polymerization Shrinkage of dental composite materials is recognized as one of the main reasons for the development of marginal leakage between a tooth and filling material. In addition, hydroscopic expansion due to water sorption is known to cause instability in dental materials. Several methods have been proposed to quantify the Polymerization Shrinkage and hydroscopic expansion. However, in the case of anisotropic materials, such as unidirectional fiber-reinforced composites (FRCs), the measurement method must allow for the discrimination of the Shrinkage or expansion in the two orthogonal directions. In this work, optical fiber sensors were employed to study strains in dental materials induced by Polymerization Shrinkage and hydroscopic expansion. Methods Four dental materials were evaluated in this study: unfilled BisGMA/TEGDMA-based resin, Z250 dental restorative composite, unidirectional and bidirectional fiber reinforced composites. The changes in the linear strain due to the Polymerization Shrinkage and hydroscopic expansion were monitored in real-time using embedded optical fiber Bragg grating (FBG) sensors. The Polymerization Shrinkage was monitored during the light curing process. FBG sensors were also used to record the hydroscopic expansion of the samples which were immersed in water up to 132 days. Results Unfilled polymer resin had the highest Polymerization Shrinkage of 0.84%. Unidirectional FRC had a relatively high Shrinkage in the transverse direction with respect to the reinforcing fibers (0.41%) whereas the Shrinkage along the reinforcing fibers was small (0.02%). Bidirectional FRC showed a low Shrinkage value (0.03%). For most tested materials the hydroscopic expansion seemed to compensate for the Polymerization Shrinkage. Significance Fiber Bragg grating sensors are suitable for accurate real-time monitoring of small internal strains of biomaterials, e.g., due to Polymerization Shrinkage and hydroscopic expansion. Detailed data on Polymerization Shrinkage and water sorption behavior of different dental materials can be used to optimize the mechanical properties of dental composite materials and to improve the longevity of a dental restoration.
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Polymerization Shrinkage of experimental short glass fiber reinforced composite with semi inter penetrating polymer network matrix
Dental Materials, 2008Co-Authors: Sufyan Garoushi, D C Watts, Lippo V J LassilaAbstract:OBJECTIVES: The aim of this study was to determine the magnitude of short fiber-reinforced composite resin, with a semi-IPN-polymer matrix, on Polymerization resin Shrinkage-strain, Shrinkage stress and marginal microleakage of the restoration. MATERIALS AND METHODS: Experimental composite FC resin was prepared by mixing 22.5 wt.% of short E-glass fibers, 22.5 wt.% of IPN-resin and 55 wt.% of silane treated silica fillers using a high speed mixing machine. As control material, commercial particulate filler composite resin (PFC) was used. Polymerization Shrinkage-strain and stress of the specimens (n=5) were measured using the bonded-disc technique and tensilometer, respectively with respect to time. FC composite and PFC were placed incrementally in class II cavities sized 4 mm x 4 mm x 6 mm (n=8/group) using total-etch adhesive system according to manufacturer's instructions. After the class II restorations were completed, the specimens were finished and polished, thermocycled, stained, sectioned, and viewed under a stereo-microscope for leakage at occlusal/enamel and gingival/dentin margins. The data were analyzed using ANOVA. RESULTS: ANOVA revealed that restorations made from experimental FC composite had a significantly lower Shrinkage stress and microleakage than those made from PFC (p<0.05). The data show that gingival margins had higher microleakage than that obtained from occlusal margins of restorations (p<0.05). CONCLUSIONS: The use of short fiber filler with semi-IPN polymer matrix reduced Polymerization Shrinkage stress and microleakage compared to a conventional restorative composite.
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Polymerization Shrinkage of experimental short glass fiber reinforced composite with semi inter penetrating polymer network matrix
Dental Materials, 2008Co-Authors: Sufyan Garoushi, Pekka K Vallittu, D C Watts, Lippo V J LassilaAbstract:OBJECTIVES: The aim of this study was to determine the magnitude of short fiber-reinforced composite resin, with a semi-IPN-polymer matrix, on Polymerization resin Shrinkage-strain, Shrinkage stress and marginal microleakage of the restoration. MATERIALS AND METHODS: Experimental composite FC resin was prepared by mixing 22.5 wt.% of short E-glass fibers, 22.5 wt.% of IPN-resin and 55 wt.% of silane treated silica fillers using a high speed mixing machine. As control material, commercial particulate filler composite resin (PFC) was used. Polymerization Shrinkage-strain and stress of the specimens (n=5) were measured using the bonded-disc technique and tensilometer, respectively with respect to time. FC composite and PFC were placed incrementally in class II cavities sized 4 mm x 4 mm x 6 mm (n=8/group) using total-etch adhesive system according to manufacturer's instructions. After the class II restorations were completed, the specimens were finished and polished, thermocycled, stained, sectioned, and viewed under a stereo-microscope for leakage at occlusal/enamel and gingival/dentin margins. The data were analyzed using ANOVA. RESULTS: ANOVA revealed that restorations made from experimental FC composite had a significantly lower Shrinkage stress and microleakage than those made from PFC (p<0.05). The data show that gingival margins had higher microleakage than that obtained from occlusal margins of restorations (p<0.05). CONCLUSIONS: The use of short fiber filler with semi-IPN polymer matrix reduced Polymerization Shrinkage stress and microleakage compared to a conventional restorative composite.
Pekka K Vallittu - One of the best experts on this subject based on the ideXlab platform.
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evaluation of Polymerization Shrinkage and hydroscopic expansion of fiber reinforced biocomposites using optical fiber bragg grating sensors
Dental Materials, 2008Co-Authors: Emilia J Anttila, Pekka K Vallittu, Lippo V J Lassila, Outi H Krintila, Toni Laurila, Rolf HernbergAbstract:Abstract Objectives Polymerization Shrinkage of dental composite materials is recognized as one of the main reasons for the development of marginal leakage between a tooth and filling material. In addition, hydroscopic expansion due to water sorption is known to cause instability in dental materials. Several methods have been proposed to quantify the Polymerization Shrinkage and hydroscopic expansion. However, in the case of anisotropic materials, such as unidirectional fiber-reinforced composites (FRCs), the measurement method must allow for the discrimination of the Shrinkage or expansion in the two orthogonal directions. In this work, optical fiber sensors were employed to study strains in dental materials induced by Polymerization Shrinkage and hydroscopic expansion. Methods Four dental materials were evaluated in this study: unfilled BisGMA/TEGDMA-based resin, Z250 dental restorative composite, unidirectional and bidirectional fiber reinforced composites. The changes in the linear strain due to the Polymerization Shrinkage and hydroscopic expansion were monitored in real-time using embedded optical fiber Bragg grating (FBG) sensors. The Polymerization Shrinkage was monitored during the light curing process. FBG sensors were also used to record the hydroscopic expansion of the samples which were immersed in water up to 132 days. Results Unfilled polymer resin had the highest Polymerization Shrinkage of 0.84%. Unidirectional FRC had a relatively high Shrinkage in the transverse direction with respect to the reinforcing fibers (0.41%) whereas the Shrinkage along the reinforcing fibers was small (0.02%). Bidirectional FRC showed a low Shrinkage value (0.03%). For most tested materials the hydroscopic expansion seemed to compensate for the Polymerization Shrinkage. Significance Fiber Bragg grating sensors are suitable for accurate real-time monitoring of small internal strains of biomaterials, e.g., due to Polymerization Shrinkage and hydroscopic expansion. Detailed data on Polymerization Shrinkage and water sorption behavior of different dental materials can be used to optimize the mechanical properties of dental composite materials and to improve the longevity of a dental restoration.
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Polymerization Shrinkage of experimental short glass fiber reinforced composite with semi inter penetrating polymer network matrix
Dental Materials, 2008Co-Authors: Sufyan Garoushi, Pekka K Vallittu, D C Watts, Lippo V J LassilaAbstract:OBJECTIVES: The aim of this study was to determine the magnitude of short fiber-reinforced composite resin, with a semi-IPN-polymer matrix, on Polymerization resin Shrinkage-strain, Shrinkage stress and marginal microleakage of the restoration. MATERIALS AND METHODS: Experimental composite FC resin was prepared by mixing 22.5 wt.% of short E-glass fibers, 22.5 wt.% of IPN-resin and 55 wt.% of silane treated silica fillers using a high speed mixing machine. As control material, commercial particulate filler composite resin (PFC) was used. Polymerization Shrinkage-strain and stress of the specimens (n=5) were measured using the bonded-disc technique and tensilometer, respectively with respect to time. FC composite and PFC were placed incrementally in class II cavities sized 4 mm x 4 mm x 6 mm (n=8/group) using total-etch adhesive system according to manufacturer's instructions. After the class II restorations were completed, the specimens were finished and polished, thermocycled, stained, sectioned, and viewed under a stereo-microscope for leakage at occlusal/enamel and gingival/dentin margins. The data were analyzed using ANOVA. RESULTS: ANOVA revealed that restorations made from experimental FC composite had a significantly lower Shrinkage stress and microleakage than those made from PFC (p<0.05). The data show that gingival margins had higher microleakage than that obtained from occlusal margins of restorations (p<0.05). CONCLUSIONS: The use of short fiber filler with semi-IPN polymer matrix reduced Polymerization Shrinkage stress and microleakage compared to a conventional restorative composite.
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the effect of fiber orientation on the Polymerization Shrinkage strain of fiber reinforced composites
Dental Materials, 2006Co-Authors: Arzu Tezvergil, L Lassila, Pekka K VallittuAbstract:Summary Objective. The aim of this study was to characterize the linear Polymerization Shrinkage strain of glass fiber-reinforced composite (FRC) according to the fiber orientation. Methods. Test specimens (n=5) (10.0×10.0×1.5 mm) were prepared from different brands of photopolymerizable resin-preimpregnated FRC; unidirectional continuous FRC, experimental random-oriented FRC, and bidirectional continuous FRC. As control materials, particulate filler composite resin and unfilled dimethacrylate monomer resin were used. Two uniaxial strain gages (gage length 2 mm) were used to measure Shrinkage strains in two directions: longitudinally and transversally to the fiber direction. The uncured composite or resin was placed on top of the strain gages, covered with a separating sheet and a glass plate, and irradiated for 40 s with a light-curing unit. The Shrinkage strain was monitored for 300 s. ANOVA and Tukey's posthoc test were used at a significance level of 0.05. Results. ANOVA revealed that orientation of fiber and brand of material had a significant effect (P Significance. Anisotropic nature of FRC exists with regard to Polymerization Shrinkage strain. The variation of Polymerization Shrinkage strains of FRC compared to those of particulate filler composites and unfilled resin might be important for future clinical applications.
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acrylic resin fiber composite part ii the effect of Polymerization Shrinkage of polymethyl methacrylate applied to fiber roving on transverse strength
Journal of Prosthetic Dentistry, 1994Co-Authors: Pekka K VallittuAbstract:Abstract This study determined the effect of Polymerization Shrinkage of polymethyl methacrylate (PMMA) coating of fiber roving on the transverse strength of an acrylic resin-glass fiber composite. The test specimens were heat-cured acrylic resin reinforced with glass fibers. The glass fiber rovings were treated with four PMMA-MMA mixtures (30 specimens per group) of various ratios assumed to have different amounts of Polymerization Shrinkage. A transverse strength test was used to determine the fracture resistance of the test specimens and the Polymerization Shrinkage of the PMMA-MMA mixtures was measured. After the specimens were fractured, single glass fibers used to reinforce the test specimens were'studied by SEM. The fracture resistance of the specimens was statistically different (p
Inbog Lee - One of the best experts on this subject based on the ideXlab platform.
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Polymerization Shrinkage modulus and Shrinkage stress related to tooth restoration interfacial debonding in bulk fill composites
Journal of Dentistry, 2015Co-Authors: Ryan Jinyoung Kim, Yujin Kim, Naksam Choi, Inbog LeeAbstract:Abstract Objectives The aim of the present study was to measure the Polymerization Shrinkage, modulus, and Shrinkage stress of bulk-fill and conventional composites during Polymerization and to investigate the relationship between tooth-composite interfacial debonding and Shrinkage stress of the composites. Methods Polymerization Shrinkage, dynamic modulus, and Shrinkage stress of two high-viscosity bulk-fill (SonicFill (SF)/Tetric N-Ceram Bulk-Fill (TNB)) and two low-viscosity bulk-fill composites (Filtek Bulk-Fill (FB)/SureFil SDR Flow (SDR)) as well as one high-viscosity conventional (Filtek Z250 (Z250)) and one low-viscosity conventional composite (Filtek Z350 XT Flowable (Z350F)) were measured using custom-made instruments. Acoustic emission (AE) analysis was performed to evaluate the tooth-composite interfacial debonding during Polymerization of the composites in Class 1 cavities on extracted third molars. Results The low-viscosity composites exhibited higher Shrinkage and lower modulus than the high-viscosity composites. Polymerization Shrinkage at 10 min ranged between 2.05% (SF) and 3.53% (Z350F). Polymerization Shrinkage stress values at 10 min ranged between 1.68 MPa (SDR) and 3.51 MPa (Z350F). The number of AE events was highest in Z350F and lowest in SDR. Conclusions Composites that exhibited greater Polymerization Shrinkage stress generated more tooth-composite interfacial debonding. In contrast to similar outcomes among the high-viscosity composites (conventional: Z250, bulk-fill: TNB and SF), the low-viscosity bulk-fill composites (FB and SDR) demonstrated better results in terms of Polymerization Shrinkage stress and tooth-composite interfacial debonding than did the low-viscosity conventional composite (Z350F). Clinical significance Despite the better performance by some of the bulk-fill composites, clinicians should be aware that the bulk-fill composites are not perfect substitutes for conventional composites.
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Polymerization Shrinkage and stress of silorane based dental restorative composite
Composites Research, 2013Co-Authors: Inbog Lee, Sunghwan Park, Hyunjeong Kweon, Naksam ChoiAbstract:The purpose of this study was to measure the volumetric Polymerization Shrinkage kinetics and stress of a silorane-based dental restorative composite and compare it with those of conventional methacrylate-based dental composites. Two methacrylate-based composites (Z250, Z350 flowable) and one silorane-based composite (P90) were investigated. The volumetric Polymerization Shrinkage of the composites during light curing was measured using a laboratory-made volume Shrinkage measurement instrument based on the Archimedes' principle, and the Polymerization stress was also determined with the strain gage method. The Shrinkage of silorane-based composites (P90) was the lowest, and that of Z350 flowable was the highest. Peak Polymerization Shrinkage rate was the lowest in P90 and the highest in Z350 flowable. The time to reach peak Shrinkage rate of P90 was longer than those of the methacrylate- based composites. The Polymerization Shrinkage stress of P90 was lower than those of the methacrylate-based composites.
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effect of layering methods composite type and flowable liner on the Polymerization Shrinkage stress of light cured composites
Dental Materials, 2012Co-Authors: Youngchul Kwon, Jack L Ferracane, Inbog LeeAbstract:Abstract Objectives The aim of this study was to investigate the effect of layering methods, flowable composite liner and use of low Shrinkage silorane-based composite on the Polymerization Shrinkage stress of light cured composites. Methods Aluminum blocks were used to prepare MOD cavities and divided into four groups. A universal hybrid methacrylate-based composite (Z250), a flowable composite (Z350 flowable), and a silorane-based composite (P90) were used to fill the cavities. Cavities were restored using four different filling protocols. Group 1 was filled in bulk with Z250, group 2 was restored by an increment technique with the same composite, group 3 by an increment technique with Z250 and a Z350 flowable lining, and group 4 was restored by an increment technique with P90. The axial Shrinkage strain and flexural modulus of the three composites were determined, and cuspal deflection of each group was measured with LVDT probes and compared among groups using ANOVA and Tukey's post hoc test (α = 0.05). Results The axial Shrinkage strains of P90, Z250, and Z350 flowable were 1.09 (0.11), 2.29 (0.06), and 4.12 (0.08)%, respectively. The flexural modulus of P90 was 10.1 (0.9), Z250 was 13.6 (2.0), and that of Z350 flowable was 7.6 (0.9) GPa. The cuspal deflections at 33 min in groups 1–4 were 18.2 (1.54), 14.5 (0.47), 16.2 (1.10), and 6.6 (0.44) μm, respectively. The incremental filling technique yielded significantly lower cuspal deflection than the bulk filling technique. Flowable composite lining under universal composite (Z250) layering showed higher cuspal deflection than that without flowable composite lining. Silorane-based (P90) composite exhibited lower cuspal deflection than metacrylate based (Z250) composite. Significance Cuspal deflection resulting from Polymerization Shrinkage stress may be reduced by an incremental filling technique and by the use of low shrinking composite to obtain optimal clinical outcomes. Flowable composite lining under conventional composite layering did not reduce Polymerization Shrinkage stress as assessed by cuspal deflection.
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a new method to measure the Polymerization Shrinkage kinetics of composites using a particle tracking method with computer vision
Dental Materials, 2012Co-Authors: Inbog Lee, Sunhong Min, Deoggyu SeoAbstract:Abstract Objectives The aim of this study was to develop a new method to measure the Polymerization Shrinkage of light cured composites and to evaluate the overall utility and significance of the technique. Methods An optical instrument to measure the linear Polymerization Shrinkage of composites without directly contacting the specimen was developed using a particle tracking method with computer vision. The measurement system consisted of a CCD color video camera, a lens, an image storage device, and image processing and analysis software. The Shrinkage kinetics of a commercial silorane-based composite (P90) and two conventional methacrylate-based composites (Z250 and a flowable Z350) were investigated and compared with the data measured using the “bonded disc method”. Results The linear Shrinkage of the composites was 0.33–1.41%. The Shrinkage value was lowest for the silorane-based (P90) composite and highest for the flowable Z350 composite. The estimated volume Shrinkages of the materials were comparable to the axial Shrinkages measured with the bonded disc method. Significance The new instrument was able to measure the true linear Shrinkage of composites without sensitivity to the specimen geometry and the viscosity of the material. Therefore, this instrument can be used to characterize the Shrinkage kinetics for a wide range of commercial and experimental visible-light-cure materials in relation to the composition and chemistry.
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a new method to measure the linear Polymerization Shrinkage of composites using a particle tracking method with computer vision
The Journal of Korean Academy of Conservative Dentistry, 2010Co-Authors: Inbog Lee, Sunhong Min, Deoggyu Seo, Sunyoung Kim, Youngchul KwonAbstract:Since the introduction of restorative dental composites, their physical properties have been significantly improved. However, Polymerization Shrinkage is still a major drawback. Many efforts have been made to develop a low shrinking composite, and silorane-based composites have recently been introduced into the market. In addition, many different methods have been developed to measure the Polymerization Shrinkage. In this study, we developed a new method to measure the linear Polymerization Shrinkage of composites without direct contact to a specimen using a particle tracking method with computer vision. The Shrinkage kinetics of a commercial silorane-based composite (P90) and two conventional methacrylate-based composites (Z250 and Z350) were investigated and compared. The results were as follows: 1. The linear Shrinkage of composites was 0.33-1.41%. Shrinkage was lowest for the silorane-based (P90) composite, and highest for the flowable Z350 composite. 2. The new instrument was able to measure the true linear Shrinkage of composites in real time without sensitivity to the specimen preparation and geometry. [J Kor Acad Cons Dent 35(3):180-187, 2010]
Sufyan Garoushi - One of the best experts on this subject based on the ideXlab platform.
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Polymerization Shrinkage of experimental short glass fiber reinforced composite with semi inter penetrating polymer network matrix
Dental Materials, 2008Co-Authors: Sufyan Garoushi, D C Watts, Lippo V J LassilaAbstract:OBJECTIVES: The aim of this study was to determine the magnitude of short fiber-reinforced composite resin, with a semi-IPN-polymer matrix, on Polymerization resin Shrinkage-strain, Shrinkage stress and marginal microleakage of the restoration. MATERIALS AND METHODS: Experimental composite FC resin was prepared by mixing 22.5 wt.% of short E-glass fibers, 22.5 wt.% of IPN-resin and 55 wt.% of silane treated silica fillers using a high speed mixing machine. As control material, commercial particulate filler composite resin (PFC) was used. Polymerization Shrinkage-strain and stress of the specimens (n=5) were measured using the bonded-disc technique and tensilometer, respectively with respect to time. FC composite and PFC were placed incrementally in class II cavities sized 4 mm x 4 mm x 6 mm (n=8/group) using total-etch adhesive system according to manufacturer's instructions. After the class II restorations were completed, the specimens were finished and polished, thermocycled, stained, sectioned, and viewed under a stereo-microscope for leakage at occlusal/enamel and gingival/dentin margins. The data were analyzed using ANOVA. RESULTS: ANOVA revealed that restorations made from experimental FC composite had a significantly lower Shrinkage stress and microleakage than those made from PFC (p<0.05). The data show that gingival margins had higher microleakage than that obtained from occlusal margins of restorations (p<0.05). CONCLUSIONS: The use of short fiber filler with semi-IPN polymer matrix reduced Polymerization Shrinkage stress and microleakage compared to a conventional restorative composite.
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Polymerization Shrinkage of experimental short glass fiber reinforced composite with semi inter penetrating polymer network matrix
Dental Materials, 2008Co-Authors: Sufyan Garoushi, Pekka K Vallittu, D C Watts, Lippo V J LassilaAbstract:OBJECTIVES: The aim of this study was to determine the magnitude of short fiber-reinforced composite resin, with a semi-IPN-polymer matrix, on Polymerization resin Shrinkage-strain, Shrinkage stress and marginal microleakage of the restoration. MATERIALS AND METHODS: Experimental composite FC resin was prepared by mixing 22.5 wt.% of short E-glass fibers, 22.5 wt.% of IPN-resin and 55 wt.% of silane treated silica fillers using a high speed mixing machine. As control material, commercial particulate filler composite resin (PFC) was used. Polymerization Shrinkage-strain and stress of the specimens (n=5) were measured using the bonded-disc technique and tensilometer, respectively with respect to time. FC composite and PFC were placed incrementally in class II cavities sized 4 mm x 4 mm x 6 mm (n=8/group) using total-etch adhesive system according to manufacturer's instructions. After the class II restorations were completed, the specimens were finished and polished, thermocycled, stained, sectioned, and viewed under a stereo-microscope for leakage at occlusal/enamel and gingival/dentin margins. The data were analyzed using ANOVA. RESULTS: ANOVA revealed that restorations made from experimental FC composite had a significantly lower Shrinkage stress and microleakage than those made from PFC (p<0.05). The data show that gingival margins had higher microleakage than that obtained from occlusal margins of restorations (p<0.05). CONCLUSIONS: The use of short fiber filler with semi-IPN polymer matrix reduced Polymerization Shrinkage stress and microleakage compared to a conventional restorative composite.