Polymerization Stress and the Influence of TOSU Addends on Methacrylate Composites

2012 ◽  
Author(s):  
Ryan R. Holmes ◽  
Jennifer R. Melander ◽  
Rachel A. Weiler ◽  
Thomas P. Schuman ◽  
Kathleen V. Kilway ◽  
...  
Keyword(s):  
Composite Resin ◽  
Mechanical Strain ◽  
Degree Of Conversion ◽  
Double Bonds ◽  
Gap Formation ◽  
Premature Failure ◽  
Aesthetic Appeal ◽  
Marginal Integrity ◽  
The Aesthetic ◽  
High Degree

The aesthetic appeal of composite-resin restoratives promotes their use, however their functional life is significantly shorter when compared to their metal counterparts.1 One possible reason is the effect of polymerization stress on marginal integrity. Shrinkage of the composite, and its associated stress, has been found to cause gap formation and stress interactions between the restorative and the adhesive. These gaps offer an ideal niche for bacteria, and, when compounded by the mechanical strain of chewing, can lead to premature failure of the restorative.2,3 Additionally, it is well known that incomplete conversion of the double bonds occurs during methacrylate polymerizations.4–7 A high degree of conversion is needed to prevent the presence of potentially hazardous monomers.8

scholarly journals Role of Composition to Degree of Conversion of Bulk Fill Composite Resins

2017 ◽  
Vol 6 (1) ◽  
pp. 33 ◽  
Author(s):  
Sefty Aryani Harahap ◽  
Yosi Kusuma Eriwati
Keyword(s):  
Composite Resin ◽  
Composite Resins ◽  
Degree Of Conversion ◽  
Resin Matrix ◽  
Double Bonds ◽  
Depth Of Cure ◽  
High Degree ◽  
Single Bonds

A recent technology of Bulk fill composite resin has been developed to save manipulation time. Bulk fill composite resinhas been claimed to have depth of cure up to 4 mm with a high degree of conversion. This paper will evaluate the role of bulk fill composite resin’s composition in increasingits degree of conversion. The degree of conversion is the percentage of carbon double bonds that were converted into single bonds as a result of polymerization. It is determined by its composition that contained filler, resin matrix and the photoinitiator. With the development and modifications of the composition, the bulk fill compositeresin  can be obtained a high degree of conversion so that the expected properties can be achieved.

The Riddle of the Sands

2017 ◽  
Author(s):  
Daniel Brayton
Keyword(s):  
Coastal Zone ◽  
North Atlantic ◽  
Intertidal Zone ◽  
Nation State ◽  
Narrative Fiction ◽  
Aesthetic Appeal ◽  
Secret Service ◽  
German Coast ◽  
The Aesthetic ◽  
Modern Nation State

The aesthetic appeal of coasts is due in part to the indeterminacy of the intertidal zone. The imagination finds room to play where land and sea meet. This chapter explores the coastal zone that lies at the heart of a novel considered by many to be the first modern spy thriller, Erskine Childers’s The Riddle of the Sands: A Record of Secret Service. Childers develops the notion of coastal indeterminacy as a figure for the boundaries, ambitions, and limitations of the modern nation-state. The journey of Childers’s characters through a north Atlantic archipelago that extends from the German coast draws a line of association between Europe and Britain, whose form depends on coastlines, estuaries, and shallows. In following this course, Childers creates a narrative fiction that shifts between charts, borders, and languages.

scholarly journals GIS-Based Aesthetic Appraisal of Short-Range Viewsheds of Coastal Dune and Forest Landscapes

Forests ◽  
2021 ◽  
Vol 12 (11) ◽  
pp. 1534
Author(s):  
Arvydas Urbis ◽  
Ramūnas Povilanskas ◽  
Egidijus Jurkus ◽  
Julius Taminskas ◽  
Domantas Urbis
Keyword(s):  
Spatial Variation ◽  
Short Range ◽  
Coastal Dune ◽  
Geographical Information ◽  
Coastal Forests ◽  
Scenic Beauty ◽  
Aesthetic Appeal ◽  
High Conservation ◽  
The Aesthetic ◽  
Management Alternatives

This paper demonstrates the possibilities of a Geographical Information System (GIS) for investigating and explicating the spatial variation of the short-range viewshed aesthetic appeal in a World Heritage coastal dune and forest area. The study pursues the following objectives: (1) develop and trial a GIS-based algorithm for computing the Aesthetic Appeal Index for a Short-Range Viewshed (ǣ); (2) deliver an output map showing the spatial variation of the computed ǣ values in the target territory and distribution of the zones with high scenic quality and potential aesthetic ecosystem services (PAES); and (3) assess management alternatives in zones with high PAES and high conservation value. This study combines two key innovative aspects. First, it integrates an objective digital map of habitats with subjective scenic preferences of coastal forest and dune landscapes based on psychophysical and cognitive perceptions of scenic beauty. Second, it applies a GIS-based algorithm to translate subjective scenic preferences to an output map of ǣ. The study’s main conclusion is that the combined aesthetic appraisal of the immediate and foreground viewshed of coastal forests and dunes, by applying a specially created GIS algorithm, allows an assessment of the scenic quality of this landscape reliably in statistical terms.

scholarly journals Evaluation of Pre-heating Effects on Marginal Adaptation of Resin-based Materials

2018 ◽  
Vol 55 (2) ◽  
pp. 238-242 ◽  
Author(s):  
Ionut Taraboanta ◽  
Simona Stoleriu ◽  
Gianina Iovan ◽  
Antonia Moldovanu ◽  
Andrei Georgescu ◽  
...  
Keyword(s):  
Room Temperature ◽  
Composite Resin ◽  
Optical Microscope ◽  
Marginal Adaptation ◽  
Gap Formation ◽  
Solution Ph ◽  
Filling Materials ◽  
Heating Effects ◽  
Direct Restoration ◽  
Materials Used

The aim of the study was to compare the marginal adaptation of three different resin-based materials used for direct restoration: hybrid composite resin (Gaenial Posterio, GC Corporation), a compomer (Dyract eXtra, Dentsply Sirona), and a giomer (Beautifil II, Shofu Dental) applied at room temperature or after preheated at preheating 50 and 60oC. Class II cavities were prepared on proximal surfaces of extracted teeth and randomly divided in 3 groups according to the material used for restoration. In each group five cavities were restored using the materials at room temperature (subgroup 1), five cavities were restored using preheated materials at 50şC (subgroup 2), and five cavities were restored using preheated materials at 60şC (subgroup 3). The teeth were stored in distilled water for 14 days and then were immersed in 2% methylene blue buffered dye solution (pH = 7) for 4 hours. The teeth were transversally cut and the sections were examined using optical microscope (Carl-Zeiss AXIO Imager A1m) at 50x magnification and the dye penetration was evaluated according to 4 scores. Decreased microleakage and fewer gap formation were recorded for all filling materials after they have been heated at 50 or 60oC. Pre-warming of resin-based materials improves the adaptation of these materials to tooth structures.

scholarly journals Cytotoxicity and degree of conversion of methacrylate and silorane

2020 ◽  
Vol 19 ◽  
pp. e200656
Author(s):  
Virgínia Angélica Silva ◽  
Sávio Morato de Lacerda Gontijo ◽  
Alexandre Gatti ◽  
Luiz Thadeu de Abreu Poletto ◽  
Hugo Henriques Alvim
Keyword(s):  
Fourier Transform ◽  
Infrared Spectroscopy ◽  
Cell Viability ◽  
Fourier Transform Infrared Spectroscopy ◽  
Mtt Assay ◽  
Composite Resin ◽  
Fourier Transform Infrared ◽  
Degree Of Conversion ◽  
Similar Degree ◽  
Bonferroni Correction

Composites have been proven to have a cytotoxiceffect on a variety of tissues and cells. Aim: The aim of thisstudy was to analyse the degree of conversion of resinsand its correlation with the cell viability in primary gingivalfibroblasts. Methods: Resin-based silorane (Filtek P90)and conventional methacrylate resins (Filtek Z100, FiltekZ250 and Filtek Z350XT) were used to evaluate cell viabilityand the degree of conversion. The resins were light-cured bya LED for 20 and 40 seconds. The degree of conversion wasanalysed by Fourier transform infrared spectroscopy. Cellularmetabolism was evaluated after 24 hours by the MTT assay(n = 6) using the storage solution of composite resin foreither 24 hours or 12 days. Variance analysis (ANOVA) witha Bonferroni correction (p < 0.05) was performed to comparethe groups. Results: The composite Filtek P90 showed ahigher degree of conversion when polymerised for 40 or20 seconds, while the composites Filtek Z100, Filtek Z250 andFiltek Z350XT showed similar degree of conversion. Only theFiltek Z100 resin was cytotoxic. Conclusion: We found nostatistically significant correlation between cell viability andthe degree of conversion.

scholarly journals Co-Blend Application Mode of Bulk Fill Composite Resin

Materials ◽  
2019 ◽  
Vol 12 (16) ◽  
pp. 2504
Author(s):  
Mohammad Al-Nabulsi ◽  
Alaa Daud ◽  
Cynthia Yiu ◽  
Hanan Omar ◽  
Salvatore Sauro ◽  
...  
Keyword(s):  
Bond Strength ◽  
Composite Resin ◽  
Degree Of Conversion ◽  
Adhesive Systems ◽  
Bonding Agents ◽  
Force Microscopy ◽  
Flowable Composite ◽  
Etch And Rinse ◽  
Significant Difference ◽  
Nanoindentation Hardness

Objective: To evaluate the effect of a new application method of bulk-fill flowable composite resin material on bond-strength, nanoleakage, and mechanical properties of dentine bonding agents. Materials and methods: Sound extracted human molars were randomly divided into: manufacturer’s instructions (MI), manual blend 2 mm (MB2), and manual blend 4 mm (MB4). Occlusal enamel was removed and flattened, dentin surfaces were bonded by Prime & Bond universal (Dentsply and Optibond FL, Kerr). For the MI group, adhesives were applied following the manufacturer’s instructions then light-cured. For MB groups, SDR flow+ bulk-fill flowable composite resin was applied in 2- or 4-mm increment then manually rubbed by a micro brush for 15 s with uncured dentine bonding agents and the mixture was light-cured. Composite buildup was fabricated incrementally using Ceram.X One, Dentsply nanohybrid composite resin restorative material. After 24-h water storage, the teeth were sectioned to obtain beams of about 0.8 mm2 for 24-h and thermocycled micro-tensile bond strength at 0.5 mm/min crosshead speed. Degree of conversion was evaluated with micro-Raman spectroscopy. Contraction gaps at 24 h after polymerization were evaluated and atomic force microscopy (AFM) nano-indentation processes were undertaken for measuring the hardness across the interface. Depth of resin penetration was studied using a scanning electron microscope (SEM). Bond strength data was expressed using two-way ANOVA followed by Tukey’s test. Nanoindentation hardness was separately analyzed using one-way ANOVA. Results: Factors “storage F = 6.3” and “application F = 30.11” significantly affected the bond strength to dentine. For Optibond FL, no significant difference in nanoleakage was found in MI/MB4 groups between baseline and aged specimens; significant difference in nanoleakage score was observed in MB2 groups. Confocal microscopy analysis showed MB2 Optibond FL and Prime & Bond universal specimens diffusing within the dentine. Contraction gap was significantly reduced in MB2 specimens in both adhesive systems. Degree of conversion (DC) of the MB2 specimens were numerically more compared to MS1 in both adhesive systems. Conclusion: Present study suggests that the new co-blend technique might have a positive effect on bond strengths of etch-and-rinse adhesives to dentine.

One-Year Clinical Evaluation of Composite Restorations in Posterior Teeth: Effect of Adhesive Systems

2012 ◽  
Vol 37 (6) ◽  
pp. E30-E37 ◽  
Author(s):  
RH Sundfeld ◽  
RS Scatolin ◽  
FG Oliveira ◽  
LS Machado ◽  
RS Alexandre ◽  
...  
Keyword(s):  
Composite Resin ◽  
Clinical Performance ◽  
Adhesive System ◽  
Composite Resins ◽  
Adhesive Systems ◽  
Posterior Teeth ◽  
Significance Level ◽  
Marginal Integrity ◽  
Composite Resin Restorations ◽  
One Year

SUMMARY This clinical study assessed the performance of posterior composite resins applied with the Adper™ Single Bond Plus (SB) and Adper™ Scotchbond SE (SE) adhesive systems and Filtek™ Supreme Plus composite resin, using modified US Public Health Service criteria. A total of 97 restorations were placed in posterior teeth by two calibrated operators. Application of the materials followed manufacturers' instructions. The restorations were evaluated by two examiners at baseline and after one year. Statistical analyses were conducted using the proportion test at a significance level of 5% (p&lt;0.05). All the restorations evaluated (ie, 100%) received an alpha rating for the criteria of marginal discoloration and marginal integrity at baseline. At one year, for marginal discoloration, 64.6% of SB and 61.2% of SE received an alpha rating. For marginal integrity, 72.9% of SB and 77.6% of SE received an alpha rating. The other restorations received bravo ratings for both criteria. None of the teeth that received the restorative systems presented caries lesions around the restorations. A total of eight teeth presented postoperative sensitivity one week after baseline, five with SB and three with SE; the symptom had disappeared one year later. One year later, composite resin restorations using either adhesive system showed satisfactory clinical performance.

A system to impose prescribed homogenous strains on cultured cells

2001 ◽  
Vol 91 (4) ◽  
pp. 1600-1610 ◽  
Author(s):  
Christopher M. Waters ◽  
Matthew R. Glucksberg ◽  
Eugene P. Lautenschlager ◽  
Chyh-Woei Lee ◽  
Reed M. Van Matre ◽  
...  
Keyword(s):  
Epithelial Cells ◽  
Cultured Cells ◽  
Large Strain ◽  
Mechanical Strain ◽  
Airway Epithelial Cells ◽  
Airway Epithelial ◽  
Degree Of Anisotropy ◽  
High Degree ◽  
Membrane Shape ◽  
First Time

There is presently significant interest in cellular responses to physical forces, and numerous devices have been developed to apply stretch to cultured cells. Many of the early devices were limited by the heterogeneity of deformation of cells in different locations and by the high degree of anisotropy at a particular location. We have therefore developed a system to impose cyclic, large-strain, homogeneous stretch on a multiwell surface-treated silicone elastomer substrate plated with pulmonary epithelial cells. The pneumatically driven mechanism consists of four plates each with a clamp to fix one edge of the cruciform elastomer substrate. Four linear bearings set at predetermined angles between the plates ensure a constant ratio of principal strains throughout the stretch cycle. We present the design of the device and membrane shape, the surface modifications of the membrane to promote cell adhesion, predicted and experimental measurements of the strain field, and new data using cultured airway epithelial cells. We present for the first time the relationship between the magnitude of cyclic mechanical strain and the extent of wound closure and cell spreading.

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