Effect of storage in artificial saliva and thermal cycling on Knoop hardness of resin denture teeth

2010 ◽  
Vol 54 (3) ◽  
pp. 123-127 ◽  
Author(s):  
Wirley Gonçalves Assunção ◽  
Érica Alves Gomes ◽  
Valentim Adelino Ricardo Barão ◽  
Débora Barros Barbosa ◽  
Juliana Aparecida Delben ◽  
...  
Keyword(s):  
Thermal Cycling ◽  
Artificial Saliva ◽  
Knoop Hardness ◽  
Denture Teeth

scholarly journals The The effect of different solutions and thermocycling on the vickers hardness of acrylic resin denture teeth

2018 ◽  
Vol 8 (3) ◽  
pp. 117-122
Author(s):  
Hatice Özdemir ◽  
Zeynep Yeşil Duymuş
Keyword(s):  
Thermal Cycling ◽  
Vickers Hardness ◽  
Artificial Saliva ◽  
Acrylic Resin ◽  
Distilled Water ◽  
Posterior Teeth ◽  
Anterior Teeth ◽  
Denture Teeth ◽  
Occlusal Surfaces ◽  
Disinfectant Solution

Aim: The aim of this study was to evaluate the effect of artificial saliva, disinfectant solution, distile water and thermocycling on Vickers hardness of 4 commercial brands of acrylic resin denture teeth. Methodology: Four different brands of acrylic resin denture teeth (Major Dent, Acry Lux, Acry Rock, Imident Lux) were evaluated. 15 anterior and 15 posterior teeth of each group embedded in autopolymerized acrylic resin.  The occlusal surfaces of posterior teeth and the vestibule surfaces of anterior teeth were flattened by using silicone carbid paper. After polishing, microhardness measurements were repeated three times for each teeth. The teeth were submitted to different conditions: (1) storage in distilled water at 37±2°C for 7 days; (2) storage in artificial saliva at 37±2°C for 30 days and (3) storage in 1 % sodium hypochlorite. After, thermal cycling between 5 and 55 °C for 2500 cycles was made. The microhardness measurements were repeated. Data were analyzed with one-way analysis of variance (ANOVA) and Duncan test ( p<0.05). Results: There was statistical significant differences between initial and final microhardness values of different barnds of acrylic resin denture teet. Anterior teeth showed lower microhardness values than posterior teeth. Conclusion: Storage in different solutions and thermal cycling significantly reduced the Vickers hardness of the acrylic resin denture teeth.

Effect of Zinc Sulfate on Human Primary Enamel Microhardness: An in vitro Study

2012 ◽  
Vol 36 (4) ◽  
pp. 369-371 ◽  
Author(s):  
M Mirkarimi ◽  
M Bargrizan ◽  
S Eskandarion ◽  
M Shahsavari
Keyword(s):  
Zinc Sulfate ◽  
Artificial Saliva ◽  
In Vitro Study ◽  
Hardness Test ◽  
Knoop Hardness ◽  
Control Group ◽  
Expected Time ◽  
Rich Solution ◽  
The Mean

Objective: The aim of this study was to assess the effect of zinc sulfate on microhardness of human primary enamel. Method: Sixteen sound primary molars were sectioned mesiodistally. For each sample one of the sections was randomly immersed in artificial saliva (Biotene,USA) and the other was immersed in artificial saliva which was charged with 10 mg/5mL concentration of zinc sulfate supplement (Razak Company, Iran) daily. After 24 days (the expected time to use up one 120-mL bottle) the surface microhardness of enamel was measured by knoop hardness test (KH) with Knoop diamond under a 50-gram load for 10 seconds. Results: The mean (± SD) microhardness values (KHV) for the tested groups were 320 ± 49.45 and 357 ± 36.35, respectively. There were statistically significant differences between the groups as exhibited by independent t-test (P=0.023). Conclusion: Primary teeth immersed in a zinc sulfate rich solution for 24 days showed higher microhardness values in comparison with the control group.

scholarly journals Enamel Remineralization with Novel Bioactive Glass Air Abrasion

2018 ◽  
Vol 97 (13) ◽  
pp. 1438-1444 ◽  
Author(s):  
A.A. Taha ◽  
P.S. Fleming ◽  
R.G. Hill ◽  
M.P. Patel
Keyword(s):  
Bioactive Glass ◽  
Artificial Saliva ◽  
Protective Layer ◽  
Knoop Hardness ◽  
Magic Angle Spinning ◽  
Mas Nmr ◽  
Magic Angle ◽  
Air Abrasion ◽  
Acid Attack ◽  
Fixed Appliance

Enamel demineralization or white spot lesions (WSLs) are a frequent complication associated with fixed appliance–based orthodontic treatment. The remineralization potential of a novel fluoride-containing bioactive glass (QMAT3) propelled via an air abrasion system was compared with Sylc glass and artificial saliva on artificially induced WSLs. Thirty extracted human premolars were randomly assigned into 3 groups ( n = 10) per method of treatment and scanned with optical coherence tomography and noncontact profilometer in the 4 enamel states: sound, demineralized, after glass propulsion, and after immersion in artificial saliva. Knoop hardness testing was also performed. Twenty additional prepared teeth samples were also randomly selected for examination by scanning electron microscopy and energy-dispersive X-ray spectroscopy (2 teeth per technique) under each of the 4 enamel conditions. 19F MAS-NMR (magic angle spinning–nuclear magnetic resonance) was also used to detect the type of apatite formed on the enamel surface. Significant enamel remineralization with surface roughness and intensity of light backscattering similar to that of sound enamel was observed following treatment with QMAT3. In addition, mineral deposits were detected on the remineralized enamel surfaces, forming a protective layer and improving its hardness. This layer was rich in calcium, phosphate, and fluoride; 19F MAS-NMR confirmed the formation of fluorapatite. This finding is particularly beneficial since fluorapatite is more chemically stable than hydroxyapatite and has greater resistance to acid attack. Hence, a promising fluoride-containing bioactive glass for enamel remineralization has been developed, although further clinical evaluation and refinement is required.

scholarly journals Thermal-cycling, simulated brushing, and beverages induced color changes and roughness of CAD/CAM poly (methyl methacrylate) denture resins

2021 ◽  
Author(s):  
Sara Mohammad Al Taweel ◽  
Afnan F Alfouzan ◽  
Hanan N. Al-Otaibi ◽  
Nawaf Labban ◽  
Huda A Alshehri
Keyword(s):  
Surface Roughness ◽  
Thermal Cycling ◽  
Artificial Saliva ◽  
Pearson Correlation ◽  
Colour Change ◽  
Lower Surface ◽  
Lemon Juice ◽  
Factorial Anova ◽  
Color Changes ◽  
Cad Cam

Abstract The aim of the present study was to evaluate and compare the effect of thermal-cycling, mechanical brushing and beverage storage on the color changes and surface roughness of conventional heat-polymerized and CAD/CAM PMMA used to fabricate complete dentures. A total of 100 specimens measuring 10 mm in diameter and 3 mm in thickness were fabricated from conventional PMMA resin (Heat-cured, Major. Base.20, Moncalieri, Italy) and CAD/CAM blocks (Opera system, Principauté de Monaco, French). The specimens were subjected to a combined surface treatment involving thermo-cycling, mechanical brushing, and immersed in either artificial saliva (AS), coffee, tea, Coca-Cola, or lemon juice. Colour differences (∆E) and surface roughness (Ra) was determined using a spectrophotometer and non-contact profilometer, respectively. The data were analyzed using IBM SPSS v.20 (α=0.05). Factorial ANOVA showed that independent factors, namely material, beverages, and the interaction between independent factors, significantly influenced ΔE (F=76.862; p<0.001) and surface roughness (F=71.685; p<0.001). The overall highest and lowest colour differences was obtained for CAD/CAM PMMA (∆E=1.93 ± 1.29) and conventional PMMA (∆E=1.41 ± 1.39) resins, respectively (p=0.061). Conventional PMMA (1.22±0.20) demonstrated significantly increased roughness compared to CAD/CAM PMMA (0.91±0.17) (p <0.001). Pearson correlation showed a low degree of correlation, which was non-significant for both the PMMA (r=0.015; p=0.917) and C-PMMA materials (r=0.097; p=0.505). CAD/CAM milled PMMA resins demonstrated greater colour change and lower surface roughness compared to conventional heat-polymerized PMMA resins. Specimens in tea and coffee demonstrated maximum colour changes and were perceivable by the human eye. On the contrary, specimens immersed in low pH acidic beverages namely Coca-Cola and lemon juice demonstrated maximum surface roughness.

scholarly journals In vitro comparison of impact of different bleaching Agents on the microhardness of Enamel

2016 ◽  
Vol 17 (3) ◽  
pp. 258-262 ◽  
Author(s):  
Sudarshan C Pujari ◽  
Subhra Dey ◽  
Vinisha Pandey ◽  
Neha Awasthi
Keyword(s):  
Artificial Saliva ◽  
Study Groups ◽  
Knoop Hardness ◽  
Minimal Invasive ◽  
Control Group ◽  
Tooth Structure ◽  
Group A ◽  
Group B ◽  
Group D

ABSTRACT Background Various agents are used these days for increasing the esthetics. One such procedure is bleaching that offers various advantages, as it is minimal invasive and cheap option to color the teeth and remove stain. The altered enamel after the bleaching process shows surface demineralization and porosities. The present study aimed to evaluate the effect of different bleaching agents on the microhardness of enamel. Materials and methods A total of 100 freshly human extracted maxillary premolar teeth were selected for the study. Teeth with sound tooth structure were included for the study. All the specimens were randomly divided into four groups with 25 specimens in each group depending upon the type of bleaching agent used: Group A, artificial saliva (Control group); Group B, 35% hydrogen peroxide (HP); Group C, 25% HP; Group D, 10% carbamide peroxide (CP). Knoop Hardness Number (KHN) was calculated at 24, 48-hour, and 7-week interval. Results Results showed no statistical significant differences between the microhardness of enamel of different groups (p < 0.005). A slight fall in the value of KHN was seen in all the groups, except for the control group, although the results were statistically nonsignificant (p > 0.005). Conclusion Although nonsignificantly, all the bleaching solutions produced some amount of alterations in the microstructure of enamel. More studies with higher study groups and more advanced estimation technologies are required to minimize microstructure alterations and promote for better outcome of bleaching procedures. How to cite this article Dey S, Pandey V, Kumar A, Awasthi N, Sahu A, Pujari SC. In vitro comparison of impact of different bleaching Agents on the microhardness of Enamel. J Contemp Dent Pract 2016;17(3):258-262.

scholarly journals Effect of Zirconia and Alumina Fillers on the Microstructure and Mechanical Strength of Dental Glass Ionomer Cements

2016 ◽  
Vol 10 (1) ◽  
pp. 58-68 ◽  
Author(s):  
Júlio C. M. Souza ◽  
Joel B. Silva ◽  
Andrea Aladim ◽  
Oscar Carvalho ◽  
Rubens M. Nascimento ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Thermal Cycling ◽  
Resin Composite ◽  
Artificial Saliva ◽  
Glass Ionomer Cement ◽  
Control Group ◽  
Glass Ionomer Cements ◽  
Glass Ionomer ◽  
Inorganic Particles ◽  
Resin Modified Glass Ionomer

Background: Glass-ionomer cements perform a protective effect on the dentin-pulp complex considering the F ions release and chemical bonding to the dental structures. On the other hand, those materials have poor physic-mechanical properties in comparison with the restorative resin composite. The main aim of this work was to evaluate the influence of zirconia and/or alumina fillers on the microstructure and strength of a resin modified glass-ionomer cement after thermal cycling. Methods: An in vitro experimental study was carried out on 9 groups (n = 10) of cylindrical samples (6 x 4 mm) made from resin modified glass-ionomer (Vitremer, 3M, USA) with different contents of alumina and/or zirconia fillers. A nano-hybrid resin composite was tested as a control group. Samples were mechanically characterized by axial compressive tests and electron scanning microscopy (SEM) coupled to energy dispersive X-ray spectrophotometry (EDS), before and after thermal cycling. Thermal cycling procedures were performed at 3000, 6000 and 10000 cycles in Fusayama´s artificial saliva at 5 and 60 oC. Results: An improvement of compressive strength was noticed on glass-ionomer reinforced with alumina fillers in comparison with the commercial glass ionomer. SEM images revealed the morphology and distribution of alumina or zirconia in the microstructure of glass-ionomers. Also, defects such as cracks and pores were detected on the glass-ionomer cements. The materials tested were not affected by thermal cycling in artificial saliva. Conclusion: Addition of inorganic particles at nano-scale such as alumina can increase the mechanical properties of glass-ionomer cements. However, the presence of cracks and pores present in glass-ionomer can negatively affect the mechanical properties of the material because they are areas of stress concentration.

Effect of polymerization methods and thermal cycling on color stability of acrylic resin denture teeth

2009 ◽  
Vol 102 (6) ◽  
pp. 385-392 ◽  
Author(s):  
Wirley Gonçalves Assunção ◽  
Valentim Adelino Ricardo Barão ◽  
Murillo Sucena Pita ◽  
Marcelo Coelho Goiato
Keyword(s):  
Thermal Cycling ◽  
Color Stability ◽  
Acrylic Resin ◽  
Denture Teeth

PENGARUH THERMAL CYCLING TERHADAP PERUBAHAN DIMENSI DAN STABILITAS WARNA BAHAN BASIS GIGI TIRUAN NILON TERMOPLASTIK

2015 ◽  
Vol 18 (3) ◽  
pp. 280-284
Author(s):  
Dwi Tjahyaning Putranti ◽  
Oktia Kiki Triana
Keyword(s):  
Thermal Cycling

Nilon termoplastik sebagai bahan basis gigi tiruan mulai menjadi pilihan perawatan. Salah satu sifat fisis nilontermoplastik yang menjadi perhatian dalam penggunaannya sebagai bahan basis gigi tiruan adalah stabilitas dimensi danstabilitas warna. Penggunaan basis gigi tiruan di rongga mulut dalam waktu tertentu akan mengakibatkan berbagaiperubahan sifat bahan. Salah satu metode yang dapat digunakan untuk mengevaluasi sifat suatu bahan yaitu thermalcycling. Sampel dibuat sesuai ADA No. 12 untuk uji perubahan dimensi dan ISO No. 1567 untuk uji stabilitas warna.Thermal cycling 70 cycles dan 300 cycles dilakukan pada masing-masing sampel perlakuan. Hasil uji dianalisismenggunakan uji ANOVA untuk mengetahui pengaruh thermal cycling terhadap perubahan dimensi dan stabilitas warnayang menunjukkan hasil signifikan (p < 0,05) dibandingkan kelompok kontrol, serta uji LSD yang menunjukkan terdapatperbedaan pengaruh thermal cycling terhadap perubahan dimensi dan stabilitas warna bahan basis gigi tiruan nilontermoplastik. Thermal cycling 70 cycle dan 300 cycle pada bahan basis gigi tiruan nilon termoplastik dapat meningkatkannilai perubahan dimensi dan menurunkan nilai stabilitas warna bahan basis gigi tiruan nilon termoplastik. Kesimpulan,penggunaan gigi tiruan selama 1 minggu dibandingkan 1 bulan menyebabkan perubahan dimensi semakin besar danberkurangnya stabilitas warna pada basis gigi tiruan nilon termoplastik.

Parallel Glide: A Fundamentally Different Type of Dislocation Motion in Ultrathin Metal Films

2003 ◽  
Vol 779 ◽  
Author(s):  
T. John Balk ◽  
Gerhard Dehm ◽  
Eduard Arzt
Keyword(s):  
Thermal Cycling ◽  
Grain Boundaries ◽  
Film Surface ◽  
Metal Films ◽  
Geometric Constraints ◽  
Film Stress ◽  
Diffusional Creep ◽  
Creep Model ◽  
Substrate Interface ◽  
Film Substrate

AbstractWhen confronted by severe geometric constraints, dislocations may respond in unforeseen ways. One example of such unexpected behavior is parallel glide in unpassivated, ultrathin (200 nm and thinner) metal films. This involves the glide of dislocations parallel to and very near the film/substrate interface, following their emission from grain boundaries. In situ transmission electron microscopy reveals that this mechanism dominates the thermomechanical behavior of ultrathin, unpassivated copper films. However, according to Schmid's law, the biaxial film stress that evolves during thermal cycling does not generate a resolved shear stress parallel to the film/substrate interface and therefore should not drive such motion. Instead, it is proposed that the observed dislocations are generated as a result of atomic diffusion into the grain boundaries. This provides experimental support for the constrained diffusional creep model of Gao et al.[1], in which they described the diffusional exchange of atoms between the unpassivated film surface and grain boundaries at high temperatures, a process that can locally relax the film stress near those boundaries. In the grains where it is observed, parallel glide can account for the plastic strain generated within a film during thermal cycling. One feature of this mechanism at the nanoscale is that, as grain size decreases, eventually a single dislocation suffices to mediate plasticity in an entire grain during thermal cycling. Parallel glide is a new example of the interactions between dislocations and the surface/interface, which are likely to increase in importance during the persistent miniaturization of thin film geometries.

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