Effect of Gamma Radiation and Endodontic Treatment on Mechanical Properties of Human and Bovine Root Dentin

Abstract This study evaluated the effect of gamma radiation and endodontic treatment on the microhardness and flexural strength of human and bovine root dentin. Forty single-rooted human teeth and forty bovine incisor teeth were collected, cleaned and stored in distilled water at 4 °C. The human and bovine teeth were divided into 4 groups (n=10) resulting from the combination of two study factors: first, regarding the endodontic treatment in 2 levels: with or without endodontic treatment; and second, radiotherapy in two levels: with or without radiotherapy by 60 Gy of Co-60 gamma radiation fractioned into 2 Gy daily doses five days per week. Each tooth was longitudinally sectioned in two parts; one-half was used for the three-point bending test and the other for the Knoop hardness test (KHN). Data were analyzed by 3-way ANOVA and Tukey HSD test (α=0.05). No significant difference was found for flexural strength values. The human dentin had significantly higher KHN than the bovine. The endodontic treatment and radiotherapy resulted in significantly lower KHN irrespective of tooth origin. The results indicated that the radiotherapy had deleterious effects on the microhardness of human and bovine dentin and this effect is increased by the interaction with endodontic therapy. The endodontic treatment adds additional negative effect on the mechanical properties of radiated tooth dentin; the restorative protocols should be designed taking into account this effect.

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Effect of microwave disinfection on physical and mechanical properties of acrylic resins

Brazilian Dental Journal ◽

10.1590/s0103-64402008000400011 ◽

2008 ◽

Vol 19 (4) ◽

pp. 348-353 ◽

Cited By ~ 8

Author(s):

Rafael Leonardo Xediek Consant ◽

Erica Brenoe Vieira ◽

Marcelo Ferraz Mesquita ◽

Wilson Batista Mendes ◽

João Neudenir Arioli-Filho

Keyword(s):

Flexural Strength ◽

Room Temperature ◽

Physical And Mechanical Properties ◽

Hardness Test ◽

Knoop Hardness ◽

Microwave Energy ◽

Bending Test ◽

Acrylic Resins ◽

Strength Tests ◽

The Impact

This study evaluated the effect of microwave energy on the hardness, impact strength and flexural strength of the Clássico, Onda-Cryl and QC-20 acrylic resins. Aluminum die were embedded in metallic or plastic flasks with type III dental stone, in accordance with the traditional packing technique. A mixing powder/liquid ratio was used according to the manufacturer's instructions. After polymerization in water batch at 74ºC for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling at room temperature, and submitted to finishing. Specimens non-disinfected and disinfected by microwave irradiation were submitted to hardness, impact and flexural strength tests. Each specimen was immersed in distilled water and disinfected in a microwave oven calibrated to 650 W for 3 min. Knoop hardness test was performed with 25 g load for 10 s, impact test was carried out using the Charpy system with 40 kpcm, and 3-point bending test with a crosshead speed of 0.5 mm/min until fracture. Data were submitted to statistical analysis by ANOVA and Tukey's test (?=0.05). Disinfection by microwave energy decreased the hardness of Clássico and Onda-Cryl acrylic resins, but no effect was observed on the impact and flexural strength of all tested resins.

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Effect of repeated disinfections by microwave energy on the physical and mechanical properties of denture base acrylic resins

Brazilian Dental Journal ◽

10.1590/s0103-64402009000200008 ◽

2009 ◽

Vol 20 (2) ◽

pp. 132-137 ◽

Cited By ~ 9

Author(s):

Rafael Leonardo Xediek Consani ◽

Douglas Duenhas de Azevedo ◽

Marcelo Ferraz Mesquita ◽

Wilson Batista Mendes ◽

Paulo César Saquy

Keyword(s):

Mechanical Properties ◽

Impact Strength ◽

Flexural Strength ◽

Physical And Mechanical Properties ◽

Knoop Hardness ◽

Microwave Energy ◽

Bending Test ◽

Denture Base ◽

Acrylic Resins ◽

The Impact

The present study evaluated the effect of repeated simulated microwave disinfection on physical and mechanical properties of Clássico, Onda-Cryl and QC-20 denture base acrylic resins. Aluminum patterns were included in metallic or plastic flasks with dental stone following the traditional packing method. The powder/liquid mixing ratio was established according to the manufacturer's instructions. After water-bath polymerization at 74ºC for 9 h, boiling water for 20 min or microwave energy at 900 W for 10 min, the specimens were deflasked after flask cooling and finished. Each specimen was immersed in 150 mL of distilled water and underwent 5 disinfection cycles in a microwave oven set at 650 W for 3 min. Non-disinfected and disinfected specimens were subjected to the following tets: Knoop hardness test was performed with 25 g load for 10 s, impact strength test was done using the Charpy system with 40 kpcm, and 3-point bending test (flexural strength) was performed at a crosshead speed of 0.5 mm/min until fracture. Data were analyzed statistically by ANOVA and Tukey's test (α= 0.05%). Repeated simulated microwave disinfections decreased the Knoop hardness of Clássico and Onda-Cryl resins and had no effect on the impact strength of QC-20. The flexural strength was similar for all tested resins.

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Effect of 5% Calcium Hypochlorite on Mechanical Properties of Root Dentin: An in vitro Study

Journal of Operative Dentistry & Endodontics ◽

10.5005/jp-journals-10047-0012 ◽

2016 ◽

Vol 1 (2) ◽

pp. 56-59

Author(s):

Natanasabapathy Velmurugan ◽

Poornima Reddy ◽

Suma Balla ◽

Sandhya S Raghu ◽

Garlapati T Gupta ◽

...

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Modulus Of Elasticity ◽

In Vitro Study ◽

Chlorine Concentration ◽

Control Group ◽

Calcium Hypochlorite ◽

Significant Difference ◽

Root Dentin

ABSTRACT Introduction The aim of this study was to compare in vitro the effect of 5% calcium hypochlorite [Ca(OCl)2] and 5% sodium hypochlorite (NaOCl) on flexural strength and modulus of elasticity of root dentin. Materials and methods The available chlorine concentration of each solution was determined using iodometric titration. Standardized planoparallel dentin bars (n= 20) were divided into two test groups and one control group. The control, group 1, consisted of dentin bars stored in normal saline. The dentin bars in the two test groups were treated by exposure to following solutions: Group 2 to 5% Ca(OCl)2; and group 3 to 5% NaOCl. All the three test solutions were changed once in 15 minutes for 30 minutes. The dentin bars were then loaded to failure using three-point bend test. Results Available chlorine concentration was 64% in both the test solutions. There was a significant reduction in the flexural strength of 5% NaOCl group compared to 5% Ca(OCl)2-treated ones. A significant difference in modulus of elasticity was observed between the test groups and the control groups and also between the 5% Ca(OCl)2 and 5% NaOCl groups. Conclusion Within the limitations of this study, 5% NaOCl reduced the flexural strength and modulus of elasticity of root dentin bars more when compared to 5% Ca(OCl)2. How to cite this article Reddy P, Balla S, Raghu SS, Velmurugan N, Gupta GT, Sahoo HS. Effect of 5% Calcium Hypochlorite on Mechanical Properties of Root Dentin: An in vitro Study. J Oper Dent Endod 2016;1(2):56-59.

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Mechanical Properties of Dental Porcelain Discs by Different Producing Methods

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.544.271 ◽

2013 ◽

Vol 544 ◽

pp. 271-275

Author(s):

Hai Ttao Wang ◽

Yi Hong Liu ◽

Yong Wang ◽

Hui Juan Chen ◽

Yan Qiu ◽

...

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Optical Microscope ◽

Bending Test ◽

Dental Porcelain ◽

Molding Method ◽

Significant Difference ◽

Before And After ◽

Micro Features ◽

Press Molding

The conventional method of producing porcelain standard disc specimens is based on the dental lab method for bilayer ceramic crowns, in order to reflect the clinical using condition. However heavy task is facing to the researchers, which is producing a large amount of the specimens efficiently. The press molding method is used to produce dental porcelain disc specimens in this study. Then, the basic mechanical properties of two groups of porcelain specimens were tested respectively, comparing with handmade and press molding method. The density was measured by Archimedes' method, the flexural strength was tested by biaxial bending test, and the hardness was checked by microhardness tester. The micro features of the specimens before and after bending test were observed under optical microscope and SEM. The results showed that there was no significant difference in the flexural strength, microhardness and density of porcelain discs made by two methods. Air pores were found in all specimens with size between 5-50 micrometers. The size and distribution of pores in the specimens by press molding method are more homogeneous than handmade method. Producing dental porcelain discs for laboratory testing specimens by press molding method was much easy than handmade method. Furthermore, the mechanical properties and microstructures of the specimens made by handmade method and press molding method were almost same.

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Calcium Silicate-Based Biocompatible Light-Curable Dental Material for Dental Pulpal Complex

Nanomaterials ◽

10.3390/nano11030596 ◽

2021 ◽

Vol 11 (3) ◽

pp. 596

Author(s):

Sung-Min Park ◽

Woo-Rim Rhee ◽

Kyu-Min Park ◽

Yu-Jin Kim ◽

Junyong Ahn ◽

...

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Calcium Ions ◽

Dental Materials ◽

Mineral Trioxide Aggregate ◽

Hardness Test ◽

Biological Properties ◽

Dental Material ◽

Ion Release ◽

Significant Difference

Dental caries causes tooth defects and clinical treatment is essential. To prevent further damage and protect healthy teeth, appropriate dental material is a need. However, the biocompatibility of dental material is needed to secure the oral environment. For this purpose, biocompatible materials were investigated for incorporated with dental capping material. Among them, nanomaterials are applied to dental materials to enhance their chemical, mechanical, and biological properties. This research aimed to study the physicochemical and mechanical properties and biocompatibility of a recently introduced light-curable mineral trioxide aggregate (MTA)-like material without bisphenol A-glycidyl methacrylate (Bis-GMA). To overcome the compromised mechanical properties in the absence of Bis-GMA, silica nanoparticles were synthesized and blended with a dental polymer for the formation of a nano-network. This material was compared with a conventional light-curable MTA-like material that contains Bis-GMA. Investigation of the physiochemical properties followed ISO 4049. Hydroxyl and calcium ion release from the materials was measured over 21 days. The Vickers hardness test and three-point flexural strength test were used to assess the mechanical properties. Specimens were immersed in solutions that mimicked human body plasma for seven days, and surface characteristics were analyzed. Biological properties were assessed by cytotoxicity and biomineralization tests. There was no significant difference between the tested materials with respect to overall physicochemical properties and released calcium ions. The newly produced material released more calcium ions on the third day, but 14 days later, the other material containing Bis-GMA released higher levels of calcium ions. The microhardness was reduced in a low pH environment, and differences between the specimens were observed. The flexural strength of the newly developed material was significantly higher, and different surface morphologies were detected. The recently produced extract showed higher cell viability at an extract concentration of 100%, while mineralization was clear at the conventional concentration of 25%. No significant changes in the physical properties between Bis-GMA incorporate material and nanoparticle incorporate materials.

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Comparison of Mechanical Properties of PMMA Disks for Digitally Designed Dentures

Polymers ◽

10.3390/polym13111745 ◽

2021 ◽

Vol 13 (11) ◽

pp. 1745

Author(s):

Tamaki Hada ◽

Manabu Kanazawa ◽

Maiko Iwaki ◽

Awutsadaporn Katheng ◽

Shunsuke Minakuchi

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Water Sorption ◽

Water Solubility ◽

Flexural Modulus ◽

Manufacturing Method ◽

Heat Curing ◽

Significant Difference ◽

Cad Cam ◽

Curing Method

In this study, the physical properties of a custom block manufactured using a self-polymerizing resin (Custom-block), the commercially available CAD/CAM PMMA disk (PMMA-disk), and a heat-polymerizing resin (Conventional PMMA) were evaluated via three different tests. The Custom-block was polymerized by pouring the self-polymerizing resin into a special tray, and Conventional PMMA was polymerized with a heat-curing method, according to the manufacturer’s recommended procedure. The specimens of each group were subjected to three-point bending, water sorption and solubility, and staining tests. The results showed that the materials met the requirements of the ISO standards in all tests, except for the staining tests. The highest flexural strength was exhibited by the PMMA-disk, followed by the Custom-block and the Conventional PMMA, and a significant difference was observed in the flexural strengths of all the materials (p < 0.001). The Custom-block showed a significantly higher flexural modulus and water solubility. The water sorption and discoloration of the Custom-block were significantly higher than those of the PMMA-disk, but not significantly different from those of the Conventional PMMA. In conclusion, the mechanical properties of the three materials differed depending on the manufacturing method, which considerably affected their flexural strength, flexural modulus, water sorption and solubility, and discoloration.

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Bending Properties of General Purpose Stainless Steel Wire Formed for Orthodontic Use

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.746.394 ◽

2013 ◽

Vol 746 ◽

pp. 394-399

Author(s):

Niwat Anuwongnukroh ◽

Yosdhorn Chuankrerkkul ◽

Surachai Dechkunakorn ◽

Pornkiat Churnjitapirom ◽

Theeralaksna Suddhasthira

Keyword(s):

Mechanical Properties ◽

Stainless Steel ◽

Orthodontic Treatment ◽

Steel Wire ◽

General Purpose ◽

Stainless Steel Wire ◽

Bending Test ◽

Bending Properties ◽

Steel Wires ◽

Significant Difference

The archwire is generally used in fixed appliances for orthodontic treatment to correct dental malocclusion. However, it is interesting to know whether general purpose stainless steel wire could replace commercial orthodontic archwire in orthodontic practice for economic reasons. The purpose of this study was to determine the bending properties of general purpose stainless steel wire compared with commercial orthodontic stainless steel wires after forming as an archwire for orthodontic use. The samples used in this study were 90 general purpose and 45 commercial (Highland) round stainless steel wires in 0.016, 0.018, and 0.020 sizes (30 general purpose and 15 commercial wires for each size). All 15 general purpose stainless steel wires with different sizes were formed into orthodontic archwire with a Universal Testing Machine. All samples were tested (three-point bending test) for mechanical properties. The results showed no significant difference between general purpose and commercial orthodontic wires in size 0.016 for 0.1 mm offset bending force, 0.2% yield strength, and springback. Although many mechanical properties of general purpose wires differed from commercial wires, their values conformed to other previous studies within the range of clinical acceptance. In conclusion, orthodontic formed general purpose round stainless steel wires had statistically different (p <0.05) mechanical properties from commercial orthodontic stainless steel wires (Highland) but the mechanical properties were acceptable to use in orthodontic treatment.

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Evaluation of Mechanical Properties of Dental Feldsphatic Porcelains for Metal and Zirconia Core

Materials Science Forum ◽

10.4028/www.scientific.net/msf.727-728.1104 ◽

2012 ◽

Vol 727-728 ◽

pp. 1104-1107

Author(s):

Antonio Alves de Almeida-Junior ◽

Gelson Luis Adabo ◽

Beatriz Regalado Galvão ◽

Diogo Longhini ◽

Claudinei dos Santos

Keyword(s):

Fracture Toughness ◽

Flexural Strength ◽

Vickers Hardness ◽

High Hardness ◽

Hardness Test ◽

Dental Prostheses ◽

Significant Incidence ◽

Significant Difference ◽

Fixed Dental Prostheses ◽

Intermediate Value

Studies has been reported a significant incidence of chipping of the feldspathic porcelain veneer in zirconia-based restorations. The purpose of this study was to compare the three-point flexural strength (MPa), Weibull parameters, Vickers hardness (VHN) and Vickers indentation fracture toughness (MPa/mm1/2) in feldspatic porcelains for metal and for zirconia frameworks. Bar specimens were made with the porcelains e.MaxCeram (EM) and VitaVM9 (V9) for zirconia core, and Duceragold (DG) and VitaVMK95 (VK) for metal core (n= 15). Kruskal-Wallis and Dun test were used for statistical analysis. There was no significant difference (p=0.31) among the porcelains in the flexural strength (Median= 73.2; 74.6; 74.5; 74.4). Weibull calculation presented highest reliability for VK (10.8) followed by EM (7.1), V9 (5.7) and DG (5.6). Vickers hardness test showed that EM (536.3), V9 (579.9) and VK (522.1) had no difference and DG (489.6) had the lowest value (p.001). The highest fracture toughness was to VK (1.77), DG (1.58) had an intermediate value while V9 (1.33) and EM (1.18) had the lowest values (p.001). Despite of the suitable flexural strength, reliability and high hardness, the porcelains used to zirconia-based fixed dental prostheses showed lower fracture toughness values.

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Bleaching Effects on Color, Chemical, and Mechanical Properties of White Spot Lesions

Operative Dentistry ◽

10.2341/15-015-l ◽

2016 ◽

Vol 41 (3) ◽

pp. 318-326 ◽

Cited By ~ 3

Author(s):

Y Kim ◽

HH Son ◽

K Yi ◽

JS Ahn ◽

J Chang

Keyword(s):

Mechanical Properties ◽

Hardness Test ◽

Knoop Hardness ◽

White Spot ◽

Control Group ◽

White Spot Lesions ◽

Lesion Area ◽

Experimental Conditions ◽

Cross Sectional ◽

The Cross

SUMMARY Objective: The purpose of the study was to evaluate the effect of bleaching on teeth with white spot lesions. Methods and Materials: Carious lesions with standardized whiteness were produced on the buccal and lingual surfaces of human premolars by pH cycling. Specimens were subjected to four experimental conditions (n=20/group) as follows: group 1, control; group 2, caries formation followed by remineralization using fluoride-containing casein phosphopeptide–amorphous calcium phosphate (CPP-ACP; Tooth Mousse Plus, GC, Tokyo, Japan); group 3, caries formation followed by bleaching using 10% carbamide peroxide; and group 4, caries formation followed by both bleaching and remineralization. The CIE L*a*b* color values were measured with a spectroradiometer, the mineral content was measured with electron probe microanalysis (EPMA) on the cross-sectional surface of each specimen, and the Knoop hardness test was carried out along the EPMA scan line. Two-way analysis of variance was performed with Tukey post hoc comparison. Results: The change in the CIE color values was not significantly different between the caries-formed (ΔE*=7.03) and the bleached enamel (ΔE*=7.60). Bleaching of the carious enamel extended the whiteness (ΔE*=3.38) without additional mineral loss (p<0.05). The remineralization treatment significantly increased the calcium (Ca), phosphate (P), and fluoride content of the subsurface lesion area (p<0.05). The cross-sectional microhardness values correlated well with the Ca and P content (R>0.80). Conclusions: Bleaching reduced the color disparities between sound and carious enamel without deteriorating the chemical and mechanical properties. The application of CPP-ACP paste enhanced mineral deposition in the subsurface lesion area of carious enamel.

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Nonthermal plasma modification of polypropylene fibres for cementitious composites

Open Chemistry ◽

10.1515/chem-2015-0029 ◽

2014 ◽

Vol 13 (1) ◽

Cited By ~ 5

Author(s):

Tomáš Morávek ◽

Monika Fialová ◽

Daniel Kopkáně ◽

Jozef Ráheľ ◽

Pavel Sťahel ◽

...

Keyword(s):

Mechanical Properties ◽

Flexural Strength ◽

Plasma Treatment ◽

Nonthermal Plasma ◽

Bending Test ◽

Plasma Modification ◽

Surface Barrier ◽

Polypropylene Fibres ◽

Temperature Plasma ◽

Concrete Matrix

AbstractThe plasma treatment of polypropylene fibres used as concrete admixtures for improving its mechanical properties is the focus of this research paper. A plasma treatment was conducted in a low-temperature plasma environment at atmospheric pressure in a DCSBD (Diffuse Coplanar Surface Barrier Discharge). The degree of hydrophilicity caused by the plasma treatment was determined by measuring the rate of penetration of water into the porous media, commonly referred to as the Washburn method. The influence of the addition of PP (polypropylene) fibres to the concrete matrix was investigated using a three point bending test which determined the flexural strength of concrete samples. Our experiments demostrate that plasma improves both the wettability of PP fibres and its adhesion to the concrete matrix. The tests of flexural strength show, that even a short plasma treatment (5 s) can have a significant impact on the mechanical properties of fibre-reinforced concrete composite.

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