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

2016 ◽  
Vol 41 (3) ◽  
pp. 318-326 ◽  
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.

scholarly journals Atrophy patterns in isolated subscapularis lesions

2021 ◽  
Vol 22 (1) ◽  
Author(s):  
Gernot Seppel ◽  
Andreas Voss ◽  
Daniel J. H. Henderson ◽  
Simone Waldt ◽  
Bernhard Haller ◽  
...  
Keyword(s):  
Muscle Atrophy ◽  
Area Ratio ◽  
Cross Sectional Area ◽  
Control Group ◽  
Sectional Area ◽  
Cross Sectional ◽  
Subscapularis Muscle ◽  
Mri Scans ◽  
The Mean ◽  
The Cross

Abstract Background While supraspinatus atrophy can be described according to the system of Zanetti or Thomazeau there is still a lack of characterization of isolated subscapularis muscle atrophy. The aim of this study was to describe patterns of muscle atrophy following repair of isolated subscapularis (SSC) tendon. Methods Forty-nine control shoulder MRI scans, without rotator cuff pathology, atrophy or fatty infiltration, were prospectively evaluated and subscapularis diameters as well as cross sectional areas (complete and upper half) were assessed in a standardized oblique sagittal plane. Calculation of the ratio between the upper half of the cross sectional area (CSA) and the total CSA was performed. Eleven MRI scans of patients with subscapularis atrophy following isolated subscapularis tendon tears were analysed and cross sectional area ratio (upper half /total) determined. To guarantee reliable measurement of the CSA and its ratio, bony landmarks were also defined. All parameters were statistically compared for inter-rater reliability, reproducibility and capacity to quantify subscapularis atrophy. Results The mean age in the control group was 49.7 years (± 15.0). The mean cross sectional area (CSA) was 2367.0 mm2 (± 741.4) for the complete subscapularis muscle and 1048.2 mm2 (± 313.3) for the upper half, giving a mean ratio of 0.446 (± 0.046). In the subscapularis repair group the mean age was 56.7 years (± 9.3). With a mean cross sectional area of 1554.7 mm2 (± 419.9) for the complete and of 422.9 mm2 (± 173.6) for the upper half of the subscapularis muscle, giving a mean CSA ratio of 0.269 (± 0.065) which was seen to be significantly lower than that of the control group (p < 0.05). Conclusion Analysis of typical atrophy patterns of the subscapularis muscle demonstrates that the CSA ratio represents a reliable and reproducible assessment tool in quantifying subscapularis atrophy. We propose the classification of subscapularis atrophy as Stage I (mild atrophy) in case of reduction of the cross sectional area ratio < 0.4, Stage II (moderate atrophy) in case of < 0.35 and Stage III (severe atrophy) if < 0.3.

Comparison of the Cross Sectional Area, the Loss in Volume and the Mechanical Properties of LAE442 and MgCa0.8 as Resorbable Magnesium Alloy Implants after 12 Months Implantation Duration

2010 ◽  
Vol 638-642 ◽  
pp. 675-680 ◽  
Author(s):  
Martina Thomann ◽  
Nina von der Höh ◽  
Dirk Bormann ◽  
Dina Rittershaus ◽  
C. Krause ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Cross Sections ◽  
Degradation Process ◽  
Cross Sectional Area ◽  
Bending Test ◽  
Sectional Area ◽  
Cross Sectional ◽  
Initial Strength ◽  
Three Point Bending ◽  
The Cross

Current research focuses on magnesium based alloys in the course of searching a resorbable osteosynthetic material which provides sufficient mechanical properties besides a good biocompatibility. Previous studies reported on a favorable biocompatibility of the alloys LAE442 and MgCa0.8. The present study compared the degradation process of cylindrical LAE442 and MgCa0.8 implants after 12 months implantation duration. Therefore, 10 extruded implants (2.5 x 25 mm, cross sectional area 4.9 mm²) of both alloys were implanted into the medullary cavity of both tibiae of rabbits for 12 months. After euthanization, the right bone-implant-compound was scanned in a µ-computed tomograph (µCT80, ScancoMedical) and nine uniformly distributed cross-sections of each implant were used to determine the residual implants´ cross sectional area (Software AxioVisionRelease 4.5, Zeiss). Left implants were taken out of the bone carefully. After weighing, a three-point bending test was carried out. LAE442 implants degraded obviously slower and more homogeneously than MgCa0.8. The mean residual cross sectional area of LAE442 implants was 4.7 ± 0.07 mm². MgCa0.8 showed an area of only 2.18 ± 1.03 mm². In contrast, the loss in volume of LAE442 pins was more obvious. They lost 64 % of their initial weight. The volume of MgCa0.8 reduced clearly to 54.4 % which corresponds to the cross sectional area results. Three point bending tests revealed that LAE442 showed a loss in strength of 71.2 % while MgCa0.8 lost 85.6 % of its initial strength. All results indicated that LAE442 implants degraded slowly, probably due to the formation of a very obvious degradation layer. Degradation of MgCa0.8 implants was far advanced.

Effects of cross-sessional area and aspect ratio coupled with orientation on mechanical properties and deformation behavior of Cu nanowires

2021 ◽  
Author(s):  
Hui Cao ◽  
Wenke Chen ◽  
Zhiyuan Rui ◽  
Changfeng Yan
Keyword(s):  
Mechanical Properties ◽  
Aspect Ratio ◽  
Yield Stress ◽  
Young’S Modulus ◽  
Young's Modulus ◽  
Cross Sectional Area ◽  
Sectional Area ◽  
Cross Sectional ◽  
Cu Nanowires ◽  
The Cross

Abstract Metal nanomaterials exhibit excellent mechanical properties compared with corresponding bulk materials and have potential applications in various areas. Despite a number of studies of the size effect on Cu nanowires mechanical properties with square cross-sectional, investigations of them in rectangular cross-sectional with various sizes at constant volume are rare, and lack of multifactor coupling effect on mechanical properties and quantitative investigation. In this work, the dependence of mechanical properties and deformation mechanisms of Cu nanowires/nanoplates under tension on cross-sessional area, aspect ratio of cross-sectional coupled with orientation were investigated using molecular dynamics simulations and the semi-empirical expressions related to mechanical properties were proposed. The simulation results show that the Young’s modulus and the yield stress sharply increase with the aspect ratio except for the <110>{110}{001} Cu nanowires/nanoplates at the same cross-sectional area. And the Young’s modulus increases while the yield stress decreases with the cross-sectional area of Cu nanowires. However, both of them increase with the cross-sectional area of Cu nanoplates. Besides, the Young’s modulus increases with the cross-sectional area at all the orientations. The yield stress shows a mildly downward trend except for the <111> Cu nanowires with increased cross-sectional area. For the Cu nanowires with a small cross-sectional area, the surface force increases with the aspect ratio. In contrast, it decreases with the aspect ratio increase at a large cross-sectional area. At the cross-sectional area of 13.068 nm2, the surface force decreases with the aspect ratio of the <110> Cu nanowires while it increases at other orientations. The surface force is a linearly decreasing function of the cross-sectional area at different orientations. Quantitative studies show that Young’s modulus and yield stress to the aspect ratio of the Cu nanowires satisfy exponent relationship. In addition, the main deformation mechanism of Cu nanowires is the nucleation and propagation of partial dislocations while it is the twinning-dominated reorientation for Cu nanoplates.

scholarly journals Evaluation of Diffusional Characteristics and Microstructure in Unilateral Vocal Fold Paralysis Using Diffusion Tensor Imaging

2019 ◽  
pp. 014556131987472
Author(s):  
Jie Cai ◽  
Logan Klein ◽  
Pinhong Wu ◽  
Azure Wilson ◽  
Xinlin Xu ◽  
...  
Keyword(s):  
Vocal Fold ◽  
Diffusion Tensor ◽  
Vocal Fold Paralysis ◽  
Cross Sectional Area ◽  
Control Group ◽  
Sectional Area ◽  
Unilateral Vocal Fold Paralysis ◽  
Cross Sectional ◽  
Injury Group ◽  
The Cross

Objective: To investigate the value of diffusion tensor imaging (DTI) in the evaluation of vocal fold tissue microstructure after recurrent laryngeal nerve (RLN) injury. Methods: Six canines were divided into 2 groups: a unilateral vocal fold paralysis group (n = 4) and a control group (n = 2). The RLN was cut in the unilateral vocal fold paralysis group, and no intervention was applied in the control group. After 4 months, the canines’ larynges were removed and placed in a small animal magnetic resonance imaging (MRI) system (9.4T BioSpec MRI; Bruker, Germany). After scanning, the vocal folds were isolated, sectioned, and stained. The slides were then analyzed for the cross-sectional area and muscle fiber density through feature extraction technology. Pearson correlation analysis was performed on the DTI scan and histological section extraction results. Results: In the vocal fold muscle layer, the fractional anisotropy (FA) of the unilateral RLN injury group was higher than that of the control group, and the Tensor Trace was lower than that of the control group. This difference was statistically significant, P < .05. In the lamina propria, the FA of the unilateral RLN injury group was lower than that of the control group, P > .05, and the Tensor Trace was lower than that of the control group, P < .05. The muscle fiber cross-sectional area of the RLN injury group was significantly smaller than the control group with statistical significance, P < .05, and the density of muscle fibers was lower, P < .05. The correlation coefficient between FA and the cross-sectional area was −0.838, P = .002, and .726; P = .017 between Tensor Trace and the cross-sectional area. Conclusion: Diffusion tensor imaging is an effective method to assess the changes in the microstructure of atrophic vocal fold muscle tissue after RLN injury.

Diet-related changes in mechanical properties of rat vertebrae

1992 ◽  
Vol 262 (2) ◽  
pp. R318-R321 ◽  
Author(s):  
G. J. Salem ◽  
R. F. Zernicke ◽  
R. J. Barnard
Keyword(s):  
Mechanical Properties ◽  
Vertebral Body ◽  
Calcium Metabolism ◽  
Bone Mineralization ◽  
Maximum Load ◽  
Control Group ◽  
Buffer Solution ◽  
Cross Sectional ◽  
Lumbar Vertebral Body ◽  
Significant Difference

High fat and sucrose (HFS) diets may induce glucose intolerance, alter calcium metabolism, and lead to deficits in bone mineralization, development, and mechanical properties. To determine the mechanical and structural consequences of a HFS diet on rapidly growing vertebrae, female Sprague-Dawley rats (8 wk) were assigned randomly (2:1) either to a control group (n = 20) fed a low-fat complex-carbohydrate diet or an experimental group (n = 10) fed a HFS diet for 10-12 wk. The sixth lumbar vertebral body (L6) was isolated from the pedicles, morphological measures were taken, and compression was tested at a fast strain rate, while immersed in a warmed (37 degrees C) isotonic physiological buffer solution. No significant difference in body mass existed between HFS and control groups; nevertheless, HFS L6 cross-sectional areas, lengths, and volumes were significantly smaller than controls. The HFS L6 also had significantly lower mechanical properties, including initial maximum load, energy at initial maximum load, and strain energy density at initial maximum load. Diets high in sucrose and fat content have been associated with changes in calcium metabolism, and the results of the current study suggest that in immature vertebrae, a HFS diet may adversely affect vertebral body mechanical integrity and strength.

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

2016 ◽  
Vol 27 (6) ◽  
pp. 670-674 ◽  
Author(s):  
Veridiana Resende Novais ◽  
Priscilla Barbosa Ferreira Soares ◽  
Carlla Martins Guimarães ◽  
Laís Rani Sales Oliveira Schliebe ◽  
Stella Sueli Lourenço Braga ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Flexural Strength ◽  
Gamma Radiation ◽  
Hardness Test ◽  
Knoop Hardness ◽  
Endodontic Treatment ◽  
Bending Test ◽  
Human Teeth ◽  
Significant Difference ◽  
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.

scholarly journals Evaluation of Some Mechanical Properties of a Maxillofacial Silicon Elastomer Reinforced with Polyester Powder

2019 ◽  
Vol 2019 ◽  
pp. 1-6 ◽  
Author(s):  
Yagthan Mohammed Haider ◽  
Zainab Salih Abdullah ◽  
Ghasak H. Jani ◽  
Norehan Mokhtar
Keyword(s):  
Mechanical Properties ◽  
Surface Roughness ◽  
Tensile Strength ◽  
Hardness Test ◽  
Silicone Elastomer ◽  
Control Group ◽  
Silicone Elastomers ◽  
Tear Strength ◽  
To Come ◽  
Post Hoc

Maxillofacial silicone elastomers are used to replace and reconstruct missing facial parts for patients with trauma or a certain disease. Although commonly favorable silicone elastomers are not ideal in properties, many studies have been carried out to improve their mechanical properties and to come out with ideal maxillofacial prosthetic materials, so as to render patients with the best maxillofacial prostheses. The aim of the current study is to evaluate the effect of addition of different concentrations of polyester powder on hardness, tear strength, surface roughness, and tensile strength of maxillofacial A-2186 RTV silicone elastomers. Polyester powder was added to the silicone elastomer in the concentrations of 1%, 3% and 5% by using an electronic digital balance, compared with the control group of 0% polyester filler. The shore A hardness test was done according to ASTM D 2240 standards. The tear test was done according to ASTM D624 type C standards. The tensile test was done according to ISO specification number 37:2011. The surface roughness test was performed according to ISO 7619-1 2010 specifications. The data collected were then analyzed using one-way analysis of variance (ANOVA) and post hoc and Fisher’s LSD tests. All three groups showed a highly significant increase in tear strength, tensile strength, hardness, and roughness, compared to the control group. Reinforcement of A-2186 Platinum RTV Silicone Elastomer with 5% polyester significantly improved the mechanical properties tested in this study.

Does Casein Phosphopeptid Amorphous Calcium Phosphate Provide Remineralization on White Spot Lesions and Inhibition of Streptococcus mutans?

2014 ◽  
Vol 38 (4) ◽  
pp. 302-306 ◽  
Author(s):  
Arzu Aykut-Yetkiner ◽  
Nazan Kara ◽  
Mustafa Ateş ◽  
Nazan Ersin ◽  
Fahinur Ertuğrul
Keyword(s):  
Calcium Phosphate ◽  
Streptococcus Mutans ◽  
Amorphous Calcium Phosphate ◽  
Saliva Sample ◽  
Test Group ◽  
White Spot ◽  
Control Group ◽  
White Spot Lesions ◽  
Sample Collection ◽  
Significant Difference

Objective: The aim of this study was to evaluate the remineralization effect of Casein Phosphopeptid Amorphous Calcium Phosphate (CPP-ACP) on white spot lesions (WSL) and its inhibitory effect on Streptococcus mutans colonization. Study design: The study group consisted of 60 children exhibiting at least 1-WSL. Subjects were randomly divided into 2 groups: a test group of using CPP-ACP cream (Tooth Mousse, GC Europe N.V., Leuven, Belgium) and a control group using only fluoride containing toothpaste for a period of 3-months. Baseline WSLs were scored using DIAGNOdent device (KaVo Germany) and the saliva samples were collected to measure S. mutans counts. After the 3-month period the WSLs were again recorded and the saliva sample collection was repeated. Wilcoxon Signed Ranks Test was used for statistical analysis. Results: DIAGNOdent measurements were increased by time (p=0.002) in control group and no statistically significant difference (p=0.217) was found in test group by the 3-month period. In both groups, the mutans counts were decreased in 3-month experimental period. Conclusions: These clinical and laboratory results suggested that CPP-ACP containing cream had a slight remineralization effect on the WSL in the 3-month evaluation period however longer observation is recommended to confirm whether the greater change in WSLs is maintained.

Semicrystalline Structure and Mechanical Properties of Polyolefin-Based Materials

2012 ◽  
Vol 441 ◽  
pp. 713-716
Author(s):  
Mizue Kuriyagawa ◽  
Koh Hei Nitta
Keyword(s):  
Mechanical Properties ◽  
Cross Section ◽  
Draw Ratio ◽  
Structural Model ◽  
Point Of View ◽  
Cross Sectional ◽  
Molecular Weights ◽  
The Cross ◽  
Sectional Shape ◽  
Structural Point

The mechanical yielding and necking behaviors of metallocene-catalyzed high density polyethylenes were investigated from a structural point of view. In particular the natural draw ratio was investigated with different crosshead speeds, molecular weights, and the cross-section shapes of sample specimens. We proposed a structural model for explaining the necking formation in addition to the molecular weight and the cross-sectional shape dependences of the natural draw ratio.

Sign in / Sign up

Export Citation Format

Share Document