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Three-dimensional presentation of the AFM contact mode images of a dentin specimen prepolished with # 2500-grit silicon carbide abrasive paper, non bleached healthy dentin (A), bleached healthy dentin (B), non bleached uremic dentin (C) and bleached uremic dentin (D).
Source publication
Using atomic force microscopy (AFM), the purpose was to investigate the effect of phosphoric acid (H3PO4) concentration and etching duration on surface roughness (Ra) and micromorphology of enamel and dentin substrates of uremic patients receiving hemodialysis.
Sixty-three enamel and dentin slabs were prepared from 42 sound natural molars collected...
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Background
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Statement of problem:
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Citations
... Considerable difference was detected in viscosity of various resin composites due to preheating, this can be explained by the great diversity in composition, chemistry and filler load. Increased molecular weight and high ability for hydrogen bonding, resin composite viscosity will be raised 14 . In addition, the chains of polymers converted into further twisted form by raising filler load owing to excess chain extension and forming excess ramifications, leading to elevated viscosity 14 . ...
... Increased molecular weight and high ability for hydrogen bonding, resin composite viscosity will be raised 14 . In addition, the chains of polymers converted into further twisted form by raising filler load owing to excess chain extension and forming excess ramifications, leading to elevated viscosity 14 . Furthermore, these barriers can be overcame by warming process through yielding adequate energy so as to allow molecules movement in a minimal drifting manner 14 . ...
... An explanation can be given in terms of changes in calcium and phosphorus metabolism caused by chronic kidney disease. Phosphate retention can cause an increase in its level in saliva and thus, along with the composition of saliva (often modified) and its alkaline pH, tooth enamel is more resistant to acid demineralization as well, as has previously been demonstrated [17]. In this way, it is normal for the changes found in the enamel after whitening to be less obvious compared to those present in the tooth enamel of healthy patients. ...
(1) Background: What is the effect of 16% and 40% concentration bleaching agents on dental structures in healthy patients compared to predialysis patients? (2) Methods: Forty teeth were included in the study (20 from healthy patients and 20 from predialysis patients). Each group was randomly divided into another two subgroups (n-10), depending on the bleaching agent concentration (16% and 40% gels). Color parameters were registered before and after the whitening process using a spectrophotometer. To determine enamel ultramicroscopic modifications, SEM and AFM analysis were performed before and after bleaching. (3) Results: An increasing trend was identified in the average values of ∆E and ∆L within the groups of predialysis teeth between teeth whitened with 40% concentration gel and those whitened with 16% concentration gel, while for the enamel samples from healthy patients the trend was reversed. The average values for roughness in the case of the two bleaching agents in healthy and predialysis teeth presented statistically significant differences (p < 0.05). (4) Conclusions: The effects of bleaching agents are less significant on teeth from predialysis compared to healthy patients. A direct link exists in terms of the clinical effect between the concentration of the whitening gel and color modifications.
... Imaging and scanning were performed in dry conditions and controlled temperature in the laboratory atmosphere. The basic operating principles have been reported elsewhere (14). The surface morphology of specimens was probed using sharp silicon nitride tips in 'contact' mode using cantilevers with a constant spring of about 7 to 10 N. The specimens were mounted with cyanoacrylate adhesive on a piezoceramic tube that provided three-dimensional movement of each sample with sub nanometer accuracy. ...
Background
Resin composite preheating is an innovative method that could be clinically beneficial by improving the handling properties, marginal adaptation, and surface properties of uncured nanofilled resin composite materials. There is conflict and unclear information regarding the effect of preheating on the microhardness, fracture toughness and surface roughness of nanofilled resin composites. Thus, it is important to assess whether dental clinicians can adopt preheating procedures without compromising composite mechanical strength. Objective: The purpose of this study was to evaluate the effect of preheating on microhardness, fracture toughness and surface roughness of nanofilled resin composite.
Material and Methods
In this study, one commercial nanofilled resin composite Filtek Z350 XT was used. A total of 28 disc-shaped specimens were fabricated in a Teflon mold (10 mm diameter x 2 mm thick) for Vickers microhardness indentation test and surface roughness test. The samples were divided into two groups of 14 samples each, one group of samples was light-cured at room temperature (24ºC) without preheating (non-heated group), and the other group was light-cured after preheating (preheated group). Vickers hardness measurements of 14 specimens (n=7) either preheated or non-heated of the top and bottom surfaces was measured by means of microhardness tester by applying 100 g load for 10 s. Surface Roughness measurements (Ra) were obtained from 14 specimens (n=7) either preheated or non-heated with the atomic force microscope. Fourteen single-edge-notched-beam specimens were prepared for fracture toughness test (n=7) either preheated or non-heated with measurements (2.5 x 5 x 25 mm3) and a crack 2.12 mm in length. The specimens were tested via three-point bending mode, using a universal testing machine at crosshead speed of 1.0 mm/min until failure occurred.
Results
Independent sample t- tests revealed no significant difference between non-heated and preheated groups for all tests (p>0.05). However, for Vickers hardness test, there were significant differences between top and bottom surfaces for non-heated and preheated groups (p<0.05). Moreover, surface roughness average Ra (nm) mean values of preheated group was higher than non-heated group but no significant difference between them was found (p>0.05).
Conclusions
Preheating procedure did not negatively affect microhardness, fracture toughness and surface roughness of nanofilled resin composites so preheating is recommended for the other potential clinical advantages.
Key words:Preheating, nanofilled composites, microhardness, fracture toughness, surface roughness.
... Finke et al. (2000) also supported the finding that prismless enamel seems to be more prone to chemical dissolution, whereas Parkinson et al. (2010) suggested that the removal is most prominent at defect sites. showed that 30 s of etching with 37% phosphoric acid was effective for removing the smear layer, most of the polishing debris and scratches, and for displaying the characteristics of interest of enamel, which is in agreement with the literature (Ge et al., 2005;Loyola-Rodriguez et al., 2009;Mahmoud et al., 2012;Sanches et al., 2009). ...
... This tissue represents the first barrier to damage for teeth. There are several studies that have focused on experiments and analysis of enamel, but there has been difficulty in standardizing the parameters, and therefore, in comparing the results(Agrawal et al., 2014;Batina et al., 2002Batina et al., ,2004Cheng et al., 2009;Choi et al., 2010;Cui and Ge, 2007;Farina et al., 1999;Finke et al., 2000;Ge et al., 2005;Guidoni et al., 2008;Lippert et al., 2004; Loyola-Rodriguez et al., 2009;Mahmoud, Ahmed, Mahmoud, Grawish and Zaher, 2012;Parkinson, Shahzad and Rees, 2010;Sanches et al., 2009;Wang et al., 2005).Enamel's unique microstructure can be seen upon direct observation of the surface as shown by the images of Group I; however, only a few authors have used native enamel in their experiments(Batina et al., 2002(Batina et al., ,2004Farina et al., 1999;Finke et al., 2000;Lippert et al., 2004;Tanaka, Shibata, Manabe, and Miyazaki, 2010; Vargas- Koudriavtsey and Herrera-Sancho, 2017). The most used pretreatments in the literature are grinding and polishing because the values for the initial roughness are standardized, which is confirmed by the lowest standard deviation among the groups(Agrawal et al., 2014;Cheng et al., 2009;Choi et al., 2010;Cui and Ge, 2007; al., 2005; Guidoni et al., 2008; Lippert et al., 2004; Loyola-Rodriguez et al., 2009; Mahmoud et al., 2012; Parkinson, Shahzad and Rees, 2010; Sanches et al., 2009; Wang et al., 2005). ...
Human dental enamel is organized by prisms that are structured between 3 and 6 µm in diameter. Determining the relationships between different treatments on the surface of enamel using ultrastructural analysis is the purpose of many in vitro experiments. Different sample pretreatments have been reported in the literature. Grinding and polishing are common procedures for enamel preparation. They provide a flat and standardized surface, which is imperative for the use of some techniques such as ATR‐FTIR. However, for morphological analysis, SEM and AFM represent easier methods to measure and reduce the biological sample variation. Therefore, the objective of this study was to establish how different forms of enamel preparation can influence the advent of artifacts during ultrastructural observation, especially by AFM analysis. Four groups (n = 10) were tested: (a) without preparation; (b) polishing with a diamond paste; (c) grinding with decreasing granulations of silicon carbide papers; (d) grinding with polishing. Images were obtained using the Peak‐Force Tapping mode. After the first images were obtained, all fragments were acid etched with 37% phosphoric acid for 30 seconds, rinsed for 60 seconds, and dried intensively. Upon grinding and polishing, the exposure of the inner enamel surfaces provided a less mineralized layer that was marked by scratches and a higher susceptibility to treatments. Moreover, using native enamel provided more valuable information on the surface and the roughness changes for clinical applications. In addition, phosphoric acid is an option for observing the prismatic arrangement after grinding and/or polishing changes the morphology.
Research Highlights
The use of native enamel samples to investigate the effects of different treatments on surface should be preferred in research, when the technique allows it.
... The duration of agent application is another factor that can effect dentin conditioning. A study on the effects of PA etching on human dentin found that increasing the duration of application produced greater surface roughness independent of acid concentration (34). Investigations on dentin adhesive bonding have used high concentrations of PA-based conditioning agents in root canals for a 15 s duration (11,35). ...
Objective:
The purpose of this study was to determine the ability of a methacrylate resin dentin bonding agent to adhere to the dentin surfaces of prepared and conditioned root canals with either 32% phosphoric acid (PA) or 17% ethylenediaminetetraacetic acid (EDTA).
Methods:
Prior to the application of the methacrylate resin, the root canals of 54 intact, caries-free, single- rooted, de-crowned, extracted human maxillary incisor and canine teeth were endodontically prepared and conditioned with either 32% PA or 17% EDTA or with distilled water as the unconditioned control. The resin-treated roots were cross-sectioned at three levels and scanning electron microscope (SEM) imaged for circumferential views of the root canals at 60-90× magnification and site-specific views at 250× magnification, and then randomly coded for independent and blind evaluation by four calibrated examiners. The circumferential surface of the root canals that showed no resin adhesion were digitally measured and subtracted from the digitally measured total root canal circumference, and resin adhesion was expressed as a percentage of the circumference.
Results:
The mean percentages of resin adhesion were 97% for the PA group, 94% for the EDTA group, and 76% for the control group. There were statistically significant differences among the PA, EDTA, and control groups.
Conclusion:
Root canals conditioned with 32% PA or 17% EDTA had more resin adhesion than unconditioned root canals. Root canals conditioned with 32% PA had more resin adhesion than those conditioned with 17% EDTA.
... The output of this study showed that increasing the concentration of the etchant gel into 42%, as well as, increasing the etching time into 60s instead of 15s (conventional regimen used with normal enamel) improved bonding to uremic enamel. [2] Not only the adhesion to uremic teeth was investigated by our studies but also the effect of bleaching agents was comprehensively evaluated. Another study was conducted to investigate the effect of 16% carbamide peroxide bleaching gel on surface micromorphology and roughness of enamel and root dentin of uremic patients receiving hemodialysis using AFM. ...
... A recently published in vitro study investigated the effect of phosphoric acid concentration and etching duration on surface roughness of enamel and dentin substrates of uremic patients receiving hemodialysis supported the use of 42% phosphoric acid for etching uremic hard tooth tissues for 60 seconds. 33 Considering the preceding information and because the success of modern luting cements is greatly dependent on the quality and the performance of their bonds to dental substrates, 16,17 deteriorated or weak bonding of these materials to tooth tissues of uremic patients could be expected. This hypothesis has not been hitherto confirmed or even dismissed in spite of the recent improvements in the chemistry of adhesive systems that have succeeded to a great extent in offsetting the difficulties associated with bonding to different tooth tissues. ...
... Recently, Mahmoud and others 33 supported the use of 42% phosphoric acid for the etching of uremic hard tooth tissues for 60 seconds. The lower performance of the resin cement and self-adhesive resin cement in comparison to both the glass ionomer and the resin-modified glass ionomer cement can be attributed to the lack of the effect of a surfaceconditioning procedure before luting and hybrid layer formation. ...
Objectives:
This study aimed to assess the retention of metal copings luted to uremic teeth with five different luting agents.
Methods:
A total of 35 sound natural molars was collected from uremic patients and randomly assigned into five groups (n=7). The teeth were prepared for metal copings using diamond tips and water coolant. Metal copings with a loop on the occlusal surface were fabricated using base metal alloy (Rexillium III). The copings were luted using Fuji I, glass ionomer (GI); Fuji Plus, resin-modified glass ionomer (RMGI); Panavia F 2.0, resin cement; Rely X Unicem, self-adhesive cement (SA); and Adhesor, zinc phosphate cement (ZPh). All specimens were incubated at 37°C for 24 hours, conditioned in artificial saliva for 7 days, and then thermocycled for 5000 cycles (5°C-55°C). The dislodging force was measured using a universal testing machine at a crosshead speed of 2 mm/min. The mode of failure of the loaded adhesive copings was evaluated. Statistical analyses were performed using one-way analysis of variance and Tukey post hoc test.
Results:
GI and SA cements had the highest and the lowest mean retentive strength, respectively (580.90±17.3, 406.6±12.7). There was no significant difference between ZPh, SA, and resin cements. These cements were inferior to GI and RMGI cements (p<0.05), which showed statistically similar retentive strengths.
Conclusions:
The results of this study support the use of glass ionomer and resin-modified glass ionomer cements for luting of metal copings to uremic teeth with retentive preparations.
... osition methods , less attention has been reserved to the inverse problem of surface etching , polishing , or erosion ( Finke et al . , 2000 ) . Atomic Force Microscopy ( AFM ) is capable of giving images with atomic resolution with minimal sample preparation . This technique has been widely used to characterize the erosion of enamel and dentine ( Mahmoud et al . , 2012 ) . More recently , also AFM nanoindentation has been applied to the study of enamel erosion ( Marshall et al . , 2001 ) . The aim of the present in vitro study was the evaluation of a CPP‐ACP paste on preventing dental erosion produced by a soft drink , by microscopic investigation using AFM and SEM . ...
The aim of the present in vitro study was the evaluation of a CPP-ACP paste on preventing dentin/enamel erosion produced by a soft drink; Atomic Force Microscopy and Scanning Electron Microscopy were used. Eighty extracted human incisors free of caries were selected and divided into four groups (each divided in two subgroups); group 1a: intact dentin; group 1b: dentin + soft drink; group 2a: intact dentin + CCP-ACP paste; group 2b: dentin + soft drink + CCP-ACP paste; group 3a: intact enamel; group 3b: enamel + soft drink; group 4a: intact enamel + CCP-ACP paste; group 4b: enamel + soft drink + CCP-ACP paste. The CPP-ACP paste was applied for 3 min at 0, 8, 24, and 36 h. The surface of each dentin/enamel specimen was imaged by AFM (R(rms) values were registered) and SEM. A statistical significant difference was recorded between groups 1b (dentin + soft drink) and 2b (dentin + soft drink + CCP-ACP paste) and between groups 3b (enamel + soft drink) and 4b (enamel + soft drink + CCP-ACP paste), suggesting that treatment of the specimens with the CPP-ACP paste had a protective effect on enamel demineralization, which was more evident for enamel specimens. Under the limitations of the present in vitro study, it can be concluded that the application of a CPP-ACP paste is effective on preventing dentin/enamel erosion produced by a soft drink. SCANNING 9999:XX-XX, 2013. © 2013 Wiley Periodicals, Inc.
... Assim, o efetivo condicionamento ácido do substrato é o primeiro passo para uma união satisfatória. Tem sido demonstrado que concentrações de ácido fosfórico entre 30 e 40% são efetivas em produzir um substrato adequado para infiltração da resina adesiva e formação da camada híbrida 10,11 . Em razão disso, os condicionadores disponibilizados comercialmente apresentam ácido fosfórico, comumente em forma de gel, com concentrações entre 30 e 40%. ...
INTRODUCTION: Despite the importance of the acid etching step on bonding procedures, little is known about the acid etchant brand effect on bond strength of adhesive to dentin. OBJECTIVE: The aim of this study was to evaluate the effect of different acid etchants at the bond strength of composite resin to dentine. MATERIAL AND METHOD: Twenty five bovine incisors had their crown sectioned in two hemi-sections. The buccal surfaces were grounded with #180 silicon carbide (SiC) abrasive paper to exposure of dentin, followed by #600 SiC paper to standardize the smear layer. The samples were randomly allocated into five groups (n = 10) according to acid etchant brands: 3M ESPE, Ultradent, Dentsply, Villevie and DFL.Only a two-step etch-and-rinse adhesive system (Ambar, FGM) was used. Silicon molds were used to build-up three resin composite cylinder per sample. After 24 hours, cylinders were submitted to shear load until the failure. Data were analyzed by one way ANOVA and Tukey`s test (a=0.05). The failure mode was evaluated under optical microscopy and the data were submitted to Chi-square test (a=0.05). RESULT: There was no statistical difference on bond strength obtained between the acid etchants evaluated. There was predominance of adhesive failures, except for etchants of Dentsply and DFL that showed similarity between mixed and adhesive failures. CONCLUSION: Different brands of acid etchants did not influence on the bond strength of composite resin to dentin.
The purpose of this study is to investigate and compare effect of bracket bonding-debonding by nano-composite and composite adhesives on mechanical properties of tooth enamel. Orthodontic brackets were bonded to the enamel surface and the mechanical properties of tooth enamel were studied by nano-indentation technique after bracket removal. Twenty human premolar teeth were prepared and divided into two groups. In one group, orthodontic brackets were bonded by a conventional composite adhesive and in the other group a dental nano-composite was used for bonding the brackets on the buccal surface of tooth enamel. The brackets were then debonded with a sharp-edged debonding pliers. After debonding the brackets, the teeth were sectioned transverse to their longitudinal axes from the middle of the bracket bonded regions. Nano-indentation experiments were performed on the enamel section at two regions: intact enamel and under-the-bracket enamel. Then mechanical properties of the enamel at these two regions, including elasticity modulus, hardness and fracture toughness were determined from the nano-indentation test results for both types of adhesives. Using the nano-composite decreases the magnitudes of elasticity modulus and hardness of the dental enamel under the brackets significantly in comparison with the conventional orthodontic adhesives. However, no significant difference is seen between the fracture toughness reductions due to the use of composite and nano-composite adhesives.
