scholarly journals A comparative study of the effects of two carbamide peroxide bleaching agents on the structure of enamel

2016 ◽  
Vol 64 (3) ◽  
pp. 293-298
Author(s):  
Roberto Paulo de ARAÚJO ◽  
Danilo Barral de ARAÚJO ◽  
Márcio Cajazeira AGUIAR
Keyword(s):  
Electron Microscopy ◽  
Artificial Saliva ◽  
Control Group ◽  
Bleaching Agent ◽  
Carbamide Peroxide ◽  
Peroxide Bleaching ◽  
The Third ◽  
Dental Whitening ◽  
Different Sources ◽  
Scanning Electron

ABSTRACT Objective: Considering that different sources of carbamide peroxide bleaching agent may cause greater or lesser damage to the enamel and may have reduced effectiveness in dental whitening, the aim of this study was to compare the effects on the structure of enamel of two bleaching agents, drugstore-compounded and commercial carbamide peroxide bleaching agents. Methods: The specimens in the first group (drugstore-compounded carbamide peroxide) and second group (commercial carbamide peroxide) were treated with to 16% carbamide peroxide for 4 h per day for 20 days. The third group served as a control and was kept in artificial saliva during the test period. After the treatments, all specimens were examined via scanning electron microscopy. Results: Changes in the enamel morphology were similar in both experimental groups, but these changes were greater than those observed in the control group. The changes were mild and included only pores. Conclusion: There were no differences regarding damage to the enamel between drugstore-compounded and commercial carbamide peroxide bleaching agents.

scholarly journals Effects of 16% Carbamide Peroxide Bleaching on the Surface Properties of Glazed Glassy Matrix Ceramics

2020 ◽  
Vol 2020 ◽  
pp. 1-7
Author(s):  
Necla Demir ◽  
Muhammet Karci ◽  
Mutlu Ozcan
Keyword(s):  
Surface Roughness ◽  
Surface Properties ◽  
Glassy Matrix ◽  
Bleaching Agent ◽  
Carbamide Peroxide ◽  
Peroxide Bleaching ◽  
Cad Cam ◽  
Ceramic Restorations ◽  
Bleaching Gels ◽  
Scanning Electron

Objective. To determine the influence of the home bleaching agent, Opalescence PF, on the surface roughness and microhardness of glazed glassy matrix CAD-CAM ceramics. Materials and Methods. The 28 sintered leucite- and lithium disilicate-reinforced ceramic specimens (IPS Empress CAD and IPS e.max CAD) were divided into control and bleached groups. The home bleaching agent was applied to specimens of bleached groups for 7 days. The surface roughness and microhardness of all specimens were measured. A scanning electron microscope was used to evaluate the surface properties. The data were statistically analyzed by two-way ANOVA. Results. The control e.max CAD showed the lowest surface roughness values. For both Empress and e.max CAD, surface roughness was significantly higher for the bleached group (p<0.05). No significant differences in microhardness were observed. Conclusions. According to our study, patients should be careful when using home bleaching agents because whitening agents can affect the mechanical properties of full ceramic restorations like e.max CAD and Empress CAD. Ceramic polishing may be required in clinical situations where ceramic restorations are accidentally exposed to bleaching gels.

scholarly journals Effect of a carbamide peroxide bleaching gel containing calcium or fluoride on human enamel surface microhardness

2005 ◽  
Vol 16 (2) ◽  
pp. 103-106 ◽  
Author(s):  
Rogério de Oliveira ◽  
Adriana Franco Paes Leme ◽  
Marcelo Giannini
Keyword(s):  
Artificial Saliva ◽  
In Vitro Study ◽  
Enamel Surface ◽  
Control Group ◽  
Carbamide Peroxide ◽  
Surface Microhardness ◽  
Treatment Groups ◽  
Peroxide Bleaching ◽  
Human Enamel

This in vitro study evaluated the surface microhardness of human enamel submitted to bleaching with 10% carbamide peroxide (CP) containing calcium or fluoride. Ninety-eight dental blocks (5 x 5 mm²) with polished enamel surfaces were randomly assigned to 7 treatment groups (n=14), as follows: without bleaching and storage in artificial saliva (control); 10% CP; 10% CP + 0.05% calcium; 10% CP + 0.1% calcium; 10% CP + 0.2% calcium; 10% CP + 0.2% fluoride; and 10% CP + 0.5% fluoride. During 14 days, enamel surfaces were daily exposed to a 6-h bleaching regimen followed by storage in artificial saliva. Surface microhardness was measured before (baseline), during (7th day), immediately after bleaching (14th day) and 1 week post bleaching. Data were analyzed by two-way ANOVA and Tukey's test (p<0.05). All treatments reduced SM significantly during the bleaching cycle (7th day), immediately after bleaching (14th day) and 1 week post bleaching, compared to baseline and to the unbleached control group. In conclusion, in spite of the addition of calcium and fluoride, all bleaching treatments affected the enamel surface microhardness.

scholarly journals Effect of Short- and Long-term Use of Home and In-Office Bleaching with Carbamide Peroxide and Hydrogen Peroxide on Bleaching with Carbamide Peroxide and Hydrogen Peroxide on Enamel Microhardness Enamel Microhardness

2020 ◽  
Vol 27 (2) ◽  
Author(s):  
Nazila Ameli ◽  
◽  
Niloofar Kianvash Rad ◽  
Farzane Nikpour ◽  
Raheb Ghorbani ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Dental Treatment ◽  
Artificial Saliva ◽  
Tooth Bleaching ◽  
Control Group ◽  
Bleaching Agent ◽  
Carbamide Peroxide ◽  
Dental Procedures ◽  
Before And After ◽  
At Home

Bleaching is a well-known esthetic dental treatment performed to lighten the tooth shade. Among different cosmetic dental procedures, including direct and indirect tooth-colored restorations, bleaching is likely the most conservative approach. Bleaching has been accepted well by patients and proven as a safe and effective approach. Objective: Tooth bleaching can be conducted at home or in offices. This study was performed to compare the enamel microhardness before bleaching and one and eight weeks after the application of different bleaching agents. Methods: Forty human premolars were randomly divided into four groups, and their buccal surface underwent a Vickers microhardness test before and after bleaching. Bleaching was performed with 40% hydrogen peroxide (HP) in-office bleaching agent (n = 10), 15% HP at-home bleaching agent (n = 10), and 15% carbamide peroxide (CP) at-home bleaching agent (n = 10) for two weeks. Ten samples were stored in artificial saliva and set as the control group. The microhardness of the samples was measured again one and eight weeks after bleaching. Results: The microhardness significantly decreased in the four groups one week after bleaching. Conclusion: The enamel microhardness was temporarily decreased by in-office bleaching. However, the microhardness increased with time and returned to the baseline value. Although the enamel microhardness initially reduced, it increased eight weeks after 15% CP at-home bleaching agent was applied.

scholarly journals Peroxide bleaching agent effects on enamel surface microhardness, roughness and morphology

2004 ◽  
Vol 18 (4) ◽  
pp. 306-311 ◽  
Author(s):  
Cristiane Franco Pinto ◽  
Rogério de Oliveira ◽  
Vanessa Cavalli ◽  
Marcelo Giannini
Keyword(s):  
Surface Roughness ◽  
Artificial Saliva ◽  
Dental Enamel ◽  
Enamel Surface ◽  
Control Group ◽  
Third Molars ◽  
Carbamide Peroxide ◽  
Peroxide Bleaching ◽  
Human Enamel ◽  
Microhardness Testing

The aim of this study was to evaluate the surface roughness, microhardness and morphology of human enamel exposed to six bleaching agents (at baseline and post-treatment). Human dental enamel samples were obtained from human third molars and randomly divided into seven groups (n = 11): control, Whiteness Perfect - 10% carbamide peroxide (10% CP), Colgate Platinum - 10% CP, Day White 2Z - 7.5% hydrogen peroxide (7.5% HP), Whiteness Super - 37% CP, Opalescence Quick - 35% CP and Whiteness HP - 35% HP. Bleaching agents were applied according to manufacturers' instructions. The control group remained not treated and stored in artificial saliva. Microhardness testing was performed with a Knoop indentor and surface roughness was analyzed with a profilometer. Morphologic observations were carried out with scanning electron microscopy (SEM). Results were statistically analyzed by two-way analysis of variance and Tukey's test (5%), and revealed a significant decrease in microhardness values and a significant increase in surface roughness post-bleaching. Changes in enamel morphology after bleaching were observed under SEM. It was concluded that bleaching agents can alter the microhardness, roughness and morphology of dental enamel surface.

The Effect of a 10% Carbamide Peroxide Bleaching Agent on the Microhardness of Four Types of Direct Resin-based Restorative Materials

2013 ◽  
Vol 38 (3) ◽  
pp. 316-323 ◽  
Author(s):  
MQ AlQahtani
Keyword(s):  
Vickers Hardness ◽  
Resin Composite ◽  
The Other ◽  
Control Group ◽  
Distilled Water ◽  
Bleaching Agent ◽  
Carbamide Peroxide ◽  
Peroxide Bleaching ◽  
Significant Difference ◽  
Restorative Materials

SUMMARY Purpose This in vitro study was undertaken to evaluate the effect of a 10% carbamide peroxide bleaching agent on the microhardness of four types of direct resin-based restorative materials. Materials and Methods Thirty disk-shaped specimens (10.0 mm diameter × 2.0 mm depth) of each material, including a microhybrid resin composite (Z250), a nanofilled resin composite (Z350), a silorane-based low-shrink resin composite (P90), and a hybrid resin composite (Valux Plus), were fabricated and then polished with medium, fine, and superfine polishing discs. After being polished, specimens were cleaned with distilled water for 2 min in an ultrasonic bath to remove any surface debris and then stored in distilled water at 37°C for 24 hours. Specimens from each material were divided into three groups (n=10). One group was selected as a control group (nontreated with bleaching agent). The other two groups were treated with bleaching agent for 14 days (group A) and for 14 days followed by immersion in artificial saliva for 14 days (group B). The top surfaces of the specimens in the different groups were also subjected to the Vickers hardness test with a load of 300 g and 15-second dwell time. Data were analyzed with a one-way analysis of variance and Tukey's HSD test (α = 0.05). Results There was a general reduction of Vickers hardness numbers (VHN) values of treated groups compared with the control group for each material used, but this reduction was minimal, with no significant difference between groups in Z250, whereas the other three materials (Z350, P90, and Valux Plus) showed a significant reduction of VHN of treated groups compared with the control group. Conversely, the findings showed no significant difference between treated groups A and B in all materials used except P90. Conclusion A 10% carbamide peroxide bleaching agent had an adverse effect on the microhardness of nanofilled, silorane-based low-shrink, and hybrid types of resin-based composite materials compared with the microhybrid type.

Human Dentine Remineralization Under Non-colagen Materials Action

2017 ◽  
Vol 68 (5) ◽  
pp. 928-932
Author(s):  
Agripina Zaharia ◽  
Viorica Ghisman Plescan ◽  
Elena Maria Anghel ◽  
Viorica Musat
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Artificial Saliva ◽  
Composite Layer ◽  
X Ray ◽  
Micro Raman Spectroscopy ◽  
Agarose Hydrogel ◽  
Human Dentine ◽  
Dentine Surface ◽  
Scanning Electron

The purpose of this work is to induce biomimetic remineralization of acid etched coronal human dentine in artificial saliva (AS) under agarose (A) hydrogel or chitosan (CS)-A hydrogel action. The investigations focused on the morphology, chemical composition and crystalline structure of the new remineralized layers grown onto the etched dentinal surface (R) using scanning electron microscopy coupled with energy dispersive X-ray spectrometry and micro-Raman spectroscopy. Experimental results showed that remineralized layers grown in the presence of A or CS-A hydrogels consist in B-type Ca-deficient hydroxyapatite (HAP). After 7 days treatment into artificial saliva under agarose hydrogel, nanorod-like extrafibrilar HAP crystals randomly self-assembled in a discontinuous layer were formed, while in presence of chitosan-agarose hydrogel a continuous compact CS-HAP composite layer was obtained. The new biomimetic layer (A-CS4) formed after 4 days on dentine surface under A-CS hydrogel has higher crystallinity. Longer exposed (7 days) dentine in the presence of agarose hydrogel shows a higher mineral-to-collagen ratio (A7). Since dentine mineralization increases, the collagen quality factor decreases in succession A-CS4]R]A7. Results show a benefic effect of chitosan on remineralization of etched dentine.

scholarly journals The force effects of two types of polyethylene terephthalate glyc-olmodified clear aligners immersed in artificial saliva

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Biao Xiang ◽  
Xingxing Wang ◽  
Gang Wu ◽  
Yichen Xu ◽  
Menghan Wang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Polyethylene Terephthalate ◽  
Artificial Saliva ◽  
Orthodontic Force ◽  
The Mean ◽  
The Stability ◽  
Scanning Electron

AbstractNumerous factors can influence the force exerted by clear aligners on teeth. This study aimed to investigate the stability of the force delivered by two different material appliances. 90 clear aligners with 2 materials and three different activations were designed and fabricated. Then, a device was employed to measure the force generated by the two types of PET-G material appliances immersed in artificial saliva for 0, 3, 7, 10, 14 days. Scanning electron microscopy was applied to observe the morphologic alterations on the aligner surfaces, respectively. The forces generated by different activation appliance exhibited differently, 0.0 mm < 0.1 mm < 0.2 mm. In addition, increasing the immersion times and the orthodontic force also decreased, but the forces decreased differently. Compared with the forces of conventional PETG appliances with 0.20 mm activation, the modified PETG appliances with the same activation exhibited significantly higher mean force. When comparing the mean force for modified PETG appliances after 10 and 14 days with conventional PETG appliances, the delivery forces exhibited significant differences (P < 0.05). The force delivered by both materials decreased obviously following artificial saliva immersion, and the force generated by modified aligners exhibited better stability than conventional aligners.

An emendation of the generic diagnosis of Phoreiobothrium Linton, 1889 (Tetraphyllidea: Onchobothriidae) with a detailed description of bothridia and hooks

1985 ◽  
Vol 63 (5) ◽  
pp. 1199-1206 ◽  
Author(s):  
J. N. Caira
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Monophyletic Group ◽  
Generic Diagnosis ◽  
The Third ◽  
Scanning Electron

Hook terminology for the three-pronged hooks of Phoreiobothrium Linton, 1889 is reconciled with that for two-pronged hooks such that the two outermost prongs are considered homologous with the prongs of a two-pronged hook and the third inner prong is termed the basal prong. Scanning electron microscopy was performed on the scolex of Phoreiobothrium lasium Linton, 1889 and the solid nature of the bothridia was reconfirmed. Examination of material of all four species of Phoreiobothrium leads to the conclusion that each species possesses three-pronged hooks that are hollow and open to the outside via pores. The bothridia of each species are considered to be horizontally divided into two loculi, the posterior one being recessed and vertically subdivided. The diagnosis of the genus Phoreiobothrium is emended, and the four species allocated to it are redescribed. Phoreiobothrium is determined to be a monophyletic group on the basis of two synapomorphies and a key to the four species of the genus is presented.

The Mechanism of active capture of animal food by the Sergestid Shrimp Acetes Sibogae Australis

1998 ◽  
Vol 78 (2) ◽  
pp. 497-508 ◽  
Author(s):  
Lachlan Mcleay ◽  
C.G. Alexander
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Prey Capture ◽  
Size Range ◽  
The Third ◽  
Feeding Modes ◽  
In Captivity ◽  
Combined Actions ◽  
Wide Size Range ◽  
Scanning Electron

Combining the use of scanning electron microscopy and microcinematography with functional and behavioural observations has clarified many aspects underlying the feeding processes of the small planktonic sergestid shrimp Acetes sibogae australis. In captivity Acetes sibogae australis is an opportunistic feeder that uses four principal feeding modes to capture a wide size range of prey: Artemia nauplii (<0.33 mm), copepods (<1mm) and moribund Acetes (up to 25 mm). Prey capture is effected by combined actions of the first three pairs of pereiopods and the third maxillipeds before transfer to the more dorsal second maxillipeds. The second maxillipeds are the principal appendages used in securing, manipulating, sorting and rejecting prey before insertion into the vicinity of the inner mouthparts.

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