Clinical study of tooth shade lightening from dentist-supervised, patient-applied treatment with two 10% carbamide peroxide gels.

PubMed

Cibirka, R M; Myers, M; Downey, M C; Nelson, S K; Browning, W D; Hawkins, I K; Dickinson, G L

1999-01-01

Prescribed, patient-applied tooth lightening agents, or nightguard vital bleaching, typically utilizes a 10% carbamide peroxide agent applied during nocturnal hours. The purpose of this randomized double-blind study was to compare the amount of tooth color change in two groups of subjects using dentist-supervised, patient-applied 10% carbamide peroxide gel. One group used Opalescence (Ultradent Products Inc., South Jordan, Utah) and the other NiteWhite Excel (Discus Dental, Inc., Los Angeles, California). Evaluation of tooth color for the six maxillary anterior teeth was done using a Vita shade guide at baseline, 1, 2, and 4 weeks. Subjects were instructed to apply the gel nocturnally using a custom-made soft tray 8 hours per day for 2 weeks. The 16 tabs of the shade guide were ranked according to value from darkest to lightest. The number (1-16) that correlated to the shade tab selected as the match for each tooth was the outcome variable. A Kruskal-Wallis one way analysis of variance on ranks was used. The test revealed no statistically significant difference between Opalescence and NiteWhite Excel for lightening the teeth (p = .807). The color change was still significant after 2 weeks without further bleaching activity. The baseline evaluation of the maxillary incisors and canines for all subjects, regardless of group, demonstrated a significant shade difference, with the canines being darker. This difference was not seen after 2 weeks of active bleaching or at the 4-week evaluation. In this study comparing bleaching products, patients using Opalescence and NiteWhite Excel experienced a significant change in the color of their teeth relative to baseline values after 2 weeks of active treatment.

Does the Use of a "Walking Bleaching" Technique Increase Bone Resorption Markers?

PubMed

Bersezio, C; Vildósola, P; Sáez, M; Sánchez, F; Vernal, R; Oliveira, O B; Jorquera, G; Basualdo, J; Loguercio, A; Fernández, E

This randomized clinical trial evaluated the effect of 35% hydrogen peroxide in comparison with 37% carbamide peroxide in a nonvital bleaching technique of "walking bleaching" (four sessions of treatment) on periodontal markers: nuclear factor kappa B-ligand (RANK-L-process of root resorption marker) and interleukin 1β (IL-1β-inflammatory response marker). Fifty volunteers presenting with discoloration of nonvital teeth and endodontic treatment in good condition participated. Fifty teeth were randomly divided into two study groups according to bleaching gel: HP = 35% hydrogen peroxide (n=25) and 37% carbamide peroxide (n=25). Nonvital bleaching was performed with a walking bleaching technique consisting of four sessions of bleach application. Gingival crevicular fluid samples were taken in order to quantify the RANK-L and IL-1β levels by enzyme-linked immunosorbent assay. Samples were obtained from six periodontal sites for each bleached tooth: three vestibular and three palatine (mesial, middle, and distal) at seven time periods: baseline, after each of the four sessions of nonvital bleaching, at one week, and at one month after nonvital bleaching. Tooth color variations were analyzed in each session by VITA Bleachedguide 3D-MASTER (ΔSGU). Significant increments in the RANK-L and IL-1β levels were detected in each evaluated time compared with baseline ( p<0.05); however, no differences were detected between hydrogen peroxide and carbamide peroxide on increments of the biomarkers studied. The change of color was effective for both nonvital bleaching therapies ( p<0.05). Nonvital bleaching induced a significant increment in the RANK-L and IL-1β levels in periodontal tissues around bleached, nonvital teeth.

Effect of various bleaching treatments on shear bond strength of different universal adhesives and application modes

PubMed Central

2018-01-01

Objectives The aim of this in vitro study was to evaluate the bond strength of 2 universal adhesives used in different application modes to bleached enamel. Materials and Methods Extracted 160 sound human incisors were used for the study. Teeth were divided into 4 treatment groups: No treatment, 35% hydrogen peroxide, 16% carbamid peroxide, 7.5% carbamid peroxide. After bleaching treatments, groups were divided into subgroups according to the adhesive systems used and application modes (n = 10): 1) Single Bond Universal, etch and rinse mode; 2) Single Bond Universal, self-etch mode; 3) Gluma Universal, etch and rinse mode; 4) Gluma Universal, self-etch mode. After adhesive procedures nanohybrid composite resin cylinders were bonded to the enamel surfaces. All specimens were subjected to shear bond strength (SBS) test after thermocycling. Data were analyzed using a 3-way analysis of variance (ANOVA) and Tukey post hoc test. Results No significant difference were found among bleaching groups (35% hydrogen peroxide, 16% carbamid peroxide, 7.5% carbamid peroxide, and no treatment groups) in the mean SBS values. There was also no difference in SBS values between Single Bond Universal and Gluma Universal at same application modes, whereas self-etch mode showed significantly lower SBS values than etch and rinse mode (p < 0.05). Conclusions The bonding performance of the universal adhesives was enhanced with the etch and rinse mode application to bleached enamel and non-bleached enamel. PMID:29765900

The effect of bleaching agents on the microhardness of dental aesthetic restorative materials.

PubMed

Türker, S B; Biskin, T

2002-07-01

This study investigated the effects of three home bleaching agents on the microhardness of various dental aesthetic restorative materials. The restorative materials were: feldspatic porcelain, microfilled composite resin and light-cured modified glass-ionomer cement and the bleaching agents Nite-White (16% carbamide peroxide), Opalescence (10% carbamide peroxide and carbapol jel) and Rembrandt (10% carbamide peroxide jel). A total of 90 restorative material samples were prepared 1 cm diameter and 6 mm thick and kept in distilled water for 24 h before commencing bleaching which was carried out for 8 h day-1 for 4 weeks. Microhardness measurements were then made using a Tukon tester. Statistically significant differences with respect to unbleached controls were found only for the feldspatic porcelain and microfilled composite resins (P <0.05) for Nite-White and Opalescence. All the bleaching agents decreased the microhardness of the porcelain and increased that of the light cured modified glass-ionomer cement. For the composite resin, whereas Nite-White increased its microhardness, the other bleaching agents decreased it. There were no significant differences between the bleaching agents for any of the restorative materials.

Influence of Bleaching Agents on Color and Translucency of Aged Resin Composites.

PubMed

Lago, Maristela; Mozzaquatro, Lisandra R; Rodrigues, Camila; Kaizer, Marina R; Mallmann, André; Jacques, Letícia B

2017-09-01

Evaluate the influence of two bleaching agents (16% carbamide peroxide-CP and 35% hydrogen peroxide-HP) on color and translucency of one resin composite (Filtek Z350 XT) in two opacities (enamel and dentin) previously aged in deionized water or red wine. Sixty specimens of each material were divided in two groups (n = 30): aged in water or red wine for 14 days. Then the specimens were divided in three subgroups (n = 10): control/no treatment, treated with 16% carbamide peroxide (Mix Night), treated with 35% hydrogen peroxide (Mix One). Color readings were performed 24 hours after polishing (baseline); after the 14 days of aging; and after bleaching treatment. Color coordinates CIE L*a*b* were measured using a spectrophotometer (SP60 X-Rite). Color change (CIEDE2000) and translucency parameter were calculated. Data were analyzed with repeated measures two-way ANOVA, and Student-Newman-Keuls tests (5%). Bleaching decreased color change in stained resin composites (aged in red wine), whereas increased it in non-stained enamel resin composites (aged in water). CP had better bleaching results with stained resin composites than HP. Translucency of non-stained dentin resin composite decreased with aging, but did not change with bleaching. For stained resin composites, aging caused reduced translucency, whereas bleaching increased it. Effective bleaching of discolored resin composites aged in an acidic and alcoholic media rich in staining agents was achieved, improving color and translucency. Carbamide peroxide showed better performance than hydrogen peroxide for the bleaching of stained resin composites. (J Esthet Restor Dent 29:368-377, 2017). © 2016 Wiley Periodicals, Inc.

Effects of conditioners on microshear bond strength to enamel after carbamide peroxide bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) treatment.

PubMed

Adebayo, O A; Burrow, M F; Tyas, M J

2007-11-01

To evaluate (a) the enamel microshear bond strength (MSBS) of a universal adhesive and (b) the effects of conditioning with a self-etching primer adhesive with/without prior bleaching and/or casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) application. Thirty-five molars were cut into four sections, assigned randomly to four groups (no treatment; 16% carbamide peroxide bleaching; CPP-ACP-containing paste (Tooth Mousse, TM); bleaching and TM) and treated accordingly. Specimens were divided into two for bonding with either a self-etching primer (Clearfil SE Bond, CSE) or a total-etch adhesive (Single Bond, SB). Specimens for CSE bonding were subdivided for one of four preconditioning treatments (no conditioning; 30-40% phosphoric acid (PA); 15% EDTA; 20% polyacrylic acid conditioner (Cavity conditioner, CC) and treated. The adhesives were applied and resin composite bonded to the enamel using microtubes (internal diameter 0.75mm). Bonds were stressed in shear until failure, mean MSBS calculated and data analysed using ANOVA with Tukey's HSD test (alpha=0.05). The modes of bond failure were assessed and classified. Two-way ANOVA revealed significant differences between treatments (P<0.0001), conditioners (P<0.0001) and a significant interaction between treatments and conditioners (P=0.001). One-way ANOVA revealed no significant differences in MSBS following any of the treatments for SB; following TM application for CSE without preconditioning; and significant differences in MSBS following bleaching with and without TM application for CSE. With preconditioning, applying PA before CSE post-bleaching and either PA or CC before CSE post-TM application, resulted in significant differences in MSBS (P<0.05). The use of conditioners prior to bonding with the self-etching primer adhesive system on treated enamel may significantly improve bond strengths.

Influence of tooth bleaching on dental enamel microhardness: a systematic review and meta-analysis.

PubMed

Zanolla, J; Marques, Abc; da Costa, D C; de Souza, A S; Coutinho, M

2017-09-01

Several studies have investigated the effect of bleaching on dental tissues. The evaluation of the effect of home bleaching with 10% carbamide peroxide is important for assessing alterations in enamel microhardness that may affect dental health in terms of resistance to masticatory forces. This meta-analysis was performed in order to determine scientific evidence regarding the effects of home vital bleaching with 10% carbamide peroxide gel on the microhardness of human dental enamel. A systematic electronic literature search was conducted in the PubMed and Web of Science databases using search terms. Two independent researchers evaluated the information and methodological quality of the studies. Inclusion and exclusion criteria were established for article selection; further, only studies published in English were selected. Thirteen studies that met all of the inclusion and exclusion criteria were selected and underwent statistical analysis. The results of this meta-analysis showed no significant changes in enamel microhardness when using the 10% carbamide peroxide bleaching gel over periods of 7, 14 and 21 days. © 2016 Australian Dental Association.

Assessment of Ca and P content variation in enamel during an eight-week bleaching protocol using energy dispersive X-ray fluorescence

NASA Astrophysics Data System (ADS)

Sorozini, M.; Dos Santos, R. S.; Silva, E. M.; Dos Anjos, M. J.; Perez, C. R.

2017-05-01

Tooth bleaching is a simple technique performed with gels based on hydrogen peroxide molecules responsible for removing the tooth structure's pigmentation. The effects of the overuse of these agents on the tooth structure are not well established. Energy dispersive X-ray fluorescence (EDXRF) can be employed to analyze objects of biological origin as bone and tooth. It is very suitable analytical technique to detect demineralization processes in these tissues. The objective of this study was to use x-ray fluorescence to evaluate the effects on mineral content of enamel submitted to eight-week protocols of home bleaching gels (10% carbamide peroxide and 9.5% hydrogen peroxide), as well as bleaching strips. Four enamel fragments obtained from five teeth were subjected to bleaching for 8 weeks: Group 1- artificial saliva; Group 2-10% carbamide peroxide gel, 6 h daily; Group 3-9.5% hydrogen peroxide gel, two 30-minute applications; and Group 4-bleaching strips, twice daily for 30 min. The change in mineral content was assessed weekly using X-ray fluorescence (Artax 200). Differences were basically found in Group 4 for the concentrations of Ca and P after treatment with bleaching strips containing 10% hydrogen peroxide. For the Ca/P ratio, the differences were found in Group 2-15% carbamide peroxide (p < 0.05). X-ray fluorescence proved to be a suitable method for the evaluation of the mineral content, presenting the advantage of being able to evaluate the same area at different stages of the methodology.

Clinical and Spectrophotometric Evaluation of LED and Laser Activated Teeth Bleaching.

PubMed

Lo Giudice, R; Pantaleo, G; Lizio, A; Romeo, U; Castiello, G; Spagnuolo, G; Giudice, G Lo

2016-01-01

Auxiliary power sources (LED and laser) are used in in-office teeth bleaching techniques to accelerate the redox reaction of the whitening gel to increase ease of use, to improve comfort and safety, and to decrease the procedure time. The aim this study is to evaluate the efficiency of the teeth whitening procedures performed with hydrogen peroxide and carbamide peroxide, LED or Laser activated. 18 patients, affected by exogenous dyschromia, were treated with a bleaching agent composed by 35% hydrogen peroxide and 10% carbamide peroxide. They were divided into two groups: in the first group the bleaching agent was activated by a LED lamp; in the second group it was activated by a Laser diode lamp. Both groups were subjected to 3 bleaching cycle of 15' each. The chromatic evaluations were performed before and after one week from the treatment, using a chromatic scale and a spectrophotometer. The mean value of pre, post bleaching and follow-up were analyzed using a T-test, with results statistically significant for P<0,05. Results showed that the variations in brightness, chroma and hue are significantly influenced by the interaction between the whitening agent and the original colour of the teeth. Laser-activation has marginally improved the bleaching effectiveness. All patients treated with laser activation complained an increase in dental sensitivity. The use of laser-activating systems did not improve the efficacy of bleaching.

Effect of different intracoronal bleaching methods on shear bond strength of ceramic brackets bonded to bleached enamel: An in-vitro study.

PubMed

Chauhan, Vikas; Kumar, Piush; Sharma, Payal; Shetty, Divya

2017-01-01

To investigate the effect of different intracoronal bleaching methods on the shear bond strength and site of failure of ceramic brackets. Sixty freshly extracted human maxillary incisors were randomly divided into four groups ( n = 15). Endodontic access cavity was prepared and root canals were filled, root fillings were removed 2mm apical to the cementoenamel junction, and a 2-mmthick layer of glass ionomer cement base was applied. Group 1 served as the control. Intracoronal bleaching was performed with 35% carbamide peroxide in group 2, sodium perborate in group 3, and 37.5% hydrogen peroxide in group 4. The teeth were immersed in artificial saliva for 4 weeks before bracket bonding. Ceramic brackets were bonded with composite resin and cured with LED light. After bonding, the shear bond strength of the brackets was tested with a universal testing machine. The site of bond failure was determined by modified ARI (Adhesive Remnant Index). The highest value of shear bond strength was measured in control group (18.67 ± 1.59 MPa), which was statistically significant from groups 2,3, and 4. There was no significant difference between groups 2 and 4. The lowest shear bond strength was measured in group 3. ARI scores were not significant from each other. Intracoronal bleaching significantly affected the shear bond strength of ceramic brackets even after 4 weeks of bleaching. Bleaching with sodium perborate affects shear bond strength more adversely than does bleaching with other agents like hydrogen peroxide and carbamide peroxide.

Erosion and abrasion on dental structures undergoing at-home bleaching

PubMed Central

Demarco, Flávio Fernando; Meireles, Sônia Saeger; Sarmento, Hugo Ramalho; Dantas, Raquel Venâncio Fernandes; Botero, Tatiana; Tarquinio, Sandra Beatriz Chaves

2011-01-01

This review investigates erosion and abrasion in dental structures undergoing at- home bleaching. Dental erosion is a multifactorial condition that may be idiopathic or caused by a known acid source. Some bleaching agents have a pH lower than the critical level, which can cause changes in the enamel mineral content. Investigations have shown that at-home tooth bleaching with low concentrations of hydrogen or carbamide peroxide have no significant damaging effects on enamel and dentin surface properties. Most studies where erosion was observed were in vitro. Even though the treatment may cause side effects like sensitivity and gingival irritation, these usually disappear at the end of treatment. Considering the literature reviewed, we conclude that tooth bleaching agents based on hydrogen or carbamide peroxide have no clinically significant influence on enamel/dentin mineral loss caused by erosion or abrasion. Furthermore, the treatment is tolerable and safe, and any adverse effects can be easily reversed and controlled. PMID:23674914

Clinical and Spectrophotometric Evaluation of LED and Laser Activated Teeth Bleaching

PubMed Central

Lo Giudice, R.; Pantaleo, G.; Lizio, A.; Romeo, U.; Castiello, G.; Spagnuolo, G.; Giudice, G. Lo

2016-01-01

Background: Auxiliary power sources (LED and laser) are used in in-office teeth bleaching techniques to accelerate the redox reaction of the whitening gel to increase ease of use, to improve comfort and safety, and to decrease the procedure time. Objective: The aim this study is to evaluate the efficiency of the teeth whitening procedures performed with hydrogen peroxide and carbamide peroxide, LED or Laser activated. Method: 18 patients, affected by exogenous dyschromia, were treated with a bleaching agent composed by 35% hydrogen peroxide and 10% carbamide peroxide. They were divided into two groups: in the first group the bleaching agent was activated by a LED lamp; in the second group it was activated by a Laser diode lamp. Both groups were subjected to 3 bleaching cycle of 15’ each. The chromatic evaluations were performed before and after one week from the treatment, using a chromatic scale and a spectrophotometer. The mean value of pre, post bleaching and follow-up were analyzed using a T-test, with results statistically significant for P<0,05. Results: Results showed that the variations in brightness, chroma and hue are significantly influenced by the interaction between the whitening agent and the original colour of the teeth. Laser-activation has marginally improved the bleaching effectiveness. All patients treated with laser activation complained an increase in dental sensitivity. Conclusion: The use of laser-activating systems did not improve the efficacy of bleaching. PMID:27386010

Effect of bleaching agents and whitening dentifrices on the surface roughness of human teeth enamel.

PubMed

Özkan, Pelin; Kansu, Gülay; Özak, Sule Tuğba; Kurtulmuş-Yilmaz, Sevcan; Kansu, Pelin

2013-01-01

The aim of this in vitro study was to evaluate the surface roughness of human enamel bleached with 10% carbamide peroxide or 10% hydrogen peroxide bleaching agents at different times and also subjected to different superficial cleaning treatments. One hundred and forty flat enamel samples were divided into 14 groups, Group 1-Group 14 (G1-G14). G1-G7 were treated with 10% carbamide peroxide and different dentifrices, G8-G14 were treated with 10% hydrogen peroxide and different dentifrices (G1 and G8: not brushed as control groups; G2 and G9: brushed with Ipana® toothpaste; G3 and G10: brushed with Clinomyn® toothpaste; G4 and G11: brushed with Moos Dent® toothpaste; G5 and G12: brushed with Signal® toothpaste; G6 and G13: brushed with Colgate® toothpaste; G7 and G14: brushed without dentifrice). A profilometer was used to measure average roughness values of the initial surface roughness and at each 7-day-interval. The bleaching was performed for 6 h a day and the surface cleaning treatment was performed 3-times a day, 2 min each time, for 4 weeks. The samples were stored in distilled water during the test period. Statistical analysis revealed significant differences in surface roughness values over time for all groups except G1 and G8 (not brushed). The results of the surface roughness of all groups were nearly the same. The bleaching with 10% hydrogen peroxide and 10% carbamide peroxide did not alter the enamel surface roughness, but when the bleaching treatment was performed combined with abrasive dentifrices, a significant increase in roughness values was observed.

Inflammatory response of human dental pulp to at-home and in-office tooth bleaching

PubMed Central

Vaz, Maysa Magalhães; Lopes, Lawrence Gonzaga; Cardoso, Paula Carvalho; de Souza, João Batista; Batista, Aline Carvalho; Costa, Nádia Lago; Torres, Érica Miranda; Estrela, Carlos

2016-01-01

ABSTRACT Tooth bleaching is a technique of choice to obtain a harmonious smile, but bleaching agents may damage the dental pulp. Objective: This study evaluated the inflammatory responses of human dental pulp after the use of two bleaching techniques. Material and Methods: Pulp samples were collected from human third molars extracted for orthodontic reasons and divided into three groups: control - no tooth bleaching (CG) (n=7); at-home bleaching with 15% carbamide peroxide (AH) (n = 10), and in-office bleaching with 38% hydrogen peroxide (IO) (n=12). Pulps were removed and stained with hematoxylin-eosin for microscopic analysis of inflammation intensity, collagen degradation, and pulp tissue organization. Immunohistochemistry was used to detect mast cells (tryptase+), blood vessels (CD31+), and macrophages (CD68+). Chi-square, Kruskal-Wallis, and Mann Whitney tests were used for statistical analysis. The level of significance was set at p<.05. Results: The inflammation intensity and the number of macrophages were significantly greater in IO than in AH and CG (p<0.05). The results of CD31+ (blood vessels per mm2) were similar in CG (61.39±20.03), AH (52.29±27.62), and IO (57.43±8.69) groups (p>0.05). No mast cells were found in the pulp samples analyzed. Conclusion: In-office bleaching with 38% hydrogen peroxide resulted in more intense inflammation, higher macrophages migration, and greater pulp damage then at-home bleaching with 15% carbamide peroxide, however, these bleaching techniques did not induce migration of mast cells and increased the number of blood vessels. PMID:27812622

Scanning Electron Microscopy and Energy-Dispersive X-Ray Microanalysis of Set CEM Cement after Application of Different Bleaching Agents.

PubMed

Samiei, Mohammad; Janani, Maryam; Vahdati, Amin; Alemzadeh, Yalda; Bahari, Mahmoud

2017-01-01

The present study evaluated the element distribution in completely set calcium-enriched mixture (CEM) cement after application of 35% carbamide peroxide, 40% hydrogen peroxide and sodium perborate as commercial bleaching agents using an energy-dispersive x-ray microanalysis (EDX) system. The surface structure was also observed using the scanning electron microscope (SEM). Twenty completely set CEM cement samples, measuring 4×4 mm 2 , were prepared in the present in vitro study and randomly divided into 4 groups based on the preparation technique as follows: the control group; 35% carbamide peroxide group in contact for 30-60 min for 4 times; 40% hydrogen peroxide group with contact time of 15-20 min for 3 times; and sodium perborate group, where the powder and liquid were mixed and placed on CEM cement surface 4 times. Data were analyzed at a significance level of 0.05 through the one Way ANOVA and Tukey's post hoc tests. EDX showed similar element distribution of oxygen, sodium, calcium and carbon in CEM cement with the use of carbamide peroxide and hydroxide peroxide; however, the distribution of silicon was different ( P <0.05). In addition, these bleaching agents resulted in significantly higher levels of oxygen and carbon ( P <0.05) and a lower level of calcium ( P <0.05) compared to the control group. SEM of the control group showed plate-like and globular structure. Sodium perborate was similar to control group due to its weak oxidizing properties. Globular structures and numerous woodpecker holes were observed on the even surface on the carbamide peroxide group. The mean elemental distribution of completely set CEM cement was different when exposed to sodium perborate, carbamide peroxide and hydrogen peroxide.

Effect of a New Bleaching Gel on Tooth Whitening.

PubMed

Barry, T N; Bailey, C W; Ashcraft-Olmscheid, D; Vandewalle, K S

The purpose of this study was to compare the whitening efficacy of a novel bleaching agent containing a unique tribarrel hydremide-peroxide gel (KöR) with a traditional bleaching system of hydrogen peroxide or carbamide peroxide (Opalescence). Bovine incisors were mounted into a custom resin, arch-shaped mounting device. Four groups of 10 teeth were created using mounting devices containing five teeth each. The in-office and home bleaching gels of KöR and Opalescence were applied to the teeth alone and in trays to simulate a combination of in-office and home bleaching or home bleaching only. Spectrophotometer readings of L* a* b* were performed at baseline, the end of active bleaching (immediate), and three and six months postbleaching. Immediately postbleaching, the use of Opalescence gel resulted in greater change in ΔE* and Δb* (less yellow) for combined and home bleaching techniques compared with KöR. After six months, Opalescence had significantly greater ΔE* and Δb* compared with KöR for home bleaching only. There was no significant difference in ΔL* between Opalescence and KöR at any time period with either technique.

Whitening Efficacy of Whitening Mouth Rinses Used Alone or in Conjunction With Carbamide Peroxide Home Whitening.

PubMed

Oliveira, Jbs; Sarlo, R S; Bresciani, E; Caneppele, Tmf

The aim of this study was to compare the effectiveness of whitening mouth rinses on teeth previously whitened or not, exposed to food dyes. One hundred twenty enamel-dentin specimens, 3 mm in diameter, were obtained from bovine incisors. The specimens were stained for 14 days in staining broth. After staining, the initial color reading was performed via a spectrophotometer CM-2600d (Konica Minolta). Half of specimens were submitted to whitening (10% carbamide peroxide [CP]) for 14 days. They were then divided into three groups and were submitted to cycles of staining (five minutes) and mouth rinses (two minutes) for 12 weeks, with the following: CP-LI, Listerine Whitening; CP-PL, Plax Whitening; CP-BP, bromelain + papain; CP-DW, deionized water. LI, PL, BP, and DW groups were submitted to the same cited cycles but with no prior bleaching. The color measurements were performed after four, eight, and 12 weeks of treatment with mouth rinses. Data were submitted to repeated measures analysis of variance (ANOVA) and Tukey's test for multiple comparisons, with significance level at 5%. The results showed that the CP-LI, CP-PL, LI, and PL groups had greater color change than did the others. The CP-BP and BP groups were similar to CP-DW and DW. We therefore conclude that Listerine Whitening mouth rinse presented the highest bleaching effect, followed by Plax Whitening mouth rinse. Both maintained CP bleaching effect after 12 weeks of dye-rinse cycles. However, none of these rinses were able to produce whitening similar to CP. Bromelain- and papain-containing mouth rinses did not show bleaching effect, being similar to the control groups.

Microhardness of demineralized enamel following home bleaching and laser-assisted in office bleaching

PubMed Central

Ghanbarzadeh, Majid; Akbari, Majid; Hamzei, Haniye

2015-01-01

Background There is little data regarding the effect of tooth whitening on microhardness of white spot lesions. This study was conducted to investigate the effect of home-bleaching and laser-assisted in-office bleaching on microhardness of demineralized enamel. Material and Methods Forty bovine incisors were selected and immersed in a demineralizing solution for 12 weeks to induce white spot lesions. Enamel blocks were prepared and randomly assigned to two groups of 20 each. The first group underwent home bleaching with 15% carbamide peroxide which was applied for 8 hours a day over a period of 15 days. In the second group, in-office bleaching was performed by 40% hydrogen peroxide and powered by irradiation from an 810 nm gallium-aluminum-arsenide (GaAlAs) diode laser (CW, 2W). This process was performed for 3 sessions every seven days, in 15 days. The specimens were stored in Fusayama Meyer artificial saliva during the experiment. Surface microhardness was assessed before and after the bleaching therapies in both groups. Results Microhardness decreased significantly following both home bleaching and laser-assisted in-office bleaching (p<0.05). There were no significant differences in hardness values among the two groups either before (p=0.131) or after (p=0.182) the bleaching procedures. Conclusions Tooth whitening through home bleaching or laser-assisted in-office bleaching can result in a significant reduction in microhardness of white spot lesions. Therefore, it is suggested to take protective measures on bleached demineralized enamel. Key words:White spot lesion, bleaching, laser, microhardness, demineralized enamel, home bleaching, in-office bleaching. PMID:26330939

Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study.

PubMed

Dantas, Andréa Abi Rached; Bortolatto, Janaina Freitas; Roncolato, Ávery; Merchan, Hugo; Floros, Michael Christopher; Kuga, Milton Carlos; Oliveira Junior, Osmir Batista de

2015-01-01

The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home). Samples were randomly distributed into five experimental groups (n=15): C - Control; BC - Bleaching toothpaste containing Blue Covarine; WBC - Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 - At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE), luminosity (ΔL), green-red axis (Δa), and blue-yellow axis (Δb). The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 - immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments.

Can a bleaching toothpaste containing Blue Covarine demonstrate the same bleaching as conventional techniques? An in vitro, randomized and blinded study

PubMed Central

DANTAS, Andréa Abi Rached; BORTOLATTO, Janaina Freitas; RONCOLATO, Ávery; MERCHAN, Hugo; FLOROS, Michael Christopher; KUGA, Milton Carlos; de OLIVEIRA, Osmir Batista

2015-01-01

ABSTRACT Objective The purpose of this in vitro study was to compare the efficacy of a bleaching toothpaste containing Blue Covarine vs. conventional tooth bleaching techniques using peroxides (both in-office and at-home). Material and Methods Samples were randomly distributed into five experimental groups (n=15): C - Control; BC – Bleaching toothpaste containing Blue Covarine; WBC – Bleaching toothpaste without Blue Covarine; HP35 - In-office bleaching using 35% hydrogen peroxide; and CP10 – At-home bleaching with 10% carbamide peroxide. The dental bleaching efficacy was determined by the color difference (ΔE), luminosity (ΔL), green-red axis (Δa), and blue-yellow axis (Δb). The CIELab coordinates were recorded with reflectance spectroscopy at different times: T0 - baseline, T1 – immediately after bleaching, T2 - 7 days, T3 - 14 days, and T4 - 21 days after the end of treatments. Data were analyzed by a repeated measures mixed ANOVA and post hoc Bonferroni test, with a significance level of 5%. Results No significant differences were found between the treatment groups C, BC, and WBC. The groups HP35 and CP10 showed significantly higher whitening efficacy than groups C, BC, and WBC. Conclusions There were no significant differences in the whitening efficacy between a Blue Covarine containing toothpaste, a standard whitening toothpaste, and a control. Neither of the whitening toothpastes tested were as effective as in-office or at-home bleaching treatments. PMID:26814462

Efficacy of hydrogen-peroxide-based mouthwash in altering enamel color.

PubMed

Jaime, Ivone Maria de Lima; França, Fabiana Mantovani Gomes; Basting, Roberta Tarkany; Turssi, Cecilia Pedroso; Amaral, Flávia Lucisano Botelho

2014-02-01

To analyze the efficacy of Colgate Plax Whitening mouthwash containing 1.5% hydrogen peroxide. 30 enamel fragments, obtained from the proximal surfaces of human third molars were darkened with Orange II methyl orange. The fragments were divided into three groups according to the type of bleaching agent applied (n = 10): (1) 10% carbamide peroxide gel (positive control, PC) was applied for 2 hours/day for 28 days; (2) a solution containing 1.5% hydrogen peroxide (Plax) was applied for 4 minutes once a day for 28 days, and (3) no bleaching agent, kept in artificial saliva (negative control, AS). The specimens were kept in artificial saliva between treatment intervals. The specimens were photographed before darkening (baseline), after darkening and before lightening and on the 28th day of whitening. Afterwards, they were analyzed with color measurement software using the CIELab system. The data for the L*, a* and b* parameters were submitted to two-way ANOVA with repeated measures. The values of deltaL *, deltaa *, deltab * and deltaE* were calculated using two procedures: (1) darkened versus original, and (2) bleached versus darkened. This data was submitted to the one-way ANOVA test. Multiple comparisons were conducted using the Tukey test (alpha = 0.05). When the specimens were subjected to bleaching agents, there was a significant increase in the brightness (L* parameter) of the enamel exposed to the gel and also to the bleaching solution. However, higher brightness was observed for the PC (gel) group. As for the axis a* parameters, there were no significant differences between the bleaching products. Regarding the axis b* parameters, the PC group underwent major changes (indicating a color change toward blue chroma), statistically greater than those of the Plax group. After bleaching, there was a significantly greater color change (deltaE*) in the PC group. Although the Plax solution caused a color change, it was less than that produced by the gel. The slightest

Does at-home bleaching induce systemic oxidative stress in healthy subjects?

PubMed

Akbari, M; Nejat, A H; Farkhondeh, N; Mehraban Moghadam, S; Hashemy, S I; Mohammadipour, H S

2017-03-01

At-home bleaching is a technique characterized by the use of carbamide peroxide or hydrogen peroxide as a tooth-whitening agent. However, no data exist regarding systemic safety of this technique. The aim of this study was to investigate the effect of at-home bleaching on serum redox homeostasis. Twenty-nine healthy volunteers who requested tooth-whitening participated in this study. Specified bleaching trays were fabricated for the maxilla and mandible arches. Each participant was given two syringes containing 9% hydrogen peroxide gel to use for 30 min/night for 14 nights consecutively. To evaluate the redox status, the serum concentrations of malondialdehyde (MDA), total antioxidant capacity (TAC) and pro-oxidant-antioxidant balance (PAB) were measured. Blood samples were obtained in the morning prior to initiation of study and the morning after expiration of the bleaching period. The collected data were analyzed using Student's t-test with 95% confidence interval. Twenty-three subjects completed the study. MDA, PAB and TAC were significantly increased after the bleaching period (P = 0.001, 0.001 and 0.002, respectively). At-home bleaching revealed the potential to disturb oxidant-antioxidant balance and induce oxidative stress. Its clinical relevance is unfavourable and potential side-effects of at-home bleaching should be considered. © 2016 Australian Dental Association.

A model for prediction of color change after tooth bleaching based on CIELAB color space

NASA Astrophysics Data System (ADS)

Herrera, Luis J.; Santana, Janiley; Yebra, Ana; Rivas, María. José; Pulgar, Rosa; Pérez, María. M.

2017-08-01

An experimental study aiming to develop a model based on CIELAB color space for prediction of color change after a tooth bleaching procedure is presented. Multivariate linear regression models were obtained to predict the L*, a*, b* and W* post-bleaching values using the pre-bleaching L*, a*and b*values. Moreover, univariate linear regression models were obtained to predict the variation in chroma (C*), hue angle (h°) and W*. The results demonstrated that is possible to estimate color change when using a carbamide peroxide tooth-bleaching system. The models obtained can be applied in clinic to predict the colour change after bleaching.

Effect of in-office bleaching agents on physical properties of dental composite resins.

PubMed

Mourouzis, Petros; Koulaouzidou, Elisabeth A; Helvatjoglu-Antoniades, Maria

2013-04-01

The physical properties of dental restorative materials have a crucial effect on the longevity of restorations and moreover on the esthetic demands of patients, but they may be compromised by bleaching treatments. The purpose of this study was to evaluate the effects of in-office bleaching agents on the physical properties of three composite resin restorative materials. The bleaching agents used were hydrogen peroxide and carbamide peroxide at high concentrations. Specimens of each material were prepared, cured, and polished. Measurements of color difference, microhardness, and surface roughness were recorded before and after bleaching and data were examined statistically by analysis of variance (ANOVA) and Tukey HSD post-hoc test at P < .05. The measurements showed that hue and chroma of silorane-based composite resin altered after the bleaching procedure (P < .05). No statistically significant differences were found when testing the microhardness and surface roughness of composite resins tested (P > .05). The silorane-based composite resin tested showed some color alteration after bleaching procedures. The bleaching procedure did not alter the microhardness and the surface roughness of all composite resins tested.

Effects of toothbrushing with fluoride abrasive and whitening dentifrices on both unbleached and bleached human enamel surface in terms of roughness and hardness: an in vitro study.

PubMed

Bolay, Sukran; Cakir, Filiz Yalcin; Gurgan, Sevil

2012-09-01

The aim of this in vitro study was to evaluate the surface roughness and hardness of both unbleached and bleached (opalescence; 10% carbamide peroxide) human enamel brushed with water (without dentifrice), fluoride abrasive dentifrice (Colgate Total) and whitening dentifrice (Natural White). Human enamel samples were obtained from third molars and randomly divided into five groups (n = 8): G1 - Control (brushed with water without dentifrice), G2 - Colgate Total (fluoride abrasive dentifrice), G3 - Natural White (whitening dentifrice), G4 - Opalescence (10% carbamide peroxide) and then brushed with Colgate Total, G5 - Opalescence (10% carbamide peroxide) and then brushed with Natural White. Bleaching regimen was applied according to manufacturers' instructions. The brushing process was performed with a modified Nyffenegger's brushing machine. Surface roughness was analyzed with a profilometer. Microhardness testing was performed with a Brinell hardness tester. Results were statistically analyzed by Kruskal-Wallis, one-way ANOVA analysis and Mann-Whitney U, Wilcoxon matched-pairs signed-ranks tests. There were significant differences in surface roughness values for all groups, which showed an increase in roughness (p < 0.05). When the bleaching treatment combined with brushing with whitening dentifrice was performed (G5), there was a significant decrease in hardness values (p < 0.05). The other groups (G1, G2, G3, G4) showed no significant hardness differences (p > 0.05). It was concluded that toothbrushing procedures increased the enamel surface roughness, and that bleaching regimen performed with cleaning treatment, through brushing with whitening dentifrice decreased hardness values. When applied together, bleaching and cleaning treatments may alter the enamel surface roughness and hardness values.

Dielectrophoresis enhances the whitening effect of carbamide peroxide on enamel.

PubMed

Ivanoff, Chris S; Hottel, Timothy L; Garcia-Godoy, Franklin; Riga, Alan T

2011-10-01

To compare the enamel whitening effect of a 20-minute dielectrophoresis enhanced electrochemical delivery to a 20-minute diffusion treatment. Forty freshly extracted human teeth without detectable caries or restoration were stored in distilled water at 4 degrees C and used within 1 month of extraction. Two different bleaching gels (Plus White 5 Minute Speed Whitening Gel and 35% Opalescence PF gel) were tested. The study had two parts: Part 1--Quantitative comparison of hydrogen peroxide (H2O2, HP) absorption--following application of an over-the-counter 35% HP whitening gel (Plus White 5 Minute Speed Whitening Gel) to 30 (n = 30) extracted human teeth by conventional diffusion or dielectrophoresis. The amount of H2O2 that diffused from the dentin was measured by a colorimetric oxidation-reduction reaction kit. HP concentration was measured by UV-Vis spectroscopy at 550 nm. Part 2--HP diffusion in stained teeth--35% carbamide peroxide whitening gel (35% Opalescence PF gel) was applied to 10 extracted human teeth (n = 10) stained by immersion in a black tea solution for 48 hours. The teeth were randomly assigned to the 20-minute dielectrophoresis or diffusion treatment group; whitening was evaluated by a dental spectrophotometer and macro-photography. Part 1: The analysis found significant differences between both groups with relative percent errors of 3% or less (a single outlier had an RPE of 12%). The average absorbance for the dielectrophoresis group in round 1 was 79% greater than the diffusion group. The average absorbance for the dielectrophoresis group in round 2 was 130% greater than the diffusion group. A single-factor ANOVA found a statistically significant difference between the diffusion and dielectrophoresis groups (P = 0.01). Part 2--The average change in Shade Guide Units (SGU) was 0.6 for the diffusion group, well under the error of measurement of 0.82 SGU. The average change in SGU for the dielectrophoresis group was 9, significantly above the

Tooth sensitivity with a desensitizing-containing at-home bleaching gel-a randomized triple-blind clinical trial.

PubMed

Maran, Bianca Medeiros; Vochikovski, Laína; de Andrade Hortkoff, Diego Rafael; Stanislawczuk, Rodrigo; Loguercio, Alessandro D; Reis, Alessandra

2018-05-01

Desensitizing agents are usually included in the composition of bleaching agents to reduce bleaching-induced tooth sensitivity (TS). This randomized clinical trial (RCT) evaluated the risk and intensity of TS and color change after at-home bleaching with a desensitizing-containing (3% potassium nitrate and 0.2% sodium fluoride) and desensitizing-free 10% carbamide peroxide (CP) gel (Whiteness Perfect, FGM). A triple-blind, within-person RCT was conducted on 60 caries-free adult patients. Each participant used the gel in a bleaching tray for 3 h daily for 21 days in both the upper and lower dental arches. The absolute risk and intensity of TS were assessed daily through the 0-10 VAS and NRS scale for 21 days. Color change was recorded using shade guides (Vita Classical and Vita Bleachedguide) and the Easyshade spectrophotometer at baseline, weekly and 30 days after the end of the bleaching. The risk and intensity of TS were evaluated by the McNemar and Wilcoxon Signed Rank tests, respectively. Color change (ΔSGU and ΔE) were evaluated by the Mann-Whitney test and a paired t-test, respectively (α = 0.05). No difference in the TS and color change was observed (p > 0.05). The incorporation of potassium nitrate and sodium fluoride in 10% carbamide peroxide at-home bleaching gel tested in this study did not reduce the TS and did not affect color change (RBR-4M6YR2). Copyright © 2018 Elsevier Ltd. All rights reserved.

Evaluation of the Efficacy and Color Stability of Two Different At-Home Bleaching Systems on Teeth of Different Shades: A Randomized Controlled Clinical Trial.

PubMed

Aka, Betül; Celik, Esra Uzer

2017-09-01

This randomized controlled clinical trial compared the bleaching efficacy of two different at-home bleaching systems on teeth of different shades and their color stability after a 6-month follow-up. Ninety-two patients (777 teeth) were randomly divided into three groups: (a) negative control, (b) patients treated with a custom-made tray containing 10% carbamide peroxide (10% CP/PF) (Opalescence PF), and (c) patients treated with a pre-loaded tray containing 6% hydrogen peroxide (6% HP/Go) (Opalescence Go). Teeth in all groups were divided into three sub-groups according to the VITA Classic Shade Guide: light (A1-C1), medium dark (C2-B3), and dark (A3.5-C4). Bleaching systems were performed in accordance with manufacturers' instructions for 14 days. The color values were measured at the baseline, 10 days and 14 days of bleaching, 2 weeks, and 6 months after bleaching. Three-way ANOVA and Mann-Whitney U tests were used for statistical analysis (α = 0.05). Irrespective of original shade, both bleaching groups showed significantly higher ΔE* values than the control groups, and the ΔE* values were significantly higher in the 10% CP/PF groups than those in the 6% HP/Go groups (p < 0.05). In both bleaching systems, the dark teeth showed higher ΔE* values than the light teeth (p < 0.05). The ΔE* values decreased significantly only in the 10% CP/PF groups after 6 months (p < 0.05). Both bleaching agents produced a bleaching effect, but 10% CP/PF was more effective. A pre-loaded tray system may be used for dental bleaching, but it is still less effective than conventional a 10% carbamide peroxide system, irrespective of the initial shade. (J Esthet Restor Dent 29:325-338, 2017). © 2017 Wiley Periodicals, Inc.

Sensory and Functionality Differences of Whey Protein Isolate Bleached by Hydrogen or Benzoyl Peroxide.

PubMed

Smith, Tucker J; Foegeding, E Allen; Drake, MaryAnne

2015-10-01

Whey protein is a highly functional food ingredient used in a wide variety of applications. A large portion of fluid whey produced in the United States is derived from Cheddar cheese manufacture and contains annatto (norbixin), and therefore must be bleached. The objective of this study was to compare sensory and functionality differences between whey protein isolate (WPI) bleached by benzoyl peroxide (BP) or hydrogen peroxide (HP). HP and BP bleached WPI and unbleached controls were manufactured in triplicate. Descriptive sensory analysis and gas chromatography-mass spectrometry were conducted to determine flavor differences between treatments. Functionality differences were evaluated by measurement of foam stability, protein solubility, SDS-PAGE, and effect of NaCl concentration on gelation relative to an unbleached control. HP bleached WPI had higher concentrations of lipid oxidation and sulfur containing volatile compounds than both BP and unbleached WPI (P < 0.05). HP bleached WPI was characterized by high aroma intensity, cardboard, cabbage, and fatty flavors, while BP bleached WPI was differentiated by low bitter taste. Overrun and yield stress were not different among WPI (P < 0.05). Soluble protein loss at pH 4.6 of WPI decreased by bleaching with either hydrogen peroxide or benzoyl peroxide (P < 0.05), and the heat stability of WPI was also distinct among WPI (P < 0.05). SDS PAGE results suggested that bleaching of whey with either BP or HP resulted in protein degradation, which likely contributed to functionality differences. These results demonstrate that bleaching has flavor effects as well as effects on many of the functionality characteristics of whey proteins. Whey protein isolate (WPI) is often used for its functional properties, but the effect of oxidative bleaching chemicals on the functional properties of WPI is not known. This study identifies the effects of hydrogen peroxide and benzoyl peroxide on functional and flavor characteristics of WPI

In-Vitro Comparative Study of In-office and Home Bleaching Agents on Surface Micro-morphology of Enamel.

PubMed

Fatima, Nazish

2016-01-01

To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide (CP) and in-office bleaching agent with 38% Hydrogen Peroxide (HP) on surface micro-morphology of enamel. An experimental study. The discs were prepared at Material Engineering Department of NED University of Engineering and Technology, Karachi, and surface morphology was analyzed at Centralized Science Laboratory of Karachi University, Pakistan. Duration of study was one year from January to December 2012. Forty five sound human third molar crowns, extracted for periodontal reason, were included in the study. Longitudinal sections were made using diamond disks (0.2 mm) under water lubrication to obtain enamel slabs measuring (3 mm x 3 mm). The slabs were embedded in polystyrene resin by using 2.0 cm diameter PVC molds, leaving the outer enamel surface uncovered by the resin. Ninety dental enamel slabs were prepared. The slabs were then randomly divided into 3 groups. Each group contained thirty specimens (n=30). Group 1 was kept in artificial saliva at 37°C in incubator (Memart, Germany) during whole experiment. Group 2 was treated with power whitening gel (White Smile 2011, Germany). Group 3 was treated with tooth whitening pen (White Smile 2011, Germany). The most central region or the region that was most representative of the entire surface area was used. The SEM (Jeol-Japan-JSM6380A, JAPAN) micrographs were examined to determine the type of surface presented. The enamel changes were classified as no or mild alteration, moderate alteration and severe altered surface. Regarding micro-morphology, the enamel surface of control groups showed smooth surface in general with some scattered clear scratches due to the polishing procedure. The specimens bleached in group 2 and group 3, represented areas of mild erosion. Bleaching with 38% Hydrogen Peroxide (HP) and 16% Carbamide Peroxide (CP) resulted in mild changes in surface micro-morphology of enamel.

An effective ostrich oil bleaching technique using peroxide value as an indicator.

PubMed

Palanisamy, Uma Devi; Sivanathan, Muniswaran; Radhakrishnan, Ammu Kutty; Haleagrahara, Nagaraja; Subramaniam, Thavamanithevi; Chiew, Gan Seng

2011-07-05

Ostrich oil has been used extensively in the cosmetic and pharmaceutical industries. However, rancidity causes undesirable chemical changes in flavour, colour, odour and nutritional value. Bleaching is an important process in refining ostrich oil. Bleaching refers to the removal of certain minor constituents (colour pigments, free fatty acid, peroxides, odour and non-fatty materials) from crude fats and oils to yield purified glycerides. There is a need to optimize the bleaching process of crude ostrich oil prior to its use for therapeutic purposes. The objective of our study was to establish an effective method to bleach ostrich oil using peroxide value as an indicator of refinement. In our study, we showed that natural earth clay was better than bentonite and acid-activated clay to bleach ostrich oil. It was also found that 1 hour incubation at a 150 °C was suitable to lower peroxide value by 90%. In addition, the nitrogen trap technique in the bleaching process was as effective as the continuous nitrogen flow technique and as such would be the recommended technique due to its cost effectiveness.

Effect of tooth-bleaching on the carbonate concentration in dental enamel by Raman spectroscopy.

PubMed

Vargas-Koudriavtsev, Tatiana; Herrera-Sancho, Óscar-Andrey

2017-01-01

There are not many studies evaluating the effects of surface treatments at the molecular level. The aim of this in vitro study was to analyze the concentration of carbonate molecules in dental enamel by Raman spectroscopy after the application of in-office and home whitening agents. Sixty human teeth were randomly divided into six groups and exposed to three different home bleaching gels (Day White) and three in-office whitening agents (Zoom! Whitespeed and PolaOffice) according to the manufacturer´s instructions. The concentration of carbonate molecules in enamel was measured prior to and during the treatment by means of Raman spectroscopy. Statistical analysis included repeated measures analysis of variance ( p ≤0.05) and Bonferroni pairwise comparisons. At home bleaching agents depicted a decrease in the carbonate molecule. This decrease was statistically significant for the bleaching gel with the highest hydrogen peroxide concentration ( p ≤0,05). In-office whitening agents caused an increase in carbonate, which was significant for all three groups ( p ≤0,05). In-office bleaching gels seem to cause a gain in carbonate of the enamel structure, whilst at-home whitening gels caused a loss in carbonate. Key words: Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, carbonate.

Effect of tooth-bleaching on the carbonate concentration in dental enamel by Raman spectroscopy

PubMed Central

Vargas-Koudriavtsev, Tatiana; Herrera-Sancho, Óscar-Andrey

2017-01-01

Background There are not many studies evaluating the effects of surface treatments at the molecular level. The aim of this in vitro study was to analyze the concentration of carbonate molecules in dental enamel by Raman spectroscopy after the application of in-office and home whitening agents. Material and Methods Sixty human teeth were randomly divided into six groups and exposed to three different home bleaching gels (Day White) and three in-office whitening agents (Zoom! Whitespeed and PolaOffice) according to the manufacturer´s instructions. The concentration of carbonate molecules in enamel was measured prior to and during the treatment by means of Raman spectroscopy. Statistical analysis included repeated measures analysis of variance (p≤0.05) and Bonferroni pairwise comparisons. Results At home bleaching agents depicted a decrease in the carbonate molecule. This decrease was statistically significant for the bleaching gel with the highest hydrogen peroxide concentration (p≤0,05). In-office whitening agents caused an increase in carbonate, which was significant for all three groups (p≤0,05). Conclusions In-office bleaching gels seem to cause a gain in carbonate of the enamel structure, whilst at-home whitening gels caused a loss in carbonate. Key words:Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, carbonate. PMID:28149472

Influence of bleaching agents on surface roughness of sound or eroded dental enamel specimens.

PubMed

Azrak, Birgül; Callaway, Angelika; Kurth, Petra; Willershausen, Brita

2010-12-01

The aim of the present in vitro study was to assess the effect of bleaching agents on eroded and sound enamel specimens. Enamel specimens prepared from human permanent anterior teeth were incubated with different bleaching agents containing active ingredients as 7.5 or 13.5% hydrogen peroxide or 35% carbamide peroxide, ranging in pH from 4.9 to 10.8. The effect of the tooth whitening agents on surface roughness was tested for sound enamel surfaces as well as for eroded enamel specimens. To provoke erosive damage, the enamel specimens were incubated for 10 hours with apple juice (pH = 3.4). Afterwards, pretreated and untreated dental slices were incubated with one of the bleaching agents for 10 hours. The surface roughness (R(a)) of all enamel specimens (N = 80) was measured using an optical profilometric device. A descriptive statistical analysis of the R(a) values was performed. The study demonstrated that exposure to an acidic bleaching agent (pH = 4.9) resulted in a higher surface roughness (p = 0.043) than treatment with a high peroxide concentration (pH = 6.15). If the enamel surface was previously exposed to erosive beverages, subsequent bleaching may enhance damage to the dental hard tissue. Bleaching agents with a high concentration of peroxide or an acidic pH can influence the surface roughness of sound or eroded enamel. © 2010, COPYRIGHT THE AUTHORS. JOURNAL COMPILATION © 2010, WILEY PERIODICALS, INC.

The effect of light-activation sources on tooth bleaching

PubMed Central

Baroudi, Kusai; Hassan, Nadia Aly

2014-01-01

Vital bleaching is one of the most requested cosmetic dental procedures asked by patients who seek a more pleasing smile. This procedure consists of carbamide or hydrogen peroxide gel applications that can be applied in-office or by the patient (at-home/overnight bleaching system). Some in-office treatments utilise whitening light with the objective of speeding up the whitening process. The objective of this article is to review and summarise the current literature with regard to the effect of light-activation sources on in-office tooth bleaching. A literature search was conducted using Medline, accessed via the National Library of Medicine Pub Med from 2003 to 2013 searching for articles relating to effectiveness of light activation sources on in-office tooth bleaching. This study found conflicting evidence on whether light truly improve tooth whitening. Other factors such as, type of stain, initial tooth colour and subject age which can influence tooth bleaching outcome were discussed. Conclusions: The use of light activator sources with in-office bleaching treatment of vital teeth did not increase the efficacy of bleaching or accelerate the bleaching. PMID:25298598

Hydrogen peroxide bleaching of cotton in ultrasonic energy.

PubMed

Mistik, S Ilker; Yükseloglu, S Müge

2005-12-01

It is well known that, conventional hydrogen peroxide bleaching process is an important and a specific step for wet processors; however it has some problems such as long time, high energy consumption. On the other hand, using ultrasonic energy in bleaching is an alternative method for the conventional processes. In this work, 100% cotton materials of different forms such as raw fibre, ring-spun yarns and knitted fabrics produced from these cottons, were treated with hydrogen peroxide in two different concentrations (5 mL/L and 10 mL/L), at three different temperatures (20 degrees C, 30 degrees C, 40 degrees C) and times (20 min, 30 min, 60 min). Whiteness Index of the samples were then measured spectrophotometrically and the overall results were compared.

The impact of iron on the bleaching efficacy of hydrogen peroxide in liquid whey systems.

PubMed

Jervis, Suzanne M; Drake, MaryAnne

2013-02-01

Whey is a value-added product that is utilized in many food and beverage applications for its nutritional and functional properties. Whey and whey products are generally utilized in dried ingredient applications. One of the primary sources of whey is from colored Cheddar cheese manufacture that contains the pigment annatto resulting in a characteristic yellow colored Cheddar cheese. The colorant is also present in the liquid cheese whey and must be bleached so that it can be used in ingredient applications without imparting a color. Hydrogen peroxide and benzoyl peroxide are 2 commercially approved chemical bleaching agents for liquid whey. Concerns regarding bleaching efficacy, off-flavor development, and functionality changes have been previously reported for whey bleached with hydrogen peroxide and benzoyl peroxide. It is very important for the dairy industry to understand how bleaching can impact flavor and functionality of dried ingredients. Currently, the precise mechanisms of off-flavor development and functionality changes are not entirely understood. Iron reactions in a bleached liquid whey system may play a key role. Reactions between iron and hydrogen peroxide have been widely studied since the reaction between these 2 relatively stable species can cause great destruction in biological and chemical systems. The actual mechanism of the reaction of iron with hydrogen peroxide has been a controversy in the chemistry and biological community. The precise mechanism for a given reaction can vary greatly based upon the concentration of reactants, temperature, pH, and addition of biological material. In this review, some hypotheses for the mechanisms of iron reactions that may occur in fluid whey that may impact bleaching efficacy, off-flavor development, and changes in functionality are presented. Cheese whey is bleached to remove residual carotenoid cheese colorant. Concerns regarding bleaching efficacy, off-flavor development, and functionality changes have

Effect of Different Anti-Oxidants on Shear Bond Strength of Composite Resins to Bleached Human Enamel

PubMed Central

Saladi, Hari Krishna; Bollu, Indira Priyadarshini; Burla, Devipriya; Ballullaya, Srinidhi Vishnu; Devalla, Srihari; Maroli, Sohani; Jayaprakash, Thumu

2015-01-01

Introduction The bond strength of the composite to the bleached enamel plays a very important role in the success and longevity of an aesthetic restoration. Aim The aim of this study was to compare and evaluate the effect of Aloe Vera with 10% Sodium Ascorbate on the Shear bond strength of composite resin to bleached human enamel. Materials and Methods Fifty freshly extracted human maxillary central incisors were selected and divided into 5 groups. Group I and V are unbleached and bleached controls groups respectively. Group II, III, IV served as experimental groups. The labial surfaces of groups II, III, IV, V were treated with 35% Carbamide Peroxide for 30mins. Group II specimens were subjected to delayed composite bonding. Group III and IV specimens were subjected to application of 10% Sodium Ascorbate and leaf extract of Aloe Vera following the Carbamide Peroxide bleaching respectively. Specimens were subjected to shear bond strength using universal testing machine and the results were statistically analysed using ANOVA test. Tukey (HSD) Honest Significant Difference test was used to comparatively analyse statistical differences between the groups. A p-value <0.05 is taken as statistically significant. Results The mean shear bond strength values of Group V showed significantly lower bond strengths than Groups I, II, III, IV (p-value <0.05). There was no statistically significant difference between the shear bond strength values of groups I, II, III, IV. Conclusion Treatment of the bleached enamel surface with Aloe Vera and 10% Sodium Ascorbate provided consistently better bond strength. Aloe Vera may be used as an alternative to 10% Sodium Ascorbate. PMID:26674656

In vitro colorimetric evaluation of the efficacy of home bleaching and over-the-counter bleaching products.

PubMed

Dietschi, Didier; Benbachir, Nacer; Krejci, Ivo

2010-06-01

Various bleaching modalities are now offered to patients, either monitored by the dental office or self-directed, for which relative efficiency is unknown. The aim of this in vitro study was to evaluate the ability of bleaching products and protocols to lighten enamel and dentin. Bovine tooth specimens of standardized thickness (2.5 +/- 0.025 mm with similar dentin and enamel thickness) were prepared and stained with whole blood and hemolysate before being submitted to seven supervised or self-directed bleaching regimens: tray-based bleaching using 10% (Opalescence, Ultradent; Nite White, Discus Dental) or light-activated 30% (Metatray, Metatray) carbamide peroxide (CP); 6% (Zoom, Discus Dental) or 9% (TresWhite, Ultradent) hydrogen peroxide (HP); strips (Whitening Strips, Oral B-Rembrandt); and paint-on gel (Paint on Plus, Ivoclar Vivadent) containing 8.1% and 6% HP, respectively. Colorimetric measurements were performed on each specimen side, according to the CIE L*a*b* system, before and after staining, as well as after 5, 10, and the recommended number of bleaching applications. Color change after recommended number of applications (DEr) varied from 15.72 (Metatray) to 29.67 (Nite White) at enamel and 14.91 (Paint on Plus) to 41.43 (Nite White) at dentin side; Nite White (10% CP) and TresWhite (9% HP) were more effective than Metatray (30% CP) and Paint on Plus (6% HP) after 5 or the recommended number of applications. In this in vitro study based on bovine teeth, tray-based systems produced the faster and better bleaching effect, regardless of the product and concentration used, at both enamel and dentin sides.

Effect of different bleaching strategies on microhardness of a silorane-based composite resin.

PubMed

Bahari, Mahmoud; Savadi Oskoee, Siavash; Mohammadi, Narmin; Ebrahimi Chaharom, Mohammad Esmaeel; Godrati, Mostafa; Savadi Oskoee, Ayda

2016-01-01

Background. Dentists' awareness of the effects of bleaching agents on the surface and mechanical properties of restorative materials is of utmost importance. Therefore, this in vitro study was undertaken to investigate the effects of different bleaching strategies on the microhardness of a silorane-based composite resin. Methods. Eighty samples of a silorane-based composite resin (measuring 4 mm in diameter and 2 mm in thickness) were prepared within acrylic molds. The samples were polished and randomly assigned to 4 groups (n=20). Group 1 (controls) were stored in distilled water for 2 weeks. The samples in group 2 underwent a bleaching procedure with 15% carbamide peroxide for two weeks two hours daily. The samples in group 3 were bleached with 35% hydrogen peroxide twice 5 days apart for 30 minutes each time. The samples in group 4 underwent a bleaching procedure with light-activated 35% hydrogen peroxide under LED light once for 40 minutes. Then the microhardness of the samples was determined using Vickers method. Data were analyzed with one-way ANOVA and post hoc Tukey tests (P < 0.05). Results. All the bleaching agents significantly decreased microhardness compared to the control group (P < 0.05). In addition, there were significant differences in microhardness between groups 2 and 4 (P = 0.001) and between groups 3 and 4 (P<0.001). However, no significant differences were detected in microhardness between groups 2 and 3 (P > 0.05). Conclusion. Bleaching agents decreased microhardness of silorane-based composite resin restorations, the magnitude of which depending on the bleaching strategy used.

Effect of bleaching on color stability and roughness of composite resins aged in staining beverage.

PubMed

Rodrigues, Camila Silva; Mozzaquatro, Lisandra Rossato; Dala Nora, Bárbara; Jacques, Letícia Borges; Mallmann, André

2017-01-01

Composite resin properties can be affected by contact with gel during bleaching procedures; however, there is no consensus about the effect of this contact on resin susceptibility to color change. This study aimed to evaluate staining susceptibility and surface roughness changes in 2 composite resins (Filtek Z250 XT and Filtek Z350 XT) after application of bleaching peroxides and storage in different media. Forty-two disc-shaped specimens of each composite were made, polished, and divided into 3 groups according to treatment type (35% hydrogen peroxide, 16% carbamide peroxide, or deionized water as a control group). These groups were subdivided into 2 groups according to immersion media (n = 7): deionized water or red wine. Color and average roughness (Ra) measurements were taken 24 hours after specimen preparation (T0), immediately after bleaching procedures (T1), and immediately after aging (staining; T2). Statistical analyses were performed using 2-way analyses of variance for repeated measurements and the Tukey test (P < 0.05). Bleaching resulted in minimal color change (ΔE* < 1) in all groups. Filtek Z350 XT specimens presented greater mean values of color change. The Ra values did not increase significantly after bleaching procedures or aging (staining) in all groups. Thus, bleaching agents did not significantly change the color or roughness of the composite resins used in this study.

ENAMEL SUSCEPTIBILITY TO RED WINE STAINING AFTER 35% HYDROGEN PEROXIDE BLEACHING

PubMed Central

Berger, Sandrine Bittencourt; Coelho, Alessandra Sanchez; Oliveira, Valéria Aparecida Pessatti; Cavalli, Vanessa; Giannini, Marcelo

2008-01-01

Concern has been expressed regarding the staining of enamel surface by different beverages after bleaching. This study investigated the influence of 35% hydrogen peroxide bleaching agents on enamel surface stained with wine after whitening treatments. Flat and polished bovine enamel surfaces were submitted to two commercially available 35% hydrogen peroxide bleaching agents or kept in 100% humidity, as a control group (n = 10). Specimens of all groups were immersed in red wine for 48 h at 37°C, immediately, 24 h or 1 week after treatments. All specimens were ground into powder and prepared for the spectrophotometric analysis. Data were subjected to two-way analysis of variance and Fisher's PLSD test at 5% significance level. The amount of wine pigments uptake by enamel submitted to bleaching treatments was statistically higher than that of control group, independently of the evaluation time. Results suggested that wine staining susceptibility was increased by bleaching treatments. PMID:19089218

Effect of ultrasonic pre-treatment of thermomechanical pulp on hydrogen peroxide bleaching

NASA Astrophysics Data System (ADS)

Loranger, E.; Charles, A.; Daneault, C.

2012-12-01

Ultrasound pre-treatments of softwood TMP had been carried to evaluate its impact on the efficiency of hydrogen peroxide bleaching. The trials were performed after a factorial design of experiment using frequency, power and time as variables. The experiments were conducted in an ultrasonic bath and then bleached with hydrogen peroxide. Measurements such as brightness, L*A*B* color system coordinate, residual hydrogen peroxide and metal content were evaluated on bleached pulp. The results indicate that the effect of ultrasonic treatment on brightness was dependent on the ultrasound frequency used; the brightness increased slightly at 68 kHz and decreased at 40 and 170 kHz. These results were correlated to the ultrasound effect on the generation of transition metals (copper, iron and manganese) which are responsible for catalytic decomposition of hydrogen peroxide. The influence of metal interference was minimized by using a chelating agent such as diethylene triamine pentaacetic acid (DTPA). With the results obtained in this study we have identified a set of option conditions, e.g. 1000 W, 40 kHz, 1.5 % consistency and 0.2% addition of DTPA prior to the bleaching stage (after ultrasonic pre-treatment) who improve brightness by 2.5 %ISO.

In Vitro Comparative Study of Two Different Bleaching Agents on Micro-hardness Dental Enamel.

PubMed

Fatima, Nazish; Ali Abidi, Syed Yawar; Meo, Ashraf Ali

2016-02-01

To evaluate the effect of home-use bleaching agent containing 16% Carbamide Peroxide (CP) and in-office bleaching agent containing 38% Hydrogen Peroxide (HP) on enamel micro-hardness. An in vitroexperimental study. Department of Operative Dentistry and Science of Dental Materials at Dr. Ishrat-ul-Ebad Khan Institute of Oral Health Sciences, Dow University of Health Sciences and Material Engineering Department of NED University of Engineering and Technology, Karachi, from July to December 2014. Atotal of 90 enamel slabs from 45 sound human 3rd molar were randomly divided into 3 groups. Each group contained 30 specimens (n=30). Group 1 was kept in artificial saliva at 37°C in incubator during the whole experiment. However, Groups 2 and 3 were treated with power whitening gel and tooth whitening pen respectively. After bleaching session, specimens were thoroughly rinsed with deionized water again for 10 seconds and then stored in artificial saliva at 37°C in incubator. Artificial saliva was changed after every 2 days. The Vickers hardness tester (Wolpert 402 MVD, Germany) was adjusted to a load of 0.1 kg (100 gm) and dwell time of 5 seconds. Three Vickers were performed on each specimen using a hardness tester according to the ISO 6507-3:1998 specification. Micro-hardness measurements were performed before and after bleaching at day 1, 7 and 14. In the control group, the baseline micro-hardness was 181.1 ±9.3 which was reduced after the storage on day 1, 7 and 14 (p = 0.104). In Group 2, baseline micro-hardness was 180.4 ±10.1 which was reduced to 179.79 ±10.0 units after day 1. Whereas, on day 7 and 14, the values of micro-hardness were 179.8 ±10 and 179.7 ±10.29, respectively (p=0.091). Furthermore, the baseline micro-hardness in Group 3 was 174.0 ±22.9 units which was reduced to 173 ±23 on day 1, 170 ±30 on day 7 and 173 ±23 on day 14 (p = 0.256). The statistically insignificant difference was found

Detection of Hydroxyl and Perhydroxyl Radical Generation from Bleaching Agents with Nuclear Magnetic Resonance Spectroscopy.

PubMed

Sharma, Himanshu; Sharma, Divya S

Children/adolescent's orodental structures are different in anatomy and physiology from that of adults, therefore require special attention for bleaching with oxidative materials. Hydroxyl radical (OH . ) generation from bleaching agents has been considered directly related to both its clinical efficacy and hazardous effect on orodental structures. Nonetheless bleaching agents, indirectly releasing hydrogen peroxide (H 2 O 2 ), are considered safer yet clinically efficient. Apart from OH . , perhydroxyl radicals (HO 2 . ) too, were detected in bleaching chemistry but not yet in dentistry. Therefore, the study aims to detect the OH . and HO 2 . from bleaching agents with their relative integral value (RIV) using 31 P nuclear magnetic resonance ( 31 PNMR) spectroscope. Radicals were generated with UV light in 30% H 2 O 2 , 35% carbamide peroxide (CP), sodium perborate tetrahydrate (SPT) and; neutral and alkaline 30% H 2 O 2 . Radicals were spin-trapped with DIPPMPO in NMR tubes for each test agents as a function of time (0, 1, 2, 3min) at their original pH. Peaks were detected for OH . and HO 2 . on NMR spectrograph. RIV were read and compared for individual radicals detected. Only OH . were detected from acidic and neutral bleaching agent (30% acidic and neutral H 2 O 2 , 35%CP); both HO 2 . and OH . from 30% alkaline H 2 O 2 ; while only HO 2 . from more alkaline SPT. RIV for OH . was maximum at 1min irradiation of acidic 30%H 2 O 2 and 35%CP and minimum at 1min irradiation of neutral 30%H 2 O 2 . RIV for HO 2 . was maximum at 0min irradiation of alkaline 30%H 2 O 2 and minimum at 2min irradiation of SPT. The bleaching agents having pH- neutral and acidic were always associated with OH . ; weak alkaline with both OH . and HO 2 . ; and strong alkaline with HO 2 . only. It is recommended to check the pH of the bleaching agents and if found acidic, should be made alkaline to minimize oxidative damage to enamel itself and then to pulp/periodontal tissues. H 2 O 2

Dentin bond strength and nanoleakage of the adhesive interface after intracoronal bleaching.

PubMed

Cavalli, Vanessa; Sebold, Maicon; Shinohara, Mirela Sanae; Pereira, Patrícia Nóbrega Rodrigues; Giannini, Marcelo

2018-04-01

This study evaluated dentin bond strength (BS) and nanoleakage of non- and pre-etched dentin immediately (T 0 ,), 7 days (T 7 ), and 14 days (T 14 ) after bleaching. Bovine incisors (150) were selected and half of them submitted to intrapulpal dentin etching (e). Non- and pre-etched dentin were subjected to the following (n = 15): no bleaching/control (C); 35% carbamide peroxide (CP); 35% hydrogen peroxide (35% HP); 25% hydrogen peroxide (25% HP); and sodium perborate (SP). Bleaching agents were applied to the pulp chamber four times within a 72-h interval. Afterwards, pulp chamber dentin was prepared for the BS test at different evaluation times (n = 5): T 0 , T 7 , and T 14 . Composite blocks were built on pulp chamber and sectioned in slices. Slices were reduced to an hour-glass shape with a cross-sectional area of 0.8 mm 2 and submitted to microtensile BS test. Two additional specimens for each group were prepared for nanoleakage evaluation by transmission electron microscopy (TEM). Results were analyzed by ANOVA (two-way) and Dunnett's test (p < .05). BS decreased immediately after intracoronal bleaching for both sound and pre-etched dentin (p < .05). At T 14 , the BS of non-etched bleached dentin increased for all groups, whereas the pre-etched SPe group presented BS similar to the Ce. Nanoleakage within the hybrid layer was perceptible immediately after bleaching, although a decrease in nanoleakage was observed for all groups at T 14 . Adhesive restorations should be performed 7-14 days after bleaching, according to the bleaching agent used. Intracoronal bleaching should be performed preferably with sodium perborate if previous dentin etching is applied. © 2018 Wiley Periodicals, Inc.

Influence of surfactants on the effectiveness of bleaching gels.

PubMed

Caneppele, Taciana Marco Ferraz; Torres, Carlos Rocha Gomes

2011-02-01

This study evaluated the influence of surfactants on the effectiveness of 35% hydrogen peroxide (HP) and 10% carbamide peroxide (CP) bleaching gels. One hundred and forty bovine teeth were used, which were stained by immersion in a coffee, red wine, and tobacco mixture for 7 days. At the end of this process, the color measurement at baseline was taken with the Vita Easyshade spectrophotometer. The teeth were divided into seven groups: (a) negative control (NC), (b) positive control for HP (PC-35), (c) HP + Tween 20 (T20-35), (d) HP + laurel sodium sulfate (LSS-35), (e) positive control for CP (PC-10), (f) CP + Tween 20 (T20-10), and (g) CP + laurel sodium sulfate (LSS-10). Group NC was kept in artificial saliva for 21 days. Groups PC-35, T20-35, and LSS 35 received three applications of bleaching gel for 10 min; the process was repeated after 7 days. Groups PC-10, T20-10, and LSS-10 received the gel for 8 h per day for 14 days. After the bleaching process, the final color was measured. The analysis of variance and Tukey tests showed statistically significant differences for the parameters of ∆L, ∆b, and ∆E of the HP gels with surfactant and positive control group (PC-35). Within the limits of this in vitro study, the addition of surfactants to HP bleaching gel increased the bleaching effectiveness.

The degree of color change, rebound effect and sensitivity of bleached teeth associated with at-home and power bleaching techniques: A randomized clinical trial

PubMed Central

Moghadam, Fatemeh Velayati; Majidinia, Sara; Chasteen, Joseph; Ghavamnasiri, Marjaneh

2013-01-01

Aim: The purpose of the present randomized clinical trial was to evaluate the color change, rebound effect and sensitivity of at-home bleaching with 15% carbamide peroxide and power bleaching using 38% hydrogen peroxide. Materials and Methods: For bleaching techniques, 20 subjects were randomized in a split mouth design (at-home and power bleaching): In maxillary and mandibular anterior teeth (n = 20). Color was recorded before bleaching, immediately after bleaching, at 2 weeks, 1, 3 and 6 month intervals. Tooth sensitivity was recorded using the visual analog scale. The Mann-Whitney test was used to compare both groups regarding bleaching effectiveness (ΔE1), rebound effect (ΔE2) and color difference between the rebounded tooth color and unbleached teeth (ΔE3) while the Wilcoxon compared ΔE within each group. Distribution of sensitivity was evaluated using the Chi-square test (α =0.05). Results: There was no significant difference between groups regarding ΔE1 and ΔE3 (P > 0.05). Even though, ΔE2 showed no significant difference between groups after bleaching as well as at 2 week, 1 month and 3 month follow-up periods (P > 0.05). Although, significant difference was found in ΔE2 (P < 0.05 Mann-Whitney) between two methods after 6 months and a high degree of rebound effect was obtained with power bleaching. Within each group, there was no significant difference between ΔE1 and ΔE3 (P < 0.05 Wilcoxon). The distribution of sensitivity was identical with both techniques (P > 0.05). Conclusion: Bleaching techniques resulted in identical tooth whitening and post-operative sensitivity using both techniques, but faster color regression was found with power bleaching even though color regression to the baseline of the teeth in both groups was the same after 6 months. PMID:24932113

In vitro Assessment of Influence of Various Bleaching Protocols on the Strength of Ceramic Orthodontic Brackets bonded to Bleached Tooth Surface: A Comparative Study.

PubMed

Iska, Divya; Devanna, Raghu; Singh, Madhvi; Chitumalla, Rajkiran; Balasubramanian, Sai C Bala; Goutam, Manish

2017-12-01

Esthetics is one of the common issues because of which patients consult dental orthodontic treatment. Two ways of tooth bleaching are available these days, which includes in-office bleach and home bleach. Various bleaching protocols are available these days for treating the tooth surfaces. Hence, we planned the present study for investigating the impact of various intracoronal bleaching protocols on shear bond strength of ceramic brackets bonded to tooth surface after bleaching. The present study included assessment of 100 extracted maxillary central incisors with the integrated buccal surface. A resin block was made and individual teeth were embedded in each block. Root canal therapy procedure was performed in all the teeth, after which 2 mm short of tooth apex up to the level of cementoenamel junction, removal of the root canal filling was done. All the samples were broadly divided into four study groups with 25 samples in each group. Bleaching procedure was carried in all the samples intracoronally followed by testing of shear bond strength using universal force testing machine. Following the modified adhesive remnant index (AI), assessment of remaining adhesive on the brackets was done. All the results were compiled and analyzed by Statistical Package for the Social Sciences (SPSS) software version 17.0. In the control group, mean shear bond strength was found to be 17.9 MPa. While comparing the carbamide peroxide (CP) group with sodium perborate study group, we observed a statistically significant difference. Nonsignificant results were obtained while comparing the shear bond strength in between sodium perborate group and hydrogen peroxide (HP) group. Intracoronal bleaching does affect the shear bond strength of ceramic brackets. Sodium perborate bleaching influences shear bond strength more strongly than other bleaching agents such as CP and HP. In patients undergoing orthodontic treatment, HP is a preferred agent where bleaching has to be followed by

Alkaline peroxide treatment of ECF bleached softwood kraft pulps. Part 1. characterizing the effect of alkaline peroxide treatment on carboxyl groups of fibers

Treesearch

Zheng Dang; Thomas Elder; Arthur J. Ragauskas

2007-01-01

The influence of alkaline peroxide treatment has been characterized on elementally chlorine-free (ECF) bleached softwood (SW) kraft pulp. The results indicate that fiber charge increased with an increase in peroxide charge: a maximum fiber charge increment of 16.6% was obtained with 8.0% more peroxide charge on oven-dried (0.d.) pulp at 60.0°C. Two primary bleaching...

Influence of Enamel Thickness on Bleaching Efficacy: An In-Depth Color Analysis

PubMed Central

Públio, Juliana do Carmo; D’Arce, Maria Beatriz Freitas; Catelan, Anderson; Ambrosano, Gláucia Maria Bovi; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

2016-01-01

This study evaluated the influence of different enamel thicknesses and bleaching agents on treatment efficacy in-depth by spectrophotometry color analysis. Eighty bovine dental fragments were previously stained in black tea solution and randomly assigned into eight groups (n=10), 1.75mm dentin thickness and different enamel thicknesses as follows: 0.5mm, 1.0mm planned, 1.0mm unplanned (aprismatic enamel), and absence of enamel. The 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching gels were applied on the enamel surface following the manufacturer's recommendations. Color of underlying dentin was evaluated at four times: after staining with tea (baseline) and after each one of the three weeks of bleaching treatment, by CIE L*a*b* system using reflectance spectrophotometer (CM 700d, Konica Minolta). The ΔE, ΔL, Δa, and Δb values were recorded and subjected to repeated measures ANOVA and Tukey’s test (α=0.05). The results showed an increase on lightness (L*), with decreased redness (a*) and yellowness (b*). At first and second week, bleaching with CP showed higher whitening effectiveness compared to bleaching with HP and the presence of aprismatic enamel significantly reduced ΔE for bleaching with CP. After three weeks of bleaching, few differences were observed between CP and HP groups, and outer enamel layer caused no influence on bleaching effectiveness. Overall, both at-home and in-office bleaching treatments were effective and the presence of aprismatic enamel did not interfere on the whitening efficacy. PMID:27708725

Influence of Enamel Thickness on Bleaching Efficacy: An In-Depth Color Analysis.

PubMed

Públio, Juliana do Carmo; D'Arce, Maria Beatriz Freitas; Catelan, Anderson; Ambrosano, Gláucia Maria Bovi; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; Lima, Débora Alves Nunes Leite

2016-01-01

This study evaluated the influence of different enamel thicknesses and bleaching agents on treatment efficacy in-depth by spectrophotometry color analysis. Eighty bovine dental fragments were previously stained in black tea solution and randomly assigned into eight groups (n=10), 1.75mm dentin thickness and different enamel thicknesses as follows: 0.5mm, 1.0mm planned, 1.0mm unplanned (aprismatic enamel), and absence of enamel. The 10% carbamide peroxide (CP) and 35% hydrogen peroxide (HP) bleaching gels were applied on the enamel surface following the manufacturer's recommendations. Color of underlying dentin was evaluated at four times: after staining with tea (baseline) and after each one of the three weeks of bleaching treatment, by CIE L*a*b* system using reflectance spectrophotometer (CM 700d, Konica Minolta). The ΔE, ΔL, Δa, and Δb values were recorded and subjected to repeated measures ANOVA and Tukey's test (α=0.05). The results showed an increase on lightness (L*), with decreased redness (a*) and yellowness (b*). At first and second week, bleaching with CP showed higher whitening effectiveness compared to bleaching with HP and the presence of aprismatic enamel significantly reduced ΔE for bleaching with CP. After three weeks of bleaching, few differences were observed between CP and HP groups, and outer enamel layer caused no influence on bleaching effectiveness. Overall, both at-home and in-office bleaching treatments were effective and the presence of aprismatic enamel did not interfere on the whitening efficacy.

Effect of tooth bleaching agents on protein content and mechanical properties of dental enamel.

PubMed

Elfallah, Hunida M; Bertassoni, Luiz E; Charadram, Nattida; Rathsam, Catherine; Swain, Michael V

2015-07-01

This study investigated the effect of two bleaching agents, 16% carbamide peroxide (CP) and 35% hydrogen peroxide (HP), on the mechanical properties and protein content of human enamel from freshly extracted teeth. The protein components of control and treated enamel were extracted and examined on sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE). Marked reduction of the protein matrix and random fragmentation of the enamel proteins after bleaching treatments was found. The mechanical properties were analyzed with Vickers indentations to characterize fracture toughness, and nanoindentation to establish enamel hardness, elastic modulus and creep deformation. Results indicate that the hardness and elastic modulus of enamel were significantly reduced after treatment with CP and HP. After bleaching, the creep deformation at maximum load increased and the recovery upon unloading reduced. Crack lengths of CP and HP treated enamel were increased, while fracture toughness decreased. Additionally, the microstructures of fractured and indented samples were examined with field emission gun scanning electron microscopy (FEG-SEM) showing distinct differences in the fracture surface morphology between pre- and post-bleached enamel. In conclusion, tooth bleaching agents can produce detrimental effects on the mechanical properties of enamel, possibly as a consequence of damaging or denaturing of its protein components. Copyright © 2015 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Association Between In-Office And At-Home Tooth Bleaching: A Single Blind Randomized Clinical Trial.

PubMed

Rodrigues, João Lima; Rocha, Patrícia Souza; Pardim, Silvia Letícia de Souza; Machado, Ana Cláudia Vieira; Faria-E-Silva, André Luis; Seraidarian, Paulo Isaías

2018-01-01

This controlled randomized clinical trial evaluated the effect of associating at-home and in-office bleaching procedures on tooth sensitivity (TS) and bleaching effectiveness. Forty patients subjected to on session of in-office bleaching with 38% peroxide hydrogen. Subsequently, the patients were randomly allocated to receive a second session of in-office bleaching or to use a tray containing 10% carbamide peroxide delivered during 7 consecutive days. The worst TS score reported during or after each bleaching procedure was recorded using a verbal rating scale and TS risk (score different from 0) was calculated. Color changes were measured 7 days after each in-office session (for patients receiving in-office procedures only) or after the end of at-home bleaching (for the combined protocol), and 6 months after the last procedure for both bleaching protocols. Color was assessed by a spectrophotometer and by color match with the Vita Classical and Bleach guide scales. Statistical analyses were carried out to assess possible differences between the protocols regarding the outcomes and to analyze the effect of time of assessment on color changes. The bleaching protocol did not affect the risk for and the maximum level of TS reported, irrespective of the time of assessment. In the color evaluation, the bleaching protocol also did not affect the ultimate tooth color. In conclusion, after one in-office bleaching session, there was no difference in bleaching effectiveness and TS between performing a second in-office session and associating it with 1-week at-home bleaching.

A review of the effect of vital teeth bleaching on the mechanical properties of tooth enamel.

PubMed

Elfallah, Hunida M; Swain, Michael V

2013-09-01

Tooth whitening is considered the easiest and most cost-effective procedure for treating tooth discoloration. Contemporary bleaching agents contain hydrogen peroxide as the active ingredient. It is either applied directly or produced from its precursor, carbamide peroxide. A review of the published literature was undertaken to investigate the potential adverse effects of whitening products on dental enamel, with a focus on its mechanical properties and the influence of various parameters on study outcomes. There appear to be considerable differences in opinion as to whether changes in mechanical properties occur as a result of tooth whitening. However, the mechanical property findings of those studies appear to be related to the load applied during the indentation tests. Most studies which used loads higher than 500mN to determine enamel hardness showed no effect of bleaching, whereas those using lower loads were able to detect hardness reduction in the surface layer of enamel. In conclusion, bleaching reduces the hardness of the enamel surface of enamel, and that is more readily detected with instrumented low load testing systems. This hardness reduction may arise due to degradation or denaturation of enamel matrix proteins by the peroxide oxidation.

Effect of bleaching agent extracts on murine macrophages.

PubMed

Fernandes, Aletéia M M; Vilela, Polyana G F; Valera, Marcia C; Bolay, Carola; Hiller, Karl Anton; Schweikl, Helmut; Schmalz, Gottfried

2018-05-01

The aim of this study was to evaluate the cytotoxicity and the influence of bleaching agents on immunologically cell surface antigens of murine macrophages in vitro. RAW 264.7 cells were exposed to bleaching gel extracts (40% hydrogen peroxide or 20% carbamide peroxide) and different H 2 O 2 concentrations after 1 and 24-h exposure periods and 1-h exposure and 23-h recovery. Tests were performed with and without N-acetyl cysteine (NAC) and buthionine sulfoximine (BSO). Cell viability was determined by MTT assay. The expression of surface markers CD14, CD40, and CD54 with and without LPS stimulation was detected by flow cytometry, while the production of TNF-α was measured by ELISA. Statistical analysis was performed using the Mann-Whitney U test (α = 0.05). Extracts of bleaching agents were cytotoxic for cells after a 1-h exposure; cells could not recover after 24 h. This effect can be mitigated by the antioxidant NAC and increased by BSO, an inhibitor of glutathione (GSH) synthesis. LPS stimulated expression of all surface markers and TNF-α production. Exposure to bleaching agent extracts and H 2 O 2 leads to a reduction of TNF-α, CD14, and CD40 expression, while the expression of CD54 was upregulated at non-cytotoxic concentrations. Whereas NAC reduced this effect, it was increased in the presence of BSO. Extracts of bleaching agents were irreversibly cytotoxic to macrophages after a 1-h exposure. Only the expression of CD54 was upregulated. The reactions are mediated by the non-enzymatic antioxidant GSH. The addition of an antioxidant can downregulate unfavorable effects of dental bleaching.

Titanium dioxide in dental enamel as a trace element and its variation with bleaching

PubMed Central

Durán-Sedó, Randall; Herrera-Sancho, Óscar-Andrey

2018-01-01

Background Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Material and Methods Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to and during whitening. Statistical analysis included repeated measures analysis of variance (p≤0.05) and Bonferroni pairwise comparisons. Results Titanium dioxide concentration was negatively affected by the longer bleaching protocols (at-home bleaching gels). All in-office whitening products increased significantly the studied molecule (p≤0,05). Conclusions All dental specimens depicted the presence of titanium dioxide as a trace element in dental enamel. Bleaching gels that have to be applied at higher concentrations but for shorter periods of time increase the concentration of titanium dioxide, whilst at-home whitening gels used for longer periods of time despite the lower concentration caused a loss in titanium. Key words:Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, titanium dioxide. PMID:29930771

Titanium dioxide in dental enamel as a trace element and its variation with bleaching.

PubMed

Vargas-Koudriavtsev, Tatiana; Durán-Sedó, Randall; Herrera-Sancho, Óscar-Andrey

2018-06-01

Titanium is a less studied trace element in dental enamel. Literature relates an increased Titanium concentration with a decreased enamel crystal domain size, which in turn is related to a higher color value. The aim of our study was to analyze the effect of tooth bleaching agents on its concentration in dental enamel by means of confocal Raman spectroscopy. Human teeth were randomly distributed in six experimental groups (n=10) and submitted to different bleaching protocols according to the manufacturer´s instructions. Confocal Raman spectroscopy was carried out in order to identify and quantify the presence of titanium dioxide molecules in enamel prior to and during whitening. Statistical analysis included repeated measures analysis of variance ( p ≤0.05) and Bonferroni pairwise comparisons. Titanium dioxide concentration was negatively affected by the longer bleaching protocols (at-home bleaching gels). All in-office whitening products increased significantly the studied molecule ( p ≤0,05). All dental specimens depicted the presence of titanium dioxide as a trace element in dental enamel. Bleaching gels that have to be applied at higher concentrations but for shorter periods of time increase the concentration of titanium dioxide, whilst at-home whitening gels used for longer periods of time despite the lower concentration caused a loss in titanium. Key words: Bleaching, whitening, hydrogen peroxide, carbamide peroxide, Raman spectroscopy, titanium dioxide.

Evaluation of cotton-fabric bleaching using hydrogen peroxide and Blue LED

NASA Astrophysics Data System (ADS)

de Oliveira, Bruno P.; Moriyama, Lilian T.; Bagnato, Vanderlei S.

2015-06-01

The raw cotton production requires multiple steps being one of them the removal of impurities acquired during previous processes. This procedure is widely used by textile industries around the world and is called bleaching. The raw cotton is composed by cellulosic and non-cellulosic materials like waxes, pectins and oils, which are responsible for its characteristic yellowish color. The bleaching process aims to remove the non-cellulosic materials concentration in the fabric, increasing its whiteness degree. The most used bleaching method utilizes a bath in an alkali solution of hydrogen peroxide, stabilizers and buffer solutions under high temperature. In the present study we evaluated the possibility of using a blue illumination for the bleaching process. We used blue LEDs (450 nm) to illuminate an acid hydrogen peroxide solution at room temperature. The samples treated by this method were compared with the conventional bleaching process through a colorimetric analysis and by a multiple comparison visual inspection by volunteers. The samples were also studied by a tensile test in order to verify the integrity of the cloth after bleaching. The results of fabric visual inspection and colorimetric analysis showed a small advantage for the sample treated by the standard method. The tensile test showed an increasing on the yield strength of the cloth after blue light bleaching. The presented method has great applicability potential due to the similar results compared to the standard method, with relative low cost and reduced production of chemical waste.

Effects of Bleaching Agents Combined with Regular and Whitening Toothpastes on Surface Roughness and Mineral Content of Enamel.

PubMed

Attia, Mariana Lerner; Cavalli, Vanessa; do Espírito Santo, Ana Maria; Martin, Airton Abrahão; D'Arce, Maria Beatriz Freitas; Aguiar, Flávio Henrique Baggio; Lovadino, José Roberto; do Rego, Marcos Augusto; Cavalcanti, Andréa Nóbrega; Liporoni, Priscila Christiane Suzy

2015-07-01

The purpose of this study was to evaluate surface roughness and changes in the composition of enamel submitted to different bleaching protocols and toothbrushing with regular and whitening toothpastes. Bleaching treatment could promote morphological and chemical changes in enamel surface. Enamel blocks were randomized into nine groups (n=10) according to the bleaching treatment (no bleaching, control group; 6% hydrogen peroxide, HP; or 10% carbamide peroxide, CP) and toothpaste used (placebo, PL; regular, R; or whitening dentifrice, W). Bleaching was performed according to manufacturers' instructions and all groups were submitted to 30,000 cycles of simulated toothbrushing with toothpaste (PL, R, or W). Mineral content evaluation and enamel roughness were evaluated initially (T1), after bleaching (T2), and after toothbrushing (T3), using an energy-dispersive micro X-ray fluorescence spectrometer and profilometry, respectively. Data were statistically analyzed with two way ANOVA, Tukey, and Dunnett tests (5%). Enamel surface roughness was influenced by bleaching and toothbrushing. Surface roughness increased for the groups that brushed with the placebo dentifrice (CP+PL, HP+PL, C+PL) and for the control group that brushed with whitening dentifrice (C+W). Enamel Ca/P ratio decreased after bleaching, but toothbrushing, regardless of the dentifrice used, did not reduce the enamel mineral content. The bleaching treatment resulted in a decrease of enamel mineral content, but the studied dentifrices did not contribute to surface mineral loss.

Dental bleaching on teeth submitted to enamel microabrasion 30 years ago-a case report of patients' compliance during bleaching treatment.

PubMed

Sundfeld, Daniel; Pavani, Caio Cesar; Schott, Timm Cornelius; Machado, Lucas Silveira; Pini, Núbia Inocêncya Pavesi; Bertoz, André Pinheiro de Magalhães; Sundfeld, Renato Herman

2018-04-20

The present dental bleaching case report describes a new method that precisely quantifies the daily wearing-times of the bleaching product by inserting a microsensor in the acetate custom tray. The bleaching efficacy was also discussed since the patient was previously submitted to enamel microabrasion. The patient was submitted to enamel microabrasion in 1987, and bleaching treatment was performed in 2005. In 2017, re-bleaching was executed using 10% peroxide carbamide. The electronic microsensor, TheraMon (TheraMon® microelectronic system; Sales Agency Gschladt, Hargelsberg, Austria), was embedded in the labial region of the upper and lower acetate trays to evaluate the wearing-times of the acetate trays/bleaching product. The patient was instructed to wear the tray for 6 to 8 h/day while sleeping. After 24 days of bleaching treatment, the data obtained from the TheraMon electronic devices was collected and interpreted. The patient did not entirely follow the bleaching treatment as recommended, as there was no evidence of use of the upper and lower trays for some days; additionally, the bleaching product was used for shorter and longer periods than was instructed. The TheraMon microeletronic device precisely measured the wearing-times of the acetate tray/bleaching product during the bleaching treatment. Teeth submitted to enamel microabrasion presented with a healthy clinical appearance after 30 years. Measuring the length and frequency of use of an acetate tray/bleaching product can be important to clinicians and patients for obtaining a controlled and adequate bleaching treatment.

Effects of bleaching agents on human enamel light reflectance.

PubMed

Markovic, Ljubisa; Fotouhi, Kasra; Lorenz, Heribert; Jordan, Rainer A; Gaengler, Peter; Zimmer, Stefan

2010-01-01

Tooth whitening has been associated with splitting-up chromogenic molecules by hydrogen peroxides. Though micromorphological alterations are well documented, little is known about optical changes as a function of shifting in wavelengths. Therefore, the aim of the current study was to measure reflectance changes after bleaching in vitro by using a spectrometer. Forty-eight enamel slabs (diameter = 5 mm) were prepared from the sound enamel of extracted human teeth that were: 1) fully impacted, 2) from juveniles ages 10 to 16 years, 3) from adults 35 to 45 years of age and 4) from seniors older than age 65. In all specimens, the baseline total reflectance measurement was performed with a computer-assisted spectrometer (Ocean Optics, Dunedin, FL, USA) within wavelengths (wl) from 430 nm to 800 nm. Four enamel samples of each age group were exposed to either 10% or 15% carbamide peroxide (Illuminé Home, Dentsply, Konstanz, Germany) or 35% hydrogen peroxide (Pola Office, SDI Limited, Victoria, Australia). After surface treatment, all slabs underwent total reflectance measurement again. Statistical analysis was calculated at wl 450, 500 and 750 nm using the Student's paired t-test and one-way variance analysis. Total reflectance significantly increased after bleaching at all enamel maturation stages, irrespective of the bleaching agent concentration, for wl 450 nm (blue) and 500 nm (green) with p<0.0001. At 750 nm (red), significant changes only occurred in enamel from adults and seniors (p<0.04). However, the efficacy of bleaching was significantly increased in the blue and green light spectra as compared to the red spectra (p<0.0001). The results of the current study showed that the exclusive assumption of the "chromophore effect" in dental bleaching could not be sustained, because whitening of the dental enamel works at different maturation stages, even in impacted teeth. This effect is irrespective of the bleaching protocol used and the bleaching agent concentration.

Smile restoration through use of enamel microabrasion associated with tooth bleaching.

PubMed

Sundfeld, Renato Herman; Rahal, Vanessa; de Alexandre, Rodrigo Sversut; Briso, André Luiz Fraga; Sundfeld Neto, Daniel

2011-01-01

Enamel microabrasion can eliminate enamel irregularities and discoloration defects, improving the appearance of teeth. This article presents the latest treatment protocol of enamel microabrasion to remove stains on the enamel surface. It has been verified that teeth submitted to microabrasion acquire a yellowish color because of the thinness of the remaining enamel, revealing the color of dentinal tissue to a greater degree. In these clinical conditions, correction of the color pattern of these teeth can be obtained with a considerable margin of clinical success using products containing carbamide peroxide in custom trays. Thus, patients can benefit from combined enamel microabrasion/tooth bleaching therapy, which yields attractive cosmetic results. Esthetics plays an important role in contemporary dentistry, especially because the media emphasizes beauty and health. Currently, in many countries, a smile is considered beautiful if it imitates a natural appearance, with clear, well-aligned teeth and defined anatomical shapes. Enamel microabrasion is one technique that can be used to correct discolored enamel. This technique has been elucidated and strongly advocated by Croll and Cavanaugh since 1986, and by other investigators who suggested mechanical removal of enamel stains using acidic substances in conjunction with abrasive agents. Enamel microabrasion is indicated to remove intrinsic stains of any color and of hard texture, and is contraindicated for extrinsic stains, dentinal stains, for patients with deficient labial seals, and in cases where there is no possibility to place a rubber dam adequately during the microabrasion procedure. It should be emphasized that enamel microabrasion causes a microreduction on the enamel surface, and, in some cases, teeth submitted to microabrasion may appear a darker or yellowish color because the thin remaining enamel surface can reveal some of the dentinal tissue color. In these situations, according to Haywood and Heymann

Spectrophotometric evaluation of dental bleaching under orthodontic bracket in enamel and dentin

PubMed Central

Correr, Americo-Bortolazzo; Rastelli, Alessandra-Nara-Souza; Lima, Débora-Alves-Nunes-Leite; Consani, Rafael-Leonardo-Xediek

2014-01-01

Aware of the diffusion capacity of bleaching in the dental tissues, many orthodontists are subjecting their patients to dental bleaching during orthodontic treatment for esthetic purposes or to anticipate the exchange of esthetic restorations after the orthodontic treatment. For this purpose specific products have been developed in pre-loaded whitening trays designed to fit over and around brackets and wires, with clinical efficacy proven. Objective: The objective of this study was to evaluate, through spectrophotometric reflectance, the effectiveness of dental bleaching under orthodontic bracket. Material and Methods: Thirty-two bovine incisors crown blocks of 8 mm x 8 mm height lengths were used. Staining of tooth blocks with black tea was performed for six days. They were distributed randomly into 4 groups (1-home bleaching with bracket, 2- home bleaching without bracket, 3- office bleaching with bracket, 4 office bleaching without bracket). The color evaluation was performed (CIE L * a * b *) using color reflectance spectrophotometer. Metal brackets were bonded in groups 1 and 3. The groups 1 and 2 samples were subjected to the carbamide peroxide at 15%, 4 hours daily for 21 days. Groups 3 and 4 were subjected to 3 in-office bleaching treatment sessions, hydrogen peroxide 38%. After removal of the brackets, the second color evaluation was performed in tooth block, difference between the area under the bracket and around it, and after 7 days to verified color stability. Data analysis was performed using the paired t-test and two-way variance analysis and Tukey’s. Results: The home bleaching technique proved to be more effective compared to the office bleaching. There was a significant difference between the margin and center color values of the specimens that were subjected to bracket bonding. Conclusions: The bracket bond presence affected the effectiveness of both the home and office bleaching treatments. Key words:Tooth bleaching, spectrophotometry

Effect of bleaching agent and topical fluoride application on color and gloss of dental ceramics.

PubMed

Pires-de-Souza, Fernanda de Carvalho Panzeri; Contente, Marta Maria Martins Giamatei; Alandia-Román, Carla Cecilia; Vicente, Sergio Augusto de Freitas; Tonani, Rafaella

2016-01-01

The aim of this study was to evaluate the effect of 16% carbamide peroxide and 1.23% acidulated phosphate fluoride application and their association with a change in color (ΔE*) and brightness of dental ceramic submitted to different finishing procedures. A total of 120 test specimens were fabricated and randomly divided into 3 groups (n = 40) according to the type of finishing: glazing; polishing; or polishing and glazing. Initial color and brightness readouts were taken, and the finished specimens were divided into groups (n = 10) according to the treatment to which they were submitted: fluoride; bleaching; bleaching and fluoride; or control. After this, final color and brightness readouts were taken. The type of polishing had no influence on ΔE* or brightness (P > 0.05). Regardless of which solution was used, a decrease in brightness occurred only for the group treated with bleach and fluoride (P < 0.05). The results showed the use of fluoride after bleaching may interfere with the esthetics of a restoration.

Clinical Comparison of At-Home and In-Office Dental Bleaching Procedures: A Randomized Trial of a Split-Mouth Design.

PubMed

Machado, Lucas Silveira; Anchieta, Rodolfo Bruniera; dos Santos, Paulo Henrique; Briso, André Luiz; Tovar, Nick; Janal, Malvin N; Coelho, Paulo Guilherme; Sundfeld, Renato Herman

2016-01-01

The objective of this split-mouth clinical study was to compare a combination of in-office and at-home dental bleaching with at-home bleaching alone. Two applications of in-office bleaching were performed, with one appointment per week, using 38% hydrogen peroxide. At-home bleaching was performed with or without in-office bleaching using 10% carbamide peroxide in a custom-made tray every night for 2 weeks. The factor studied was the bleaching technique on two levels: Technique 1 (in-office bleaching combined with home bleaching) and Technique 2 (home bleaching only). The response variables were color change, dental sensitivity, morphology, and surface roughness. The maxillary right and left hemiarches of the participants were submitted to in-office placebo treatment and in-office bleaching, respectively (Phase 1), and at-home bleaching (Phase 2) treatment was performed on both hemiarches, characterizing a split-mouth design. Enamel surface changes and roughness were analyzed with scanning electron microscopy and optical interferometry using epoxy replicas. No statistically significant differences were observed between the bleaching techniques for either the visual or the digital analyses. There was a significant difference in dental sensitivity when both dental bleaching techniques were used, with in-office bleaching producing the highest levels of dental sensitivity after the baseline. Microscopic analysis of the morphology and roughness of the enamel surface showed no significant changes between the bleaching techniques. The two techniques produced similar results in color change, and the combination technique produced the highest levels of sensitivity. Neither technique promoted changes in morphology or surface roughness of enamel.

Sonochemical and hydrodynamic cavitation reactors for laccase/hydrogen peroxide cotton bleaching.

PubMed

Gonçalves, Idalina; Martins, Madalena; Loureiro, Ana; Gomes, Andreia; Cavaco-Paulo, Artur; Silva, Carla

2014-03-01

The main goal of this work is to develop a novel and environmental-friendly technology for cotton bleaching with reduced processing costs. This work exploits a combined laccase-hydrogen peroxide process assisted by ultrasound. For this purpose, specific reactors were studied, namely ultrasonic power generator type K8 (850 kHz) and ultrasonic bath equipment Ultrasonic cleaner USC600TH (45 kHz). The optimal operating conditions for bleaching were chosen considering the highest levels of hydroxyl radical production and the lowest energy input. The capacity to produce hydroxyl radicals by hydrodynamic cavitation was also assessed in two homogenizers, EmulsiFlex®-C3 and APV-2000. Laccase nanoemulsions were produced by high pressure homogenization using BSA (bovine serum albumin) as emulsifier. The bleaching efficiency of these formulations was tested and the results showed higher whiteness values when compared to free laccase. The combination of laccase-hydrogen peroxide process with ultrasound energy produced higher whiteness levels than those obtained by conventional methods. The amount of hydrogen peroxide was reduced 50% as well as the energy consumption in terms of temperature (reduction of 40 °C) and operating time (reduction of 90 min). Copyright © 2013 Elsevier Inc. All rights reserved.

In vitro Comparison of Impact of Different Bleaching Agents on the Microhardness of Enamel.

PubMed

Dey, Subhra; Pandey, Vinisha; Kumar, Anuj; Awasthi, Neha; Sahu, Anshu; Pujari, Sudarshan C

2016-03-01

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. 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 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). 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.

Assessing the effects of hydrogen peroxide bleaching agent on the shear bond strength of orthodontic brackets.

PubMed

Andrighetto, Augusto Ricardo; de Leão Withers, Eduardo Henrique; Grando, Karlos Giovani; Ambrosio, Aldrieli Regina; Shimizu, Roberto Hideo; Melo, Ana Cláudia

2016-01-01

Tooth bleaching is, today, one of the most widespread cosmetic treatments in dental practice,  so it is important to determine whether it can interfere with orthodontic bonding or not. The aim of this study was to assess the in vitro effects of 35% hydrogen peroxide bleaching agent on the shear bond strength of orthodontic brackets. Forty-five upper bicuspids were divided into three groups (n = 15). In the control Group (C), the brackets were bonded without previous bleaching treatment. Group 1 (G1) was treated with 35% hydrogen peroxide bleaching agent 24 h before bracket bonding. Group 2 was also bleached, and the brackets were bonded after 30 days. The shear bond strength of the brackets was measured using an EMIC machine, and the results were analyzed by ANOVA. There were no statistically significant differences between the three groups (P > 0.05), with Group C showing a mean bond strength of 9.72 ± 2.63 MPa, G1 of 8.09 ± 2.63 MPa, and G2 of 11.15 ± 4.42 MPa. It was possible to conclude that 35% hydrogen peroxide bleaching agent does not affect the shear strength of orthodontic brackets bonded 24 h and 30 days after bleaching.

Quantification of peroxide ion passage in dentin, enamel, and cementum after internal bleaching with hydrogen peroxide.

PubMed

Palo, R M; Bonetti-Filho, I; Valera, M C; Camargo, C H R; Camargo, Sea; Moura-Netto, C; Pameijer, C

2012-01-01

The aim of this study was to evaluate the amount of peroxide passage from the pulp chamber to the external enamel surface during the internal bleaching technique. Fifty bovine teeth were sectioned transversally 5 mm below the cemento-enamel junction (CEJ), and the remaining part of the root was sealed with a 2-mm layer of glass ionomer cement. The external surface of the samples was coated with nail varnish, with the exception of standardized circular areas (6-mm diameter) located on the enamel, exposed dentin, or cementum surface of the tooth. The teeth were divided into three experimental groups according to exposed areas close to the CEJ and into two control groups (n=10/group), as follows: GE, enamel exposure area; GC, cementum exposed area; GD, dentin exposed area; Negative control, no presence of internal bleaching agent and uncoated surface; and Positive control, pulp chamber filled with bleaching agent and external surface totally coated with nail varnish. The pulp chamber was filled with 35% hydrogen peroxide (Opalescence Endo, Ultradent). Each sample was placed inside of individual flasks with 1000 μL of acetate buffer solution, 2 M (pH 4.5). After seven days, the buffer solution was transferred to a glass tube, in which 100 μL of leuco-crystal violet and 50 μL of horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to Kruskal-Wallis and Dunn-Bonferroni tests (α=0.05). All experimental groups presented passage of peroxide to the external surface that was statistically different from that observed in the control groups. It was verified that the passage of peroxide was higher in GD than in GE (p<0.01). The GC group presented a significantly lower peroxide passage than did GD and GE (p<0.01). It can be concluded that the hydrogen peroxide placed into the pulp chamber passed through the

The effect of three different mouthrinses on the surface hardness, gloss and colour change of bleached nano composite resins.

PubMed

Gurgan, Sevil; Yalcin Cakir, Filiz

2008-09-01

This in vitro study evaluated the effects of three mouthrinses (Listerine--alcohol containing, Oral B--alcohol free and Rembrandt Plus--peroxide whitening rinse) on the surface hardness, gloss and colour of a nanofill (Filtek Supreme) and nanohybrid (Simile) composite resin that had been subjected to bleaching treatment. 30 specimens of each material were fabricated and randomly divided into three groups of 10. The hardness, gloss and CIE Lab colour parameters of each specimen were assessed prior to the experiments. Specimens were exposed to the 10% carbamide peroxide bleaching agent (Vivastyle) for 2 hours per day for 14 days. Following the bleaching treatment measurements were repeated. The specimens were then conditioned with mouthrinses for 12 hours which was equivalent in time to 1 year of two minutes daily use. The specimens were measured again for hardness, gloss and colour and data were subjected to the statistical analysis. The result of this study showed no statististical difference between the restorative materials after bleaching and the use of mouthrinses (p > 0.05). Bleaching treatment and the use of mouthrinses af fected the hardness, gloss and colour of both resins. Significant differences were observed with the use of mouthrinses for all parameters (p < 0.05). Rembrandt Plus promoted the greatest changes, followed by Listerine and Oral B.

Nanotribological and Nanomechanical Properties Changes of Tooth After Bleaching and Remineralization in Wet Environment.

PubMed

Yu, Dandan; Gao, Shanshan; Min, Jie; Zhang, Qianqian; Gao, Shuai; Yu, Haiyang

2015-12-01

Teeth bleaching cases had increased with people's desire for oral aesthetic; however, bleached teeth would still undertake chewing actions and remineralizing process in saliva. Nanotribological and nanomechanical properties are proper displays for dental performance of bleached teeth. The purpose of the research was to reveal the effect of bleaching and remineralization on the nanotribological and nanomechanical properties of teeth in wet environment. The specimens were divided into four groups according to the bleaching products used: 12 % hydrogen peroxide (HP) (12HP group); 15 % carbamide peroxide (CP) (15CP group); 35 % CP (35CP group); and artificial saliva (control group). The nanotribological and nanomechanical property changes of tooth enamel after bleaching and remineralization were evaluated respectively by nanoscratch and nanoindentation tests in wet environment, imitating the wet oral environment. The morphology changes were evaluated by statistical parametric mapping (SPM) and scanning electron microscopy (SEM). After bleaching, 12HP group and 15CP group showed increased scratch depth with more pile ups on the scratch edges, decreased nanohardness, and corroded surface appearance. While the 35CP group showed an increase in nanoscratch depth, no change in nanohardness and surface appearance was observed. The control group showed no change in these measurements. After remineralization, the three bleaching groups showed decreased nanoscratch depth and no change of nanohardness compared with the bleached teeth. And the control group showed no changes in nanotribological and nanomechanical properties. The nanotribological and nanomechanical properties of the 12HP group and 15CP group were affected by bleaching, but the nanotribological properties recovered partly and the nanomechanical properties got no change after 1 week of remineralization. As for the 35CP group, the nanotribological properties were influenced and the nanomechanical properties were

Nanotribological and Nanomechanical Properties Changes of Tooth After Bleaching and Remineralization in Wet Environment

NASA Astrophysics Data System (ADS)

Yu, Dandan; Gao, Shanshan; Min, Jie; Zhang, Qianqian; Gao, Shuai; Yu, Haiyang

2015-12-01

Teeth bleaching cases had increased with people's desire for oral aesthetic; however, bleached teeth would still undertake chewing actions and remineralizing process in saliva. Nanotribological and nanomechanical properties are proper displays for dental performance of bleached teeth. The purpose of the research was to reveal the effect of bleaching and remineralization on the nanotribological and nanomechanical properties of teeth in wet environment. The specimens were divided into four groups according to the bleaching products used: 12 % hydrogen peroxide (HP) (12HP group); 15 % carbamide peroxide (CP) (15CP group); 35 % CP (35CP group); and artificial saliva (control group). The nanotribological and nanomechanical property changes of tooth enamel after bleaching and remineralization were evaluated respectively by nanoscratch and nanoindentation tests in wet environment, imitating the wet oral environment. The morphology changes were evaluated by statistical parametric mapping (SPM) and scanning electron microscopy (SEM). After bleaching, 12HP group and 15CP group showed increased scratch depth with more pile ups on the scratch edges, decreased nanohardness, and corroded surface appearance. While the 35CP group showed an increase in nanoscratch depth, no change in nanohardness and surface appearance was observed. The control group showed no change in these measurements. After remineralization, the three bleaching groups showed decreased nanoscratch depth and no change of nanohardness compared with the bleached teeth. And the control group showed no changes in nanotribological and nanomechanical properties. The nanotribological and nanomechanical properties of the 12HP group and 15CP group were affected by bleaching, but the nanotribological properties recovered partly and the nanomechanical properties got no change after 1 week of remineralization. As for the 35CP group, the nanotribological properties were influenced and the nanomechanical properties were not

Effect of postoperative peroxide bleaching on the marginal seal of composite restorations bonded with self-etch adhesives.

PubMed

Roubickova, A; Dudek, M; Comba, L; Housova, D; Bradna, P

2013-01-01

The aim of this study was to determine the effect of peroxide bleaching on the marginal seal of composite restorations bonded with several adhesive systems. Combined cylindrical Class V cavities located half in enamel and half in dentin were prepared on the buccal and lingual surfaces of human molars. The cavities were bonded with the self-etch adhesives Clearfil SE-Bond (CLF), Adper Prompt (ADP), and iBond (IBO) and an etch-and-rinse adhesive Gluma Comfort Bond (GLU) and restored with a microhybrid composite Charisma. Experimental groups were treated 25 times for eight hours per day with a peroxide bleaching gel Opalescence PF 20, while the control groups were stored in distilled water for two months and then subjected to a microleakage test using a dye penetration method. Scanning electron microscopy was used to investigate the etching and penetration abilities of the adhesives and morphology of debonded restoration-enamel interfaces after the microleakage tests. Statistical analyses were performed using nonparametric Kruskal-Wallis, Mann-Whitney, and Wilcoxon tests at p=0.05. The microleakage of all GLU groups was low and not significantly affected by peroxide bleaching. Low microleakage was recorded for CLF control groups, but after bleaching, a small but significant increase in microleakage at the enamel margin indicated its sensitivity to peroxide bleaching. For ADP and IBO control groups, the microleakage at the enamel margins was significantly higher than for GLU and CLF and exceeded that at the dentin margins. Bleaching did not induce any significant changes in the microleakage. Electron microscopy analysis indicated that in our experimental setup, decreased adhesion and mechanical resistance of the ADP- and IBO-enamel interfaces could be more important than the chemical degradation effects induced by the peroxide bleaching gel.

A randomized CIE L*a*b* evaluation of external bleaching therapy effects on fluorotic enamel stains.

PubMed

Knösel, Michael; Attin, Rengin; Becker, Klaus; Attin, Thomas

2008-05-01

To evaluate the effect of external bleaching on the color and luminosity of fluorotic stains and adjacent, normally mineralized enamel areas by means of CIE L*a*b* colorimetry. Eighteen adolescents with mild to moderate fluorotic stains were randomly assigned to either bleaching group A (n = 9) or control group B. Eligibility criteria were fluorotic stained maxillary incisors or canines and the informed consent of the participants and their guardians. Using a colorimeter, CIE L*a*b* values of maxillary incisors and canines were assessed at baseline (T1) in the center of the fluorotic stained area (F1) and at adjacent, normally mineralized enamel areas (F2). Then, external bleaching with Illumine office (30% hydrogen peroxide, Dentsply DeTrey) was performed for 60 minutes, followed by color reassessment (T2). After 14 days (T3), a 2-week home bleaching period with a daily bleaching time of 1 hour with Illumine home (15% carbamide peroxide, Dentsply DeTrey) was conducted with subsequent color determination (T4). After completion of bleaching therapy, 96.0% of all fluorotic areas (F1) and 100% of normal enamel areas (F2) showed a significant change within group A, compared to 29.4% in control group B. Comparing the collective DeltaE (L*, a*, b*) of F1 and F2, 60.0% of all areas showed significant differences after completion of bleaching therapy, compared to 88.0% initially. Of group B sites, 82.4% showed color differences in the beginning (T1) and 88.2% at the end (T4). Whereas a single 1-hour session of in-office bleaching with 30% hydrogen peroxide does not significantly affect the color and luminosity of fluorotic teeth, a 14-day period of home bleaching leads to an assimilation of the color of the fluorotic stain with the color of surrounding enamel areas due to different responses of sound and fluorotic enamel to the bleaching regime.

Effect of two in-office whitening agents on the enamel surface in vivo: a morphological and non-contact profilometric study.

PubMed

Cadenaro, Milena; Breschi, Lorenzo; Nucci, Cesare; Antoniolli, Francesca; Visintini, Erika; Prati, Carlo; Matis, Bruce A; Di Lenarda, Roberto

2008-01-01

This study evaluated the morphological effects produced in vivo by two in-office bleaching agents on enamel surface roughness using a noncontact profilometric analysis of epoxy replicas. The null hypothesis tested was that there would be no difference in the micromorphology of the enamel surface during or after bleaching with two different bleaching agents. Eighteen subjects were selected and randomly assigned to two treatment groups (n=9). The tooth whitening materials tested were 38% hydrogen peroxide (HP) (Opalescence Xtra Boost) and 35% carbamide peroxide (CP) (Rembrandt Quik Start). The bleaching agents were applied in accordance with manufacturer protocols. The treatments were repeated four times at one-week intervals. High precision impressions of the upper right incisor were taken at baseline as the control (CTRL) and after each bleaching treatment (T0: first application, T1: second application at one week, T2: third application at two weeks and T3: fourth application at three weeks). Epoxy resin replicas were poured from impressions, and the surface roughness was analyzed by means of a non-contact profilometer (Talysurf CLI 1000). Epoxy replicas were then observed using SEM. All data were statistically analyzed using ANOVA and differences were determined with a t-test. No significant differences in surface roughness were found on enamel replicas using either 38% hydrogen peroxide or 35% carbamide peroxide in vivo. This in vivo study supports the null hypothesis that two in-office bleaching agents, with either a high concentration of hydrogen or carbamide peroxide, do not alter enamel surface roughness, even after multiple applications.

The effect of home-use and in-office bleaching treatments combined with experimental desensitizing agents on enamel and dentin

PubMed Central

Pintado-Palomino, Karen; Tirapelli, Camila

2015-01-01

Objective: This study aimed to evaluate in vitro the effect of formulations containing Biosilicate to treat enamel and dentin bovine samples exposed to dental bleaching agents. Materials and Methods: On enamel and dentin bleached with commercial gels containing 16% carbamide peroxide (CP) (14 days/4 h) or 35% hydrogen peroxide (single session/45 min), desensitizing dentifrices (Sensodyne®; experimental dentifrice of Biosilicate®; Odontis RX®; Sorriso®) were applied along 14 days and desensitizing pastes (Biosilicate®/water 1:1; Dessensebilize NanoP®; Bioglass type 45S5/water 1:1) were applied on days 1, 3, 7, 10 and 14. Distilled water was the control. Microhardness (MH) and roughness measurements were the variables measured on the samples before and after the treatments. Student's t-test analyzed differences before and after the treatments. Two-way analysis of variance and post-hoc Tukey test analyzed differences among the factors desensitizing, bleaching agents and substrate. Results: Tukey test showed no differences in roughness for both bleaching treatments and among the desensitizing agents (P > 0.05). Differences in MH appeared on enamel treated with in-home bleaching when control group (lower values) was compared with Sensodyne, Biosilicate dentifrice, Biosilicate paste, and Bioglass paste (higher values). Comparisons between desensitizing agents on dentin treated with both bleaching gels showed no statistical differences. Conclusions: The effect of formulations containing Biosilicate (Biosilicate dentifrice and paste) was significant in the MH of enamel bleached with 16% CP. PMID:25713487

Effect of bleaching on color change and surface topography of composite restorations.

PubMed

Pruthi, Gunjan; Jain, Veena; Kandpal, H C; Mathur, Vijay Prakash; Shah, Naseem

2010-01-01

This study was conducted to determine the effect of 15% carbamide peroxide bleaching agent on color change and surface topography of different composite veneering materials (Filtek Z350 (3M ESPE), Esthet X (Dentsply India), and Admira (Voco, Germany). Methods. 30 samples were fabricated for evaluation of color change using CIELAB color system and Gonioreflectometer (GK 311/M, ZEISS). 45 disc-shaped specimens were made for evaluation of surface topography after bleaching (Nupro White Gold; Dentsply) using SEM. Statistical analysis. One way ANOVA and Multiple comparison tests were used to analyze the data. Statistical significance was declared if the P value was .05 or less. Results and conclusion. All the specimens showed significant discoloration (ΔE > 3.3) after their immersion in solutions representing food and beverages. The total color change after bleaching as compared to baseline color was significant in Filtek Z350 (P = .000) and Esthet X (P = .002), while it was insignificant for Admira (P = .18). Esthet X showed maximum surface roughness followed by Admira and Filtek Z350. Bleaching was effective in reducing the discoloration to a clinically acceptable value in all the three groups (ΔE < 3.3).

Improved tooth bleaching combining ozone and hydrogen peroxide--A blinded study.

PubMed

Al-Omiri, Mahmoud K; Abul Hassan, Ra'ed S; AlZarea, Bader K; Lynch, Edward

2016-03-01

To evaluate the efficacy of tooth bleaching using ozone after hydrogen peroxide (H2O2) in comparison to the use of H2O2 alone. 70 extracted teeth were randomly distributed into two groups. Teeth surfaces in group 1 (n=35) were treated using 38% H2O2 and then were exposed to ozone for 60s and this ozonated peroxide mixture was left on the teeth for 20 min. Meanwhile, teeth in group 2 (n=35) were treated with H2O2 38% for 20 min. The L* a* b* and Vita Classic shade values of teeth were evaluated in both groups at base line, after application of H2O2 and ozone in group 1, and after application of H2O2 and then again after another application of ozone in group 2. The statistically significant changes were set at P ≤ 0.05. Baseline L* a* b* and Vita shade values were comparable between groups (P>0.05). Teeth obtained lighter shades following bleaching with both H2O2 and ozone or with H2O2 alone (P ≤ 0.05). Further bleaching with ozone for teeth already bleached with H2O2 alone showed further improvement of the shades of teeth (P<0.001). Teeth treated with H2O2 and ozone had more shade improvements than those only treated with H2O2 (P<0.001). Also, L* values were increased while b* values were decreased (teeth obtained lighter shades) following bleaching in both groups (P ≤ 0.05). More changes were obtained when both ozone and H2O2 were used (P ≤ 0.05). Bleaching with 38% H2O2 and ozone resulted in teeth with lighter shades than bleaching with 38% H2O2 alone. Copyright © 2016 Elsevier Ltd. All rights reserved.

Toothbrushing abrasion susceptibility of enamel and dentin bleached with calcium-supplemented hydrogen peroxide gel.

PubMed

Borges, A B; Santos, L F T F; Augusto, M G; Bonfiette, D; Hara, A T; Torres, C R G

2016-06-01

The objective of this study was to evaluate enamel and dentin susceptibility to toothbrushing abrasion, after bleaching with 7.5% hydrogen peroxide (HP) gel supplemented or not with 0.5% calcium gluconate (Ca). Toothbrushing was performed immediately and 1h after bleaching, with two suspensions (high and low abrasivity). Bovine enamel and dentin specimens were divided into 12 groups (n=10) according to the bleaching gel (with and without Ca), slurry abrasivity (high or low) and elapsed time after bleaching (immediately and after 1h). As control, a group was not bleached, but abraded. The treatment cycle (7 d) consisted of bleaching (1h) and toothbrushing (135 strokes/day) immediatelly or after 1h of artificial saliva exposure. Surface roughness and surface loss (μm) were measured by profilometry and analysed by three-way ANOVA (5%). Surface roughness means were significantly influenced by slurry abrasivity (p<0.0001). For enamel loss, significant triple interaction was observed (p<0.0001). HP-bleached groups and immediately brushed with high-abrasive slurry exhibited increased loss (1.41±0.14) compared to other groups (μm). Control and HP+Ca-bleached groups brushed after 1h with low abrasive slurry presented the lowest loss (0.21±0.03/0.27±0.02). For dentin loss, significant interaction was observed for bleaching and interval factors (p<0.001). 7.5%HP-bleached groups and immediately brushed showed significantly higher loss (8.71±2.45) than the other groups. It was concluded that surface roughness increased when high abrasive was used, independently of bleaching. 7.5%HP increased enamel and dentin loss, mainly with high abrasive slurries. Calcium supplementation of bleaching gel reduced surface loss. Additionally, in order to minimize tooth wear susceptibility, it is recommended to delay brushing after bleaching. After bleaching gel application, postponing toothbrushing is recommended, as well as brushing with low abrasive dentifrices. Additionally

Effects of at-home and in-office bleaching agents on the shear bond strength of metal, ceramic, and composite brackets to enamel.

PubMed

Rahul, M; Kumar, P Anil; Nair, Amal S; Mathew, Shino; Amaladas, Antony Shijoy; Ommen, Anna

2017-01-01

This study aimed to evaluate the effects of at-home and in-office bleaching on the shear bond strength (SBS) of metal, ceramic, and composite orthodontic brackets and to compare their SBSs. A total of 96 human lower premolar teeth were used for this study. Six teeth were used for scanning electron microscopic study while the remaining ninety were divided into three equal groups. Each group was further subdivided into three subgroups with ten samples each. Three protocols were used. In the at-home bleaching group (n = 30), opalescence non-PF (potassium nitrate and fluoride) bleaching agent (10% carbamide peroxide) was applied onto the teeth daily for 14 days and left for 8 h each day. Teeth in the in-office group (n = 30) were treated twice in consecutive days with Opalescence boost PF (40% hydrogen peroxide). After bleaching, the specimens were stored in distilled water for 1 day before bonding. SBS testing was performed on all teeth using Instron universal testing machine. Analysis of variance indicated a significant difference (P < 0.005) among the groups. Maximum SBS was shown by ceramic brackets in control group (Ib) and minimum was shown by composite brackets of in-office bleached group (IIIc). The results showed that at-home bleaching did not affect the SBS significantly whereas in-office bleaching reduced SBS of metal, ceramic, and composite brackets significantly. It is preferable to use metal or ceramic brackets than composite brackets for bonding 24 h after bleaching.

Color alteration, hydrogen peroxide diffusion, and cytotoxicity caused by in-office bleaching protocols.

PubMed

de Almeida, Letícia Cunha Amaral Gonzaga; Soares, Diana Gabriela; Gallinari, Marjorie Oliveira; de Souza Costa, Carlos Alberto; Dos Santos, Paulo Henrique; Briso, André Luiz Fraga

2015-04-01

This study evaluated the color alteration, cytotoxicity, and hydrogen peroxide (HP) diffusion associated with different in-office bleaching protocols. Bovine enamel/dentin disks were subjected to three bleaching sessions with 35 % HP (three 15-min applications), 35 % HP (one 45-min application), or 20 % HP (one 45-min application). The control group was not bleached. Before bleaching, the disks were adapted to artificial pulp chambers positioned in compartments containing 1 ml of acetate buffer or medium, so that the dentin remained in contact with these substances. Immediately after bleaching, the HP that diffused through the disks was stabilized by acetate buffer and was quantified (two-way repeated measures ANOVA/Fisher's protected least significant difference (PLSD) test; α = 5 %). Cells of mouse dental papilla cell-23 (MDPC-23) were incubated in this culture media for 1 h, followed by analysis of cellular metabolism (methyl tetrazolium assay) (one-way ANOVA/Tukey test; α = 5 %) and morphology (scanning electron microscopy). The specimen color alteration (ΔE) was analyzed by reflection spectrophotometry (two-way repeated measures ANOVA/Fisher's PLSD test; α = 5 %). All protocols showed equal effectiveness at the end of the treatment. HP diffusion was significantly higher in the groups bleached with 35 % HP. Reapplication of 35 % HP resulted in increased diffusion only in the first session; however, the decrease in cell metabolism was similar for all studied protocols. Despite greater peroxide diffusion in the groups treated with 35 % HP, all protocols showed the same effectiveness and were cytotoxic to MDPC-23 cells. Bleaching protocols using high HP concentrations should be avoided because they exert aggressive actions on odontoblast-like cells.

Depletion Rate of Hydrogen Peroxide from Sodium Perborate Bleaching Agent.

PubMed

Tran, Liliann; Orth, Rebecca; Parashos, Peter; Tao, Ying; Tee, Calvin W J; Thomas, Vineet Thenalil; Towers, Georgina; Truong, Diem Thuy; Vinen, Cynthia; Reynolds, Eric C

2017-03-01

Internal bleaching of discolored teeth uses sodium perborate reacting with water to form the active agent, hydrogen peroxide (H 2 O 2 ). Sodium perborate is replaced at varying time intervals depending on clinician preference and until esthetically acceptable results are achieved, but this is done without scientific basis. This study measured the depletion rate of hydrogen peroxide from sodium perborate as a bleaching agent. Two sodium perborate bleaching products (Odontobleach [Australian Dental Manufacturing, Kenmore Hills, Queensland, Australia] and Endosure Perborate Micro [Dentalife, Ringwood, Victoria, Australia]) and distilled deionized water mixtures at ratios of 25 μg/mL, 50 μg/mL, and 100 μg/mL were placed into sealed microtubes and incubated at 37°C. H 2 O 2 concentrations were measured at 23 time points over 4 weeks. Quantification of H 2 O 2 concentrations was obtained using a ferrothiocyanate oxidation reduction reaction followed by spectrophotometry readings. The H 2 O 2 concentration rapidly peaked within 27 hours and reached a plateau by about 3 days (75 hours). Low levels of H 2 O 2 were evident beyond 3 days and for at least 28 days. No significant differences were found between the 2 sodium perborate products. There was also no significant difference in the depletion rate between the different ratios. Based on the chemistry of H 2 O 2 depletion, the minimum replacement interval for the bleaching agent is 3 days. Frequent replacements of the perborate clinically may be unnecessary because of the continued presence of low H 2 O 2 levels for at least 28 days. Although these data cannot be extrapolated to the clinical situation, they set a baseline for further studies to address the many clinical variables influencing internal bleaching. Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.

Mechanistic insights into the bleaching of melanin by alkaline hydrogen peroxide.

PubMed

Smith, R A W; Garrett, B; Naqvi, K R; Fülöp, A; Godfrey, S P; Marsh, J M; Chechik, V

2017-07-01

This work aims to determine the roles of reactive oxygen species HO∙ and HO 2 - in the bleaching of melanins by alkaline hydrogen peroxide. Experiments using melanosomes isolated from human hair indicated that the HO∙ radical generated in the outside solution does not contribute significantly to bleaching. However, studies using soluble Sepia melanin demonstrated that both HO 2 - and HO∙ will individually bleach melanin. Additionally, when both oxidants are present, bleaching is increased dramatically in both rate and extent. Careful experimental design enabled the separation of the roles and effects of these key reactive species, HO∙ and HO 2 - . Rationalisation of the results presented, and review of previous literature, allowed the postulation of a simplified general scheme whereby the strong oxidant HO∙ is able to pre-oxidise melanin units to o-quinones enabling more facile ring opening by the more nucleophilic HO 2 - . In this manner the efficiency of the roles of both species is maximised. Copyright © 2017 Elsevier Inc. All rights reserved.

Effect of Home Bleaching on the Translucency of CAD/CAM Systems.

PubMed

Karci, Muhammet; Demir, Necla

2017-11-10

To evaluate the effect of a home bleaching agent (Opalescence PF) on the translucency of CAD/CAM ceramic systems. The 28 sintered ceramic specimens (IPS Empress CAD and IPS e.max CAD; 15 mm long, 10 mm wide, 1 mm thick) were divided into two subgroups as control and bleaching groups (n = 7). Carbamide peroxide (CP), 16%, home bleaching agent was applied onto the surface of each specimen for 6 hours per day for 7 days. A spectrophotometer (VITA Easyshade Advance) was used to measure the CIE L * a * b * coordinates and the reflectance value (Y) of the specimens on white and black backgrounds. The translucency parameter (TP), contrast ratio (CR), and opalescence parameter (OP) of the specimens were calculated. The data were statistically analyzed using Kolmogorov-Smirnov, one-way ANOVA, Tukey's test, and Pearson's correlation. Statistically significant differences in the TP values after 16% CP bleaching treatment were observed (p ˂ 0.05); however, no significant differences were found in the OP and CR values after the surface treatment (p ˃ 0.05). According to our study, patients who have all-ceramic restorations in their mouths should be careful when using home bleaching agents, because whitening agents can affect the translucency of all-ceramic restorations such as e.max CAD and Empress CAD. © 2017 by the American College of Prosthodontists.

The effect of long-term use of tooth bleaching products on the human enamel surface.

PubMed

Polydorou, Olga; Scheitza, Sophia; Spraul, Mathias; Vach, Kirstin; Hellwig, Elmar

2018-01-01

The aim of this in vitro study was to evaluate the long-term effect of bleaching on human enamel. Four groups of enamel specimens were prepared (n = 20): group 1: bleaching with Opalescence Boost [40% hydrogen peroxide (H 2 O 2 ), 3 × 20 min/week]; group 2: control group (the specimens were stored in human saliva); group 3: beaching with Vivastyle Paint on Plus (6% H 2 O 2 , 2 × 10 min/day), and group 4: bleaching with Opalescence PF 16% [16% carbamide peroxide (CP), 6 h/day]. After each bleaching session the specimens were stored in human saliva. Knoop microhardness and surface roughness were measured: before bleaching, after 2-week and after 8-week bleaching. After 2-week treatment, surface roughness was significantly increased in all experimental groups (p < 0.05), while among them no significant difference was found (p > 0.05). The roughness changes exerted after 8-week bleaching were not significantly higher than the ones after 2 weeks (p > 0.05). After 8-week treatment, the increase in roughness caused by 16% CP was significantly higher (p < 0.05) than the one caused by 40% H 2 O 2 . Microhardness increased in all groups including control; however, only 40% H 2 O 2 increased the microhardness significantly (p < 0.05). The effect of bleaching on enamel was not shown to be dependent on the method or the H 2 O 2 concentration. Bleaching with CP 16% resulted in higher roughness than bleaching with H 2 O 2 , while 40% H 2 O 2 caused the higher microhardness increase. The present study showed that in-office bleaching with 40% H 2 O 2 seems to be at least as safe as home bleaching as far as their effects on human enamel are concerned.

The Influence of Post Bleaching Treatments in Stain Absorption and Microhardness.

PubMed

Moosavi, Horieh; Darvishzadeh, Fatemeh

2016-01-01

This study investigated the effects of post bleaching treatments to prevent restaining and the change of enamel surface microhardness after dental bleaching in vitro. Sixty intact human incisor teeth were stained in tea solution and randomly assigned into four groups (n=15). Then samples were bleached for two weeks (8 hours daily) by 15% carbamide peroxide. Tooth color was determined both with a spectrophotometer and visually before bleaching (T1) and immediately after bleaching (T2). Next, it was applied in group 1 fluoride (Naf 2%) gel for 2 minutes, and in group 2 a fractional CO2 laser (10 mJ, 200 Hz, 10 s), and in group 3, nanohydroxyapatite gel for 2 minutes. The bleached teeth in group 4 remained untreated (control group). Then teeth placed in tea solution again. Color examinations were repeated after various post bleaching treatments (T3) and restaining with tea (T4) and color change values recorded. The microhardness was measured at the enamel surface of samples. Data was analyzed using ANOVA, Tukey HSD test and Dunnett T3 (α = 0.05). Directly after bleaching (ΔE T3-T2), the treatment with nanohydroxyapatite showed significantly the least color lapse in colorimetric evaluation. In experimental groups, the color change between T3 and T4 stages (ΔE T4-T3) was significantly lower than control group (P < 0.05). Different methods of enamel treatment caused a significant increase in surface microhardness compared to control group (P < 0.05). Application of fluoride, fractional CO2 laser and nanohydroxyapatite as post bleaching treatments are suggested for prevention of stain absorption and increasing the hardening of bleached enamel.

Long-term efficacy of in-office and at-home bleaching: a 2-year double-blind randomized clinical trial.

PubMed

Tay, Lidia Yileng; Kose, Carlos; Herrera, Daniel Rodrigo; Reis, Alessandra; Loguercio, Alessandro Dourado

2012-08-01

This parallel, double-blind randomized clinical trial evaluated the 2-year bleaching efficacy and sensitivity produced by at-home (AH) and in-office (IO) bleaching therapies. 60 participants with tooth color darker than C2, without restorations in the anterior dentition and older than 18 years old, were randomly allocated into two groups to receive either IO with 35% hydrogen peroxide or AH with 16% carbamide peroxide. Color was recorded at baseline (BA); 1-week (1W); end of the treatment (ET); and 2 years (2Y) after bleaching, using the Vita Classical shade guide. The perception of TS was recorded on a 0-4 scale during and 2Y after bleaching. The variation in shade guide units (deltaSGU) from BA vs. 1W was compared to deltaSGU from BA vs. 2Y using paired t-test. The percentage of subjects who reported TS was evaluated by Fisher's exact test. The intensity of TS was evaluated by a Mann-Whitney test (alpha=0.05). Both bleaching techniques demonstrated equivalent and significant tooth color shade lightening. No significant color rebound occurred after 2Y for both techniques (P= 0.77 and 0.87, for AH and IO respectively). The absolute risk of TS was similar for IO and AH (P= 0.12), however the intensity of TS was significantly higher for IO (P= 0.001). No subjects reported sensitivity after 2Y.

Safety of nonthermal atmospheric pressure plasma for tooth bleaching evaluated in terms of microhardness and mineral content

NASA Astrophysics Data System (ADS)

Nam, S. H.; Hong, J. W.; Lee, H. J.; Jeon, Y. C.; Kim, G. C.

2017-08-01

The purpose of this study was to evaluate the influence of bleaching with nonthermal atmospheric pressure plasma and 15% hydrogen peroxide (HP) or 15% carbamide peroxide (CP). Sixty human enamel and dentin slabs were randomly assigned to six groups as follows: Group 1 was a control group and did not receive any treatment; Group 2 was exposed only to plasma, as a negative control; Group 3 was treated with 15% HP; Group 4 was treated with 15% HP plus plasma; Group 5 was treated with 15% CP alone; and Group 6 was treated with 15% CP plus plasma during 30 min bleaching treatments. A microhardness measurement was conducted according to a microhardness tester. The amount of calcium (Ca), phosphorus (P), chloride (Cl), sodium (Na), magnesium (Mg), and zinc (Zn) in the enamel and dentin was quantified with an electron probe microanalyzer (EPMA). The data were analyzed by using the Student’s t test and one-way analysis of variance (ANOVA), complemented by Tukey’s test. The statistical analysis did not show any significant differences in microhardness values and six mineral contents in all groups (p  >  0.05). Therefore, we believe that the application of nonthermal atmospheric pressure plasma is a safe energy source for tooth bleaching.

Effect of temperature and concentration on benzoyl peroxide bleaching efficacy and benzoic acid levels in whey protein concentrate.

PubMed

Smith, T J; Gerard, P D; Drake, M A

2015-11-01

Much of the fluid whey produced in the United States is a by-product of Cheddar cheese manufacture and must be bleached. Benzoyl peroxide (BP) is currently 1 of only 2 legal chemical bleaching agents for fluid whey in the United States, but benzoic acid is an unavoidable by-product of BP bleaching. Benzoyl peroxide is typically a powder, but new liquid BP dispersions are available. A greater understanding of the bleaching characteristics of BP is necessary. The objective of the study was to compare norbixin destruction, residual benzoic acid, and flavor differences between liquid whey and 80% whey protein concentrates (WPC80) bleached at different temperatures with 2 different benzoyl peroxides (soluble and insoluble). Two experiments were conducted in this study. For experiment 1, 3 factors (temperature, bleach type, bleach concentration) were evaluated for norbixin destruction using a response surface model-central composite design in liquid whey. For experiment 2, norbixin concentration, residual benzoic acid, and flavor differences were explored in WPC80 from whey bleached by the 2 commercially available BP (soluble and insoluble) at 5 mg/kg. In liquid whey, soluble BP bleached more norbixin than insoluble BP, especially at lower concentrations (5 and 10 mg/kg) at both cold (4°C) and hot (50°C) temperatures. The WPC80 from liquid whey bleached with BP at 50°C had lower norbixin concentration, benzoic acid levels, cardboard flavor, and aldehyde levels than WPC80 from liquid whey bleached with BP at 4°C. Regardless of temperature, soluble BP destroyed more norbixin at lower concentrations than insoluble BP. The WPC80 from soluble-BP-bleached wheys had lower cardboard flavor and lower aldehyde levels than WPC80 from insoluble-BP-bleached whey. This study suggests that new, soluble (liquid) BP can be used at lower concentrations than insoluble BP to achieve equivalent bleaching and that less residual benzoic acid remains in WPC80 powder from liquid whey

Kinetic release of hydrogen peroxide from different whitening products.

PubMed

da Silva Marques, Duarte Nuno; Silveira, Joao Miguel; Marques, Joana Rita; Amaral, Joao Almeida; Guilherme, Nuno Marques; da Mata, António Duarte

2012-01-01

The objective of this in vitro study was to evaluate the kinetics of hydrogen peroxide (HP) release from five different bleaching products: VivaStyle® 10% fitted tray gel, VivaStyle® 30% in-office bleaching gel, VivaStyle® Paint-On Plus paint-on bleaching varnish, Opalescence PF® 10% carbamide peroxide gel and Trèswhite Supreme™ 10% HP gel. Each product was firstly titrated for its HP content by a described method. HP release kinetics was assessed by a modified spectrophotometric technique. One sample t test was performed to test for differences between the manufacturers' claimed HP concentrations and the titrated HP content in the whitening products. Analysis of variance plus Tamhane's post hoc tests and Pearson correlation analysis were used as appropriate. Values of P < 0.05 were taken as significant. Titrated HP revealed an increased content when compared to the manufacturer's specifications for all the products tested (P < 0.05), although only products from one manufacturer produced significantly higher results. All products presented a significant (P < 0.05) and sustained release of HP. However, the product with paint-on cellulose-based matrix resulted in significantly (P < 0.05) faster kinetics when compared to other products tested. These results are consistent with manufacturers' reduced recommended application times. The results of this study suggest that modifying the matrix composition may be a viable alternative to HP concentration increase, since this may result in faster release kinetics without exposure to high HP concentrations.

The Influence of Post Bleaching Treatments in Stain Absorption and Microhardness

PubMed Central

Moosavi, Horieh; Darvishzadeh, Fatemeh

2016-01-01

Objectives: This study investigated the effects of post bleaching treatments to prevent restaining and the change of enamel surface microhardness after dental bleaching in vitro. Methods: Sixty intact human incisor teeth were stained in tea solution and randomly assigned into four groups (n=15). Then samples were bleached for two weeks (8 hours daily) by 15% carbamide peroxide. Tooth color was determined both with a spectrophotometer and visually before bleaching (T1) and immediately after bleaching (T2). Next, it was applied in group 1 fluoride (Naf 2%) gel for 2 minutes, and in group 2 a fractional CO2 laser (10 mJ, 200 Hz, 10 s), and in group 3, nanohydroxyapatite gel for 2 minutes. The bleached teeth in group 4 remained untreated (control group). Then teeth placed in tea solution again. Color examinations were repeated after various post bleaching treatments (T3) and restaining with tea (T4) and color change values recorded. The microhardness was measured at the enamel surface of samples. Data was analyzed using ANOVA, Tukey HSD test and Dunnett T3 (α = 0.05). Results: Directly after bleaching (ΔE T3-T2), the treatment with nanohydroxyapatite showed significantly the least color lapse in colorimetric evaluation. In experimental groups, the color change between T3 and T4 stages (ΔE T4-T3) was significantly lower than control group (P < 0.05). Different methods of enamel treatment caused a significant increase in surface microhardness compared to control group (P < 0.05). Significance: Application of fluoride, fractional CO2 laser and nanohydroxyapatite as post bleaching treatments are suggested for prevention of stain absorption and increasing the hardening of bleached enamel. PMID:27099635

Evaluation of several clinical parameters after bleaching with hydrogen peroxide at different concentrations: A randomized clinical trial.

PubMed

Lima, Suellen Nogueira Linares; Ribeiro, Izabella Santos; Grisotto, Marcos Augusto; Fernandes, Elizabeth Soares; Hass, Viviane; de Jesus Tavarez, Rudys Rodolfo; Pinto, Shelon Cristina Souza; Lima, Darlon Martins; Loguercio, Alessandro D; Bandeca, Matheus Coelho

2018-01-01

This randomized double-blind clinical trial compared tooth sensitivity (TS), bleaching efficacy, and cytokine levels after applying in-office bleaching treatments containing 15% and 35% hydrogen peroxide (HP15% and HP35%, respectively). Twenty-five volunteers were randomly assigned to receive HP15% or HP35% treatment. The bleaching agent was applied in three 15-min applications per session. Two bleaching sessions were separated by a 1-week interval. The participants scored TS using a visual analog scale and numerical rating scale. Bleaching efficacy was determined by subjective and objective methods. Gingival crevicular fluid was collected from three jaws sites per patient for the analysis of fluid volume. Flow cytometry was used to analyze gingival crevicular fluid levels of interleukin (IL)-1β, IL-2, IL-4, IL-6, IL-10, tumor necrosis factor, and interferon-gamma. All measurements were obtained before and after bleaching. All data were statistically analyzed (α=0.05). The absolute risk and intensity of TS was higher for HP35% than for HP15% (p>0.002). One month post-bleaching, HP35% produced more bleaching than HP15% (p=0.02). However patient perception (p=0.06) and patient satisfaction (p=0.53) with regard to bleaching were not significantly different. No significant differences existed in the gingival fluid volume (p>0.38) or in any cytokine level (p>0.05) for either HP concentration. Treatment: with HP35% is more effective than HP15%, but generates a greater risk and intensity of TS. No inflammatory changes occurred despite the difference in the HP concentrations. Hydrogen peroxide at a lower concentration (e.g., 15%) should be considered a good treatment alternative for in-office bleaching because the higher concentration for in-office bleaching generates a greater risk and intensity of TS for patients. Copyright © 2017 Elsevier Ltd. All rights reserved.

Penetration of 38% hydrogen peroxide into the pulp chamber in bovine and human teeth submitted to office bleach technique.

PubMed

Camargo, Samira Esteves Afonso; Valera, Marcia Carneiro; Camargo, Carlos Henrique Ribeiro; Gasparoto Mancini, Maria Nadir; Menezes, Marcia Maciel

2007-09-01

This study evaluated the pulp chamber penetration of peroxide bleaching agent in human and bovine teeth after office bleach technique. All the teeth were sectioned 3 mm apical of the cement-enamel junction and were divided into 2 groups, A (70 third human molars) and B (70 bovine lateral incisors), that were subdivided into A1 and B1 restored by using composite resin, A2 and B2 by using glass ionomer cement, and A3 and B3 by using resin-modified glass ionomer cement; A4, A5, B4, and B5 were not restored. Acetate buffer was placed in the pulp chamber, and the bleaching agent was applied for 40 minutes as follows: A1-A4 and B1-B4, 38% hydrogen peroxide exposure and A5 and B5, immersion into distilled water. The buffer solution was transferred to a glass tube in which leuco crystal violet and horseradish peroxidase were added, producing a blue solution. The optical density of the blue solution was determined by spectrophotometer and converted into microgram equivalents of hydrogen peroxide. Data were submitted to analysis of variance and Dunnett, Kruskal-Wallis, and Tukey tests (5%). A higher level of hydrogen peroxide penetrated into the pulp chamber in resin-modified glass ionomer cements in bovine (0.79 +/- 0.61 microg) and human (2.27 +/- 0.41 microg) groups. The bleaching agent penetration into the pulp chamber was higher in human teeth for any experimental situation. The penetration of the hydrogen peroxide depends on restorative materials, and under the conditions of this study human teeth are more susceptible to penetration of bleaching agent into the pulp chamber than bovine teeth.

Surface discoloration of composite resins: Effects of staining and bleaching.

PubMed

Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Chiesa, Marco

2012-09-01

The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet•X HD, Clearfil AP-X, Gradia Direct) and five nanohybrid composite resins (Ceram•X, GC Kalore, G-aenial, Grandio, GrandioSO), after staining and bleaching procedures. The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany) into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness) to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h), for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco). The color of specimens was measured with a spectrophotometer according to the CIE L(*)a(*)b(*) system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DEab(*)) between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA). All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested.

Effect of bleaching on microhardness of esthetic restorative materials.

PubMed

Malkondu, Özlem; Yurdagüven, Haktan; Say, Esra Can; Kazazoğlu, Ender; Soyman, Mübin

2011-01-01

This study evaluated the effect of a high-concentration carbamide peroxide–containing home bleaching system (Opalescence PF) and a hydrogen peroxide–containing over-the-counter bleaching system (Treswhite Supreme) on the microhardness of two nanocomposites (Filtek Supreme XT and Premise) and leucite-reinforced glass ceramic (Empress Esthetic), glass ceramic (Empress 2 layering), and feldspathic porcelain (Matchmaker MC). A total of 100 specimens, 20 of each kind of the restorative materials, 2 mm in thickness and 10 mm in diameter, were fabricated. Then the specimens were polished with SiC paper and 1 μm alumina polishing paste. After polishing, porcelain specimens were glazed in accordance with the manufacturer's instructions. Each type of restorative material was then randomly divided into two groups (n=10), and the specimens were treated with either Opalescence PF or Treswhite Supreme. The microhardness of the specimens before bleaching (baseline) and after bleaching was determined using a digital microhardness tester. Data were analyzed using the Mann-Whitney U-test and the Wilcoxon test. Opalescence PF significantly influenced the hardness of all the restorative materials. Statistically significant decreases with respect to before bleaching were found for Premise (p=0.005), Empress Esthetic (p=0.003), Empress 2 layering (p=0.005), and Matchmaker-MC (p=0.003), whereas a statistically significant increase was observed in Filtek Supreme XT (p=0.028). The difference in the microhardness values between before and after bleaching using Treswhite Supreme was statistically significant only for Premise (p=0.022). High-concentration carbamide peroxide–containing home bleaching may affect the microhardness of restorative materials.

Acid demineralization susceptibility of dental enamel submitted to different bleaching techniques and fluoridation regimens.

PubMed

Salomão, Dlf; Santos, Dm; Nogueira, Rd; Palma-Dibb, Rg; Geraldo-Martins, Vr

2014-01-01

The aim of the current study was to assess the acid demineralization susceptibility of bleached dental enamel submitted to different fluoride regimens. One hundred bovine enamel blocks (6×6×3 mm) were randomly divided into 10 groups (n=10). Groups 1 and 2 received no bleaching. Groups 3 to 6 were submitted to an at-home bleaching technique using 6% hydrogen peroxide (HP; G3 and G4) or 10% carbamide peroxide (CP; G5 and G6). Groups 7 to 10 were submitted to an in-office bleaching technique using 35% HP (G7 and G8) or 35% CP (G9 and G10). During bleaching, a daily fluoridation regimen of 0.05% sodium fluoride (NaF) solution was performed on groups 3, 5, 7, and 9, while weekly fluoridation with a 2% NaF gel was performed on groups 4, 6, 8, and 10. The samples in groups 2 to 10 were pH cycled for 14 consecutive days. The samples from all groups were then assessed by cross-sectional Knoop microhardness at different depths from the outer enamel surface. The average Knoop hardness numbers (KHNs) were compared using one-way analysis of variance and Tukey tests (α=0.05). The comparison between groups 1 and 2 showed that the demineralization method was effective. The comparison among groups 2 to 6 showed the same susceptibility to acid demineralization, regardless of the fluoridation method used. However, the samples from groups 8 and 10 showed more susceptibility to acid demineralization when compared with group 2 (p<0.05). Groups 7 and 9 provided similar results to group 2, but the results of those groups were different when compared with groups 8 and 10. The use of 6% HP and 10% CP associated with daily or weekly fluoridation regimens did not increase the susceptibility of enamel to acid demineralization. However, the use of 35% HP and 35% CP must be associated with a daily fluoridation regimen, otherwise the in-office bleaching makes the bleached enamel more susceptible to acid demineralization.

The effect of enamel bleaching on the shear bond strengths of metal and ceramic brackets.

PubMed

Oztaş, E; Bağdelen, G; Kiliçoğlu, H; Ulukapi, H; Aydin, I

2012-04-01

The aim of this study was to evaluate the effects of bleaching and delayed bonding on the shear bond strengths of metal and ceramic brackets bonded with light and chemically cure composite resin to human enamel. One hundred and twenty extracted human premolar teeth were randomly divided into three groups of 40 each. The first two groups were bleached with 20 per cent carbamide peroxide (CP) at-home bleaching agent. No bleaching procedures were applied to the third group and served as control. The first two and control groups were divided into equal subgroups according to different adhesive-bracket combinations. Specimens in group 1 (n = 40) were bonded 24 hours after bleaching process was completed while the specimens in group 2 (n = 40) were bonded 14 days after. The specimens in all groups were debonded with a Universal testing machine while the modified adhesive remnant index was used to evaluate fracture properties. No statistically significant differences were found between the shear bond strengths of metal and ceramic brackets bonded to bleached enamel after 24 hours, 14 days, and unbleached enamel with light or chemical cure adhesives (P > 0.05). The mode of failure was mostly at the bracket/adhesive interface and cohesive failures within the resin were also observed. Our findings indicated that at-home bleaching agents that contain 20 per cent CP did not significantly affect the shear bond strength of metal and ceramic orthodontic brackets to enamel when bonding is performed 24 hours or 14 days after bleaching.

Efficacy of whitening oral rinses and dentifrices on color stability of bleached teeth

PubMed Central

Karadas, Muhammet

2015-01-01

Abstract Objective: This study aimed to evaluate the effect of whitening toothpastes and mouthrinses on the color stability of teeth bleached with 16% carbamide peroxide (CP) after immersion in coffee solution. Materials and methods: Specimens obtained from bovine incisors were bleached with 16% CP for 14 days. After bleaching, the specimens were stained in coffee solution for 24 h and randomly divided into eight groups according to the following products (n = 10): distilled water (control group, DW), Scope White mouthrinse (SW), Crest 3D White mouthrinse (CWR), Crest 3D White toothpaste (CWT), Crest 3D White toothpaste and Crest 3D White mouthrinse (CWT + CWR), Listerine Whitening toothpaste (LWT), Listerine Whitening mouthrinse (LWR), and Listerine Whitening mouthrinse and Listerine Whitening toothpaste (LWR + LWT). Color measurements were conducted using a spectrophotometer. The data were assessed by analysis of variance for repeated measures and Tukey’s multiple comparison test (p < 0.05). Results: Immersion in coffee solution after bleaching caused perceptible staining on tooth specimens (ΔE > 3.46). The whitening effect of CWR on teeth stained after bleaching was significantly greater than that in the other groups (p < 0.001). Tooth whitening (ΔE) in each group showed no significant difference from 6 to 12 weeks (p > 0.05). The combination of mouthrinse and toothpaste did not increase the degree of tooth whitening. Conclusion: Whitening mouthrinse and toothpaste had similar effects on the control group in terms of whitening of teeth stained after bleaching. Nevertheless, Crest 3D White mouthrinse produced the greatest recovery whitening effect among all the products tested. PMID:28642898

Randomized controlled clinical trial on bleaching sensitivity and whitening efficacy of hydrogen peroxide versus combinations of hydrogen peroxide and ozone.

PubMed

Al-Omiri, Mahmoud K; Al Nazeh, Abdullah A; Kielbassa, Andrej M; Lynch, Edward

2018-02-05

The clinical efficacy regarding bleaching sensitivity and tooth shade lightening using a standard hydrogen peroxide (H 2 O 2 ) bleaching gel was compared with the additional use of ozone either before or after application of H 2 O 2 . Using computer-generated tables, 45 participants were randomly allocated into three groups (n = 15 each) in this investigator-driven, single-centre trial. In Group 1, upper anterior teeth were bleached using ozone (produced via a healOzone X4 device) for 60 seconds, then 38% H 2 O 2 for 20 minutes; in Group 2, 38% H 2 O 2 application (20 min) was followed by ozone (60 s); air produced by the healOzone machine (60 s) followed by 38% H 2 O 2 (20 min) was used in Group 3 (control). Bleaching sensitivity was evaluated via visual analogue scales, and a treatment-blinded reader objectively recorded tooth shades using a colorimeter before and 24 hours after bleaching (at α = 0.05). The H 2 O 2 /ozone combination did not result in pain sensations, while both ozone/H 2 O 2 and H 2 O 2 alone increased bleaching sensitivity (p < 0.001). Teeth achieved lighter shades (higher L*/lower b* values) after bleaching in all groups (p < 0.001), while Ozone boosted lighter tooth shades, irrespective of its use before or after H 2 O 2 (p < 0.05). Due to the complimentary effects, applying ozone after H 2 O 2 seems preferable for bleaching.

Surface discoloration of composite resins: Effects of staining and bleaching

PubMed Central

Poggio, Claudio; Beltrami, Riccardo; Scribante, Andrea; Colombo, Marco; Chiesa, Marco

2012-01-01

Background: The purpose of this in vitro study was to evaluate surface discoloration of three microhybrid composite resins (Esthet•X HD, Clearfil AP-X, Gradia Direct) and five nanohybrid composite resins (Ceram•X, GC Kalore, G-aenial, Grandio, GrandioSO), after staining and bleaching procedures. Materials and Methods: The composite resins were polymerized with a curing light (Celalux II, Voco, Cuxhaven, Germany) into 160 silicon molds (6,4 mm in diameter and 2 mm in thickness) to obtain identical specimens. Twenty samples for each composite resin were prepared. The specimens were polished using an automated polishing machine with the sequence of 600-, 800-, 1000-grit abrasive paper under water irrigation. The specimens were immersed in tea and distilled water: the specimens were dipped for 20 min, once a day (every 24 h), for 14 days into the drinks. The specimens were then bleached with carbamide peroxide at 17% (Perfect Bleach-Voco). The color of specimens was measured with a spectrophotometer according to the CIE L*a*b* system after light-polymerization of composite resin specimens, after 7 days, after 14 days, and after bleaching. The color difference h index (DEab*) between each measurement was calculated. Statistical analysis was made using analysis of variance (ANOVA). Results: All specimens showed a significant increase in staining with a similar trend and no significant differences between microhybrid and nanohybrid composite resins. After whitening procedures, materials tested showed both significant and unsignificant differences of the h index. Conclusions: Microhybrid and nanohybrid composite resins had similar in vitro surface discoloration in tea. After bleaching, discoloration was removed from some composite resins tested. PMID:23559921

Bleaching agent action on color stability, surface roughness and microhardness of composites submitted to accelerated artificial aging.

PubMed

Rattacaso, Raphael Mendes Bezerra; da Fonseca Roberti Garcia, Lucas; Aguilar, Fabiano Gamero; Consani, Simonides; de Carvalho Panzeri Pires-de-Souza, Fernanda

2011-04-01

The purpose of this study was to evaluate the bleaching agent action on color stability, surface roughness and microhardness of composites (Charisma, Filtek Supreme and Heliomolar - A2) submitted to accelerated artificial aging (AAA). A Teflon matrix (12 x 2 mm) was used to fabricate 18 specimens (n=6) which, after polishing (Sof-Lex), were submitted to initial color reading (ΔE), Knoop microhardness (KHN) (50 g/15 s load) and roughness (R(a)) (cut-off 0.25 mm) tests. Afterwards, the samples were submitted to AAA for 384 hours and new color, microhardness and roughness readings were performed. After this, the samples were submitted to daily application (4 weeks) of 16% Carbamide Peroxide (NiteWhite ACP) for 8 hours and kept in artificial saliva for 16 hours. New color, microhardness and roughness readings were made at the end of the cycle, and 15 days after bleaching. Comparison of the ΔE means (2-way ANOVA, Bonferroni, P<.05) indicated clinically unacceptable color alteration for all composites after AAA, but without significant difference. Statistically significant increase in the KHN values after AAA was observed, but without significant alterations 15 days after bleaching. For R(a) there was no statistically significant difference after AAA and 15 days after bleaching. The alterations promoted by the bleaching agent and AAA are material dependent.

Effect of vital bleaching with solutions containing different concentrations of hydrogen peroxide and pineapple extract as an additive on human enamel using reflectance spectrophotometer: An in vitro study.

PubMed

Vejai Vekaash, Chitra Janardhanan; Kumar Reddy, Tripuravaram Vinay; Venkatesh, Kondas Vijay

2017-01-01

This study aims to evaluate the color change in human enamel bleached with three different concentrations of hydrogen peroxide, containing pineapple extract as an additive in two different timings, using reflectance spectrophotometer. The study aimed to investigate the bleaching efficacy on natural teeth using natural enzymes. Baseline color values of 10 randomly selected artificially stained incisors were obtained. The specimens were divided into three groups of 20 teeth each: Group 1 - 30% hydrogen peroxide, Group II - 20% hydrogen peroxide, and Group III - 10% hydrogen peroxide. One half of the tooth was bleached with hydrogen peroxide, and other was bleached with hydrogen peroxide and pineapple extract for 20 min (Subgroup A) and 10 min (Subgroup B). The results were statistically analyzed using student's t -test. The mean ΔE values of Group IA (31.62 ± 0.9), Group IIA (29.85 ± 1.2), and Group IIIA (28.65 ± 1.2) showed statistically significant higher values when compared to the mean Δ E values of Group 1A (25.02 ± 1.2), Group IIA (22.86 ± 1.1), and Group IIIA (16.56 ± 1.1). Identical results were obtained in Subgroup B. The addition of pineapple extract to hydrogen peroxide resulted in effective bleaching.

Effect of 10% sodium ascorbate on the calcium: Phosphorus ratio of enamel bleached with 35% hydrogen peroxide: an in vitro quantitative energy-dispersive X-ray analysis.

PubMed

Poorni, Saravanan; Kumar, R Anil; Shankar, P; Indira, Rajamani; Ramachandran, S

2010-10-01

The study assessed quantitatively the calcium and phosphorous loss from the enamel surface following bleaching with 35% hydrogen peroxide and reversal with 10% sodium ascorbate using energy-dispersive X-ray analysis (EDAX). Eight non-carious, freshly extracted human permanent maxillary central incisors without any visible defects were used. Each specimen was bleached with 35% hydrogen peroxide activated by light and reversed with sodium ascorbate antioxidant gel. The calcium and phosphorous content in weight percent of sound, bleached and reversed enamel was acquired using EDAX. The Ca/P ratio was calculated from the obtained data. One-way ANOVA followed by Post Hoc Tukey test was used for comparing the Ca/P ratio of sound, bleached and reversed enamel. All the samples subjected to bleaching using 35% hydrogen peroxide showed a statistically significant decrease in the Ca/P ratio as compared with samples in which no bleaching procedure was performed (P-value < 0.01). The striking finding was that there was a significant increase in the Ca/P ratio on application of sodium ascorbate antioxidant gel when compared with the bleached enamel (P-value < 0.01). The authors concluded that 35% hydrogen peroxide causes a significant decrease in the Ca/P ratio. This decrease in the Ca/P ratio can be restored by the application of 10% sodium ascorbate antioxidant gel.

Peroxide as a Novel Treatment for Ecchymoses

PubMed Central

Sroa, Novie; Campbell, Shannon M.; Bechtel, Mark A.; Mitch Opremcak, E.

2010-01-01

Ecchymoses, commonly known as bruises, frequently occur after injury to the skin causes extravasation of red blood cells into interstitial tissue. This extravasation can lead to an inflammatory cascade. The case report presented details one patient who displayed rapid improvement in the pain and appearance of a partially treated bruise on her thigh after an eight-hour application of hydrogen peroxide 15% carbamide gel under occlusion. Hydrogen peroxide 15% carbamide gel may represent a novel treatment for ecchymoses. This potential new treatment for bruises needs to be studied further to detail its adverse effects, safety profile, and efficacy profile. PMID:21103315

Effect of bleaching agents and soft drink on titanium surface topography.

PubMed

Faverani, Leonardo P; Barão, Valentim A R; Ramalho-Ferreira, Gabriel; Ferreira, Mayara B; Garcia-Júnior, Idelmo R; Assunção, Wirley G

2014-01-01

The effects of carbamide peroxide, hydrogen peroxide and cola soft drink on the topographic modifications of commercially-pure titanium (CP-Ti) and Ti-6Al-4V were investigated. Ti discs were divided into 18 groups (n = 4) based on the solution treatment and Ti type. Specimens were immersed in 3 mL of each solution for 4 h per day (for the remaining 20 h, discs were left dry or immersed in artificial saliva) for 15 days. For control, specimens were immersed in only artificial saliva. Ti surfaces were examined using scanning electron (SEM) and atomic force (AFM) microscopes and their surface roughness (in µm) and surface chemical modifications were investigated. Data were analyzed by ANOVA and Tukey's test (α = 0.05). Groups immersed in 35% hydrogen peroxide showed the highest roughness (Ra) (171.65 ± 4.04 for CP-Ti and 145.91 ± 14.71 for Ti-6Al-4V) (p < 0.05), followed by groups treated with carbamide peroxide 16% (110.91 ± 0.8 for CP-Ti and 49.28 ± 0.36 for Ti-6Al-4V) and 35% (65.67 ± 1.6 for CP-Ti and 53.87 ± 1.98 for Ti-6Al-4V); treatment with artificial saliva did not affect the results. These values were statistically superior to those observed prior to the treatment and to those of the control group (31.0 ± 0.99 for CP-Ti and 29.95 ± 0.58 for Ti-6Al-4V). Cola soft drink did not alter the surface roughness of either Ti type (p > 0.05). SEM and AFM revealed dramatic changes in the specimens surfaces immersed in the 35% hydrogen peroxide, mainly for CP-Ti. No detectable chemical modifications on the Ti surface were observed. Bleaching agents promoted significant changes in Ti topography, which could affect the longevity of implants treatments. Copyright © 2013 Wiley Periodicals, Inc.

Effect of vital bleaching with solutions containing different concentrations of hydrogen peroxide and pineapple extract as an additive on human enamel using reflectance spectrophotometer: An in vitro study

PubMed Central

Vejai Vekaash, Chitra Janardhanan; Kumar Reddy, Tripuravaram Vinay; Venkatesh, Kondas Vijay

2017-01-01

Aim: This study aims to evaluate the color change in human enamel bleached with three different concentrations of hydrogen peroxide, containing pineapple extract as an additive in two different timings, using reflectance spectrophotometer. Background: The study aimed to investigate the bleaching efficacy on natural teeth using natural enzymes. Materials and Methods: Baseline color values of 10 randomly selected artificially stained incisors were obtained. The specimens were divided into three groups of 20 teeth each: Group 1 – 30% hydrogen peroxide, Group II – 20% hydrogen peroxide, and Group III – 10% hydrogen peroxide. One half of the tooth was bleached with hydrogen peroxide, and other was bleached with hydrogen peroxide and pineapple extract for 20 min (Subgroup A) and 10 min (Subgroup B). Statistical Analysis: The results were statistically analyzed using student's t-test. Results: The mean ΔE values of Group IA (31.62 ± 0.9), Group IIA (29.85 ± 1.2), and Group IIIA (28.65 ± 1.2) showed statistically significant higher values when compared to the mean Δ E values of Group 1A (25.02 ± 1.2), Group IIA (22.86 ± 1.1), and Group IIIA (16.56 ± 1.1). Identical results were obtained in Subgroup B. Conclusion: The addition of pineapple extract to hydrogen peroxide resulted in effective bleaching. PMID:29386782

Mineral loss and color change of enamel after bleaching and staining solutions combination.

PubMed

de Araújo, Larissa Sgarbosa Napoleão; dos Santos, Paulo Henrique; Anchieta, Rodolfo Bruniera; Catelan, Anderson; Fraga Briso, André Luiz; Fraga Zaze, Ana Carolina Soares; Sundfeld, Renato Herman

2013-10-01

Pigments of food and beverages could affect dental bleaching efficacy. The aim of this investigation was to evaluate color change and mineral loss of tooth enamel as well as the influence of staining solutions normally used by adolescent patients undergoing home bleaching. Initial hardness and baseline color were measured on enamel blocks. Specimens were divided into five groups (n=5): G1 (control) specimens were kept in artificial saliva throughout the experiment (3 weeks); G2 enamel was exposed to 10% carbamide peroxide for 6 h daily, and after this period, the teeth were cleaned and stored in artificial saliva until the next bleaching session; and G3, G4, and G5 received the same treatments as G2, but after bleaching, they were stored for 1 h in cola soft drink, melted chocolate, or red wine, respectively. Mineral loss was obtained by the percentage of hardness reduction, and color change was determined by the difference between the data obtained before and after treatments. Data were subjected to analysis of variance and Fisher's test (α=0.05). G3 and G5 showed higher mineral loss (92.96 ± 5.50 and 94.46 ± 1.00, respectively) compared to the other groups (p ≤ 0.05). G5 showed high-color change (9.34 ± 2.90), whereas G1 presented lower color change (2.22 ± 0.44) (p ≤ 0.05). Acidic drinks cause mineral loss of the enamel, which could modify the surface and reduce staining resistance after bleaching.

Changes in surface morphology and mineralization level of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation.

PubMed

Berger, Sandrine Bittencourt; Cavalli, Vanessa; Ambrosano, Glaucia Maria Bovi; Giannini, Marcelo

2010-01-01

The objective of this study was to evaluate the alterations on surface morphology and mineral loss of human enamel following in-office bleaching with 35% hydrogen peroxide and light irradiation. Dental enamel samples were obtained from human third molars and randomly divided into 10 groups (n = 10). The control group remained untreated. Bleached groups were treated with one of three whitening products. Bleaching was performed in a single session, during which bleaching gel was applied to the enamel surface three times for 10 minutes each time. During treatment, the bleaching agents were either irradiated by a halogen light or an LED/diode laser or were not irradiated at all. Microhardness testing was performed with a Knoop indentor and the surface morphologic observations were carried out by scanning electron microscopy (SEM). Cross-sectional microhardness (CSMH) and polarized light microscopy (PLM) were used to measure the depth of demineralization. The results revealed a significant decrease in surface microhardness values and changes to the enamel morphology after bleaching. CSMH and PLM showed that bleached enamel presented lower volume percentage of mineral up to 40 micrometers from the enamel surface and demineralization areas located in the subsuperficial region of enamel, respectively. It was concluded that 35% hydrogen peroxide can alter the surface morphology and the mineralization level of the dental enamel surface and sub-surface regardless of what type of bleaching light is used.

Effect of two different bleaching regimens on the gloss of tooth colored restorative materials.

PubMed

Yalcin, Filiz; Gürgan, Sevil

2005-05-01

Vital tooth bleaching with peroxide is one of the most common cosmetic procedures in dentistry and can be accomplished using a variety of methods or regimens. Recently, new generation of tooth color restorative materials were introduced to market. The purpose of this in vitro study was to determine the gloss changes of three different tooth color restorative materials: Flowable composite (Filtek Flow/3M), packable composite (Filtek P60/3M) and ormocer (Definite/DEGUSSA) after two different bleaching regimens (Vivastyle/VIVADENT) and (Crest Professional Whitestrips/PROCTER and GAMBLE). 16 specimens 30 x 30 x 2 mm size were fabricated from each restorative material. After gloss values were measured with gloss meter, at two different angles of illumination (20 and 60 degrees ), 10% carbamide peroxide (Vivastyle) was applied for 2 h per day for fourteen days to the half of the specimens while 6.5% hydrogen peroxide strip bands (Crest Professional Whitestrips) were applied to the remaining eight of the specimens for 30 min twice daily for 14 days. During the test period the specimens were stored in 37 degrees C and 100% relative humidity. At the end of bleaching regimen the gloss measurements were repeated and the data were subjected to statistical analysis. The Wilcoxon Signed Rank Test analysis revealed that the gloss values were affected by both bleaching regimens (P=0.012). Whitestrips decreased the gloss values of Filtek P60 (at 20 and 60 degrees , P<0.001) and Filtek Flow (at 20 degrees , P=0.05 and at 60 degrees , P=0.05) significantly compared to Vivastyle, while the gloss values of Definite did not show any significant change between Vivastyle and Whitestrips application (at 20 degrees P=0.279; at 60 degrees , P=0.279, Mann-Whitney U Test). The gloss values of materials were significantly different before (at 20 degrees P<0.001; at 60 degrees , P=0.003) and after bleaching (at 20 degrees P<0.05; at 60 degrees , P<0.05) with the highest value of Filtek Flow

The corrosion of titanium in alkaline peroxide bleach liquors

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wyllie, W.E. II; Brown, B.E.; Duquette, D.J.

1994-12-31

An experimental program to determine the effects of hydrogen peroxide (H{sub 2}O{sub 2}) and of potential corrosion inhibitors on the corrosion behavior of titanium has been developed. Corrosion rates less than 0.25 mm/y were observed in laboratory bleach liquor at pH 12 to which 5 g/l of H{sub 2}O{sub 2} were added. At pH 13, with 10 g/l H{sub 2}O{sub 2}, the corrosion rates were unacceptably high in both sodium hydroxide (NaOH) and laboratory bleach liquor solutions (>8.38 mm/y). The preliminary results of inhibitor studies indicated that the addition of 3.7 g/l sodium silicate or 0.01 g/l calcium nitrate (Ca(NO{submore » 3}){sub 2}) effectively inhibited the corrosion of titanium exposed to 5 g/l of H{sub 2}O{sub 2} in NaOH solutions of pH 12. It was also found that in simulated paper mill chemistries, i.e., basic solutions containing 3.7 g/l sodium silicate and 0.6 g/l EDTA (ethylenediaminetetraacetic acid), corrosion rates increased markedly with the addition of 5 g/l H{sub 2}O{sub 2}. However, subsequent additions of peroxide resulted in corrosion rates which were even lower than those found in NaOH. This is believed to be due to the formation of a black scale on the surface of the sample. The addition of magnesium sulfate (MgSO{sub 4}) in the 0.1--0.5 g/l range also was shown to inhibit corrosion in the NaOH solution, but only after prior exposure to H{sub 2}O{sub 2}.« less

[Effects of hydrogen peroxide-containing bleaching on the growth of Streptococcus mutans biofilm on enamel disc surface].

PubMed

Zheng, Chun-yan; Pan, Jie; Wang, Zu-hua; Wang, Yang

2014-02-18

To evaluate the effects of a commercial bleaching agent containing 35% (mass fraction) hydrogen peroxide on the growth of Streptococcus mutans biofilm on enamel disc surface. A total of 20 enamel disks were made from human extracted teeth and the enamel surfaces were kept intact. The discs were autocalved and randomly divided into two groups: bleaching group and control group. Each group contained 10 discs. For bleaching group, the enamel discs were whitened by commercial 35% hydrogen peroxide according to the instruction (Beyond(TM) Professional Dental Whitening Kit, Beyond Technology, TX,USA ); no treatment for control group. All the discs were kept in sterile human saliva for 3.5 hours, and then the mixture of brain heart infusion broth (BHI) medium and Streptococcus mutans were added. The discs and Streptococcus mutans were incubated together in BHI medium with 5% CO(2) (volume fraction), at 37 °C. After 3, 7, 14, 21 and 28 d's incubation, two discs of each group were taken out and the biofilms on the enamel surfaces were evaluated by using conventional bacteria counts and confocal laser scanning microscope (CLSM). The bacteria in the biofilm on one disc enamel surface were analyzed by plating on BHIS agar and the colony-forming units were counted. The biofilm on the other disc surface was stained using a two-colour fluorescent dye kit (Bacerial Viability Kit L-7012) for CLSM. The vital bacteria counts of vital cells in the 3, 7, and 14 d's biofilms of the bleaching group were significantly fewer than those of the control group. Especially in the 3 days' biofilm on the whitened surface, the vital bacteria counts [(3 595 ± 2 903) μm(2) vs. (89 155 ± 65 963) μm(2),t = 8.71,P = 0.00] and proportion of vital bacteria [(26.0% ± 16.4%) vs.(92.2% ± 10.9%), t = 19.93, P = 0.00] were significantly fewer than those of the control. While, for the 21d's biofilm, the vital bacteria counts and the percentage of the vital cells of the bleaching group were more than

Double-blind whitening Night-Guard study using ten percent carbamide peroxide.

PubMed

Ouellet, D; Los, S; Case, H; Healy, R

1992-01-01

The conservative technique of professionally dispensed and supervised, home-administered vital bleaching is now a routine treatment in the dental profession. This double-blind study evaluated the Rembrandt Lightening Gel and Whitening Toothpaste for shade change, colorimeter shade change. As well, it evaluated soft tissue health by periodontal probing, plaque index, and bleeding index. A patient questionnaire evaluated perception of whitening, perception of oral hygiene, average hours per day, and average days per week. Bleaching trays were worn over a 4-week period. The bleaching system showed definitive whitening effects as evaluated with the Vita shade guide and the colorimeter. The bleaching system had no deleterious effects on the soft tissue. The Rembrandt toothpaste alone demonstrated two-shade lightening. This vital bleaching system shows definitive whitening of the teeth in short periods of time with no adverse effects.

Color assessment after bleaching with hydrogen peroxide versus ozone: a randomized controlled clinical trial.

PubMed

Aykut-Yetkiner, Arzu; Ertuğrul, Fahinur; Eden, Ece; Aladağ, Akin; Ergin, Ecem; Özcan, Mutlu

2017-01-01

This randomized controlled clinical trial evaluated the color change of teeth bleached with either hydrogen peroxide (HP) or ozone (OZ). A total of 26 patients with a mean age of 36.2 years (SD, 8.7 years) who met the inclusion criteria were enrolled in the study. The subjects were randomly assigned to receive chairside bleaching using 40% HP or gaseous OZ. Maxillary dental arch vacuum trays were constructed with circumferential openings in the middle portion of the maxillary incisors at their labial surfaces. These trays were used for measuring color-first at baseline and then immediately and 48 hours after postbleaching-and were not used in bleaching. Changes in color were determined using CIE L*a*b* coordinates. Analysis of the data revealed that, while overall color change (ΔE*) values of the HP and OZ groups did not show statistically significant differences immediately after bleaching (P = 0.114), ΔE* values were significantly different 48 hours postbleaching (P = 0.00). Visible color changes were not obtained with either HP or OZ immediately postbleaching. The greatest visible color change occurred with HP 48 hours postbleaching.

Influence of storage, heat treatment, and solids composition on the bleaching of whey with hydrogen peroxide.

PubMed

Li, Xiaomeng E; Campbell, Rachel E; Fox, Aaron J; Gerard, Patrick D; Drake, MaryAnne

2012-07-01

The residual annatto colorant in liquid whey is bleached to provide a desired neutral color in dried whey ingredients. This study evaluated the influence of starter culture, whey solids and composition, and spray drying on bleaching efficacy. Cheddar cheese whey with annatto was manufactured with starter culture or by addition of lactic acid and rennet. Pasteurized fat-separated whey was ultrafiltered (retentate) and spray dried to 34% whey protein concentrate (WPC34). Aliquots were bleached at 60 °C for 1 h (hydrogen peroxide, 250 ppm), before pasteurization, after pasteurization, after storage at 3 °C and after freezing at -20 °C. Aliquots of retentate were bleached analogously immediately and after storage at 3 or -20 °C. Freshly spray dried WPC34 was rehydrated to 9% (w/w) solids and bleached. In a final experiment, pasteurized fat-separated whey was ultrafiltered and spray dried to WPC34 and WPC80. The WPC34 and WPC80 retentates were diluted to 7 or 9% solids (w/w) and bleached at 50 °C for 1 h. Freshly spray-dried WPC34 and WPC80 were rehydrated to 9 or 12% solids and bleached. Bleaching efficacy was measured by extraction and quantification of norbixin. Each experiment was replicated 3 times. Starter culture, fat separation, or pasteurization did not impact bleaching efficacy (P > 0.05) while cold or frozen storage decreased bleaching efficacy (P < 0.05). Bleaching efficacy of 80% (w/w) protein liquid retentate was higher than liquid whey or 34% (w/w) protein liquid retentate (P < 0.05). Processing steps, particularly holding times and solids composition, influence bleaching efficacy of whey. Optimization of whey bleaching conditions is important to reduce the negative effects of bleaching on the flavor of dried whey ingredients. This study established that liquid storage and whey composition are critical processing points that influence bleaching efficacy. © 2012 Institute of Food Technologists®

Micro-structural integrity of dental enamel subjected to two tooth whitening regimes.

PubMed

Tanaka, Reina; Shibata, Yo; Manabe, Atsufumi; Miyazaki, Takashi

2010-04-01

Colour modification of tooth enamel has proven successful, but it is unclear how various bleaching applications affect micro-structural integrity of the whitened enamel. To investigate the internal structural integrity of human intact tooth enamel with the application of two commonly used whitening regimes (in-office power bleaching with 35% hydrogen peroxide and home bleaching with 10% carbamide peroxide), evaluations were performed on teeth of identical colour classification. After the bleaching applications, the enamel mineral density was quantified and visualised with micro-computed tomography. The micro-structural differences between the whitened tooth enamel samples were distinctive, though the colour parameter changes within the samples were equivalent. Home bleaching achieved colour modification by demineralisation, whereas in-office bleaching depended on redistribution of the minerals after treatment and subsequent enhanced mineralisation.

Neurosensory analysis of tooth sensitivity during at-home dental bleaching: a randomized clinical trial.

PubMed

Briso, André Luiz Fraga; Rahal, Vanessa; Azevedo, Fernanda Almeida de; Gallinari, Marjorie de Oliveira; Gonçalves, Rafael Simões; Santos, Paulo Henrique Dos; Cintra, Luciano Tavares Angelo

2018-01-01

Objective The objective of this study was to evaluate dental sensitivity using visual analogue scale, a Computerized Visual Analogue Scale (CoVAS) and a neurosensory analyzer (TSA II) during at-home bleaching with 10% carbamide peroxide, with and without potassium oxalate. Materials and Methods Power Bleaching 10% containing potassium oxalate was used on one maxillary hemi-arch of the 25 volunteers, and Opalescence 10% was used on the opposite hemi-arch. Bleaching agents were used daily for 3 weeks. Analysis was performed before treatment, 24 hours later, 7, 14, and 21 days after the start of the treatment, and 7 days after its conclusion. The spontaneous tooth sensitivity was evaluated using the visual analogue scale and the sensitivity caused by a continuous 0°C stimulus was analyzed using CoVAS. The cold sensation threshold was also analyzed using the TSA II. The temperatures obtained were statistically analyzed using ANOVA and Tukey's test (α=5%). Results The data obtained with the other methods were also analyzed. 24 hours, 7 and 14 days before the beginning of the treatment, over 20% of the teeth presented spontaneous sensitivity, the normal condition was restored after the end of the treatment. Regarding the cold sensation temperatures, both products sensitized the teeth (p<0.05) and no differences were detected between the products in each period (p>0.05). In addition, when they were compared using CoVAS, Power Bleaching caused the highest levels of sensitivity in all study periods, with the exception of the 14th day of treatment. Conclusion We concluded that the bleaching treatment sensitized the teeth and the product with potassium oxalate was not able to modulate tooth sensitivity.

Evaluation of the effect of a home bleaching agent on surface characteristics of indirect esthetic restorative materials--part II microhardness.

PubMed

Torabi, Kianoosh; Rasaeipour, Sasan; Ghodsi, Safoura; Khaledi, Amir Ali Reza; Vojdani, Mahroo

2014-07-01

The exponential usage of esthetic restorative materials is beholden to society needs and desires. Interaction between the bleaching agents and the esthetic restorative materials is of critical importance. This in vitro study has been conducted to evaluate the effect of a home bleaching agent, carbamide peroxide (CP) 38%, on the microhardness of the fiber reinforced composite (FRC), overglazed, autoglazed, or polished porcelain specimens. For overglazed, autoglazed, polished ceramics and also FRC cylindrical specimens (n = 20 per group) were prepared. The specimens were stored in distilled water at 37°C for 48 hours prior to testing. Six samples from each group were selected randomly as negative controls which were stored in distilled water at 37°C that was changed daily. CP 38% was applied on the test specimens for 15 minutes, twice a day for 14 days. By using Knoop-microhardness tester microhardness testing for baseline, control and test specimens was conducted. Data were statistically analyzed using paired t-test, Mann-Whitney test, and Kruskal-Wallis test. Home bleaching significantly decreased the surface microhardness of all the test samples (p < 0.05), whereas the control groups did not show statistically significant changes after 2 weeks. The polished porcelain and polished composite specimens showed the most significant change in microhard-ness after bleaching process (p < 0.05). Although the type of surface preparation affects the susceptibility of the porcelain surface to the bleaching agent, no special preparation can preclude such adverse effects. The contact of home bleaching agents with esthetic restorative materials is unavoidable. Therefore protecting these restorations from bleaching agents and reglazing or at least polishing the restorations after bleaching is recommended.

Effect of CO2, Nd:YAG and Er:YAG Lasers on Microtensile Bond Strength of Composite to Bleached-Enamel.

PubMed

Basir, Mahshid Mohammadi; Rezvani, Mohammad Bagher; Chiniforush, Nasim; Moradi, Zohreh

2016-01-01

Tooth restoration immediately after bleaching is challenging due to the potential problems in achieving adequate bond strength. The aim of this study was to evaluate the effect of surface treatment with ER:YAG, ND:YAG, CO2 lasers and 10% sodium ascorbate solution on immediate microtensile bond strength of composite resin to recently bleached enamel. Ninety sound molar teeth were randomly divided into three main groups (n:30) : NB (without bleaching), HB (bleached with 38% carbamide peroxide) and OB (bleached with Heydent bleaching gel assisted by diode laser). Each group was divided into five subgroups (n:6) : Si (without surface treatment), Er (Er:YAG laser), CO2 (CO2 laser), Nd (Nd:YAG laser) and As (Immersion in 10% sodium ascorbate solution). The bonding system was then applied and composite build-ups were constructed. The teeth were sectioned by low speed saw to obtain enamel- resin sticks and submitted to microtensile bond testing. Statistical analyses were done using two- way ANOVA, Tukey and Tamhane tests. µTBS of bleached teeth irradiated with ND:YAG laser was not significantly different from NB-Nd group. Microtensile bond strength of OB-Er group was higher than NB-Er and HB-Er groups. The mean µTBS of HB-CO2 group was higher than NB-CO2 group; the average µTBS of HB-As and OB-As groups was also higher than NB-As group. Use of Nd:YAG, CO2 lasers and 10% sodium ascorbate solution could improve the bond strength in home-bleached specimens. Application of ND:YAG laser on nonbleached specimens and Er:YAG laser on office-bleached specimens led to the highest µTBS in comparison to other surface treatments in each main group.

Crown discoloration promoted by materials used in regenerative endodontic procedures and effect of dental bleaching: spectrophotometric analysis.

PubMed

Santos, Luciane Geanini Pena Dos; Felippe, Wilson Tadeu; Souza, Beatriz Dulcineia Mendes de; Konrath, Andrea Cristina; Cordeiro, Mabel Mariela Rodríguez; Felippe, Mara Cristina Santos

2017-01-01

To assess tooth crown's color after intracanal treatment with triple antibiotic paste (TAP) or calcium hydroxide (CH); cervical sealing with glass ionomer cement (GIC) or mineral trioxide aggregate (MTA); and bleaching with carbamide peroxide. After pulp removal and color spectrophotometer measurement, 50 bovine incisors were divided into 4 experimental groups and one control (untreated). Experiments were performed in phases (Ph). Ph1: TAP (ciprofloxacin, metronidazole, minocycline), TAPM (ciprofloxacin, metronidazole, amoxicillin), DAP (ciprofloxacin, metronidazole), or CH treatment groups. After 1 and 3 days (d); 1, 2, 3 weeks (w); and 1, 2, 3 and 4 months (m), color was measured and medications were removed. Ph2: GIC or MTA cervical sealing, each using half of the specimens from each group. Color was assessed after 1d, 3d; 1w, 2w, 3w; 1m and 2m. Ph3: Two bleaching sessions, each followed by color measurement. Data were analyzed with ANOVA and post-hoc Holm-Sidak method. Ph1: Specimens of TAP group presented higher color alteration (ΔE) mean than those of TAPM group. No significant difference was found among TAP or TAPM and CH, DAP or Control groups. Ph2: cervical sealing materials showed no influence on color alteration. Ph3: Different ΔE means (from different groups), prior to bleaching, became equivalent after one bleaching session. TAP induces higher color alteration than TAPM; color alteration increases over time; cervical sealing material has no influence on color alteration; and, dental bleaching was able to recover, at least partially, the tooth crown's color.

Evaluation of the effect of a home-bleaching agent on the surface characteristics of indirect esthetic restorative materials: part I--roughness.

PubMed

Torabi, Kianoosh; Rasaeipour, Sasan; Khaledi, Amir Alireza; Vojdani, Mahroo; Ghodsi, Safoura

2014-05-01

Pressing esthetic demands of good looking make people undergo bleaching procedures. However, the effect of bleaching agents on esthetic restorative materials with different surface preparations has been poorly studied. The aim of this study was to examine the effect of a homebleaching agent (carbamide peroxide: CP 38%) on the surface roughness of the polished fiber reinforced composite (FRC), overglazed, autoglazed, or polished ceramic samples. Twenty standardized cylindrical specimens were made of each of the following groups: over-glazed, autoglazed, polished porcelain and also FRC. The test specimens exposed to the CP 38%, 15 minutes, twice a day for 2 weeks according to the manufacturer's recommendation. Six samples from each group were selected randomly to form negative controls. Surface roughness measurements (Ra, micrometer) for baseline, test and control specimens were performed by use of a profilometer. Paired t-test, Mann-Whitney test, and Kruskal-Wallis test were used for statistical analyses. The data showed that bleaching with CP 38% significantly increased the surface roughness of all the test samples (p < 0.05). The type of surface preparation caused significant differences between the susceptibility of porcelain subgroups to bleaching (p < 0.05). The polished porcelain specimens showed the highest changes after bleaching. CP 38% significantly increases the surface roughness of the porcelains and FRC. The type of surface condition affects the amenability of the porcelain surface to the bleaching agent. Glazed porcelains were more resistant to roughness than the polished porcelains and also the composite. Roughening of porcelain and FRC occur following bleaching procedure. No special surface preparation of indirect esthetic restorative materials can completely preserve these materials from adverse effects of bleaching agents.

The effect of different drinks on tooth color after home bleaching

PubMed Central

Karadas, Muhammet; Seven, Nilgun

2014-01-01

Objective: This study evaluated the influence of coffee, tea, cola, and red wine staining on the color of teeth after home bleaching. Materials and Methods: A total of 45 samples were obtained from 45 sound maxillary central incisors. The home bleaching procedure was performed using 10% carbamide peroxide gel applied to the sample surface for a period of 6 h each day, for 14 days. After bleaching, baseline color measurements were taken, and the samples were immersed in four staining solutions (coffee, tea, cola, and red wine) or artificial saliva (n = 9). Following 15 min and 6 h of immersion on the first day and next day, respectively, the samples were washed with distilled water for 10 s. After 15 min, 6 h, 1 week, and 1 month immersions, the color values of each sample were remeasured and the color change values (∆E) were calculated. Color change analysis was performed using a spectrophotometer. The results were analyzed using analysis of variance and Tukey's honestly significant difference test (P <0.05). Results: Of all the staining solutions, the lowest ∆E values were observed with coffee staining versus artificial saliva (control group), for all time intervals evaluated after whitening. Although no statistically differences were observed between the coffee and control group at all the time points evaluated, there were statistically significant differences between the red wine, cola, and tea solutions. Conclusion: Following tooth whitening, patients should avoid drinks that cause tooth staining, particularly red wine, tea and cola. PMID:24966778

Bleaching and enamel surface interactions resulting from the use of highly-concentrated bleaching gels.

PubMed

Grazioli, Guillermo; Valente, Lisia Lorea; Isolan, Cristina Pereira; Pinheiro, Helena Alves; Duarte, Camila Gonçalves; Münchow, Eliseu Aldrighi

2018-03-01

Tooth bleaching is considered a non-invasive treatment, although the use of highly-concentrated products may provoke increased surface roughness and enamel demineralization, as well as postoperative sensitivity. Thus, the aim of this study was to investigate whether hydrogen peroxide (H 2 O 2 ) concentration would affect tooth bleaching effectiveness and the enamel surface properties. Enamel/dentin bovine specimens (6 × 4 mm) were immersed in coffee solution for 7 days and evaluated with a spectrophotometer (Easyshade; baseline), using the CIEL * a * b * color parameters. Hardness was measured using a hardness tester. The specimens were randomly assigned into four groups: one negative control, in which the specimens were not bleached, but they were irradiated with a laser-light source (Whitening Lase II, DMC Equipments); and three groups using distinct H 2 O 2 concentration, namely LP15% (15% Lase Peroxide Lite), LP25% (25% Lase Peroxide Sensy), and LP35% (35% Lase Peroxide Sensy), all products from DMC. The bleached specimens were also irradiated with the laser-light source. After bleaching, all specimens were evaluated using scanning electron microscopy (SEM). pH kinetics and rate was monitored during bleaching. The data were analyzed using ANOVA and Tukey's test (p < 0.05). All bleaching gels produced similar color change (p > 0.05). Concerning hardness, only the LP25% and LP35% significantly reduced hardness after bleaching; also, there was a progressive tendency for a greater percentage reduction in hardness with increased H 2 O 2 concentration of the gel (R 2  = 0.9973, p < 0.001). SEM showed that LP25% and LP35% produced an etching pattern on enamel with prism rods exposure. In conclusion, H 2 O 2 concentration above the 15% level does not increase bleaching effectiveness, and may increase the possibility for alteration of enamel hardness, surface morphology, and acidity of the medium. When using H 2 O 2 -based bleaching agents

The effect of home bleaching agents on the surface roughness of five different composite resins: A SEM evaluation.

PubMed

Cengiz, Esra; Kurtulmus-Yilmaz, Sevcan; Ulusoy, Nuran; Deniz, Sule Tugba; Yuksel-Devrim, Ece

2016-05-01

The aim of this study was to investigate the effect of hydrogen peroxide (HP) and carbamide peroxide (CP) on the surface roughness of five different composite resins using profilometer and scanning electron microscope (SEM). Thirty-six specimens (1 mm thick, 10 mm in diameter) of five composite resins were fabricated. Each composite group was equally divided into three subgroups as control, CP and HP. In control group, specimens were stored in daily refreshed distilled water during the 14-day testing period. In other groups, 10% HP (Opalescence Treswhite) and 10% CP (Opalescence PF) were applied and surface roughness values (Ra) of each specimen were measured with a profilometer at the end of 14 days. Additionally, SEM analysis was performed to evaluate the surface deformations of composite resins. Data were analyzed with Kruskal-Wallis and Mann-Whitney U tests. Ra values of composite groups exposed to bleaching agents were statistically higher than control group (p < 0.05). There was no significant difference between Ra values after HP and CP application within each composite group while SEM micrographs showed higher surface alterations at HP group compared to CP. Among the composite resins tested, Ceram-X Mono revealed the lowest Ra values after CP and HP applications as seen at SEM images. Home bleaching agents increased the surface roughness of all composites. Except CP applied Ceram-X mono specimens, Ra values of all composite resins evaluated in this study exceeded the critical limit of 0.2 μm. Ceram-X mono was the least affected composite material after bleaching application. SCANNING 38:277-283, 2016. © 2016 Wiley Periodicals, Inc. © Wiley Periodicals, Inc.

Effect of Delayed Bonding and Antioxidant Application on the Bond Strength to Enamel after Internal Bleaching.

PubMed

Kılınç, Halil İbrahim; Aslan, Tuğrul; Kılıç, Kerem; Er, Özgür; Kurt, Gökmen

2016-07-01

This study evaluated the effect of delayed bonding and antioxidant application (AA, 10% sodium ascorbate) after internal bleaching (35% carbamide peroxide) on the shear bond strength of an adhesive cement to enamel. Eighty-four human maxillary central incisors were endodontically treated. The control group remained unbleached with no AA. Experimental groups were all internally bleached. The buccal enamel was finished and polished with metallographic paper to a refinement of #600, in order to obtain a 5-mm(2) flat bonding area. An adhesive cement (Clearfil Esthetic) was placed into a plastic tube with internal diameter of 3 mm and a 3-mm height and cured on the enamel. Bonding occurred either immediately after bleaching (group Im), a 7-day delay (group 7), or a 14-day delay (group 14), and half the specimens were treated with antioxidant application (groups Im-AA, 7-AA, and 14-AA). Shear bond strength testing was performed on a universal testing machine, and data were analyzed with ANOVA and Fisher test (5%). Delaying of bonding is a useful factor for enhancing shear bond strength (p < 0.05), whereas AA only enhanced shear bond strength after 7 days delayed bleaching (p < 0.05). The highest bond strength was noted in groups 7-AA (20.51 ± 4.5 MPa), 14 (19.82 ± 4.6), 14-AA (20.27 ± 4.4), and control (20.51 ± 5.1), which were not significantly different from each other. After internal bleaching, adhesive cementation to enamel is recommended only when delayed 14 days, or delayed 7 days with sodium ascorbate application. © 2015 by the American College of Prosthodontists.

Short communication: The influence of solids concentration and bleaching agent on bleaching efficacy and flavor of sweet whey powder.

PubMed

Jervis, M G; Smith, T J; Drake, M A

2015-04-01

Recent studies have demonstrated the effect of bleaching conditions and bleaching agent on flavor and functional properties of whey protein ingredients. Solids concentration at bleaching significantly affected bleaching efficacy and flavor effects of different bleaching agents. It is not known if these parameters influence quality of sweet whey powder (SWP). The purpose of this study was to determine the effects of solids concentration and bleaching agent on the flavor and bleaching efficacy of SWP. Colored cheddar whey was manufactured, fat separated, and pasteurized. Subsequently, the whey (6.7% solids) was bleached, concentrated using reverse osmosis (RO) to 14% solids, and then spray dried, or whey was concentrated before bleaching and then spray dried. Bleaching treatments included a control (no bleaching, 50 °C, 60 min), hydrogen peroxide (HP; 250 mg/kg, 50 °C, 60 min), benzoyl peroxide (50 mg/kg, 50 °C, 60 min), lactoperoxidase (20 mg/kg of HP, 50 °C, 30 min), and external peroxidase (MaxiBright, DSM Food Specialties, Delft, the Netherlands; 2 dairy bleaching units/mL, 50 °C, 30 min). The experiment was repeated in triplicate. Sensory properties and volatile compounds of SWP were evaluated by a trained panel and gas chromatography-mass spectrometry, respectively. Bleaching efficacy (norbixin destruction) and benzoic acid were measured by HPLC. Differences in bleaching efficacy, sensory and volatile compound profiles, and benzoic acid were observed with different bleaching agents, consistent with previous studies. Solids concentration affected bleaching efficacy of HP, but not other bleaching agents. The SWP from whey bleached with HP or lactoperoxidase following RO had increased cardboard and fatty flavors and higher concentrations of lipid oxidation compounds compared with SWP from whey bleached before RO. The SWP bleached with benzoyl peroxide after RO contained less benzoic acid than SWP from whey bleached before RO. These results indicate that

Neurosensory analysis of tooth sensitivity during at-home dental bleaching: a randomized clinical trial

PubMed Central

Briso, André Luiz Fraga; Rahal, Vanessa; de Azevedo, Fernanda Almeida; Gallinari, Marjorie de Oliveira; Gonçalves, Rafael Simões; dos Santos, Paulo Henrique; Cintra, Luciano Tavares Angelo

2018-01-01

Abstract Objective The objective of this study was to evaluate dental sensitivity using visual analogue scale, a Computerized Visual Analogue Scale (CoVAS) and a neurosensory analyzer (TSA II) during at-home bleaching with 10% carbamide peroxide, with and without potassium oxalate. Materials and Methods Power Bleaching 10% containing potassium oxalate was used on one maxillary hemi-arch of the 25 volunteers, and Opalescence 10% was used on the opposite hemi-arch. Bleaching agents were used daily for 3 weeks. Analysis was performed before treatment, 24 hours later, 7, 14, and 21 days after the start of the treatment, and 7 days after its conclusion. The spontaneous tooth sensitivity was evaluated using the visual analogue scale and the sensitivity caused by a continuous 0°C stimulus was analyzed using CoVAS. The cold sensation threshold was also analyzed using the TSA II. The temperatures obtained were statistically analyzed using ANOVA and Tukey's test (α=5%). Results The data obtained with the other methods were also analyzed. 24 hours, 7 and 14 days before the beginning of the treatment, over 20% of the teeth presented spontaneous sensitivity, the normal condition was restored after the end of the treatment. Regarding the cold sensation temperatures, both products sensitized the teeth (p<0.05) and no differences were detected between the products in each period (p>0.05). In addition, when they were compared using CoVAS, Power Bleaching caused the highest levels of sensitivity in all study periods, with the exception of the 14th day of treatment. Conclusion We concluded that the bleaching treatment sensitized the teeth and the product with potassium oxalate was not able to modulate tooth sensitivity. PMID:29742258

High-performance liquid chromatography method for the determination of hydrogen peroxide present or released in teeth bleaching kits and hair cosmetic products.

PubMed

Gimeno, Pascal; Bousquet, Claudine; Lassu, Nelly; Maggio, Annie-Françoise; Civade, Corinne; Brenier, Charlotte; Lempereur, Laurent

2015-03-25

This manuscript presents an HPLC/UV method for the determination of hydrogen peroxide present or released in teeth bleaching products and hair products. The method is based on an oxidation of triphenylphosphine into triphenylphosphine oxide by hydrogen peroxide. Triphenylphosphine oxide formed is quantified by HPLC/UV. Validation data were obtained using the ISO 12787 standard approach, particularly adapted when it is not possible to make reconstituted sample matrices. For comparative purpose, hydrogen peroxide was also determined using ceric sulfate titrimetry for both types of products. For hair products, a cross validation of both ceric titrimetric method and HPLC/UV method using the cosmetic 82/434/EEC directive (official iodometric titration method) was performed. Results obtained for 6 commercialized teeth whitening products and 5 hair products point out similar hydrogen peroxide contain using either the HPLC/UV method or ceric sulfate titrimetric method. For hair products, results were similar to the hydrogen peroxide content using the cosmetic 82/434/EEC directive method and for the HPLC/UV method, mean recoveries obtained on spiked samples, using the ISO 12787 standard, ranges from 100% to 110% with a RSD<3.0%. To assess the analytical method proposed, the HPLC method was used to control 35 teeth bleaching products during a market survey and highlight for 5 products, hydrogen peroxide contents higher than the regulated limit. Copyright © 2015 Elsevier B.V. All rights reserved.

Alternative bleaching methods for Cheddar cheese whey.

PubMed

Kang, E J; Smith, T J; Drake, M A

2012-07-01

Residual annatto colorant (norbixin) in fluid Cheddar cheese whey can be bleached. The 2 approved chemical bleaching agents for whey, hydrogen peroxide (HP) and benzoyl peroxide (BP), negatively impact the flavor of dried whey protein. The objective of this study was to evaluate alternative methods for bleaching liquid whey: ultraviolet radiation (UV), acid-activated bentonite (BT), and ozone (OZ). Colored Cheddar cheese whey was manufactured followed by pasteurization and fat separation. Liquid whey was subjected to one of 5 treatments: control (CT) (no bleaching; 50 °C, 1 h), HP (250 mg/kg; 50 °C, 1 h), UV (1 min exposure; 50 °C), BT (0.5% w/w; 50 °C, 1 h), or OZ (2.2g/h, 50 °C, 1 h). The treated whey was then ultrafiltered, diafiltered, and spray-dried to 80% whey protein concentrate (WPC80). The entire experiment was replicated 3 times. Color (norbixin extraction and measurement), descriptive sensory, and instrumental volatile analyses were conducted on WPC80. Norbixin elimination was 28%, 79%, 39%, and 15% for HP, BT, UV, and OZ treatments, respectively. WPC80 from bleached whey, regardless of bleaching agent, had lower sweet aromatic and cooked/milky flavors compared to unbleached CT (P < 0.05). The HP and BT WPC80 had higher fatty flavor compared to the CT WPC80 (P < 0.05), and the UV and OZ WPC80 had distinct mushroom/burnt and animal flavors. Volatile compound results were consistent with sensory results and confirmed higher relative abundances of volatile aldehydes in UV, HP, and OZ WPC80 compared to CT and BT WPC80. Based on bleaching efficacy and flavor, BT may be an alternative to chemical bleaching of fluid whey. The 2 approved chemical bleaching agents for whey, hydrogen peroxide (HP) and benzoyl peroxide (BP), negatively impact flavor of dried whey protein, and restrictions on these agents are increasing. This study evaluated 3 alternatives to chemical bleaching of fluid whey: UV radiation, ozone, and bentonite. © 2012 Institute of Food

Nitroxide free radicals protect macular carotenoids against chemical destruction (bleaching) during lipid peroxidation

PubMed Central

Zareba, M.; Widomska, J.; Burke, J. M.; Subczynski, W. K.

2016-01-01

Macular xanthophylls (MXs) lutein and zeaxanthin are dietary carotenoids that are selectively concentrated in the human eye retina, where they are thought to protect against age-related macular degeneration (AMD) by multiple mechanisms, including filtration of phototoxic blue light and quenching of singlet oxygen and triplet states of photosensitizers. These physical protective mechanisms require that MXs be in their intact structure. Here, we investigated the protection of the intact structure of zeaxanthin incorporated into model membranes subjected to oxidative modification by water- and/or membrane-soluble small nitroxide free radicals. Model membranes were formed from saturated, monounsaturated, and polyunsaturated phosphatidylcholines (PCs). Oxidative modification involved autoxidation, iron-mediated, and singlet oxygen-mediated lipid peroxidation. The extent of chemical destruction (bleaching) of zeaxanthin was evaluated from its absorption spectra and compared with the extent of lipid peroxidation evaluated using the thiobarbituric acid assay. Nitroxide free radicals with different polarity (membrane/water partition coefficients) were used. The extent of zeaxanthin bleaching increased with membrane unsaturation and correlated with the rate of PC oxidation. Protection of the intact structure of zeaxanthin by membrane-soluble nitroxides was much stronger than that by water-soluble nitroxides. The combination of zeaxanthin and lipid-soluble nitroxides exerted strong synergistic protection against singlet oxygen-induced lipid peroxidation. The synergistic effect may be explained in terms of protection of the intact zeaxanthin structure by effective scavenging of free radicals by nitroxides, therefore allowing zeaxanthin to quench the primary oxidant, singlet oxygen, effectively by the physical protective mechanism. The redox state of nitroxides was monitored using electron paramagnetic resonance spectroscopy. Both nitroxide free radicals and their reduced form

Nitroxide free radicals protect macular carotenoids against chemical destruction (bleaching) during lipid peroxidation.

PubMed

Zareba, M; Widomska, J; Burke, J M; Subczynski, W K

2016-12-01

Macular xanthophylls (MXs) lutein and zeaxanthin are dietary carotenoids that are selectively concentrated in the human eye retina, where they are thought to protect against age-related macular degeneration (AMD) by multiple mechanisms, including filtration of phototoxic blue light and quenching of singlet oxygen and triplet states of photosensitizers. These physical protective mechanisms require that MXs be in their intact structure. Here, we investigated the protection of the intact structure of zeaxanthin incorporated into model membranes subjected to oxidative modification by water- and/or membrane-soluble small nitroxide free radicals. Model membranes were formed from saturated, monounsaturated, and polyunsaturated phosphatidylcholines (PCs). Oxidative modification involved autoxidation, iron-mediated, and singlet oxygen-mediated lipid peroxidation. The extent of chemical destruction (bleaching) of zeaxanthin was evaluated from its absorption spectra and compared with the extent of lipid peroxidation evaluated using the thiobarbituric acid assay. Nitroxide free radicals with different polarity (membrane/water partition coefficients) were used. The extent of zeaxanthin bleaching increased with membrane unsaturation and correlated with the rate of PC oxidation. Protection of the intact structure of zeaxanthin by membrane-soluble nitroxides was much stronger than that by water-soluble nitroxides. The combination of zeaxanthin and lipid-soluble nitroxides exerted strong synergistic protection against singlet oxygen-induced lipid peroxidation. The synergistic effect may be explained in terms of protection of the intact zeaxanthin structure by effective scavenging of free radicals by nitroxides, therefore allowing zeaxanthin to quench the primary oxidant, singlet oxygen, effectively by the physical protective mechanism. The redox state of nitroxides was monitored using electron paramagnetic resonance spectroscopy. Both nitroxide free radicals and their reduced form

Hydrogen peroxide bleaching induces changes in the physical properties of dental restorative materials: Effects of study protocols.

PubMed

Yu, Hao; Zhang, Chang-Yuan; Wang, Yi-Ning; Cheng, Hui

2018-03-01

The purpose of this study was to evaluate the influence of study protocols on the effects of bleaching on the surface roughness, substance loss, flexural strength (FS), flexural modulus (FM), Weibull parameters, and color of 7 restorative materials. The test materials included 4 composite resins, 1 glass-ionomer cement, 1 dental ceramic, and 1 polyacid-modified composite. The specimens were randomly divided into 4 groups (n = 20) according to different study protocols: a bleaching group at 25°C (group 25B), a bleaching group at 37°C (group 37B), a control group at 25°C (group 25C), and a control group at 37°C (group 37C). The specimens in the bleaching group were treated with 40% hydrogen peroxide for 80 min at the respective environmental temperatures. The surface roughness, substance loss, FS, FM, and color of the specimens were measured before and after treatment. FS data were also subjected to Weibull analysis, which was used to estimate of the Weibull modulus (m) and the characteristic strength (σ 0 ). Surface roughness increased and significant color changes were observed for all tested specimens after bleaching treatment, except for the ceramic. After bleaching at 37°C, the polyacid-modified composite showed significantly reduced FS, FM, m, and σ 0 values in comparison to the control specimens stored at 37°C in whole saliva. Significant differences were also found between the 37B and 25B polyacid-modified composite groups in terms of surface roughness, FS, m, σ 0 , and color changes. Varying effects of bleaching on the physical properties of dental restorative materials were observed, and the influences of the study protocols on bleaching effects were found to be material-dependent. The influence of study protocols on the effects of bleaching on the surface roughness, flexural properties, and color of dental restorative materials are material-dependent and should be considered when evaluating the effects of bleaching on dental restorative

Crown discoloration promoted by materials used in regenerative endodontic procedures and effect of dental bleaching: spectrophotometric analysis

PubMed Central

dos SANTOS, Luciane Geanini Pena; FELIPPE, Wilson Tadeu; de SOUZA, Beatriz Dulcineia Mendes; KONRATH, Andrea Cristina; CORDEIRO, Mabel Mariela Rodríguez; FELIPPE, Mara Cristina Santos

2017-01-01

Abstract Regenerative endodontic procedure (REP) has been proposed as a new approach to treat immature permanent teeth. However, materials used in REP for root canal disinfection or cervical sealing may induce tooth discoloration. Objectives To assess tooth crown’s color after intracanal treatment with triple antibiotic paste (TAP) or calcium hydroxide (CH); cervical sealing with glass ionomer cement (GIC) or mineral trioxide aggregate (MTA); and bleaching with carbamide peroxide. Material and Methods After pulp removal and color spectrophotometer measurement, 50 bovine incisors were divided into 4 experimental groups and one control (untreated). Experiments were performed in phases (Ph). Ph1: TAP (ciprofloxacin, metronidazole, minocycline), TAPM (ciprofloxacin, metronidazole, amoxicillin), DAP (ciprofloxacin, metronidazole), or CH treatment groups. After 1 and 3 days (d); 1, 2, 3 weeks (w); and 1, 2, 3 and 4 months (m), color was measured and medications were removed. Ph2: GIC or MTA cervical sealing, each using half of the specimens from each group. Color was assessed after 1d, 3d; 1w, 2w, 3w; 1m and 2m. Ph3: Two bleaching sessions, each followed by color measurement. Data were analyzed with ANOVA and post-hoc Holm-Sidak method. Results Ph1: Specimens of TAP group presented higher color alteration (ΔE) mean than those of TAPM group. No significant difference was found among TAP or TAPM and CH, DAP or Control groups. Ph2: cervical sealing materials showed no influence on color alteration. Ph3: Different ΔE means (from different groups), prior to bleaching, became equivalent after one bleaching session. Conclusions TAP induces higher color alteration than TAPM; color alteration increases over time; cervical sealing material has no influence on color alteration; and, dental bleaching was able to recover, at least partially, the tooth crown’s color. PMID:28403365

Clinical efficacy of a bleaching enzyme-based toothpaste. A double-blind controlled clinical trial.

PubMed

Llena, Carmen; Oteo, Carlos; Oteo, Jesús; Amengual, José; Forner, Leopoldo

2016-01-01

To assess the efficacy of a bleaching enzyme-based toothpaste. A randomized clinical trial was carried out, comprising 48 participants with teeth exhibiting color A3 or higher according to the Vita Classical guide. One-half of the sample received the bleaching enzyme-based toothpaste (White Kin(®)), while the other received placebo toothpaste. Both products were supplied in identical containers and had the same composition except for the active components. The teeth color was measured with a spectrophotometer. The patients were instructed to brush their teeth three times a day during 3 min with the assigned product, during 12 weeks. The color measurements were repeated after 3, 6, 9 and 12 weeks of treatment. Color variation was based on the CIE L*a*b* coordinates, ΔE and the EW index. The relationship of these variables at different observation times were performed using a generalized estimating equations model, which evaluated the effect of treatment, time and interaction. The patients using the bleaching enzyme-based toothpaste showed an increase in lightness (80.14 -treatment- versus 79.25 -control group-) and a reduction in component b*. ΔE was found higher in the treatment group (p=0.064), close to statistical significance. The bleaching enzyme-based toothpaste could be potentially efficient in the modification in tooth color progressing from the third to ninth week of treatment, tending to stabilize after the ninth week. A very low carbamide peroxide concentration, with the incorporation of lactoperoxidase, tooth paste, tends to offer clinically satisfactory results, in terms of modifications in tooth color, nevertheless no significant differences were founded when compared to the control group, with an oral hygiene controlled along the study. Copyright © 2015 Elsevier Ltd. All rights reserved.

A comparative study of different bleaching agents on the morphology of human enamel: an in vitro SEM study.

PubMed

Uthappa, Roshan; Suprith, M L; Bhandary, Shreetha; Dash, Sumit

2012-11-01

The purpose of the study was to compare two different commercial bleaching agents, Opalescence with Colgate Platinum, and 30% phosphoric acid used as aggressive agent on the morphology of human enamel. Ten freshly extracted, noncarious, human maxillary central incisors extracted for periodontal reasons were used in this study. The labial surface of the disinfected teeth were polished using a polishing paste with the help of rubber cup and a slow speed handpiece. Each tooth was sectioned at cement-enamel junction and the crown was separated into four specimens, all taken from labial surface. Group 1 was treated with Colgate Platinum for 7 hours, group 2 with Opalescence for 7 hours, group 3 was treated with 30% phosphoric acid for 30 seconds and group 4 was untreated and used as control. After the treatment period, the specimens were washed with normal saline and stored in sterile bottle and sealed. Photomicrographs obtained from the scanning electron microscopy (SEM) after surface treatments were examined for no alteration, slight alteration, moderate alteration and severe alterations. The specimens treated with commercial bleaching agents revealed no enamel surface morphologic alterations compared to control group. The specimen treated with phosphoric acid showed severe alterations. Ten percent carbamide peroxide evaluated in this study does not etch tooth enamel or alter enamel surface morphology as do conventional etching techniques. Carbamine peroxide is a safe and effective tooth whitening agent even when used for extended period of time. The enamel surface remains smooth which reduces caries due to plaque collection.

Effects of drying agents on bond strength of etch-and-rinse adhesive systems to enamel immediately after bleaching.

PubMed

Niat, Alireza Boruzi; Yazdi, Fatmeh Maleknejad; Koohestanian, Niloufar

2012-12-01

To determine the effect of drying agents and adhesive solvents on the bond strength of resin composite to enamel immediately after bleaching. Sixty healthy human premolars were bleached using 15% carbamide peroxide gel and randomly divided into three groups according to the immersing solutions applied immediately after bleaching: 70% alcohol, acetone, and distilled water. Each group was randomly divided into two subgroups according to the adhesives that were applied: an alcohol-based adhesive (Single Bond) and an acetone-based adhesive (One Step). By using rubber washers, composite Z100 was placed onto the enamel and shear bond strength was evaluated in a universal testing machine at a crosshead speed of 1 mm/min. The type of failure was also assessed using a stereomicroscope. The data were statistically analyzed by two-way ANOVA and Tukey's post-hoc test (α = 0.05). Fisher's Exact test was used to evaluate differences in the failure modes. Statistical analysis showed that the bond strength of the distilled water groups was significantly lower than that of the other groups, but the bond strengths of the two groups where a drying agent was applied were similar to that of the unbleached group. The acetone-based adhesive (One Step) provided higher bond strength than did the alcohol-based adhesive (Single Bond) (p < 0.05). There was no interaction between the two variables (p > 0.05). Fisher's Exact test showed there was no significant difference in the failure mode of all the experimental groups (p > 0.05). The application of drying agents improves the bond strength of resin composite to bleached enamel. Furthermore, the acetone-based adhesive used in the study had a higher bond strength to bleached enamel than did the alcohol-based adhesive used.

Evaluation of enamel by scanning electron microscopy green LED associated to hydrogen peroxide 35% for dental bleaching

NASA Astrophysics Data System (ADS)

Monteiro, Juliana S. C.; de Oliveira, Susana C. P. S.; Zanin, Fátima A. A.; Santos, Gustavo M. P.; Sampaio, Fernando J. P.; Gomes Júnior, Rafael Araújo; Gesteira, Maria F. M.; Vannier-Santos, Marcos A.; Pinheiro, Antônio Luiz B.

2014-02-01

Dental bleaching is a frequently requested procedure in clinical dental practice. The literature is contradictory regarding the effects of bleaching agents on both morphology and demineralization of enamel after bleaching. The aim of this study was to analyze by SEM the effect of 35% neutral hydrogen peroxide cured by green LED. Buccal surfaces of 15 pre-molars were sectioned and marked with a central groove to allow experimental and control groups on the same specimen. For SEM, 75 electron micrographs were evaluated by tree observers at 43X, 220X and 1000X. Quantitative analysis for the determination of the surface elemental composition of the samples through X-ray microanalysis by SEM was also performed. The protocol tested neither showed significant changes in mineral composition of the samples nor to dental enamel structure when compared to controls. SEM analysis allowed inferring that there were marked morphological differences between the enamel samples highlighting the need for the use of the same tooth in comparative morphological studies. The tested protocol did not cause morphological damage the enamel surface when compared to their respective controls.

Effect of temperature and bleaching agent on bleaching of liquid Cheddar whey.

PubMed

Listiyani, M A D; Campbell, R E; Miracle, R E; Barbano, D M; Gerard, P D; Drake, M A

2012-01-01

The use of whey protein as an ingredient in foods and beverages is increasing, and thus demand for colorless and mild-tasting whey protein is rising. Bleaching is commonly applied to fluid colored cheese whey to decrease color, and different temperatures and bleach concentrations are used. The objectives of this study were to compare the effects of hot and cold bleaching, the point of bleaching (before or after fat separation), and bleaching agent on bleaching efficacy and volatile components of liquid colored and uncolored Cheddar whey. First, Cheddar whey was manufactured, pasteurized, fat-separated, and subjected to one of a number of hot (68°C) or cold (4°C) bleaching applications [hydrogen peroxide (HP) 50 to 500 mg/kg; benzoyl peroxide (BP) 25 to 100 mg/kg] followed by measurement of residual norbixin and color by reflectance. Bleaching agent concentrations were then selected for the second trial. Liquid colored Cheddar whey was manufactured in triplicate and pasteurized. Part of the whey was collected (no separation, NSE) and the rest was subjected to fat separation (FSE). The NSE and FSE wheys were then subdivided and bleaching treatments (BP 50 or 100 mg/kg and HP 250 or 500 mg/kg) at 68°C for 30 min or 4°C for 16 h were applied. Control NSE and FSE with no added bleach were also subjected to each time-temperature combination. Volatile compounds from wheys were evaluated by gas chromatography-mass spectrometry, and norbixin (annatto) was extracted and quantified to compare bleaching efficacy. Proximate analysis, including total solids, protein, and fat contents, was also conducted. Liquid whey subjected to hot bleaching at both concentrations of HP or at 100mg/kg BP had greater lipid oxidation products (aldehydes) compared with unbleached wheys, 50mg/kg BP hot-bleached whey, or cold-bleached wheys. No effect was detected between NSE and FSE liquid Cheddar whey on the relative abundance of volatile lipid oxidation products. Wheys bleached with BP had

In-office tooth bleaching with 38% hydrogen peroxide promotes moderate/severe pulp inflammation and production of ll-1β, TNF-β, GPX, FGF-2 and osteocalcin in rats.

PubMed

Silva-Costa, Renata Suellen Galvão da; Ribeiro, Andressa Eveline de Lima; Assunção, Isauremi Vieira de; Araújo Júnior, Raimundo Fernandes de; Araújo, Aurigena Antunes de; Guerra, Gerlane Coelho Bernardo; Borges, Boniek Castillo Dutra

2018-06-11

To study the intensity of inflammatory infiltrate and production of interleukin-1β (ll-1β), tumor necrosis factor-β (TNF-β), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats. Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1β, TNF-β, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05). The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1β, TNF-β, and GPX in bleached groups at 24 h and strong staining for ll-1β, TNF-β, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01). Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days.

Comparison of bleaching efficacy of two bleaching agents on teeth discoloured by different antibiotic combinations used in revascularization.

PubMed

Yasa, Bilal; Arslan, Hakan; Akcay, Merve; Kavrik, Fevzi; Hatirli, Huseyin; Ozkan, Bulent

2015-07-01

To investigate the whitening effects of different bleaching agents on teeth discoloured by different antibiotic combinations of ciprofloxacin and metronidazole with minocycline, doxycycline, amoxicillin or cefaclor. Forty extracted bovine incisors were collected and discoloured with triple antibiotic pastes (TAP) with minocycline, doxycycline, amoxicillin and cefaclor throughout 30 days. The specimens were then randomly divided into two subgroups and each group received different bleaching materials: 35% hydrogen peroxide and sodium perborate. Spectrophotometric measurements were obtained on the buccal surfaces of the crown, firstly in the beginning, then on the 4th, 8th and 12th days after the placement of the bleaching materials. The acceptability threshold was set to 3.5. The ∆E values were calculated and the data was analysed using the repeated measures analysis of variance (P = .05). All the test groups induced colour changes exceeding the acceptability threshold 30 days after the antibiotic pastes were placed. The 35% hydrogen peroxide was more effective than sodium perborate in the whitening of discoloured teeth by antibiotic pastes (P = .001). The whitening effect after the 8th and 12th days was significantly more than after 4 days of treatment (P <.001). The discolouration caused by the TAP with minocycline and cefaclor showed greater whitening compared to the TAP with doxycycline and amoxicillin groups (P <.05). The whitening treatment effect of 35% hydrogen peroxide on teeth discoloured by antibiotic pastes seems to have significantly outperformed the sodium perborate treatment. Both bleaching agents were allowed to bleach the teeth gradually each day and the effects on the 8th and 12th days were superior to the one on the 4th day. The use of 35% hydrogen peroxide could be advantageous to bleach the teeth discoloured with antibiotic pastes compared to sodium perborate.

The bleaching of teeth: a review of the literature.

PubMed

Joiner, Andrew

2006-08-01

To review current knowledge of tooth whitening with respect to external bleaching methods. The scope is the external bleaching of vital teeth and focuses on mechanisms; in vivo and in vitro measurement methods, and factors influencing the efficacy of the whitening process. "Medline" and "ISI Web of Science" databases from 1966 and 1974, respectively were searched electronically with key words tooth, teeth, colo*r, white*, bleach* and peroxide. The importance of tooth whitening for patients and consumers has seen a dramatic increase in the number of products and procedures over recent years, with a concomitant rise in publications on this topic. Literature suggests that the mechanisms of tooth whitening by peroxide occur by the diffusion of peroxide through enamel to cause oxidation and hence lightening of coloured species, particularly within the dentinal regions. A number of approaches are available for measuring changes in tooth colour. These include visual measurements by trained clinicians and instrumental measurements using spectrophotometry, chromameters and digital image analysis. The key factors that affect tooth whitening efficacy by peroxide containing products are concentration and time. In general, higher concentrations are faster than lower concentrations. However, lower concentrations can approach the efficacy of higher concentrations with extended treatment times. Alternative bleach systems to peroxide have received only minor attention. The efficacy of light activated systems versus non-light activated controls in clinical studies is limited and conflicting. Other factors which can influence tooth bleaching outcome include type of stain, initial tooth colour and subject age.

Release time of residual oxygen after dental bleaching with 35% hydrogen peroxide: effect of a catalase-based neutralizing agent.

PubMed

Guasso, Bárbara; Salomone, Paloma; Nascimento, Paulo Cícero; Pozzobon, Roselaine Terezinha

2016-01-01

This article assessed the effect of a catalase-based agent on residual oxygen (O2) release from teeth exposed to 35% hydrogen peroxide (H2O2). The use of the catalase-based neutralizer agent for 2-3 minutes was able to release residual O2 5 days after exposure to a 35% H2O2-based bleaching gel.

Effects of pH values of hydrogen peroxide bleaching agents on enamel surface properties.

PubMed

Xu, B; Li, Q; Wang, Y

2011-01-01

This study investigated the influence of pH values of bleaching agents on the properties of the enamel surface. Sixty freshly extracted premolars were embedded in epoxy resin and mesiodistally sectioned through the buccal aspect into two parts. The sectioned slabs were distributed among six groups (n=10) and treated using different solutions. Group HCl was treated with HCl solution (pH=3.0) and served as a positive control. Group DW, stored in distilled water (pH=7.0), served as a negative control. Four treatment groups were treated using 30% hydrogen peroxide solutions with different pH values: group HP3 (pH=3.0), group HP5 (pH=5.0), group HP7 (pH=7.0), and group HP8 (pH=8.0). The buccal slabs were subjected to spectrophotometric evaluations. Scanning electron microscopy investigation and Micro-Raman spectroscopy were used to evaluate enamel surface morphological and chemical composition alterations. pH value has a significant influence on the color changes after bleaching (p<0.001). Tukey's multiple comparisons revealed that the order of color changes was HP8, HP7>HP5, HP3>HCl>DW. No obvious morphological alterations were detected on the enamel surface in groups DW, HP7, and HP8. The enamel surface of groups HCl and HP3 showed significant alterations with an erosion appearance. No obvious chemical composition changes were detected with respect to Micro-Raman analysis. Within the limitations of this study, it was concluded that no obvious morphological or chemical composition alterations of enamel surface were detected in the neutral or alkaline bleaching solutions. Bleaching solutions with lower pH values could result in more significant erosion of enamel, which represented a slight whitening effect.

Microtensile bond strength of enamel after bleaching.

PubMed

Lago, Andrea Dias Neves; Garone-Netto, Narciso

2013-01-01

To evaluate the bond strength of a composite resin to the bovine enamel bleached with 35% hydrogen peroxide. It was used an etching-and-rinse adhesive system employed immediately, 7 and 14 days after the bleaching. Twenty bovine teeth were randomly distributed into 4 groups (n = 5), 3 experimental and 1 control. G1: Unbleached + restoration 14 days after storage in artificial saliva (control); G2: Bleached + restoration immediately after bleaching; G3: Bleached + restoration 7 days after bleaching; G4: Bleached + restoration 14 days after bleaching. Their buccal enamel surfaces were flattened, and a 25 mm² (5 × 5 mm) area from each one of these regions was outlined so as to standardize the experimental region. Universal hybrid composite resin Filtek™Z350 was inserted into four layers of 1 mm each and photo-activated. The bond strength was quantitatively evaluated by a microtensile test (1.0 mm/min) 24 h after the restorative procedures. The failure mode was assessed through scanning electron microscopy (SEM). There was a significant reduction in the bond strength of the restored teeth immediately after the bleaching (G2). There were no significant differences in enamel bond strength between groups G1, G3, and G4. There was a predominance of adhesive and mixed (cohesive + adhesive) failure in all groups. The 7-day-period after the end of the bleaching with 35% hydrogen peroxide was enough to achieve the appropriate values of bond strength to the enamel.

In-office tooth bleaching with 38% hydrogen peroxide promotes moderate/severe pulp inflammation and production of ll-1β, TNF-β, GPX, FGF-2 and osteocalcin in rats

PubMed Central

2018-01-01

Abstract Objectives: To study the intensity of inflammatory infiltrate and production of interleukin-1β (ll-1β), tumor necrosis factor-β (TNF-β), fibroblast growth factor-2 (FGF-2), glutathione peroxidase (GPX), and osteocalcin in response to in-office tooth bleaching in rats. Material and Methods: Twenty male Wistar rats were randomized into four groups (n=5) according to the received treatment (tooth bleaching or no treatment - control) and the period of euthanasia after treatment (24 h or 10 days). We performed tooth bleaching using a 38% hydrogen peroxide gel on maxillary and mandibular incisors. After euthanasia, incisors (20 per group) were processed for histological analysis, immunohistochemistry staining of ll-1β, TNF-β, FGF-2 and GPX and osteocalcin by immunofluorescence. We analyzed data using the Mann-Whitney and Kruskal-Wallis/Dunn tests (p<0.05). Results: The bleached groups presented statistically significant differences regarding the pulp inflammation stage compared with the control groups. Bleached teeth showed moderate/severe inflammatory infiltrate and control groups presented absent inflammatory cells or a negligible number of mononuclear cells (p<0.001) at two times (24 h and 10 days). There was strong staining for ll-1β, TNF-β, and GPX in bleached groups at 24 h and strong staining for ll-1β, TNF-β, GPX and FGF-2 at 10 days. After 10 days of tooth bleaching, the bleached group showed a statistically superior amount of osteocalcin than the other groups (p<0.01). Conclusions: Tooth bleaching with 38% hydrogen peroxide causes severe pulp inflammation, but characteristics of tissue repair after 10 days.

Efficacy of Home-use Bleaching Agents Delivered in Customized or Prefilled Disposable Trays: A Randomized Clinical Trial.

PubMed

Carlos, N R; Bridi, E C; Amaral, Flb; França, Fmg; Turssi, C P; Basting, R T

The purpose of this study was to evaluate bleaching methods containing hydrogen peroxide (HP) or carbamide peroxide (CP), dispensed in customized or prefilled trays, in terms of color change, tooth sensitivity, gingival irritation, acceptance, and comfort. Seventy-five volunteers were randomly selected and distributed according to the whitening agent (n=25): 10% HP dispensed in prefilled trays (Opalescence Go 10%) and 9.5% HP (Pola Day) and 10% CP both delivered in customized trays (Opalescence PF 10%). HP was applied for 30 min/d for 14 days (d), and CP for 8 h/d for 14 days. Evaluations were performed at baseline and at 7 days and 14 days of treatment. Color change was measured with Commission internationale de l'éclairage color coordinates (L*, a*, b*), Vita Classical, and 3D Master scales. A visual analog scale was used to assess tooth sensitivity, acceptance of the method and degree of comfort of the tray. Gingival irritation was evaluated as present or absent and localized or generalized. Regarding gingival irritation, tray acceptance, and tooth sensitivity, no differences were observed among the groups at any time (p>0.05). As for degree of comfort, 10% HP showed lower scores (comfortable) than 10% CP, with significant differences (p<0.05) from the other groups (comfortable to very comfortable). In terms of ΔL, Δa, and ΔE, no difference was observed among the groups or between the time periods (p>0.05). The Δb average was higher at 14 days (p<0.05), and there was no difference among the groups (p>0.05). Localized gingival irritation was observed in both tray methods. Mild tooth sensitivity was observed with time, regardless of the bleaching agent concentration or the application time. Color change was similar for all the groups at 7 days and 14 days, but there was a greater reduction in the yellow hue at 14 days. All the bleaching methods were highly accepted and effective in promoting whitening. Although prefilled trays are generally comfortable, they

Ultrasonic pilot-scale reactor for enzymatic bleaching of cotton fabrics.

PubMed

Gonçalves, Idalina; Herrero-Yniesta, Victor; Perales Arce, Iratxe; Escrigas Castañeda, Monica; Cavaco-Paulo, Artur; Silva, Carla

2014-07-01

The potential of ultrasound-assisted technology has been demonstrated by several laboratory scale studies. However, their successful industrial scaling-up is still a challenge due to the limited pilot and commercial sonochemical reactors. In this work, a pilot reactor for laccase-hydrogen peroxide cotton bleaching assisted by ultrasound was scaled-up. For this purpose, an existing dyeing machine was transformed and adapted by including piezoelectric ultrasonic devices. Laboratory experiments demonstrated that both low frequency, high power (22 kHz, 2100 W) and high frequency, low power ultrasounds (850 kHz, 400 W) were required to achieve satisfactory results. Standard half (4 g/L H2O2 at 90 °C for 60 min) and optical (8 g/L H2O2 at 103 °C for 40 min) cotton bleaching processes were used as references. Two sequential stages were established for cotton bleaching: (1) laccase pretreatment assisted by high frequency ultrasound (850 kHz, 400 W) and (2) bleaching using high power ultrasound (22 kHz, 2100 W). When compared with conventional methods, combined laccase-hydrogen peroxide cotton bleaching with ultrasound energy improved the whitening effectiveness. Subsequently, less energy (temperature) and chemicals (hydrogen peroxide) were needed for cotton bleaching thus resulting in costs reduction. This technology allowed the combination of enzyme and hydrogen peroxide treatment in a continuous process. The developed pilot-scale reactor offers an enhancement of the cotton bleaching process with lower environmental impact as well as a better performance of further finishing operations. Copyright © 2014 Elsevier B.V. All rights reserved.

Effectiveness of a new non-hydrogen peroxide bleaching agent after single use - a double-blind placebo-controlled short-term study.

PubMed

Bizhang, Mozhgan; Domin, Julia; Danesh, Gholamreza; Zimmer, Stefan

2017-01-01

Tooth whitening represents perhaps the most common aesthetic procedure in dentistry worldwide. The efficacy of bleaching depends on three aspects: bleaching agent, bleaching method, and tooth color. This in vivo study aimed to examine whitening effects on frontal teeth of the upper and lower jaws using an over-the-counter (OTC) non-hydrogen peroxide bleaching agent in comparison to a placebo after one single use. Forty subjects (25 female; 15 male) participated in this double-blind randomized placebo-controlled trial. The subjects were randomly allocated to two groups (n=20). The test group received the OTC product (iWhite Instant) and the placebo group received an identically composed product except for the active agents. Each subject was treated with a prefilled tray containing iWhite Instant or the placebo for 20 minutes. The tooth shade of the front teeth (upper and lower jaws) was assessed before (E_0), immediately after (E_1) and 24 h after treatment (E_2), using a shade guide (VITA classical). Statistical testing was accomplished using the Mann-Whitney U test (p<0.001). The dropout rate was 0%. There were no significant differences at E_0 between placebo and test groups regarding the tooth color. Differences in tooth color changes immediately after (ΔE1_0) and 24 h after treatment (ΔE2_0) were calculated for both groups. The mean values (standard deviations) of tooth color changes for ΔE1_0 were 2.26 (0.92) in the test group and 0.01 (0.21) in the placebo group. The color changes for ΔE2_0 showed mean values of 2.15 (1.10) in the test group and 0.07 (0.35) in the placebo group. For ΔE1_0 and ΔE2_0 significant differences were found between the groups. In this short-term study, the results showed that a non-hydrogen peroxide bleaching agent has significant whitening effects immediately and 24 h after a single-use treatment.

Effect of at-home bleaching with different thickeners and aging on physical properties of a nanocomposite.

PubMed

Gouveia, Thayla Hellen Nunes; Públio, Juliana do Carmo; Ambrosano, Glaucia Maria Bovi; Paulillo, Luís Alexandre Maffei Sartini; Aguiar, Flávio Henrique Baggio; Lima, Débora Alves Nunes Leite

2016-01-01

To evaluate the influence of 16% carbamide peroxide (CP) containing different thickeners on the physical characteristics of a nanocomposite resin submitted or not to accelerated artificial aging (AAA). One hundred samples were randomly distributed into two groups (n = 50) according to AAA. Each group was divided into 5 subgroups (n = 10) depending on the bleaching/thickener treatment: CP + carbopol, CP + natrosol, carbopol, natrosol, and no treatment (control). The physical properties tested were color (ΔE), gloss (GU), mean roughness (Ra), and Knoop microhardness (KHN). The resin surface was performed with atomic force microscopy (AFM). The color (variable Δ E) was assessed with two-way analysis of variance (ANOVA) and additionally with Tukey's and Dunnett's tests, the roughness values were submitted to Kruskal-Wallis, Dunn's, and Mann-Whitney's tests. Data on gloss and KHN were submitted to two-way ANOVA and Tukey's test (α = 0.05). Among the physical properties evaluated, CP + carbopol promoted a reduction in composite microhardness only, thus differing statistically from the controls. As for CP + natrosol, such a change was not observed. The aging process reduced all the physical properties, thus differing statistically from the nonaging group. CP + carbopol increased the roughness and decreased the gloss of aged resins, whereas natrosol reduced gloss only, which differed statistically from the controls. AFM showed evidence of the loss of organic matrix and exposure to load particles in the aged samples. Therefore, the replacement of carbopol with natrosol provided maintenance of the composite microhardness following bleaching. The aging process reduced the physical properties evaluated, and some changes were enhanced by the application of bleaching.

The influence of bleaching agent and temperature on bleaching efficacy and volatile components of fluid whey and whey retentate.

PubMed

Fox, A J; Smith, T J; Gerard, P D; Drake, M A

2013-10-01

Fluid whey or retentate are often bleached to remove residual annatto Cheddar cheese colorant, and this process causes off-flavors in dried whey proteins. This study determined the impact of temperature and bleaching agent on bleaching efficacy and volatile components in fluid whey and fluid whey retentate. Freshly manufactured liquid whey (6.7% solids) or concentrated whey protein (retentate) (12% solids, 80% protein) were bleached using benzoyl peroxide (BP) at 100 mg/kg (w/w) or hydrogen peroxide (HP) at 250 mg/kg (w/w) at 5 °C for 16 h or 50 °CC for 1 h. Unbleached controls were subjected to a similar temperature profile. The experiment was replicated three times. Annatto destruction (bleaching efficacy) among treatments was compared, and volatile compounds were extracted and separated using solid phase microextraction gas chromatography mass spectrometry (SPME GC-MS). Bleaching efficacy of BP was higher than HP (P < 0.05) for fluid whey at both 5 and 50 °C. HP bleaching efficacy was increased in retentate compared to liquid whey (P < 0.05). In whey retentate, there was no difference between bleaching with HP or BP at 50 or 5 °C (P > 0.05). Retentate bleached with HP at either temperature had higher relative abundances of pentanal, hexanal, heptanal, and octanal than BP bleached retentate (P < 0.05). Liquid wheys generally had lower concentrations of selected volatiles compared to retentates. These results suggest that the highest bleaching efficacy (within the parameters evaluated) in liquid whey is achieved using BP at 5 or 50 °C and at 50 °C with HP or BP in whey protein retentate. © 2013 Institute of Food Technologists®

Effects on gastric mucosa induced by dental bleaching--an experimental study with 6% hydrogen peroxide in rats.

PubMed

Paula, Anabela Baptista; Dias, Maria Isabel; Ferreira, Manuel Marques; Carrilho, Teresa; Marto, Carlos Miguel; Casalta, João; Cabrita, António Silvério; Carrilho, Eunice

2015-10-01

The value of aesthetic dentistry has precipitated several developments in the investigation of dental materials related to this field. The free marketing of these products is a problem and it is subject to various interpretations regarding its legality. There are several techniques for tooth whitening, the most used one being the external bleaching. It is the later version of such technique that poses the greatest danger of ingesting the product. The present study analysed the systemic effect of these products when they are swallowed. This experimental study aimed to observe the effects of a tooth whitening product, whose active agent is 6% hydrogen peroxide, on the gastric mucosa of healthy and non-tumour gastric pathology animals. Fifty Wistar-Han rats were used and then distributed into 5 groups, one for control and four test groups in which the bleaching product was administered in animals with and without non-tumour gastric pathology (induced by the administration of 1 sample of 50% ethanol and 5% of drinking water during 6 days) at different times of study by gavage. There was a decrease in body weight in animals of groups handled during the study period, which was most pronounced in IV and VA groups. Changes in spleen weight relative to body weight revealed no statistically significant changes. An analysis of the frequency was performed on the results of macroscopic observation of the gastric mucosa. The gastric mucosa revealed lesions in all manipulated groups, being more frequent in groups III and IV. It appears that there is a synergism when using hydrogen peroxide and 50% ethanol in the same group. Therefore, it seems that there are some signs of toxicity 3 to 4 days after administration of 6% hydrogen peroxide. The prescription of these therapies must be controlled by the clinician and the risks must be minimized.

Use of xylanase in the TCF bleaching of eucalyptus kraft pulp

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roncero, B.; Vidal, T.; Torres, A.L.

1996-10-01

Environmental pressures are forcing the pulp and paper industry to develop new technologies that reduce or eliminate the presence of various contaminants in bleaching plant effluents. Oxygen delignification techniques, replacement of elemental chlorine with chlorine dioxide, ozone, hydrogen peroxide and new agents as well as the use of xylanase enzymes for biobleaching, reduce o eliminate the production of chlorinated organic substances. This paper compares the sequence XOZP with OZP in the bleaching of Eucalyptus globulus kraft pulps. It has been studied the influence of enzymatic treatment on the consumption of bleaching agents: ozone and hydrogen peroxide. Chemical, physical, optical andmore » refining properties of pulps, as well as COD and colour of effluent are also studied. The xylanase treatment is positive and it is possible to manufacture fully bleached pulps at high brightness and viscosity without using chlorine compounds at a low ozone and hydrogen peroxide consumption.« less

Catalase and sodium fluoride mediated rehabilitation of enamel bleached with 37% hydrogen peroxide.

PubMed

Thakur, Ruchi; Shigli, Anand L; Sharma, Divya; Thakur, Gagan

2015-01-01

Bleaching agents bring about a range of unwanted changes in the physical structure of enamel which needs to be restored qualitatively and timely. Catalase being an antioxidant ensures the effective removal of free radicals and improvement in fluoride mediated remineralization from the enamel microstructure which if retained may harm the integrity and affect the hardness of enamel. Thirty freshly extracted incisors were sectioned to 6 slabs which were divided into 5 groups: Group A, control; Group B, treatment with 37% hydrogen peroxide (HP); Group C, treatment with 37% HP and catalase, Group D, treatment with 37% HP and 5% sodium fluoride application, Group E, treatment with 37% HP followed by catalase and 5% sodium fluoride. Scanning electron microscope and microhardness analysis were done for all slabs. One-way ANOVA test was applied among different groups. Vicker's microhardness number (VHN) of Group B and C was significantly lower. No significant difference between VHN of Group B and C. VHN of Group D was significantly higher than Group A, B, and C; but significantly lower than Group E. VHN of Group E was significantly higher than any other experimental group. One-way ANOVA revealed a highly significant P value (P = 0.0001) and so Tukey's post-hoc Test for the group comparisons was employed. Subsequent treatment of bleached enamel with catalase and fluoride varnish separately results in repairing and significantly increasing the microhardness.

A clinical evaluation of 10 percent vs. 15 percent carbamide peroxide tooth-whitening agents.

PubMed

Kihn, P W; Barnes, D M; Romberg, E; Peterson, K

2000-10-01

Agents with carbamide peroxide, or CP, in various concentrations are widely prescribed for at-home tooth whitening. It is not clear, however, if the more concentrated gels will whitening teeth to a greater extent, as no controlled clinical trials have been reported. The authors conducted a double-blind study of human subjects to evaluate whether a 15 percent CP tooth-whitening system was more effective than a 10 percent CP system, and to determine if tooth sensitivity increased with use of the higher concentration. The authors recruited 57 subjects with maxillary anterior teeth of shade A3 or darker (as gauged against a value-oriented shade guide). The subjects were 18 to 65 years of age and in good general and dental health. After matching the subjects by sex and age, the authors randomly assigned them to either a control group, which used a 10 percent CP whitening agent, or an experimental group, which used a 15 percent CP agent. The results indicated that there was no significant difference in shade change between the groups after one week of treatment (t = 1.455, P = .05), but there was a significant difference at the end of the treatment period (t = 2.303, P < .05), as well as two weeks after treatment concluded (t = 2.248, P < .05). There was no significant difference in sensitivity (t = 1.399, P > .05). There was a significant difference in color change between the 10 percent CP and 15 percent CP groups at the end of the study period. There was no significant difference in level of tooth sensitivity between the two groups, and the incidence was equal; there was, however, a significant difference in variability of tooth sensitivity between the two groups. If performed under the careful guidance of a dentist, at-home whitening is an effective treatment, regardless of whether 10 percent CP or 15 percent CP is used. There may be added color change and varying sensitivity with the use of 15 percent CP.

Toxicity and efficiency study of plant extracts-based bleaching agents.

PubMed

Baldea, Ioana; Olteanu, Diana Elena; Filip, Adriana Gabriela; Cenariu, Mihai; Dudea, Diana; Tofan, Alina; Alb, Camelia; Moldovan, Marioara

2017-05-01

Tooth bleaching is one of the most required dental esthetic treatments. However, it can generate side effects like oral irritation, enamel alteration, tooth sensitivity, especially caused by hydrogen peroxide, the main bleaching component of the commercial products. Therefore, development of new tooth bleaching agents, based on natural products, with comparable esthetic results and lower side effects is needed. The aim of this study was to evaluate the biological effects and bleaching efficacy of four experimental bleaching agents, derived from fruit juices, against the commercially available Opalescence (Ultradent, USA). Organic acid composition of the gels was characterized by HPLC. Bleaching efficiency was tested by spectrophotometry on composite restorative materials. Biological testing was done in vitro, on human fibroblasts. Cells were exposed to dilutions of the bleaching gel-conditioned medium. Viability was measured by MTS, apoptosis by FACS-AnnexinV FITC/Propidium iodide, NF-kB activation by western blot, malondyaldehide, and superoxide dismutase activity by spectrophotometry. All gels exhibited physical stability and dental bleaching capabilities. Experimental gels induced significantly better viability and apoptosis rates, lower lipid peroxidation, and increased antioxidant defense, compared to Opalescence. The studied experimental gel formulations exhibited a good safety profile in vitro, as well as bleaching efficiency on restorative composite materials. These data open new possibilities for the use of new natural products in dental bleaching treatments that can insure significant esthetic results and lower side effects.

Effects on gastric mucosa induced by dental bleaching – an experimental study with 6% hydrogen peroxide in rats

PubMed Central

PAULA, Anabela Baptista; DIAS, Maria Isabel; FERREIRA, Manuel Marques; CARRILHO, Teresa; MARTO, Carlos Miguel; CASALTA, João; CABRITA, António Silvério; CARRILHO, Eunice

2015-01-01

The value of aesthetic dentistry has precipitated several developments in the investigation of dental materials related to this field. The free marketing of these products is a problem and it is subject to various interpretations regarding its legality. There are several techniques for tooth whitening, the most used one being the external bleaching. It is the later version of such technique that poses the greatest danger of ingesting the product. The present study analysed the systemic effect of these products when they are swallowed. Objective This experimental study aimed to observe the effects of a tooth whitening product, whose active agent is 6% hydrogen peroxide, on the gastric mucosa of healthy and non-tumour gastric pathology animals. Material and Methods Fifty Wistar-Han rats were used and then distributed into 5 groups, one for control and four test groups in which the bleaching product was administered in animals with and without non-tumour gastric pathology (induced by the administration of 1 sample of 50% ethanol and 5% of drinking water during 6 days) at different times of study by gavage. There was a decrease in body weight in animals of groups handled during the study period, which was most pronounced in IV and VA groups. Changes in spleen weight relative to body weight revealed no statistically significant changes. An analysis of the frequency was performed on the results of macroscopic observation of the gastric mucosa. Results The gastric mucosa revealed lesions in all manipulated groups, being more frequent in groups III and IV. It appears that there is a synergism when using hydrogen peroxide and 50% ethanol in the same group. Conclusion Therefore, it seems that there are some signs of toxicity 3 to 4 days after administration of 6% hydrogen peroxide. The prescription of these therapies must be controlled by the clinician and the risks must be minimized. PMID:26537721

Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel.

PubMed

Soares, Ana Flávia; Bombonatti, Juliana Fraga Soares; Alencar, Marina Studart; Consolmagno, Elaine Cristina; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia

2016-01-01

Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10), each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL) or diode laser/violet LED (VHL) (experimental): Control (C); 35% Total Blanc Office (TBO35HL); 35% Lase Peroxide Sensy (LPS35HL); 25% Lase Peroxide Sensy II (LPS25HL); 15% Lase Peroxide Lite (LPL15HL); and 10% hydrogen peroxide (experimental) (EXP10VHL). pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm). ANOVA and Tukey´s tests were applied (α=0.05). The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups.

Effectiveness of and Dental Sensitivity to At-home Bleaching With 4% and 10% Hydrogen Peroxide: A Randomized, Triple-blind Clinical Trial.

PubMed

Chemin, K; Rezende, M; Loguercio, A D; Reis, A; Kossatz, S

To evaluate the risk for and intensity of tooth sensitivity and color change of at-home dental bleaching with 4% and 10% hydrogen peroxide (HP). For this study, 78 patients were selected according to the inclusion and exclusion criteria and randomized into two groups: HP 4 (White Class 4%, FGM) and HP 10 (White Class 10%, FGM). In both groups, the at-home bleaching was performed for a period of 30 minutes twice a day for two weeks. The color was assessed by Vita Classical, Vita Bleachedguide 3D-MASTER and spectrophotometer Vita Easyshade (Vita Zahnfabrik) at baseline, during bleaching (first and second weeks) and after bleaching (one month). Patients recorded their tooth sensitivity using a numeric rating scale (0-4) and visual analog scale (0-10). Data from color change (DeltaE data) was submitted to two-way analysis of variance. The color change data in Delta SGU from the two shade guide units were compared with the Mann Whitney test. The risk of tooth sensitivity was evaluated by χ 2 test and the intensity of tooth sensitivity from both scales was evaluated by a Mann-Whitney test (α=0.05). The absolute risk and intensity of tooth sensitivity was higher in the group that used HP 10 than the one that used HP 4. Data from change in the number of shade guide units and color variation after one month of bleaching for both groups showed significant whitening, with no difference between groups. At-home bleaching is effective with 4% and 10% HP concentrations, but 10% HP increased the absolute risk and intensity of tooth sensitivity during at-home bleaching.

Application of TAED/H2O2 system for low temperature bleaching of crude cellulose extracted from jute fiber

NASA Astrophysics Data System (ADS)

Wen, Zuoqiang; Zou, Linbo; Wang, Weiming

2018-03-01

Tetraacetylethylenediamine (TAED) activated hydrogen peroxide system had been applied for bleaching of crude cellulose extracted from jute fiber. Comparing with conventional hydrogen peroxide bleaching system, those results showed that bleaching temperature and time could be effectively reduced, and a preferable whiteness could be produced under faint alkaline condition. And the optimum conditions for activated bleaching system could be summarized as molar ratio of H2O2/TAED 1:0.7, pH 8, pure hydrogen peroxide 0.09 mol/L, temperature 70 °C and time 60min.

Influence of remineralizing gels on bleached enamel microhardness in different time intervals.

PubMed

Borges, Alessandra Bühler; Yui, Karen Cristina Kazue; D'Avila, Thaís Corrêa; Takahashi, Camila Lurie; Torres, Carlos Rocha Gomes; Borges, Alexandre Luis Souto

2010-01-01

This study evaluated the influence of bleaching gel pH, the effect of applying remineralizing gels after bleaching and the effect of artificial saliva on enamel microhardness. Seventy bovine incisors were divided into three groups: Group 1 (n=10) received no bleaching procedure (control); Group 2 was bleached with a 35% hydrogen peroxide neutral gel (n=30) and Group 3 was bleached with a 35% hydrogen peroxide acid gel (n=30). Each experimental group was subdivided into three groups (n=10) according to the post-bleaching treatment: storage in artificial saliva, application of a fluoride gel and application of a combination of calcium and fluoride gel. The specimens were stored in artificial saliva for 7, 15 and 30 days and enamel microhardness was evaluated. The Vickers microhardness data were analyzed by three-way RM ANOVA, which revealed a significant difference only for treatment factor. The Tukey's test showed that the groups bleached followed by no additional treatment exhibited microhardness means significantly lower than the bleached groups treated with remineralizing gels. The Dunnet's test showed a significant difference only for the group bleached with acid gel without remineralizing treatment compared to the control group measured immediately after bleaching. It was concluded that acid bleaching gel significantly reduced enamel microhardness and that use of remineralizing gels after bleaching can significantly enhance the microhardness of bleached enamel.

Effects of combined use of light irradiation and 35% hydrogen peroxide for dental bleaching on human enamel mineral content.

PubMed

Berger, Sandrine Bittencourt; Cavalli, Vanessa; Martin, Airton Abrahão; Soares, Luis Eduardo Silva; Arruda, Marco Aurelio Zezzi; Brancalion, Marcel Luis; Giannini, Marcelo

2010-08-01

The objective of this study was to evaluate the effects of the combined use of light irradiation (LIR, halogen light, or LED/diode laser) and 35% hydrogen peroxide (35%HP) on human enamel mineral content. The use of high-intensity light has been indicated for acceleration of the rate of chemical bleaching; however, it is not known whether LIR can promote additional effects on enamel surfaces during the bleaching. One hundred enamel samples were obtained from third molars and randomly divided into 10 groups (n = 10). The control group (CG) remained untreated. Three whitening products were used: Whiteness HP Maxx, Pola Office, and Opalescence Xtra. Bleaching consisted of one session, and the products were applied three times to each specimen for 10 min each. The products were subjected, or not, to LIR during treatment with halogen light or LED/diode laser. The mineral concentration of enamel was determined before and after treatments using an FT-Raman spectroscope (FT-RS), and the amount of calcium lost from the bleached enamel surfaces was quantified with an atomic absorption spectrometer (AAS). FT-RS results showed a decreased mineral content after all treatments, with the exception of Pola Office when irradiated with LED/diode laser and the CG. The losses of calcium detected for Pola Office and Opalescence Xtra were similar for the three situations (without or with light irradiations), whereas for Whiteness HP Maxx the lowest calcium loss was detected without LIR. Most of the bleaching treatments investigated, in combination with LIR or not, can reduce the mineral content of enamel surface. LIR increased the calcium loss for Whiteness HP Maxx; no effects were observed for Pola Office and Opalescence Xtra.

Influence of pH, bleaching agents, and acid etching on surface wear of bovine enamel

PubMed Central

Soares, Ana Flávia; Bombonatti, Juliana Fraga Soares; Alencar, Marina Studart; Consolmagno, Elaine Cristina; Honório, Heitor Marques; Mondelli, Rafael Francisco Lia

2016-01-01

ABSTRACT Development of new materials for tooth bleaching justifies the need for studies to evaluate the changes in the enamel surface caused by different bleaching protocols. Objective The aim of this study was to evaluate the bovine dental enamel wear in function of different bleaching gel protocols, acid etching and pH variation. Material and Methods Sixty fragments of bovine teeth were cut, obtaining a control and test areas. In the test area, one half received etching followed by a bleaching gel application, and the other half, only the bleaching gel. The fragments were randomly divided into six groups (n=10), each one received one bleaching session with five hydrogen peroxide gel applications of 8 min, activated with hybrid light, diode laser/blue LED (HL) or diode laser/violet LED (VHL) (experimental): Control (C); 35% Total Blanc Office (TBO35HL); 35% Lase Peroxide Sensy (LPS35HL); 25% Lase Peroxide Sensy II (LPS25HL); 15% Lase Peroxide Lite (LPL15HL); and 10% hydrogen peroxide (experimental) (EXP10VHL). pH values were determined by a pHmeter at the initial and final time periods. Specimens were stored, subjected to simulated brushing cycles, and the superficial wear was determined (μm). ANOVA and Tukey´s tests were applied (α=0.05). Results The pH showed a slight decrease, except for Group LPL15HL. Group LPS25HL showed the highest degree of wear, with and without etching. Conclusion There was a decrease from the initial to the final pH. Different bleaching gels were able to increase the surface wear values after simulated brushing. Acid etching before bleaching increased surface wear values in all groups. PMID:27008254

Alkaline peroxide treatment of ECF bleached softwood kraft pulps: part 2. effect of increased fiber charge on refining, wet-end application, and hornification

Treesearch

Zheng Dang; Thomas Elder; Jeffery S. Hsieh; Arthur J. Ragauskas

2007-01-01

The effect of increased fiber charge on refining, cationic starch adsorption, and hornification was examined. Two pulps were investigated: (1) a softwood (SW) kraft pulp (KP) which was bleached elementally chlorine-free (ECF) and sewed as control; and (2) a control pulp treated with alkaline peroxide, which had a higher fiber charge. It was shown that increased fiber...

Effects of in-office bleaching on human enamel and dentin. Morphological and mineral changes.

PubMed

Llena, Carmen; Esteve, Irene; Forner, Leopoldo

2018-05-01

The effects of HP-based products upon dental enamel and dentin are inconclusive. To evaluate changes in micromorphology and composition of calcium (Ca) and phosphate (P) in enamel and dentin after the application of 37.5% hydrogen peroxide (HP) and 35% carbamide peroxide (CP) METHODS: Crowns of 20 human teeth were divided in two halves. One half was used as control specimen and the other as experimental specimen. The control specimens were kept in artificial saliva, and the experimental specimens were divided into four groups (n=5 each): group 1 (enamel HP for 45min); group 2 (dentin HP for 45min); group 3 (enamel CP for 90min); and group 4 (dentin CP for 90min). The morphological changes were evaluated using confocal laser scanning microscopy (CLSM), while the changes in the composition of Ca and P were assessed using environmental scanning electron microscopy combined with a microanalysis system (ESEM+EDX). The results within each group and between groups were compared using the Wilcoxon test and Mann-Whitney U-test, respectively (p<0.05). Similar morphological changes in the enamel and no changes in dentin were assessed with both products. Ca and P decreased in enamel and dentin, without significant differences between them or with respect to their control specimens (p>0.05). When bleaching products with a neutral pH are used in clinical practice, both, the concentration and the application time should be taken into account in order to avoid possible structural and mineral changes in enamel and dentin. Copyright © 2018 Elsevier GmbH. All rights reserved.

FT–Raman investigation of bleaching of spruce thermomechanical pulp

Treesearch

U.P. Agarwal; L.L. Landucci

2004-01-01

Spruce thermomechanical pulp was bleached initially by alkaline hydrogen peroxide and then by sodium dithionite and sodium borohydride. Near-infrared Fourier-transform–Raman spectroscopy revealed that spectral differences were due primarily to coniferaldehyde and p-quinone structures in lignin, new direct evidence that bleaching removes p-quinone structures. In...

Analysis of shade, temperature and hydrogen peroxide concentration during dental bleaching: in vitro study with the KTP and diode lasers.

PubMed

Fornaini, C; Lagori, G; Merigo, E; Meleti, M; Manfredi, M; Guidotti, R; Serraj, A; Vescovi, P

2013-01-01

Many dental bleaching techniques are now available, several of them using a laser source. However, the literature on the exact role of coherent light in the biochemical reaction of the whitening process is very discordant. The aims of this in vitro study were: (1) to compare two different laser sources, a KTP laser with a wavelength of 532 nm and a diode laser with a wavelength of 808 nm, during dental bleaching, and (2) to investigate the relationships among changes in gel temperature, tooth shade and hydrogen peroxide (HP) concentration during laser irradiation. Altogether, 116 bovine teeth were bleached using a 30% HP gel, some of them with gel only and others with gel plus one of the two lasers (532 or 808 nm) at two different powers (2 and 4 W). The KTP laser produced a significant shade variation with a minimal temperature increase. The diode laser led to a higher temperature increase with a greater reduction in HP concentration, but the change in shade was only statistically significant with a power of 4 W. At a power of 2 W, the KTP laser caused a greater change in shade than the diode laser. No significant correlations were found among temperature, HP concentration and shade variation. The KTP laser appears to provide better results with less dangerous thermal increases than the diode laser. This might call into question most of the literature affirming that the action of laser bleaching is by increasing the gel temperature and, consequently, the speed of the redox reaction. Further study is required to investigate the correlations between the parameters investigated and efficacy of the bleaching process.

Dental whitening--revisiting the myths.

PubMed

Perdigão, Jorge

2010-01-01

The popularity of dental bleaching has increased with the introduction of at-home whitening. Currently available whitening methods include those prescribed by a dental professional for use at home, those applied by the professional in the dental office, a combination of the two, or systems available over the counter. This article reviews the effect, efficacy, and safety of bleaching techniques and materials. Most whitening techniques are considered effective and safe when carried out under the supervision of a dental professional. This article also compares the efficacy and safety of some of the most popular bleaching techniques, including at-home whitening with carbamide peroxide, over-the-counter (OTC) systems, and in-office whitening. Some of these whitening techniques are illustrated in this article.

Bleaching augments lipid peroxidation products in pistachio oil and its cytotoxicity

USDA-ARS?s Scientific Manuscript database

Pistachio consumption is associated with reductions in serum cholesterol and oxidative stress due to their constituents of unsaturated fats, phytosterols, fiber, and antioxidants. Bleaching has been applied to whiten nut shells for antifungal and cosmetic purposes. However, the impact of bleaching o...

Present and future technologies of tooth whitening.

PubMed

Viscio, D; Gaffar, A; Fakhry-Smith, S; Xu, T

2000-01-01

Dental stains can be broadly classified as intrinsic or extrinsic. Intrinsic stains are a result of defects in tooth development, fluorosis, or acquired through the use of tetracycline. Extrinsic stains are localized mainly in the pellicle and are generated by the reaction between sugars and amino acids or acquired from the retention of exogenous chromophores in the pellicle. Three clinical methods are currently used for measuring stain removal and tooth whitening in the development of new whitening technologies: Lobene Stain Index, Shade Guide Color Change, and Minolta ChromaMeter. Professional tooth whitening products rely on proven technologies--35% hydrogen peroxide for in-office power bleaching or 10% to 15% carbamide peroxide for at-home bleaching--to reduce intrinsic stain and change the inherent tooth color. Over-the-counter tooth whitening products use a combination of surfactants, abrasives, anticalculus agents, and low levels of hydrogen peroxide to reduce extrinsic stain and help maintain tooth whiteness after professional treatment. Future technologies for whitening teeth could involve the use of activating agents to enhance the performance of hydrogen peroxide and natural enzymes.

Does the hybrid light source (LED/laser) influence temperature variation on the enamel surface during 35% hydrogen peroxide bleaching? A randomized clinical trial.

PubMed

de Freitas, Patricia Moreira; Menezes, Andressa Nery; da Mota, Ana Carolina Costa; Simões, Alyne; Mendes, Fausto Medeiros; Lago, Andrea Dias Neves; Ferreira, Leila Soares; Ramos-Oliveira, Thayanne Monteiro

2016-01-01

The present study investigated how a hybrid light source (LED/laser) influences temperature variation on the enamel surfaces during 35% hydrogen peroxide (HP) bleaching. Effects on the whitening effectiveness and tooth sensitivity were analyzed. Twenty-two volunteers were randomly assigned to two different treatments in a split-mouth experimental model: group 1 (control), 35% HP; group 2 (experimental), 35% HP + LED/laser. Color evaluation was performed before treatment, and 7 and 14 days after completion of bleaching, using a color shade scale. Tooth sensitivity was assessed using a visual analog scale (VAS; before, immediately, and 24 hours after bleaching). During the bleaching treatment, thermocouple channels positioned on the tooth surfaces recorded the temperature. Data on color and temperature changes were subjected to statistical analysis (α = 5%). Tooth sensitivity data were evaluated descriptively. Groups 1 and 2 showed mean temperatures (± standard deviation) of 30.7 ± 1.2 °C and 34.1 ± 1.3 °C, respectively. It was found that there were statistically significant differences between the groups, with group 2 showing higher mean variation (P < .0001). The highest temperature variation occurred for group 2, with an increase of 5.3 °C at the enamel surface. The color change results showed no differences in bleaching between the two treatment groups (P = .177). The variation of the average temperature during the treatments was not statistically associated with color variation (P = .079). Immediately after bleaching, it was found that 36.4% of the subjects in group 2 had mild to moderate sensitivity. In group 1, 45.5% showed moderate sensitivity. In both groups, the sensitivity ceased within 24 hours. Hybrid light source (LED/ laser) influences temperature variation on the enamel surface during 35% HP bleaching and is not related to greater tooth sensitivity.

Electrochemical mercerization, souring, and bleaching of textiles

DOEpatents

Cooper, J.F.

1995-10-10

Economical, pollution-free treatment of textiles occurs in a low voltage electrochemical cell that mercerizes (or scours), sours, and optionally bleaches without effluents and without the purchase of bulk caustic, neutralizing acids, or bleaches. The cell produces base in the cathodic chamber for mercerization and an equivalent amount of acid in the anodic chamber for neutralizing the fabric. Gas diffusion electrodes are used for one or both electrodes and may simultaneously generate hydrogen peroxide for bleaching. The preferred configuration is a stack of bipolar electrodes, in which one or both of the anode and cathode are gas diffusion electrodes, and where no hydrogen gas is evolved at the cathode. 5 figs.

Electrochemical mercerization, souring, and bleaching of textiles

DOEpatents

Cooper, John F.

1995-01-01

Economical, pollution-free treatment of textiles occurs in a low voltage electrochemical cell that mercerizes (or scours), sours, and optionally bleaches without effluents and without the purchase of bulk caustic, neutralizing acids, or bleaches. The cell produces base in the cathodic chamber for mercerization and an equivalent amount of acid in the anodic chamber for neutralizing the fabric. Gas diffusion electrodes are used for one or both electrodes and may simultaneously generate hydrogen peroxide for bleaching. The preferred configuration is a stack of bipolar electrodes, in which one or both of the anode and cathode are gas diffusion electrodes, and where no hydrogen gas is evolved at the cathode.

Electrochemical corrosion and surface analyses of a ni-cr alloy in bleaching agents.

PubMed

Tamam, Evşen; Aydın, A Kevser; Bilgiç, Semra

2014-10-01

The aim of this study was to evaluate the corrosion behavior of a Ni-Cr dental casting alloy subjected to 10% hydrogen peroxide (HP) and 10% carbamide peroxide (CP) bleaching solutions and to determine the composition of the surface oxide layer formed on the alloy specimens. Ten cylindrical specimens (4 mm in diameter × 25 mm in height) were cast from a Ni-Cr alloy (Wiron 99) and divided into two groups (n = 5). A potentiodynamic polarization test was used to compare the corrosion rates of specimens in HP and CP (pH = 6.5). Before cyclic polarization tests, all alloy specimens were allowed to reach a steady open circuit potential (Ecorr ) for a period of 1 hour. Then tests were initiated at 100 mV versus standard calomel electrode (SCE) below Ecorr and scanned at a rate of 1 mV/s in the anodic direction until reaching 1000 mV over the Ecorr value. The scan then was reversed back to the Ecorr of the specimens. The open circuit potentials (Ecorr ) and the current densities (Icorr ) were determined using the anodic Tafel regions extrapolating from the curves. Differences in Ecorr and Icorr were determined using one-way ANOVA (α = 0.05). In addition, corrosion rates were calculated from these curves. Before and after polarization tests, a scanning electron microscope (SEM) examination accompanied by energy dispersive X-ray spectroscopy (EDS) was used to analyze the surface morphology. The surface characterization of the passive film formed on alloy specimens was also performed by using X-ray photoelectron spectroscopy (XPS). In this study, bleaching agents had an effect on the anodic process for two groups. Although no statistical difference was identified between the groups for both corrosion parameters, results indicated that the effect of CP on the corrosion behavior was less than that of HP. These results agreed with the SEM observations. XPS data showed that oxide layers formed on all groups contained mainly Cr2 O3 , NiO, and MoO3 , and the amounts of oxides

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2013 CFR

2013-04-01

... grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in dough conditioning. (c) It is used or intended for...

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2010 CFR

2010-04-01

... grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in dough conditioning. (c) It is used or intended for...

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2011 CFR

2011-04-01

... grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in dough conditioning. (c) It is used or intended for...

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2012 CFR

2012-04-01

... grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in dough conditioning. (c) It is used or intended for...

Laser and LED external teeth-bleaching

NASA Astrophysics Data System (ADS)

Zanin, Fatima; Brugnera, Aldo, Jr.; Marchesan, Melissa A.; Pecora, Jesus D.

2004-05-01

Teeth-bleaching is an initial phase in the reproduction of an aesthetic smile; thus, it is very important that the dentist knows how to diagnose the causes of color changes and indicate whitening before proposing dental treatment. Technological advances in teeth-whitening lead to the development of new techniques, improving comfort, security and decreasing time of execution: argon laser, diode laser, LED whitening, xenon light whitening. The clearing agent used in all techniques, including home whitening, is hydrogen peroxide (H2O2) in different concentrations. In this study, the authors describe mechanisms of gel activation, the use of Laser and LED's for teeth-bleaching, the importance of diagnosis and the comfort of the patient in in-office teeth-bleaching techniques.

Laser and LED external teeth-bleaching

NASA Astrophysics Data System (ADS)

Zanin, Fatima A.; Brugnera, Aldo, Jr.; Marchesan, Melissa A.; Pecora, Jesus D.

2004-09-01

Teeth-bleaching is an initial phase in the reproduction of an aesthetic smile; thus, it is very important that the dentist knows how to diagnose the causes of color changes and indicate whitening before proposing dental treatment. Technological advances in teeth-whitening lead to the development of new techniques, improving comfort, security and decreasing time of execution: argon laser, diode Laser, LED whitening, xenon light whitening. The clearing agent used in all techniques, including home whitening, is hydrogen peroxide (H2O2) in different concentrations. In this study, the authors describe mechanisms of gel activation, the use of Laser and LED"s for teeth-bleaching, the importance of diagnosis and the comfort of the patient in in-office teeth-bleaching techniques.

21 CFR 172.802 - Acetone peroxides.

Code of Federal Regulations, 2014 CFR

2014-04-01

... may be mixed with an edible carrier to give a concentration of: (1) 3 grams to 10 grams of hydrogen peroxide equivalent per 100 grams of the additive, plus carrier, for use in flour maturing and bleaching; or (2) approximately 0.75 gram of hydrogen peroxide equivalent per 100 grams of the additive, plus...

Efficacy and persistence of tooth bleaching using a diode laser with three different treatment regimens.

PubMed

Al Quran, Firas A M; Mansour, Yasar; Al-Hyari, Sabaa; Al Wahadni, Ahed; Mair, Lawrence

2011-01-01

Studies have measured the effectiveness of tooth bleaching, however there are very few studies that have measured the persistence in color change after a 6-month follow-up. This study assessed the efficacy of the laser bleaching process using different regimens, and the persistence of color change over a 6-month period. Sixty patients divided into three equal groups were subjected to bleaching using a diode laser with 34% hydrogen peroxide. Group 1: patients subjected to one session of laser bleaching. Group 2: patients subjected to two sessions of laser bleaching with a 1-week interval. Group 3: the same as Group 2 but followed by home bleaching once a month for 3 months. The color was assessed four times: before bleaching, directly after bleaching, 3 months after bleaching, and 6 months after bleaching. All teeth had a significant color change at 6 months, but all teeth had regressed from the maximum value. There was significantly less regression in color for Group 3, followed by Groups 2 and 1, respectively. The combined technique of in-office laser bleaching for two sessions with a 1-week interval, followed by home bleaching once a month for 3 months gave more persistence in color change. In-office power bleaching using a laser assisted hydrogen peroxide system repeated after a week, combined with home bleaching once a month for 3 months, is an effective bleaching regimen with less color regression after 6 months compared to a regimen of in-office bleaching alone.

Enhancing activated-peroxide formulations for porous materials: Test methods and results

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krauter, Paula; Tucker, Mark D.; Tezak, Matthew S.

2012-12-01

During an urban wide-area incident involving the release of a biological warfare agent, the recovery/restoration effort will require extensive resources and will tax the current capabilities of the government and private contractors. In fact, resources may be so limited that decontamination by facility owners/occupants may become necessary and a simple decontamination process and material should be available for this use. One potential process for use by facility owners/occupants would be a liquid sporicidal decontaminant, such as pHamended bleach or activated-peroxide, and simple application devices. While pH-amended bleach is currently the recommended low-tech decontamination solution, a less corrosive and toxic decontaminantmore » is desirable. The objective of this project is to provide an operational assessment of an alternative to chlorine bleach for low-tech decontamination applications activated hydrogen peroxide. This report provides the methods and results for activatedperoxide evaluation experiments. The results suggest that the efficacy of an activated-peroxide decontaminant is similar to pH-amended bleach on many common materials.« less

Nightguard vital bleaching: side effects and patient satisfaction 10 to 17 years post-treatment.

PubMed

Boushell, Lee W; Ritter, André V; Garland, Glenn E; Tiwana, Karen K; Smith, Lynn R; Broome, Angela; Leonard, Ralph H

2012-06-01

  The long-term patient satisfaction and safety of nightguard vital bleaching (NGVB) requires further evaluation.   The purpose of this study was to evaluate patients' satisfaction and identify side effects of NGVB up to 17 years post-treatment.   Thirty-one participants who had completed previous NGVB studies using 10% carbamide peroxide were contacted at least 10 years post-treatment (range 10-17 years, average 12.3 years). Participants reported shade satisfaction (very satisfied [VS], partially satisfied [PS], or not satisfied [NS]) as well as potential complications. Participants had teeth # 6 to 11 examined for tooth vitality, gingival inflammation (Löe's Gingival Index [GI]), and radiographically for external cervical resorption (ECR).   All of the participants had successful lightening of their teeth. Sixty-one percent (19) had not retreated their teeth. Of those who had not retreated their teeth and who responded to the question of whitening satisfaction, 31% (4/13) were VS, 54% (7/13) were PS, and 15% (2/13) were NS with their current shade. Of those who had retreated their teeth, all were VS or PS. Ninety-one percent of the examined teeth had GI = 0 (normal), 7% had GI = 1 (mild inflammation), and 2% had GI = 2 (moderate inflammation). Sixty-nine percent of teeth tested responded to a cold stimulus. Radiographs did not detect ECR or apical lesions. No participant reported having a gingival biopsy post-treatment, and 87% would whiten again.   Patient satisfaction with NGVB may last as long as 12.3 years in average (range 10-17 years) post-treatment. GI and ECR findings were considered within the normal expectations for the sample studied, suggesting minimal clinical post-NGVB side effects up to 17 years. Nightguard vital bleaching provides patient satisfaction with minimal side effects up to 17 years post-treatment. © 2011 Wiley Periodicals, Inc.

Effects of the concentration and composition of in-office bleaching gels on hydrogen peroxide penetration into the pulp chamber.

PubMed

Mena-Serrano, A P; Parreiras, S O; do Nascimento, E M S; Borges, C P F; Berger, S B; Loguercio, A D; Reis, A

2015-01-01

In tooth whitening, the hydrogen peroxide (HP) diffuses in the enamel and dentin, reaching the pulp. This in vitro study aimed to quantify the penetration of HP in the pulp chamber in teeth submitted to bleaching agents of different concentrations of HP without calcium (HP 20% [20CF], HP 35% [35CF]) and with calcium (HP 20% [20CC], HP 35% [35CC]). Fifty human premolars were sectioned 3 mm from the cemento-enamel junction and the pulp tissue was removed. The teeth were divided into five groups according to treatment and with a control group (n=10). An acetate buffer solution was placed in the pulp chamber of all teeth. The control group was exposed only to distilled water, while the other groups were treated with a bleaching procedure, according to the manufacturer's recommendations. After treatment, the acetate buffer solution was transferred to a glass tube in which leuco-crystal violet and peroxidase solutions were added, resulting in a blue solution. The optical density of this blue solution was determined spectrophotometrically and converted into micrograms equivalent to the HP. Data were analyzed using analysis of variance and Tukey tests (α=0.05). The HP concentration did not affect the HP inside the pulp chamber, but the presence of calcium significantly reduced it (p<0.0001). The amount of HP that reaches the pulp chamber depends on the bleaching protocol and the product employed, and it seems to be less affected by HP concentration.

In vitro activity of readily available household materials against HIV-1: is bleach enough?

PubMed

Flynn, N; Jain, S; Keddie, E M; Carlson, J R; Jennings, M B; Haverkos, H W; Nassar, N; Anderson, R; Cohen, S; Goldberg, D

1994-07-01

This report describes experiments assessing the effectiveness against HIV of potential disinfecting agents that are commonly available to IDU when they are sharing syringes. We exposed cell-free HIV, HIV-infected cells, and HIV-infected blood containing known quantities of HIV to household cleaning agents, alcohols, peroxide, and highly acidic materials for 1 min, in order to examine the effects of these materials on the infectivity of the HIV. Undiluted liquid laundry bleach and dilute liquid dish detergent reduced the number of culturable HIV to an undetectable level under the experimental conditions used. Diluted bleach was not completely effective. Other potential disinfecting agents, including ethanol, isopropyl alcohol, and hydrogen peroxide, were unable to disinfect high numbers of HIV-infected cells or infected blood. Liquid dish detergent warrants further study as a possible acceptable alternative to bleach. Our data provide support for recommendations to IDU that they disinfect shared syringes every time between users with full-strength liquid laundry bleach to reduce their risk of acquiring or transmitting HIV. When bleach is not available, liquid dish detergent or other available disinfecting agents such as rubbing alcohol, hydrogen peroxide, or high alcohol content beverages are more effective than water at disinfecting HIV, recognizing that these materials are less effective than bleach. Although these materials are effective, they should not be viewed as a substitute for decreased sharing of injection equipment by IDU, or increased availability of sterile needles and syringes.

A comparative evaluation of explosion hazards in chemical and mechanical pulp bleaching systems

Treesearch

P.W. Hart; Alan Rudie

2010-01-01

Three pulp mills in North America using 50% hydrogen peroxide have suffered explosions of pumps, mixers, and tanks. In two instances, alkali-catalyzed decomposition of peroxide is implicated in the explosion. Although many mechanical pulping facilities use hydrogen peroxide to bleach pulp, no &-catalyzed explosions have been reported. This research uses a kinetic...

Cold enzymatic bleaching of fluid whey.

PubMed

Campbell, R E; Drake, M A

2013-01-01

Chemical bleaching of fluid whey and retentate with hydrogen peroxide (HP) alone requires high concentrations (100-500 mg of HP/kg) and recent studies have demonstrated that off-flavors are generated during chemical bleaching that carry through to spray-dried whey proteins. Bleaching of fluid whey and retentate with enzymes such as naturally present lactoperoxidase or an exogenous commercial peroxidase (EP) at cold temperatures (4°C) may be a viable alternative to traditional chemical bleaching of whey. The objective of this study was to determine the optimum level of HP for enzymatic bleaching (both lactoperoxidase and EP) at 4°C and to compare bleaching efficacy and sensory characteristics to HP chemical bleaching at 4°C. Selected treatments were subsequently applied for whey protein concentrate with 80% protein (WPC80) manufacture. Fluid Cheddar whey and retentate (80% protein) were manufactured in triplicate from pasteurized whole milk. The optimum concentration of HP (0 to 250 mg/kg) to activate enzymatic bleaching at 4°C was determined by quantifying the loss of norbixin. In subsequent experiments, bleaching efficacy, descriptive sensory analysis, and volatile compounds were monitored at selected time points. A control with no bleaching was also evaluated. Enzymatic bleaching of fluid whey and retentate at 4°C resulted in faster bleaching and higher bleaching efficacy (color loss) than bleaching with HP alone at 250 mg/kg. Due to concentrated levels of naturally present lactoperoxidase, retentate bleached to completion (>80% norbixin destruction in 30 min) faster than fluid whey at 4°C (>80% norbixin destruction in 12h). In fluid whey, the addition of EP decreased bleaching time. Spray-dried WPC80 from bleached wheys, regardless of bleaching treatment, were characterized by a lack of sweet aromatic and buttery flavors, and the presence of cardboard flavor concurrent with higher relative abundance of 1-octen-3-ol and 1-octen-3-one. Among enzymatically

Effects of combining ozone and hydrogren peroxide on tooth bleaching: A clinical study.

PubMed

Al-Omiri, Mahmoud K; Hassan, Ra'ed S Abul; AlZarea, Bader K; Lynch, Edward

2016-10-01

The purpose of this study was to evaluate the efficiency of bleaching after combining ozone and 38% H2O2 in comparison to the sole use of 38% H2O2. Consecutive 26 participants (13 males and 13 females) were recruited into this study. They were randomly allocated into 2 groups (n=13 for each group). In group 1 (test group); the participants' upper anterior teeth were treated with 38% H2O2 for 20min then the teeth were exposed to ozone for 60s (healOzone(®) X4, KaVo Dental, Biberach, Germany). In group 2 (controls); the upper anterior teeth were treated with 20min of 38% H2O2 only. The shade of teeth was evaluated by recording the L* a* b* values and Vita Classic shades at study baseline and after bleaching in both groups. The statistically significant changes were set at P≤0.05. Tooth sensitivity and teeth shades were comparable between groups at study baseline (p>0.05). Controls reported more tooth sensitivity following bleaching (p<0.001). Teeth achieved better Vita shades, higher L* values (lighter shades), and lower a* and b* values (lighter shades) after bleaching in both groups (P≤0.05). However, teeth bleached with H2O2 and ozone achieved better Vita shades, higher L* values and lower a* values (lighter shades) than those bleached with H2O2 alone (p<0.001). Changes in b* values were not significantly different between groups. Bleaching with 38% H2O2 for 20min followed by 60s of ozone application would result in teeth with lighter shades than bleaching with 38% H2O2 alone. Copyright © 2016 Elsevier Ltd. All rights reserved.

Clinical and patient reported outcomes of bleaching effectiveness.

PubMed

Klaric Sever, Eva; Budimir, Zrinka; Cerovac, Matea; Stambuk, Mario; Par, Matej; Negovetic Vranic, Dubravka; Tarle, Zrinka

2018-01-01

The objective of this study is to evaluate clinical and patient reported outcomes of different bleaching products. Thirty participants were randomly divided into three bleaching groups (n = 10). Bleaching was performed with high concentrations of hydrogen peroxide (HP) - Boost (40%) and Dash (30%), and with prefabricated splints Bite&White (6% HP). Tooth colour was measured before, immediately after, and 1 and 6 months after the bleaching by using classical shade guide and spectrophotometer. Tooth hypersensitivity was self-rated by patients on the Wong-Baker's face scale. Patient satisfaction was evaluated on a 7-point Likert-type scales that measured perceived performance and importance of different characteristics of bleaching treatment. All products were effective in teeth colour change (ΔE > 3.3), which was significantly higher for Boost (p = .016) and Dash (p = .024) than Bite&White treatment. Perception of hypersensitivity was the highest in Boost group, followed by Dash and Bite&White treatment. Most of the patients were satisfied with final tooth colour, length and comfort during treatment, but were dissatisfied with the stability of bleached tooth colour. Materials with the higher concentrations of bleaching agent demonstrated greater bleaching effectiveness than at-home bleaching product, but also a greater hypersensitivity. Lengthening the treatment process, but achieving a more stable tooth colour may improve the perceived value of a bleaching service.

A Three-Step Synthesis of Benzoyl Peroxide

ERIC Educational Resources Information Center

Her, Brenda; Jones, Alexandra; Wollack, James W.

2014-01-01

Benzoyl peroxide is used as a bleaching agent for flour and whey processing, a polymerization initiator in the synthesis of plastics, and the active component of acne medication. Because of its simplicity and wide application, benzoyl peroxide is a target molecule of interest. It can be affordably synthesized in three steps from bromobenzene using…

Tooth Whitening And Temperature Rise With Two Bleaching Activation Methods

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abu-ElMagd, D. M.; El-Sayad, I. I.; Abd El-Gawad, L. M.

2009-09-27

To measure the tooth whitening and the surface and Intrapulpal temperature increase in vitro on freshly extracted upper human central incisors after chemical, Zoom AP light and diode laser activated bleaching. Thirty caries-free upper human incisors were selected. Teeth were divided into three equal groups according to the methods of activation of the bleaching agent (n = 10). A whitening gel containing hydrogen peroxide was applied to the buccal surface of all teeth. Group I was bleached using chemically activated hydrogen peroxide gel, for three applications of 15 min each. Group II was bleached with high intensity advanced power Zoommore » activation light (Zoom AP), for three applications of 15 min each. Group III was bleached with diode laser activation technique, where the teeth were irradiated with 2 Watt diode laser for three applications of 30 sec each. The whitening degree was assessed using an image analysis system, while temperature rise was recorded using a thermocouple on the external tooth surface and Intrapulpal. The degree of whitening increased significantly in all groups. However, the percentage of whitening was not statistically significantly different between the three groups. In addition, group II showed statistically significant higher mean rise in both surface and pulp temperatures than group I and group III. Chemical bleaching produces the same whitening effect as Zoom AP light and laser, with no surface or pulpal temperature rise. Laser application is faster and produces less surface and pulp temperature increase than Zoom AP light. Diode laser used to activate bleaching gels is not considered dangerous to the vitality of dental pulp using power settings of 2 W.« less

The effect of cold-light-activated bleaching treatment on enamel surfaces in vitro

PubMed Central

Shi, Xin-Chang; Ma, He; Zhou, Jing-Lin; Li, Wei

2012-01-01

This in vitro study aims to evaluate the crystal and surface microstructure of dental enamel after cold-light bleaching treatment. Twelve sound human premolars were cross-split into four specimens, namely, mesio-buccal (Group LP), disto-buccal (Group P), mesio-lingual (Group NP) and disto-lingual (Group L) specimens. These four groups were treated using the standard cold-light bleaching procedure, a bleaching agent, a peroxide-free bleaching agent and cold-light, respectively. Before and after treatment, all specimens were analyzed by high-resolution, micro-area X-ray diffraction and scanning electron microscopy. Using a spectrometer, tooth color of all specimens was measured before and after treatment. The phase of the enamel crystals was identified as hydroxyapatite and carbonated hydroxyapatite. After treatment, specimens in Groups LP and P showed significantly weaker X-ray diffraction peaks, significant reduction in crystal size and crystallinity, significant increase in L* but decrease in a* and b*, and obvious alterations in the surface morphology. However, specimens in Groups NP and L did not show any significant changes. The cold-light bleaching treatment leads to demineralization in the enamel surface. The acidic peroxide-containing bleaching agent was the major cause of demineralization, whereas cold-light did not exhibit significant increase or decrease effect on this demineralization. PMID:23258380

In Situ and In Vitro Effects of Two Bleaching Treatments on Human Enamel Hardness.

PubMed

Henn-Donassollo, Sandrina; Fabris, Cristiane; Gagiolla, Morgana; Kerber, Ícaro; Caetano, Vinícius; Carboni, Vitor; Salas, Mabel Miluska Suca; Donassollo, Tiago Aurélio; Demarco, Flávio Fernando

2016-01-01

The aim of this study was to evaluate in vitro and in situ the effects of two bleaching treatments on human enamel surface microhardness. Sixty enamel slabs from recently extracted thirty molars were used. The specimens were polished with sandpapers under water-cooling. The enamel samples were randomly divided in four groups, treated with 10% hydrogen peroxide (HP) or Whitening Strips (WS) containing 10% hydrogen peroxide and using two conditions: in vitro or in situ model. For in situ condition, six volunteers wore an intra-oral appliance containing enamel slabs, while for in vitro condition the specimens were kept in deionized water after the bleaching protocols. The bleaching treatments were applied one-hour daily for 14 days. Similar amounts of bleaching agents were used in both conditions. Before and after bleaching treatments, microhardness was measured. Statistical analysis (ANOVA and Tukey test) showed that in the in situ condition there was no statistically significant microhardness reduction in the bleached enamel (p>0.05). Significant decrease in hardness was observed for enamel slabs bleached with both treatments in the in vitro condition (p<0.05). Regarding the bleaching agents, in situ results showed no difference between HP and WS, while in vitro WS produced the lowest hardness value. It could be concluded that there was no deleterious effect on enamel produced by any of the bleaching protocols used in the in situ model. The reduction of hardness was only observed in vitro.

Physical-chemical characteristics of whitening toothpaste and evaluation of its effects on enamel roughness.

PubMed

Hilgenberg, Sérgio Paulo; Pinto, Shelon Cristina Souza; Farago, Paulo Vitor; Santos, Fábio André; Wambier, Denise Stadler

2011-01-01

This in vitro study evaluated the physical-chemical characteristics of whitening toothpastes and their effect on bovine enamel after application of a bleaching agent (16% carbamide peroxide). Physical-chemical analysis was made considering mass loss by desiccation, ash content and pH of the toothpastes. Thirty bovine dental enamel fragments were prepared for roughness measurements. The samples were subjected to bleaching treatments and simulated brushing: G1. Sorriso Dentes Brancos (Conventional toothpaste), G2. Close-UP Whitening (Whitening toothpaste), and G3. Sensodyne Branqueador (Whitening toothpaste). The average roughness (Ra) was evaluated prior to the bleaching treatment and after brushing. The results revealed differences in the physical-chemical characteristics of the toothpastes (p < 0.0001). The final Ra had higher values (p < 0.05) following the procedures. The mean of the Ra did not show significant differences, considering toothpaste groups and bleaching treatment. Interaction (toothpaste and bleaching treatment) showed significant difference (p < 0.0001). The whitening toothpastes showed differences in their physical-chemical properties. All toothpastes promoted changes to the enamel surface, probably by the use of a bleaching agent.

In-office bleaching efficacy on stain removal from CAD/CAM and direct resin composite materials.

PubMed

Alharbi, Amal; Ardu, Stefano; Bortolotto, Tissiana; Krejci, Ivo

2018-01-01

To evaluate the efficacy of in-office bleaching on stain removal from stained resin composite and ceramic computer-assisted design/computer-assisted manufacturing (CAD/CAM) blocks and direct resin composites. Forty disk-shaped samples were fabricated from each of nine materials: six CAD/CAM (VITABLOCS Mark II, Paradigm MZ100, Exp Vita Hybrid Ceramic, VITA ENAMIC, Exp Kerr, and LAVA Ultimate) and three direct resin composites (Filtek Supreme, Venus Diamond, and Filtek Silorane). Samples were randomly divided into five groups (n = 8), each stained with a particular staining solution. Using a calibrated spectrophotometer and a black background, L*a*b* values were assessed before and after 120 days of staining. Samples were subjected to in-office bleaching using 40% hydrogen peroxide gel for one hour. At subsequent assessment, color change (ΔE) was calculated as the difference between L*a*b* values. Both ANOVA and the Duncan test were used to identify differences between groups (α = 0.05). Bleaching resulted in significant differences in ΔE values for all materials (P < .001). Bleaching efficacy was highly influenced by material composition and staining solution. Residual color values after bleaching for ceramic and hybrid ceramics ranged from -0.49 to 2.35, within the clinically acceptable maximum of 3.3. Values after bleaching for resin-based CAD/CAM ranged from -0.7 to 7.08 while direct resin composites values ranged from -1.47 to 25.13. Coffee left the greatest residual color on all materials. Based on material nature, 40% hydrogen peroxide bleaching can remove staining. The new resin-based CAD/CAM blocks showed promising results in terms of color stability. Bleaching using 40% hydrogen peroxide can be an effective method to remove stains from dental restorations. In this way, restoration replacement as a result of discoloration may no longer be necessary. © 2017 Wiley Periodicals, Inc.

Effects of hydrogen peroxide on the light reflectance and morphology of bovine enamel.

PubMed

Kwon, Y H; Huo, M S; Kim, K H; Kim, S K; Kim, Y J

2002-05-01

The purpose of this study was to examine the effects of a bleaching agent (30% hydrogen peroxide) on the surface of bovine enamel using a scanning electron microscope and a UV-VIS-NIR spectrophotometer. Five non-carious bovine incisors were bleached for 0, 1, 2 and 3 days using 30% hydrogen peroxide. The light reflectance spectrum was measured using a spectrophotometer with diffuse reflectance mode. Colour values and colour differences in the teeth were evaluated from the reflectance measurements with the CIE L*a*b* colour coordinate system. Surface alterations in the bleached and unbleached teeth were studied using a scanning electron microscope. The change of reflectance in the teeth was related to the change of colour. Most reflectance change occurred within a 1-day bleaching, and this result was confirmed by a CIE L*a*b* colour coordinate system. The colour differences in the bleached teeth were significant enough to be perceived by the observer's eye. The comparison of bleached to unbleached bovine enamel revealed that the bleached surface showed non-uniform slight morphological alterations, and it developed varying degrees of surface porosity. This study indicates that the bleached bovine teeth showed apparent colour differences as well as slight morphological alterations after bleaching.

Influence of Bleaching on Flavor of 34% Whey Protein Concentrate and Residual Benzoic Acid Concentration in Dried Whey Proteins

USDA-ARS?s Scientific Manuscript database

Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations...

Influence of bleaching on flavor of 34% whey protein concentrate and residual benzoic acid concentration in dried whey products

USDA-ARS?s Scientific Manuscript database

Previous studies have shown that bleaching negatively affects the flavor of 70% whey protein concentrate (WPC70), but bleaching effects on lower-protein products have not been established. Benzoyl peroxide (BP), a whey bleaching agent, degrades to benzoic acid (BA) and may elevate BA concentrations...

Effect of laser-assisted bleaching with Nd:YAG and diode lasers on shear bond strength of orthodontic brackets.

PubMed

Mirhashemi, Amirhossein; Emadian Razavi, Elham Sadat; Behboodi, Sara; Chiniforush, Nasim

2015-12-01

The aim of the present study was to assess the effect of laser-assisted bleaching with neodymium:yttrium-aluminum-garnet (Nd:YAG) and diode lasers on shear bond strength (SBS) of orthodontic brackets. One hundred and four extracted human premolars were randomly divided into four groups: group 1: No bleaching applied (control group); group 2: Teeth bleached with 40 % hydrogen peroxide; group 3: Teeth treated with 30 % hydrogen peroxide activated with Nd:YAG laser (1064 nm, 2.5 W, 25 Hz, pulse duration of 100 μs, 6 mm distance); and group 4: Teeth treated with 30 % hydrogen peroxide activated with diode laser (810 nm, 1 W, CW, 6 mm distance). Equal numbers of teeth in groups 2, 3, and 4 were bonded at start, 1 h, 24 h, and 1 week after bleaching. A universal testing machine measured the SBS of the samples 24 h after bonding. After bracket debonding, the amount of residual adhesive on the enamel surface was observed under a stereomicroscope to determine the adhesive remnant index (ARI) scores. The SBS in the unbleached group was significantly higher than that in the bleached groups bonded immediately and 1 h after laser-assisted bleaching (P < 0.05). In groups 3 and 4 at start and group 2 at start and 1 h after laser-assisted bleaching, the SBS was found to be significantly lower than that in the control group. Significant differences in the ARI scores existed among groups as well. The SBS of brackets seems to increase quickly within an hour after laser-assisted bleaching and 24 h after conventional bleaching. Thus, this protocol can be recommended if it is necessary to bond the brackets on the same day of bleaching.

Evaluation of the Diode laser (810nm, 980 nm) on color change of teeth after external bleaching.

PubMed

Kiomars, Nazanin; Azarpour, Pouneh; Mirzaei, Mansooreh; Hashemi Kamangar, Sedighe Sadat; Kharazifard, Mohammad Javad; Chiniforush, Nasim

2016-12-30

Subject and aim: The aim of this study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. Materials & Methods: 40 premolars with intact enamel surfaces were selected for five external bleaching protocols (n=8). Two different wavelengths of diode laser (810 and 980 nm) with two different hydrogen peroxide concentrations (30% and 46%) were selected for laser bleaching. Group 1 received bleaching (Heydent- Germany) with a 810 nm diode laser; Group 2 received bleaching (Heydent- Germany) with a 980 nm diode laser; Group 3 received bleaching (laser white*20- Biolase) with a 810 nm diode laser; Group 4 received bleaching (laser white*20- Biolase) with a 980 nm diode laser, with an output power of 1.5 W, in continuous wave (cw) mode for each irradiation. Group 5 as control group received 40% hydrogen peroxide (Opalescence Boost, Ultradent-USA) with no light activation. The color of teeth was scored at baseline and 1 week after bleaching with spectrophotometer. Color change data on the CIEL*a*b* system were analyzed statistically by the one-way ANOVA and Tukey's HSD test. Results: All the bleaching techniques resulted in shade change. According to ΔE values, all techniques were effective to bleach the teeth (ΔE ≥ 3). Statistically significant differences were detected among bleaching protocols (p=0.06). Regarding shade change values expressed as ΔL*, Δa*, Δb*, ΔE*, laser bleached groups were no statistically different with each other (p>0.05). Conclusion: Bleaching with different wavelengths of diode laser resulted in the same results.

AC electrokinetic drug delivery in dentistry using an interdigitated electrode assembly powered by inductive coupling.

PubMed

Ivanoff, Chris S; Wu, Jie Jayne; Mirzajani, Hadi; Cheng, Cheng; Yuan, Quan; Kevorkyan, Stepan; Gaydarova, Radostina; Tomlekova, Desislava

2016-10-01

AC electrokinetics (ACEK) has been shown to deliver certain drugs into human teeth more effectively than diffusion. However, using electrical wires to power intraoral ACEK devices poses risks to patients. The study demonstrates a novel interdigitated electrode arrays (IDE) assembly powered by inductive coupling to induce ACEK effects at appropriate frequencies to motivate drugs wirelessly. A signal generator produces the modulating signal, which multiplies with the carrier signal to produce the amplitude modulated (AM) signal. The AM signal goes through the inductive link to appear on the secondary coil, then rectified and filtered to dispose of its carrier signal, and the positive half of the modulating signal appears on the load. After characterizing the device, the device is validated under light microscopy by motivating carboxylate-modified microspheres, tetracycline, acetaminophen, benzocaine, lidocaine and carbamide peroxide particles with induced ACEK effects. The assembly is finally tested in a common dental bleaching application. After applying 35 % carbamide peroxide to human teeth topically or with the IDE at 1200 Hz, 5 Vpp for 20 min, spectrophotometric analysis showed that compared to diffusion, the IDE enhanced whitening in specular optic and specular optic excluded modes by 215 % and 194 % respectively. Carbamide peroxide absorbance by the ACEK group was two times greater than diffusion as measured by colorimetric oxidation-reduction and UV-Vis spectroscopy at 550 nm. The device motivates drugs of variable molecular weight and structure wirelessly. Wireless transport of drugs to intraoral targets under ACEK effects may potentially improve the efficacy and safety of drug delivery in dentistry.

Effect of Two-minute Application of 35% Sodium Ascorbate on Composite Bond Strength following Bleaching.

PubMed

Ismail, Eman H; Kilinc, Evren; Hardigan, Patrick C; Rothrock, James K; Thompson, Jeffrey Y; Garcia-Godoy, Cristina

2017-10-01

The aim of this study is to assess the effect of 35% sodium ascorbate on microtensile bond strength of dentin immediately after bleaching with 35% hydrogen peroxide. A total of 25 sound human 3 rd molars were collected. Teeth were randomly divided into five groups for different treatments: Group I [bleaching + immediate bonding (i.e., restoration)], group II (bleaching + delayed bonding), group III (bleaching + sodium ascorbate + immediate bonding), group IV (bleaching + sodium ascorbate + delayed bonding), and group V (bonding only). After bleaching, but before bonding, groups II and IV were stored for 1 week in deionized water at 37°C. All samples were bonded using OptiBoned FL (Kerr) and Filtek Supreme (3M/ESPE). Teeth were sectioned into 1 × 1 mm 2 bars, and microtensile bond strength was tested with a universal testing machine (Instron 8841) at a cross-head speed of 0.5 mm/minute. Microtensile bond strength differed significantly across the five groups, with a significant reduction in microtensile bond strength observed for samples in group I relative to samples in any of the other treatment groups (p < 0.05). The application of a high concentration of sodium ascorbate for a shorter time reversed the negative effect of 35% hydrogen peroxide bleaching on composite bonding strength to dentin. The negative effects of bleaching on composite bonding can be neutralized by the application of the reversing agent sodium ascorbate thus, increasing the efficiency of clinic chair time. This is clinically relevant for those patients requiring restorative treatment immediately after in-office bleaching.

Lycopene control of benzophenone-sensitized lipid peroxidation

NASA Astrophysics Data System (ADS)

Cvetković, Dragan; Marković, Dejan

2012-05-01

Lycopene antioxidant activity in the presence of two different mixtures of phospholipids in hexane solution, under continuous regime of UV-irradiation from three different ranges (UV-A, UV-B, and UV-C) has been evaluated in this work. Lycopene expected role was to control lipid peroxidation, by scavenging free radicals generated by UV-irradiation, in the presence and in the absence of selected photosensitizer, benzophenone. This work shows that lycopene undergoes to UV-induced destruction (bleaching), highly dependent on the incident photons energy input, more expressed in the presence than in the absence of benzophenone. The further increase ("excess") of its bleaching is undoubtedly related to the further increase of its antioxidant activity in the presence of benzophenone, having the same cause: increase of (phospholipids peroxidation) chain-breaking activities.

Evaluation of the Diode laser (810nm, 980 nm) on color change of teeth after external bleaching

PubMed Central

Kiomars, Nazanin; Azarpour, Pouneh; Mirzaei, Mansooreh; Hashemi kamangar, Sedighe Sadat; Kharazifard, Mohammad Javad

2016-01-01

Subject and aim: The aim of this study was to evaluate the efficiency of diode laser-activated bleaching systems for color change of teeth. Materials & Methods: 40 premolars with intact enamel surfaces were selected for five external bleaching protocols (n=8). Two different wavelengths of diode laser (810 and 980 nm) with two different hydrogen peroxide concentrations (30% and 46%) were selected for laser bleaching. Group 1 received bleaching (Heydent- Germany) with a 810 nm diode laser; Group 2 received bleaching (Heydent- Germany) with a 980 nm diode laser; Group 3 received bleaching (laser white*20- Biolase) with a 810 nm diode laser; Group 4 received bleaching (laser white*20- Biolase) with a 980 nm diode laser, with an output power of 1.5 W, in continuous wave (cw) mode for each irradiation. Group 5 as control group received 40% hydrogen peroxide (Opalescence Boost, Ultradent-USA) with no light activation. The color of teeth was scored at baseline and 1 week after bleaching with spectrophotometer. Color change data on the CIEL*a*b* system were analyzed statistically by the one-way ANOVA and Tukey's HSD test. Results: All the bleaching techniques resulted in shade change. According to ΔE values, all techniques were effective to bleach the teeth (ΔE ≥ 3). Statistically significant differences were detected among bleaching protocols (p=0.06). Regarding shade change values expressed as ΔL*, Δa*, Δb*, ΔE*, laser bleached groups were no statistically different with each other (p>0.05). Conclusion: Bleaching with different wavelengths of diode laser resulted in the same results. PMID:28765671

Effects of the bleaching procedures on enamel micro-hardness: Plasma Arc and diode laser comparison.

PubMed

Nematianaraki, Saeid; Fekrazad, Reza; Naghibi, Nasim; Kalhori, Katayoun Am; Junior, Aldo Brugnera

2015-10-02

One of the major side effects of vital bleaching is the reduction of enamel micro-hardness. The purpose of this study was to evaluate the influence of two different bleaching systems, Plasma Arc and GaAlAs laser, on the enamel micro-hardness. 15 freshly extracted human third molars were sectioned to prepare 30 enamel blocks (5×5 mm). These samples were then randomly divided into 2 groups of 15 each (n=15): a plasma arc bleaching group (: 350-700 nm) + 35% Hydrogen Peroxide whitening gel and a laser bleaching group (GaAlAs laser, λ: 810 nm, P: 10 W, CW, Special Tip) + 35% Hydrogen Peroxide whitening gel. Samples were subjected to the Vickers micro-hardness test (VHN) at a load of 50 g for 15s before and after treatment. Data were statistically analyzed by a Mann-Whitney test (p≤0.05). In the GaAlAs laser group, the enamel micro-hardness was 618.2 before and was reduced to 544.6 after bleaching procedures. In the plasma arc group, the enamel micro-hardness was 644.8 before and 498.9 after bleaching. Although both techniques significantly reduced VHN, plasma arc bleaching resulted in a 22.62% reduction in VHN for enamel micro-hardness, whereas an 11.89% reduction in VHN was observed for laser bleaching; this difference is statistically significant (p<0.001). Both bleaching techniques reduced enamel micro-hardness, although the reduction is much less significant with the GaAlAs laser than with the plasma arc. Therefore GaAlAs laser bleaching has fewer harmful effects than plasma arc in respect to enamel micro-hardness reduction.

Effect of enamel sealants on tooth bleaching and on the color stability of the result.

PubMed

Corcodel, N; Hassel, A J; Sen, S; Saure, D; Rammelsberg, P; Lux, C J; Zingler, S

2017-04-01

The purpose of this in vitro study was to evaluate the effect of enamel sealants on bleaching of natural teeth by use of 40 % hydrogen peroxide in a dental surgery. The color stability of the results from bleaching was, furthermore, determined 10 months after the bleaching procedure. In a standardized setting, four sealants (Pro Seal ® , Light Bond™ Sealant, Protecto ® , and Clinpro™ XT Varnish) were applied to and removed from human teeth in accordance with the manufacturer's instructions. Natural teeth served as medium; half of the teeth were sealed and the others served as controls. Hydrogen peroxide gel (40 %; Opalescence Boost; Ultradent Products, South Jordan, UT, USA) was used as bleaching agent. Color measurement was performed with a spectroradiometer (Photoresearch PR670) before the bleaching process (T1) and 24 h (T2) and 10 months (T3) after bleaching. The spectroradiometer results were expressed by use of the Commission Internationale de l'Éclairage (CIE) L*a*b* color notation. The L*, a*, and b* values of the sealed and the unsealed surfaces were not significantly different at any time during the study (p > 0.05), irrespective of the sealant used. Ten months after the bleaching process, mean L*, a*, and b* values were lower than at 1-day post-bleaching; the mean value of ΔE between 1-day post-bleaching and 10 months post-bleaching was 2.46 (±3.1). The results of the study suggest that the effectiveness of professional tooth whitening is not appreciably affected by the application of the four sealants tested.

Effect of four different opalescence tooth-whitening products on enamel microhardness.

PubMed

Majeed, A; Grobler, S R; Moola, M H; Rossouw, R J; van Kotze, T J W

2008-06-01

The purpose was to evaluate the effect of various Opalescence tooth-whitening products on enamel. Enamel blocks were exposed to Opalescence PF 10% Carbamide Peroxide (n = 10), Opalescence PF 20% Carbamide Peroxide (n = 10), Opalescence Trèswhite Supreme 10% Hydrogen Peroxide (n = 10) and Opalescence Quick PF 45% Carbamide Peroxide (n = 10) according to the manufacturer's instructions. The control group was enamel blocks (n = 10) kept in artificial saliva. The values were obtained before exposure and after the 14-days treatment period. Enamel blocks were kept in saliva between treatments. Indent marks on enamel blocks were examined using the scanning electron microscope for treatment effects. All four different Opalescence products damaged enamel. The most damage was done when treated for a long period (112 hours). SEM images also showed damage to enamel by all 4 products. Opalescence with 10% and with 20% Carbamide Peroxide showed the highest damage, which also differed significantly (p < 0.05) from the saliva control group (p < 0.05; Tukey-Kramer Multiple comparison test). All 4 Opalescence products damaged enamel. Higher damage was done by the 10% carbamide peroxide and 20% carbamide peroxide products because of the much longer exposure period (112 hours in comparison to 7 hours).

Real-time local experimental monitoring of the bleaching process.

PubMed

Rakic, Mario; Klaric, Eva; Sever, Ivan; Rakic, Iva Srut; Pichler, Goran; Tarle, Zrinka

2015-04-01

The purpose of this article was to investigate a new setup for tooth bleaching and monitoring of the same process in real time, so to prevent overbleaching and related sideeffects of the bleaching procedure. So far, known bleaching procedures cannot simultaneously monitor and perform the bleaching process or provide any local control over bleaching. The experimental setup was developed at the Institute of Physics, Zagreb. The setup consists of a camera, a controller, and optical fibers. The bleaching was performed with 25% hydrogen peroxide activated by ultraviolet light diodes, and the light for monitoring was emitted by white light diodes. The collected light was analyzed using a red-green-blue (RGB) index. A K-type thermocouple was used for temperature measurements. Pastilles made from hydroxylapatite powder as well as human teeth served as experimental objects. Optimal bleaching time substantially varied among differently stained specimens. To reach reference color (A1, Chromascop shade guide), measured as an RGB index, bleaching time for pastilles ranged from 8 to >20 min, whereas for teeth it ranged from 3.5 to >20 min. The reflected light intensity of each R, G, and B component at the end of bleaching process (after 20 min) had increased up to 56% of the baseline intensity. The presented experimental setup provides essential information about when to stop the bleaching process to achieve the desired optical results so that the bleaching process can be completely responsive to the characteristics of every individual, leading to more satisfying results.

Effect of three nanobiomaterials on microhardness of bleached enamel

PubMed Central

Kaveh, Sara

2016-01-01

Objectives The aim of this in vitro study was to evaluate the effect of incorporating three different nanobiomaterials into bleaching material on microhardness of bleached enamel. Materials and Methods The crowns of 24 extracted sound human molars were sectioned. Sixty enamel specimens (2 × 3 × 4 mm) were selected and divided into five groups (n = 12): Group 1 received no bleaching procedure (control); Group 2 underwent bleaching with a 40% hydrogen peroxide (HP) gel; Groups 3, 4, and 5 were bleached with a 40% HP gel modified by incorporation of bioactive glass (BAG), amorphous calcium phosphate (ACP) and hydroxyapatite (HA), respectively. The enamel microhardness was evaluated. The differences in Knoop microhardness data of each group were analyzed by one-way ANOVA, followed by post hoc Tukey tests. Results Significant differences were observed between the study groups. The enamel microhardness changes in Groups 1, 3, 4, and 5 were significantly lower than that of Group 2 (p < 0.001). Conclusions Within the limitations of this study, it can be concluded that incorporation of each one of the three tested biomaterials as remineralizing agents might be effective in decreasing enamel microhardness changes subsequent to in-office bleaching. PMID:27508161

Enamel Mineral Content Changes After Bleaching With High and Low Hydrogen Peroxide Concentrations: Colorimetric Spectrophotometry and Total Reflection X-ray Fluorescence Analyses.

PubMed

Pinto, Avd; Bridi, E C; Amaral, Flb; França, Fmg; Turssi, C P; Pérez, C A; Martinez, E F; Flório, F M; Basting, R T

The purpose of this study was to evaluate the calcium (Ca) and phosphorous (P) content in enamel bleached with high and low concentrations of hydrogen peroxide (HP) using Total Reflection X-Ray Fluorescence (TXRF) and colorimetric spectrophotometry (SPEC). Forty-eight sound human third molars were used. Their roots were embedded in polystyrene resin and immersed for seven days in an artificial saliva solution. Then they were distributed into six groups to receive the bleaching treatments. The agents of high HP concentration (for in-office use) evaluated were Whiteness HP Maxx/FGM (35% HP), Whiteness HP Blue/FGM (35% HP, 2% calcium gluconate), Pola Office+/SDI (37.5% HP, 5% potassium nitrate), and Opalescence Boost/Ultradent (38% HP, 1.1% ion fluoride, 3% potassium nitrate); these agents were applied to enamel in three sessions. The agents of low HP concentration (for home use) evaluated were Pola Day/SDI (9.5% HP) and White Class 10%/FGM (10% HP, potassium nitrate, calcium, fluoride), and these agents were applied for 14 days. Enamel microbiopsies were evaluated by TXRF and SPEC analysis before the bleaching treatment (baseline), during the treatment, and 14 days after the end of the treatment. For TXRF, the Kruskal-Wallis test showed that Ca and P were not influenced by agent (p>0.05). For SPEC, Pola Office+, Opalescence Boost, Pola Day, and White Class 10% caused a decrease of Ca over time; there was a significant decrease of P over time to Pola Office+ and White Class 10%. The Spearman test showed no correlation between the Ca (p=0.987; r 2 =-0.020) and P (p=0.728, r 2 =0.038) obtained by SPEC and TXRF. For TXRF and SPEC, changes in Ca and P during bleaching occurred independently of the HP concentration used.

Conservative reconstruction of the smile by orthodontic, bleaching, and restorative procedures

PubMed Central

Sundfeld, Renato Herman; Machado, Lucas Silveira; de Oliveira, Fernanda Garcia; Santos, Eduardo Almada; Lugato, Isabel Cristina Prado Torres; Sundfeld Neto, Daniel

2012-01-01

The following is a clinical case report of a patient whose chief complaint was the presence of generalized spacing in the maxillary anterior segment following orthodontic treatment. After meticulous clinical analyses and discussions of the clinical procedures to be adopted, dental bleaching was performed in both arches with 10% hydrogen peroxide (Opalescence Trèswhite Supreme 10% Hydrogen Peroxide - Ultradent Products, Inc., South Jordan, USA) after the conclusion and stabilization of orthodontic treatment. Then, the orthodontic appliance was removed and the diastemas in the maxillary anterior teeth were closed with Amelogen Plus (Ultradent Products, Inc., South Jordan, USA) resin composite. It was observed that the association of orthodontic, bleaching, and restorative procedures was capable of restoring dental shape, function, and esthetics, allowing the patient to smile without hesitation. PMID:22229015

Effect of coffe and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching

PubMed Central

PIROLO, Rodrigo; MONDELLI, Rafael Francisco Lia; CORRER, Gisele Maria; GONZAGA, Carla Castiglia; FURUSE, Adilson Yoshio

2014-01-01

There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. Objective: To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Materials and methods: Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max) and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO) before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD) at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E) and lightness (∆L) variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (p<0.05). Results: Significant differences were observed between groups for both the ∆L and ∆E values (p<0.001). All specimens presented a decrease in brightness (negative ∆L). The highest ∆E values were observed for teeth stained with a CBSD at 10 min and 1 h (4.12 and 4.16, respectively). Teeth pigmented with coffee presented ∆E values below 3.3 units for all evaluation times. Conclusion: The exposure to coffee after bleaching causes less color changes than the exposure to a CBSD regardless of the time after bleaching. PMID:25075672

Effect of coffee and a cola-based soft drink on the color stability of bleached bovine incisors considering the time elapsed after bleaching.

PubMed

Pirolo, Rodrigo; Mondelli, Rafael Francisco Lia; Correr, Gisele Maria; Gonzaga, Carla Castiglia; Furuse, Adilson Yoshio

2014-01-01

There is no consensus about the waiting time necessary for the patient to start consuming beverages containing colorants again after bleaching. To evaluate the influence of beverages with coloring agents on bleached bovine incisors considering the time elapsed after bleaching. Sixty bovine incisors were bleached with 35% hydrogen peroxide for in-office use (Whiteness HP Max) and divided into 10 groups. The color was evaluated with a spectrophotometer (Spectro Shade MICRO) before and after bleaching, employing the CIE-Lab system. After bleaching, the teeth were exposed for 5 min to coffee or cola-based soft drink (CBSD) at different periods after bleaching: 10 min, 1 h, 24 h, 48 h, and 72 h. Color (∆E) and lightness (∆L) variations were obtained from the CIE-Lab coordinates. Data were subjected to two-way ANOVA and Tukey HSD tests (p<0.05). Significant differences were observed between groups for both the ∆L and ∆E values (p<0.001). All specimens presented a decrease in brightness (negative ∆L). The highest ∆E values were observed for teeth stained with a CBSD at 10 min and 1 h (4.12 and 4.16, respectively). Teeth pigmented with coffee presented ∆E values below 3.3 units for all evaluation times. The exposure to coffee after bleaching causes less color changes than the exposure to a CBSD regardless of the time after bleaching.

Effect of cementum defects on radicular penetration of 30% H2O2 during intracoronal bleaching.

PubMed

Rotstein, I; Torek, Y; Misgav, R

1991-05-01

Bleaching pulpless teeth with 30% hydrogen peroxide has been reported to cause external cervical root resorption. It has been hypothesized that H2O2 penetrating through open dentin tubules can initiate an inflammatory reaction which could result in root resorption. Extracted human premolars were treated endodontically and bleached intracoronally using the thermocatalytic technique. The teeth were divided into three groups; one group with no cementum defects at the cementoenamel junction, one group with artificial cementum defects at the cementoenamel junction, and another group with artificial cementum defects at the middle third of the root. The radicular penetration of 30% hydrogen peroxide in the three groups was assessed directly and compared using an in vitro model. Radicular penetration of hydrogen peroxide was found in all of the groups tested. The penetration of hydrogen peroxide was significantly higher in teeth with cementum defects at the cementoenamel junction than in those without defects.

Effect of the Purple Corn Beverage "Chicha Morada" in Composite Resin during Dental Bleaching.

PubMed

Acuña, Eric Dario; Delgado-Cotrina, Leyla; Rumiche, Francisco Aurelio; Tay, Lidia Yileng

2016-01-01

During dental bleaching the staining potential of the surface would increase. This study aims to evaluate the staining susceptibility of one bleached composite resin after the exposure to three different beverages: Peruvian purple corn based beverage (chicha morada), green tea, and distilled water. Thirty disk-shaped specimens of one nanofill composite resin were prepared. The specimens were then divided into six groups (n = 5): purple corn (P), purple corn + bleaching (PB), green tea (T), green tea + bleaching (TB), distilled water (W), and distilled water + bleaching (WB). In groups that received bleaching, two sessions of bleaching with 35% hydrogen peroxide were done. Following bleaching, specimens were exposed to each liquid thirty minutes daily. Color was measured with a digital spectrophotometer. For statistical analysis, color measurement differences between the obtained results were used: during bleaching, after bleaching, and during + after bleaching. Two-way ANOVA was used to compare the color changes in the resins of all groups (p < 0.05). We conclude that all the evaluated beverages produced changes of color in the composite resin regardless of the bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3).

Randomized clinical trial of the effect of NovaMin and CPP-ACPF in combination with dental bleaching.

PubMed

Alexandrino, Larissa Dias; Alencar, Cristiane de Melo; Silveira, Ana Daniela Silva da; Alves, Eliane Bemerguy; Silva, Cecy Martins

2017-01-01

This randomized, controlled, double-blind clinical study evaluated the effect of calcium sodium phosphosilicate (NovaMin) and casein phosphopeptide-amorphous calcium phosphate with fluoride (CPP-ACPF) on the prevention of post-operative sensitivity and on the effects of clinical bleaching treatment. Sixty volunteers were selected according to inclusion and exclusion criteria and were randomly assigned into three groups (n=20): CG (control group) patients, who were treated with 35% hydrogen peroxide; NOVAG (NovaMin group) patients, who were treated with 35% hydrogen peroxide followed by the application of NovaMin; and CPPG (CPP group) patients, who were treated with 35% hydrogen peroxide followed by the application of CPP-ACPF. Both bioactive agents were applied for five minutes. An evaporative stimulus associated with a modified visual scale was used to analyze sensitivity 24 hours after each bleaching session. The color evaluation was performed on the maxillary central incisors using a spectrophotometer. Associations between the intervention group, bleaching session, and reported sensitivity were tested using Chi-square partitioning. Color change values (ΔE) were analyzed using analysis of variance (ANOVA). The significance level used for both tests was 5%. In the intragroup assessment, the Friedman test showed that only the CPP-ACPF group showed no statistically significant difference (p<0.05) between baseline and first bleaching session. In the intergroup assessment, the Kruskal-Wallis test showed that the CPPG had less postoperative sensitivity after the first session, when compared to the other groups (p<0.05). Color change analysis (ΔE) showed a significant difference between the means obtained in the different bleaching sessions in all groups (p<0.05). This study showed that the combination of CPP-ACPF with 35% hydrogen peroxide significantly reduced post-operative sensitivity in the first session, compared with the other evaluated treatments. The

The potential of low-power laser for reducing dental sensitivity after in-office bleaching: a case report.

PubMed

Mayer-Santos, Eric; Anhesini, Brunna Haddad; Shimokawa, Carlos Alberto Kenji; Aranha, Ana Cecília Corrêa; Eduardo, Carlos Paula; de Freitas, Patricia Moreira

2017-01-01

Postoperative sensitivity is one of the most common side effects of in-office bleaching with hydrogen peroxide. Laser phototherapy (LPT) has been suggested as an adjunctive treatment to prevent or minimize tooth sensitivity. This case report aimed to verify the efficacy of LPT in the reduction of sensitivity after in-office bleaching. Tooth bleaching was performed with 35% hydrogen peroxide activated with a hybrid LED-laser device. Immediately after the bleaching treatment, the patient reported dental sensitivity, as measured with a visual analog scale (VAS). To reduce sensitivity, LPT was applied with a 780-nm laser using the following parameters: 70 mW, exposure time of 10 seconds per point of irradiation (middle region of the buccal surfaces of each compromised tooth) in contact mode, energy of 1 J per point. Immediately after LPT, the patient reported a substantially lower level of pain on the VAS. Twenty-four hours after bleaching, the score on the VAS indicated that sensitivity levels had rebounded, and the patient received additional LPT. After 48 hours, the patient reported no dental sensitivity. The results in this patient indicated that irradiation with an infrared low-power laser substantially reduced dental pain generated by bleaching, suggesting that LPT should be considered as an auxiliary method to reduce postbleaching tooth sensitivity.

Comparative evaluation of effects of bleaching on color stability and marginal adaptation of discolored direct and indirect composite laminate veneers under in vivo conditions.

PubMed

Jain, Veena; Das, Taposh K; Pruthi, Gunjan; Shah, Naseem; Rajendiran, Suresh

2015-01-01

Change in color and loss of marginal adaptation of tooth colored restorative materials is not acceptable. Bleaching is commonly used for treating discolored teeth. However, the literature is scanty regarding its effect on color and marginal adaptation of direct and indirect composite laminate veneers (CLVs) under in vivo conditions. Purpose of the study was to determine the effect of bleaching on color change and marginal adaptation of direct and indirect CLVs over a period of time when exposed to the oral environment. For this purpose, a total of 14 subjects irrespective of age and sex indicated for CLV restorations on maxillary anterior teeth were selected following the inclusion and exclusion criteria. For each subject, indirect CLVs were fabricated and looted in the first quadrant (Group 1) and direct CLV's (Group 2), were given in the second quadrant. Color change was assessed clinically using intra-oral digital spectrophotometer and marginal adaptation was assessed on epoxy resin replica of the tooth-restoration interface under scanning electron microscope. After 6 months, the subjects underwent a home bleaching regimen for 14 days using 10% carbamide peroxide. The assessment of color change and marginal adaptation was done at 6 months after veneering (0-180 days), immediately after the bleaching regimen (0-194 days) and 3 months after the bleaching regimen (0-284 days). The difference in median color change (ΔE) between the groups was tested using Wilcoxon rank sum test while the median color change with time within the groups was tested using Wilcoxon signed rank test. The difference in the rates of marginal adaptation was tested between the groups using Chi-square/Fisher's exact test. Bleaching led to statistically significant color change at cervical (CE), middle and incisal (IE) regions when direct and indirect composites were compared (P < 0.05). During intra-group comparison, direct CLV's showed significant color change at CE and IE regions when �

Effect of the Purple Corn Beverage “Chicha Morada” in Composite Resin during Dental Bleaching

PubMed Central

Acuña, Eric Dario; Delgado-Cotrina, Leyla; Rumiche, Francisco Aurelio

2016-01-01

During dental bleaching the staining potential of the surface would increase. This study aims to evaluate the staining susceptibility of one bleached composite resin after the exposure to three different beverages: Peruvian purple corn based beverage (chicha morada), green tea, and distilled water. Thirty disk-shaped specimens of one nanofill composite resin were prepared. The specimens were then divided into six groups (n = 5): purple corn (P), purple corn + bleaching (PB), green tea (T), green tea + bleaching (TB), distilled water (W), and distilled water + bleaching (WB). In groups that received bleaching, two sessions of bleaching with 35% hydrogen peroxide were done. Following bleaching, specimens were exposed to each liquid thirty minutes daily. Color was measured with a digital spectrophotometer. For statistical analysis, color measurement differences between the obtained results were used: during bleaching, after bleaching, and during + after bleaching. Two-way ANOVA was used to compare the color changes in the resins of all groups (p < 0.05). We conclude that all the evaluated beverages produced changes of color in the composite resin regardless of the bleaching procedure. However, purple corn was the only beverage that caused a perceptible color change (ΔE > 3.3). PMID:27034897

Shear bond strength to enamel after power bleaching activated by different sources.

PubMed

Can-Karabulut, Deniz C; Karabulut, Baris

2010-01-01

The purpose of the present study was to evaluate enamel bond strength of a composite resin material after hydrogen peroxide bleaching, activated by a diode laser (LaserSmile), an ozone device (HealOzone), a light-emitting diode (BT Cool whitening system), and a quartz-Plus. Fifty extracted caries-free permanent incisors were used in this study. Thirty-eight percent hydrogen peroxidegel was applied to sound, flattened labial enamel surfaces and activated by different sources. Enamel surfaces that had received no treatment were used as control samples. Bonding agent was applied according to the manufacturer's instructions and the adhesion test was performed according to ISO/TS 11405. Statistical analysis showed significant influence of the different activation technique of hydrogen peroxide on shear bond strength to enamel (ANOVA, LSD, P < 0.05). The data in this vitro explorative study suggest the activation of hydrogen peroxide by different sources may further affect the shear bond strength of subsequent composite resin restoration to enamel. Within the limitations of this in vitro study, further studies examining the structural changes of activated hydrogen peroxide-treated enamel are needed. Due to the different activation methods; duration of light irradiation effects, longer time periods may be needed before application of adhesive restorations to enamel, compared with non-activated bleaching.

In-office dental bleaching with light vs. without light: A systematic review and meta-analysis.

PubMed

Maran, Bianca Medeiros; Burey, Adrieli; de Paris Matos, Thalita; Loguercio, Alessandro D; Reis, Alessandra

2018-03-01

A systematic review and meta-analysis were performed to answer the following research question: Does light-activated in-office vital bleaching have a greater whitening efficacy and higher tooth sensitivity (TS) in comparison with in-office vital bleaching without light when used in adults? Only randomized clinical trials (RCTs) involving adults who had in-office bleaching with and without light activation were included. Controlled vocabulary and keywords were used in a comprehensive search for titles and abstracts in PubMed, and this search was adapted for Scopus, Web of Science, LILACS, BBO, Cochrane Library, and SIGLE without restrictions in May 2016 and was updated in August 2017. IADR abstracts (1990-2016), unpublished- and ongoing-trial registries, dissertations, and theses were also searched. The risk-of-bias tool of the Cochrane Collaboration was used for quality assessment. The quality of the evidence was rated using the Grading of Recommendations: Assessment, Development, and Evaluation approach. Through the use of the random effects model, a meta-analysis with a subgroup analysis (low and high hydrogen peroxide concentration) was conducted for color change (ΔE*, ΔSGU) as well as the risk and intensity of TS. We retrieved 6663 articles, but after removing duplicates and non-relevant articles, only 21 RCTs remained. No significant difference in ΔE*, ΔSGU, and risk and intensity of TS was observed (p > .05). For ΔE and risk of TS, the quality of the evidence was graded as moderate whereas the evidence for ΔSGU and intensity of TS was graded as very low and low, respectively. Without considering variations in the protocols, the activation of in-office bleaching gel with light does not seem to improve color change or affect tooth sensitivity, regardless of the hydrogen peroxide concentration. (PROSPERO - CRD42016037630). Although it is commercially claimed that in-office bleaching associated with light improves and accelerates color change, this

Effects of green tea on the shear bond strength of orthodontic brackets after in-office vital bleaching.

PubMed

Berger, Sandrine Bittencourt; Guiraldo, Ricardo Danil; Lopes, Murilo Baena; Oltramari-Navarro, Paula Vanessa; Fernandes, Thais Maria; Schwertner, Renata de Castro Alves; Ursi, Wagner José Silva

2016-01-01

The application of bleaching agents before placement of resin-bonded fixed appliances significantly, but temporarily, reduces bond strength to tooth structure. Antioxidants have been studied as a means to remove residual oxygen that compromises bonding to bleached enamel. This in vitro study evaluated whether green tea (GT) could restore the shear bond strength between bonded orthodontic brackets and bleached enamel. Six experimental groups were compared: group 1, no bleaching plus bracket bonding (positive control); group 2, bleaching with 35% hydrogen peroxide (HP) plus bracket bonding (negative control); group 3, 35% HP plus 10% sodium ascorbate (SA) plus bracket bonding; group 4, 35% HP plus 10% GT plus bracket bonding; group 5, no bleaching plus 10% SA plus bracket bonding; group 6, no bleaching plus 10% GT plus bracket bonding. Results suggested that GT, like SA, may be beneficial for bracket bonding immediately after bleaching.

Use of Hydrogen Peroxide to Disinfect Hydroponic Plant Growth Systems

NASA Technical Reports Server (NTRS)

Barta, Daniel J.; Henderson, Keith

2000-01-01

Hydrogen peroxide was studied as an alternative to conventional bleach and rinsing methods to disinfect hydroponic plant growth systems. A concentration of 0.5% hydrogen peroxide was found to be effective. Residual hydrogen peroxide can be removed from the system by repeated rinsing or by flowing the solution through a platinum on aluminum catalyst. Microbial populations were reduced to near zero immediately after treatment but returned to pre-disinfection levels 2 days after treatment. Treating nutrient solution with hydrogen peroxide and planting directly into trays being watered with the nutrient solution without replenishment, was found to be detrimental to lettuce germination and growth.

Preemptive use of etodolac on tooth sensitivity after in-office bleaching: a randomized clinical trial.

PubMed

Vaez, Savil Costa; Faria-E-Silva, André Luís; Loguércio, Alessandro Dourado; Fernandes, Micaelle Tenório Guedes; Nahsan, Flávia Pardo Salata

2018-02-01

This study determined the effectiveness of the preemptive administration of etodolac on risk and intensity of tooth sensitivity and the bleaching effect caused by in-office bleaching using 35% hydrogen peroxide. Fifty patients were selected for this tripleblind, randomized, crossover, and placebo-controlled clinical trial. Etodolac (400 mg) or placebo was administrated in a single-dose 1 hour prior to the bleaching procedure. The whitening treatment with 35% hydrogen peroxide was carried out in two sessions with a 7-day interval. Tooth sensitivity was assessed before, during, and 24 hours after the procedure using the analog visual scale and the verbal rating scale. Color alteration was assessed by a bleach guide scale, 7 days after each session. Relative risk of sensitivity was calculated and adjusted by session, while overall risk was compared by the McNemar's test. Data on the sensitivity level of both scales and color shade were subjected to Friedman, Wilcoxon, and Mann-Whitney tests, respectively (α=0.05). The preemptive administration of etodolac did not affect the risk of tooth sensitivity and the level of sensitivity reported, regardless of the time of evaluation and scale used. The sequence of treatment allocation did not affect bleaching effectiveness, while the second session resulted in additional color modification. The preemptive administration of etodolac in a single dose 1 hour prior to in-office tooth bleaching did not alter tooth color, and the risk and intensity of tooth sensitivity reported by patients. A single-dose preemptive administration of 400 mg of etodolac did not affect either risk of tooth sensitivity or level of sensitivity reported by patients, during or after the in-office tooth bleaching procedure.

Manganese peroxidase, produced by Trametes versicolor during pulp bleaching, demethylates and delignifies kraft pulp

DOE Office of Scientific and Technical Information (OSTI.GOV)

Paice, M.G.; Reid, I.D.; Bourbonnais, R.

1993-01-01

The white rot fungus Trametes (Coriolus) versicolor delignifies and bleaches kraft pulp. However, the process is slow compared with chemical bleaching and the cellulose is also attacked. This study attempts to determine the enzymology of fungal delignification and then applies the relevant enzymes directly to the pulp. Lignin peroxidase and manganese peroxidase (MnP) have both been implicated in lignin biodegradations. However, the researchers show that MnP is the critical enzyme. It is produced by bleaching cultures of T. versicolor; its peak production occurs at the same time as the maximum rate of fungal culture bleaching, and the manganese-and peroxide-dependent demethylationmore » and delignification of kraft pulp occurs in vitro. 50 refs., 4 figs., 7 tabs.« less

Laser Teeth Bleaching: Evaluation of Eventual Side Effects on Enamel and the Pulp and the Efficiency In Vitro and In Vivo

PubMed Central

De Moor, Roeland Jozef Gentil; Meire, Maarten August; De Coster, Peter Jozef

2015-01-01

Light and heat increase the reactivity of hydrogen peroxide. There is no evidence that light activation (power bleaching with high-intensity light) results in a more effective bleaching with a longer lasting effect with high concentrated hydrogen peroxide bleaching gels. Laser light differs from conventional light as it requires a laser-target interaction. The interaction takes place in the first instance in the bleaching gel. The second interaction has to be induced in the tooth, more specifically in the dentine. There is evidence that interaction exists with the bleaching gel: photothermal, photocatalytical, and photochemical interactions are described. The reactivity of the gel is increased by adding photocatalyst of photosensitizers. Direct and effective photobleaching, that is, a direct interaction with the colour molecules in the dentine, however, is only possible with the argon (488 and 415 nm) and KTP laser (532 nm). A number of risks have been described such as heat generation. Nd:YAG and especially high power diode lasers present a risk with intrapulpal temperature elevation up to 22°C. Hypersensitivity is regularly encountered, being it of temporary occurrence except for a number of diode wavelengths and the Nd:YAG. The tooth surface remains intact after laser bleaching. At present, KTP laser is the most efficient dental bleaching wavelength. PMID:25874258

Ultrastructural evaluation of enamel after dental bleaching associated with fluoride.

PubMed

Dominguez, John A; Bittencourt, Bruna; Michel, Milton; Sabino, Nilson; Gomes, João Carlos; Gomes, Osnara M M

2012-08-01

This study evaluated the effects on human enamel after two bleaching procedures: with a fluoridated bleaching agent and with topical fluoride application postbleaching. It used 43 enamel blocks (3 mm(2) ) that were ground flat (600-2,000 grit) and polished with polishing paste (one and one-fourth). Specimens were randomly divided into three groups according to the bleaching procedure: (1) control group, (2) hydrogen peroxide 35% (HPF) and topical application of fluoride 1.23%, and (3) HP 38% (OP) with fluoride in its composition. Bleaching agents were used according to the manufacturer's instructions. Three methodologies were used: nanoindentation, to observe surface hardness and elastic modulus; atomic force microscopy, to observe surface roughness (R(a) - R(z)); and scanning electron microscopy, to observe the enamel surface effects. Group OP had a decrease in the elastic modulus after bleaching, which was recovered at 14 days. An increased roughness (R(a); 32%) was observed on group HPF and had an increased erosion on enamel surface (67%). It was concluded that topical application of fluoride, after using the nonfluoridated whitening agent, increased the roughness values and erosion of enamel. Copyright © 2012 Wiley Periodicals, Inc.

Clinical study of the safety and effectiveness of a novel over-the-counter bleaching tray system

PubMed Central

Ghalili, K Michael; Khawaled, Kamal; Rozen, Doran; Afsahi, Veda

2014-01-01

We investigated color change, gingival irritation, and tooth sensitivity in patients undergoing at-home vital tooth bleaching with a novel over-the-counter bleaching tray system. Tooth color shade in anterior teeth, supragingival plaque and gingivitis in Ramfjord teeth, as well as visual assessment of teeth gingival tissues and mucosa were evaluated in-office prior to treatment, after two consecutive applications of the 9% hydrogen peroxide bleaching product, after eight applications (10 minutes/day for 3 days at home), and after ten applications (50 minutes exposure over 5 days). Color stability was evaluated at 3 months after completing the treatment regimen. Over-the-counter bleaching products can be used by the patient at home without dentist supervision, but are frequently associated with gingival irritation and tooth sensitivity despite low concentrations of peroxide agents. Our investigations showed that the treatment is tolerable and safe with a low incidence of adverse effects. Any adverse effects associated with use of the whitening gel and tray are temporary, easily controlled, and often disappear within minutes of treatment. Statistical analysis revealed significant improvement in teeth whitening following treatment (mean color change of seven shades) and at three months after treatment. PMID:24591847

In vitro study on tooth enamel lesions related to whitening dentifrice.

PubMed

de Araújo, Danilo Barral; Silva, Luciana Rodrigues; Campos, Elisângela de Jesus; Correia de Araújo, Roberto Paulo

2011-01-01

The tooth whitening substances for extrinsic use that are available in Brazil contain hydrogen peroxide or carbamide peroxide. Several studies have attributed the appearance of lesions in the enamel morphology, including hypersensitivity, to these substances. Such lesions justify fluoride therapy and application of infrared lasers, among other procedures. However, there is no consensus among researchers regarding the relevance of the severity of lesions detected on the tooth surface. The present study was carried out with an aim of evaluating in vitro the effects of the hydrogen peroxide, carbamide peroxide and sodium bicarbonate contained in dentifrice formulations, on human tooth enamel. After darkening process in laboratory, human premolars were brushed using dentifrice containing the two whitening substances (Rembrandt - carbamide peroxide and Mentadent - hydrogen peroxide) and the abrasive product (Colgate - sodium bicarbonate). The degree of specimen staining before and after this procedure was determined using spectrophotometry. Scanning electron microscopy (SEM) was used to obtain images, which were analyzed to show the nature of the lesions that appeared on the enamel surface. The effectiveness of the whitening caused by hydrogen peroxide and carbamide peroxide and the abrasion caused by bicarbonate were confirmed, given that the treated test pieces returned to their original coloration. Based on SEM, evaluation of the enamel surfaces subjected to the test products showed that different types of morphologic lesions of varying severity appeared. Whitening dentifrice containing hydrogen peroxide and carbamide peroxide produced lesions on the enamel surface such that the greatest sequelae were associated with exposure to hydrogen peroxide.

Effect of three nanobiomaterials on the surface roughness of bleached enamel

PubMed Central

Khoroushi, Maryam; Shirban, Farinaz; Doustfateme, Samaneh; Kaveh, Sara

2015-01-01

Background: The ever-increasing demand for enhanced esthetic appearance has resulted in significant developments in bleaching products. However, the enamel surface roughness (SR) might be negatively affected by bleaching agents. This in vitro study was undertaken to compare the effects of three nanobiomaterials on the enamel SR subsequent to bleaching. Materials and Methods: The crowns of six extracted intact nonerupted human third molars were sectioned. Five dental blocks measuring 2 mm × 3 mm × 4 mm were prepared from each tooth and placed in colorless translucent acrylic resin. The enamel areas from all the specimens were divided into five groups (n = 6): Group 1 did not undergo any bleaching procedures; Group 2 was bleached with a 40% hydrogen peroxide (HP) gel; Groups 3, 4, and 5 were bleached with a 40% HP gel modified by bioactive glass (BAG), amorphous calcium phosphate, and hydroxyapatite, respectively. The enamel SR was evaluated before and after treatment by atomic force microscopy. The data were analyzed by Kruskal–Wallis and Mann–Whitney tests. Results: SR increased significantly in the HP group. SR decreased significantly in the HP gel modified by BAG group as compared to other groups. Conclusions: Within the limitations of this study, incorporation of each one of the three test biomaterials proved effective in decreasing enamel SR subsequent to in-office bleaching technique. PMID:26681849

Effect of hydrogen peroxide on the three-dimensional polymer network in composites.

PubMed

Durner, Jürgen; Stojanovic, Marija; Urcan, Ebru; Spahl, Werner; Haertel, Ursula; Hickel, Reinhard; Reichl, Franx-Xaver

2011-06-01

Less data are available about the effects of hydrogen peroxide on the three-dimensional polymer network of polymerized composites. Therefore the study was performed to test the effects of hydrogen peroxide on the three-dimensional polymer network in composites. Polymerized specimens from Tetric Flow®, Tetric Ceram® and Filtek™ Supreme XT were bleached with Opalescence® PF 15% for 5h or PF 35% for 0.5h, respectively, and then stored in methanol for 1d and 7d. Controls were unbleached specimens. The eluates were analyzed by gas chromatography/mass spectrometry. More methacrylic acid (MAA), bisphenol-A (BPA), ethoxylated bisphenol-A-dimethacrylate (BisEMA), hydroquinone monomethyl ether (HQME), 1,10-decanediol dimethacrylate (DDDMA) and/or triethylene glycol dimethacrylate (TEGDMA) were eluted from bleached specimens compared with non bleached controls (1d). The highest DDDMA amount of 419.8 μmol/l was found in the eluates after 7d in Tetric Flow® specimens treated with PF 15. The highest HQME amount of 159.6 μmol/l was found in eluates from Tetric Ceram® specimens treated with PF after 7d. The highest TEGDMA amount of 178.7 μmol/l was found in eluates from Filtek™ Supreme XT specimens treated with PF 35 after 7d. Bleaching with hydrogen peroxide has an effect on the three-dimensional polymer network in polymerized composites leading to an increase in the release of unpolymerized monomers, additives and unspecific oxidative products. Copyright © 2011 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Preemptive use of etodolac on tooth sensitivity after in-office bleaching: a randomized clinical trial

PubMed Central

Vaez, Savil Costa; Faria-e-Silva, André Luís; Loguércio, Alessandro Dourado; Fernandes, Micaelle Tenório Guedes; Nahsan, Flávia Pardo Salata

2018-01-01

Abstract Purpose This study determined the effectiveness of the preemptive administration of etodolac on risk and intensity of tooth sensitivity and the bleaching effect caused by in-office bleaching using 35% hydrogen peroxide. Material and methods Fifty patients were selected for this tripleblind, randomized, crossover, and placebo-controlled clinical trial. Etodolac (400 mg) or placebo was administrated in a single-dose 1 hour prior to the bleaching procedure. The whitening treatment with 35% hydrogen peroxide was carried out in two sessions with a 7-day interval. Tooth sensitivity was assessed before, during, and 24 hours after the procedure using the analog visual scale and the verbal rating scale. Color alteration was assessed by a bleach guide scale, 7 days after each session. Relative risk of sensitivity was calculated and adjusted by session, while overall risk was compared by the McNemar's test. Data on the sensitivity level of both scales and color shade were subjected to Friedman, Wilcoxon, and Mann-Whitney tests, respectively (α=0.05). Results The preemptive administration of etodolac did not affect the risk of tooth sensitivity and the level of sensitivity reported, regardless of the time of evaluation and scale used. The sequence of treatment allocation did not affect bleaching effectiveness, while the second session resulted in additional color modification. The preemptive administration of etodolac in a single dose 1 hour prior to in-office tooth bleaching did not alter tooth color, and the risk and intensity of tooth sensitivity reported by patients. Conclusion A single-dose preemptive administration of 400 mg of etodolac did not affect either risk of tooth sensitivity or level of sensitivity reported by patients, during or after the in-office tooth bleaching procedure. PMID:29412363

Hydrogen peroxide-induced apoptosis in human gingival fibroblasts

PubMed Central

Gutiérrez-Venegas, Gloria; Guadarrama-Solís, Adriana; Muñoz-Seca, Carmen; Arreguín-Cano, Juan Antonio

2015-01-01

In the process of bleaching vital, discolored teeth, low concentrations of hydrogen peroxide (H2O2) are effective alternatives to heat-activated 30% H2O2. However, interest has been expressed in the assessment of pathological effects of long-term exposure to bleaching agents such as irritation and ulceration of the gingival or other soft tissues. The aim of the present study was to determine the effect of hydrogen peroxide on apoptosis in human gingival fibroblasts (HGF). Cytochrome c, Bcl-2, Bax, Bid and caspase-3 protein expression were detected by Western blotting. HGF cell apoptosis induced by H2O2 was both dose and time dependent. The addition of H2O2 resulted in the release of cytochrome c to the cytosol, and an increase of Caspase-3 cleavage. Data suggest that oxidative stress-induced apoptosis in HGF is intrinsic pathway involved the release of apoptotic signal from mitochondria. PMID:26884825

Calcium release rates from tooth enamel treated with dentifrices containing whitening agents and abrasives.

PubMed

Araujo, Danilo Barral; Silva, Luciana Rodrigues; de Araujo, Roberto Paulo Correia

2010-01-01

Tooth whitening agents containing hydrogen peroxide and carbamide peroxide are used frequently in esthetic dental procedures. However, lesions on the enamel surface have been attributed to the action of these products. Using conventional procedures for separating and isolating biological structures, powdered enamel was obtained and treated with hydrogen peroxide, carbamide peroxide, and sodium bicarbonate, ingredients typically found in dentifrices. The enamel was exposed to different pH levels, and atomic emission spectrometry was used to determine calcium release rates. As the pH level increased, the rate of calcium release from enamel treated with dentifrices containing whitening agents decreased. Carbamide peroxide produced the lowest amount of decalcification, while sodium bicarbonate produced the highest release rates at all pH levels.

Hydrogen peroxide and caustic soda: Dancing with a dragon while bleaching

Treesearch

Peter W. Hart; Carl Houtman; Kolby Hirth

2013-01-01

When hydrogen peroxide is mixed with caustic soda, an auto-accelerating reaction can lead to generation of significant amounts of heat and oxygen. On the basis of experiments using typical pulp mill process concentration and temperatures, a relatively simple kinetic model has been developed. Evaluation of these model results reveals that hydrogen peroxide-caustic soda...

Hydrogen peroxide poisoning.

PubMed

Watt, Barbara E; Proudfoot, Alex T; Vale, J Allister

2004-01-01

Hydrogen peroxide is an oxidising agent that is used in a number of household products, including general-purpose disinfectants, chlorine-free bleaches, fabric stain removers, contact lens disinfectants and hair dyes, and it is a component of some tooth whitening products. In industry, the principal use of hydrogen peroxide is as a bleaching agent in the manufacture of paper and pulp. Hydrogen peroxide has been employed medicinally for wound irrigation and for the sterilisation of ophthalmic and endoscopic instruments. Hydrogen peroxide causes toxicity via three main mechanisms: corrosive damage, oxygen gas formation and lipid peroxidation. Concentrated hydrogen peroxide is caustic and exposure may result in local tissue damage. Ingestion of concentrated (>35%) hydrogen peroxide can also result in the generation of substantial volumes of oxygen. Where the amount of oxygen evolved exceeds its maximum solubility in blood, venous or arterial gas embolism may occur. The mechanism of CNS damage is thought to be arterial gas embolisation with subsequent brain infarction. Rapid generation of oxygen in closed body cavities can also cause mechanical distension and there is potential for the rupture of the hollow viscus secondary to oxygen liberation. In addition, intravascular foaming following absorption can seriously impede right ventricular output and produce complete loss of cardiac output. Hydrogen peroxide can also exert a direct cytotoxic effect via lipid peroxidation. Ingestion of hydrogen peroxide may cause irritation of the gastrointestinal tract with nausea, vomiting, haematemesis and foaming at the mouth; the foam may obstruct the respiratory tract or result in pulmonary aspiration. Painful gastric distension and belching may be caused by the liberation of large volumes of oxygen in the stomach. Blistering of the mucosae and oropharyngeal burns are common following ingestion of concentrated solutions, and laryngospasm and haemorrhagic gastritis have been

The influence of hair bleach on the ultrastructure of human hair with special reference to hair damage.

PubMed

Imai, Takehito

2011-05-01

The influence of human hair bleaching agents with different bleaching strength on the ultrastructure of human hair was studied using a transmission electron microscope (TEM) and an energy dispersive X-ray spectrometer equipped with TEM (EDS-TEM). Two kinds of bleaching agents were used: a lightener agent with a weak bleaching effect and a powder-bleach with a stronger bleaching effect. From the comparison of the bleaching properties obtained by the electronic staining of black and white hair samples, it was suggested that the permeability of hair was increased by bleaching, and there was an increase of the stainability of hair subjected to electronic staining. The bleaching action provoked the decomposition of melanin granules and the flow out of granular contents into the intermacrofibrillar matrix. Some metal elements were detected in the melanin granular matrix by EDS-TEM. As a result, the diffusion of metal elements into the intermacrofibrillar matrix promoted further damage to the hair by catalytic action with the hydrogen peroxide in the bleaching agents outside the melanin granules. Further study will lead us to the edge of the development of a new bleaching agent, which reacts only with melanin granules and causes the minimum of damage to outside the melanin granules.

Dentin hypersensitivity after teeth bleaching with in-office systems. Randomized clinical trial.

PubMed

Martin, Javier; Fernandez, Eduardo; Bahamondes, Valeria; Werner, Andrea; Elphick, Klaus; Oliveira, Osmir Batista; Moncada, Gustavo

2013-02-01

To comparatively and prospectively compare in a randomized clinical trial, dentin hypersensitivity after treatment with three in-office bleaching systems, based on hydrogen peroxide at different concentrations, with and without light source activation. 88 individuals were included according to inclusion and exclusion criteria. Subjects were randomly divided into the following three treatment groups: Group 1 was treated with three 15-minute applications of hydrogen peroxide at 15% with titanium dioxide (Lase Peroxide Lite) that was light-activated (Light Plus Whitening Lase) with five cycles of 1 minute and 30 seconds each cycle, giving a total treatment time of 45 minutes; Group 2 was treated with three 10-minute applications of hydrogen peroxide at 35% (Lase Peroxide Sensy), activated by light (LPWL) same activation cycles than Group 1, with a total treatment time of 30 minutes; Group 3 was treated with only one application for 45 minutes of hydrogen peroxide at 35% (Whitegold Office) without light activation. Each subject underwent one session of bleaching on the anterior teeth according to the manufacturers' instructions. Dentin sensitivity was recorded with a visual analogue scale (VAS) at baseline, immediately after, and at 7 and 30 days after treatment using a stimulus of an evaporative blowing triple syringe for 3 seconds on the upper central incisors from a distance of 1 cm. A Kruskal-Wallis test followed by Mann-Whitney test was performed for statistical analysis. All groups showed increased sensitivity immediately after treatment. Group 1 displayed less changes relative to baseline with no significant differences (P = 0.104). At 7 and 30 days after treatment, a comparison of VAS values indicated no significant differences between all groups (P = 0.598 and 0.489, respectively).

Patterns of coral bleaching: Modeling the adaptive bleaching hypothesis

USGS Publications Warehouse

Ware, J.R.; Fautin, D.G.; Buddemeier, R.W.

1996-01-01

Bleaching - the loss of symbiotic dinoflagellates (zooxanthellae) from animals normally possessing them - can be induced by a variety of stresses, of which temperature has received the most attention. Bleaching is generally considered detrimental, but Buddemeier and Fautin have proposed that bleaching is also adaptive, providing an opportunity for recombining hosts with alternative algal types to form symbioses that might be better adapted to altered circumstances. Our mathematical model of this "adaptive bleaching hypothesis" provides insight into how animal-algae symbioses might react under various circumstances. It emulates many aspects of the coral bleaching phenomenon including: corals bleaching in response to a temperature only slightly greater than their average local maximum temperature; background bleaching; bleaching events being followed by bleaching of lesser magnitude in the subsequent one to several years; higher thermal tolerance of corals subject to environmental variability compared with those living under more constant conditions; patchiness in bleaching; and bleaching at temperatures that had not previously resulted in bleaching. ?? 1996 Elsevier Science B.V. All rights reserved.

The effect of fiber bleaching treatment on the properties of poly(lactic acid)/oil palm empty fruit bunch fiber composites.

PubMed

Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

2014-08-22

In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant.

The Effect of Fiber Bleaching Treatment on the Properties of Poly(lactic acid)/Oil Palm Empty Fruit Bunch Fiber Composites

PubMed Central

Rayung, Marwah; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Saad, Wan Zuhainis; Razak, Nur Inani Abdul; Chieng, Buong Woei

2014-01-01

In this work, biodegradable composites from poly(lactic acid) (PLA) and oil palm empty fruit bunch (OPEFB) fiber were prepared by melt blending method. Prior to mixing, the fiber was modified through bleaching treatment using hydrogen peroxide. Bleached fiber composite showed an improvement in mechanical properties as compared to untreated fiber composite due to the enhanced fiber/matrix interfacial adhesion. Interestingly, fiber bleaching treatment also improved the physical appearance of the composite. The study was extended by blending the composites with commercially available masterbatch colorant. PMID:25153628

A colourimetric evaluation of the effect of bacterial contamination on teeth stained with blood in vitro: Evaluation of the efficacy of two different bleaching regimes.

PubMed

Wang, S; Cathro, P; Heithersay, G; Briggs, N; Ratnayake, J; Zilm, P

2018-02-27

Tooth discolouration could occur due to bacterial contamination in traumatized teeth. Hydrogen peroxide is the commonly used bleaching agent. However, due to concerns over safety, alternative bleaching regimes such as sodium perborate (S) and thiourea-hydrogen peroxide (T) have been investigated. Apices resected and pulp extirpated 99 premolars were divided into two groups. Group 1 and 2 was injected with blood and blood/bacteria, stored anaerobically for 35 days. The two groups were treated by bleaching with water, S or T. Teeth were rebleached after 7 days. Colourimetric evaluation was assessed using digital imaging, CasMatch standardization and CIE L*a*b colour system preoperatively, 35 days of staining and 7 and 14 of bleaching. A linear mixed model with fixed effects of time, group and bleach was used to examine colour difference. Blood-stained teeth were significantly redder and darker on day 35 compared with blood/bacteria-stained teeth. After bleaching, blood-stained teeth retained significant redness compared with blood/bacteria-stained teeth using either S or T. T produced a significantly whiter shade in both the groups after 14 days. Blood-stained teeth were significantly darker and red compared with blood/bacteria-stained teeth. T bleaching regime was more effective than S. © 2018 Australian Dental Association.

[Effect of bleaching agents on the color of indirect and direct composite resins].

PubMed

Xing, Wenzhong; Jiang, Tao; Chen, Xiaodong; Wang, Yining

2014-09-01

To evaluate the effect of bleaching agents on the color of indirect and direct composite resins. Five resin composite materials were tested in this in vitro study. The five composites were as follow: two indirect composite resins (Adoro SR, Ceramage) and three direct composite resins (Filtek Z350, Clearfil Majesty Esthetic, and Gradia Direct Anterior). For each material, twenty disk-shaped specimens were prepared and randomly divided into five groups according to the color parameters of specimens before bleaching treatment. The composite resin specimens were treated by one of five sample solutions which were at-home bleaching agents (10% and 15% carbarmide peroxide), in- office bleaching agents (38% H(2)O(2) and 35%H(2)O(2)) and deionized water (control group). The color parameters of specimens were measured by spectrophotometer at baseline and after bleaching treatments. The color differences (ΔE values) between baseline and post-treatments were calculated. The data of color differences were evaluated statistically using two-way analysis with a significance level of 0.05. The color changes of the resin composites were less than 2.0 after bleaching agent treatment, therefore were not perceptible. Slight increase of L(*) values and decrease of C(*)ab values in color parameters of specimens were observed. There were statistically significant differences in ΔE values for different bleaching treatments and resin materials (P = 0.001). The bleaching agents did not affect the color of indirect and direct composite resins tested.

Titrimetric and photometric methods for determination of hypochlorite in commercial bleaches.

PubMed

Jonnalagadda, Sreekanth B; Gengan, Prabhashini

2010-01-01

Two methods, simple titration and photometric methods for determination of hypochlorite are developed, based its reaction with hydrogen peroxide and titration of the residual peroxide by acidic permanganate. In the titration method, the residual hydrogen peroxide is estimated by titration with standard permanganate solution to estimate the hypochlorite concentration. The photometric method is devised to measure the concentration of remaining permanganate, after the reaction with residual hydrogen peroxide. It employs 4 ranges of calibration curves to enable the determination of hypochlorite accurately. The new photometric method measures hypochlorite in the range 1.90 x 10(-3) to 1.90 x 10(-2) M, with high accuracy and with low variance. The concentrations of hypochlorite in diverse commercial bleach samples and in seawater which is enriched with hypochlorite were estimated using the proposed method and compared with the arsenite method. The statistical analysis validates the superiority of the proposed method.

Effects of different preparation procedures during tooth whitening on enamel bonding.

PubMed

Wilson, Dustin; Xu, Changqi; Hong, Liang; Wang, Yong

2009-04-01

The objective of this study was to assess effects of some clinically related preparation procedures during tooth whitening on enamel bonding properties. Sixty-two extracted human teeth were cleaned and divided into four groups. Forty-two of the teeth were left with their natural surface intact while 20 teeth were polished to form a flat surface. Half of the tooth served as the experimental side and received one of the two whitening products: Opalescence (10% carbamide peroxide) and Crest Whitestrips (6.5% hydrogen peroxide), for 2 weeks. Post-bleaching intervals included: 1 day, 1 week, and 2 weeks. On these days, tooth (10 mm x 1.5 mm x 1.5 mm) sections were evaluated using Raman spectroscopy, scanning electron microscopy and tensile bond strength tests. T-test, ANOVA test, and mixed model regression analysis were used to assess the differences. No significant difference existed between natural surface and polished surface teeth for all groups at both Day One and Week Two (P > 0.05). On Day One, both treated groups had significant lower bond strength than the control group (P = 0.002). After 2 weeks, no significant difference existed between any group (P = 0.381). SEM indicated that resin-enamel interfaces in bleached enamel exhibited more defects in granular formations when compared to the control. Raman results indicated a lower degree of polymerization (DP) of adhesive at the interface for treated teeth surfaces. In summary, pre-bleaching surface treatments such as polish or non-polish, had no effect on bond strength. Bleaching significantly decreased bond strength initially, but after 2 weeks, bleaching had no significant effect on bond strength. Storage time had significant effect on Opalescence treated enamel, but not on control and Whitestrip treated enamel. The decrease of bond strength may be related to interfacial defects and low DP due to oxygen release after bleaching.

The influence of the Nd:YAG laser bleaching on physical and mechanical properties of the dental enamel.

PubMed

Marcondes, Maurem; Paranhos, Maria Paula Gandolfi; Spohr, Ana Maria; Mota, Eduardo Gonçalves; da Silva, Isaac Newton Lima; Souto, André Arigony; Burnett, Luiz Henrique

2009-07-01

The Nd:YAG laser can be used in Dentistry to remove soft tissue, disinfect canals in endodontic procedures and prevent caries. However, there is no protocol for Nd:YAG laser application in dental bleaching. The aims of this in vitro study were: (a) to observe the tooth shade alteration when hydrogen peroxide whitening procedures are associated with dyes with different wavelengths and irradiated with Nd:YAG laser or halogen light; (b) to measure the Vickers (VHN) enamel microhardness before and after the whitening procedure; (c) to evaluate the tensile bond strength of two types of adhesive systems applied on bleached enamel; (d) to observe the failure pattern after bond strength testing; (e) to evaluate the pulpal temperature during the bleaching procedures with halogen light or laser; (f) to measure the kinetic reaction of hydrogen peroxide. Extracted sound human molar crowns were sectioned in the mesiodistal direction to obtain 150 fragments that were divided into five groups for each adhesive system: WL (H(2)O(2) + thickener and Nd:YAG), WH (H(2)O(2) + thickener and halogen light), QL (H(2)O(2) + carbopol + Q-switch and Nd:YAG), QH (H(2)O(2) + carbopol + Q-switch and halogen light), and C (Control, without whitening agent). Shade assessment was made with a shade guide and the microhardness tests were performed before and after the bleaching procedures. Immediately afterwards, the groups were restored with the adhesive systems Adper Single Bond 2 or Solobond M plus composite resin, and the tensile bond strength test was performed. The temperature was measured by thermocouples placed on the enamel surface and intrapulpal chamber. The kinetics of hydrogen peroxide was observed by ultraviolet analysis. The shade changed seven levels for Nd:YAG laser groups and eight levels for halogen light. According to the student's t-test, there was no statistical difference between the VHN before and after the whitening protocols (p > 0.05). The tensile bond strength showed no

Spectrophotometric analysis of discoloration and internal bleaching after use of different antibiotic pastes.

PubMed

Fundaoğlu Küçükekenci, Funda; Çakici, Fatih; Küçükekenci, Ahmet Serkan

2018-04-14

To investigate teeth's antibiotic-induced color differences after bleaching using two different techniques. One hundred twenty extracted maxillar human incisors were examined. The specimens were randomly divided into six groups, each receiving one of six antibiotic paste fillings: (1) triple antibiotic paste (TAP) with minocycline, (2) double antibiotic paste (DAP), (3) TAP with amoxicillin, (4) TAP with cefaclor, (5) TAP with doxycycline, and (6) no filling (control group). Spectrophotometric measurements were obtained at baseline and then during the first, second, and third weeks after paste placement. The specimens discolored by antibiotics pastes were randomly divided into two subgroups: (1) internal bleaching with hydrogen peroxide (H 2 O 2) and (2) internal bleaching with H 2 O 2 plus Nd-YAG laser irradiation. The ∆E value was calculated and analyzed using a two-way analysis of variance and post-hoc Tukey's test (α = 0.05). The ∆E for all groups showed color differences exceeding the perceptibility threshold (∆E ˃ 3.7) at all time points except in the control and DAP groups. Minocycline-induced TAP showed the most severe coronal discoloration (32.42). When the ∆E was examined, thermo/photo bleaching (22.01 ± 8.23) caused more bleaching than walking bleaching (19.73 ± 5.73) at every time point (P = 0.19). No group returned to the original color after bleaching (P < 0.05). Except for DAP, all antibiotic pastes caused discoloration. Internal bleaching with Nd-YAG laser can be useful for bleaching/removing this discoloration. For clinically successful final appearances, understanding the effects of bleaching procedures on antibiotic paste discoloration is important.

Enamel alteration following tooth bleaching and remineralization.

PubMed

Coceska, Emilija; Gjorgievska, Elizabeta; Coleman, Nichola J; Gabric, Dragana; Slipper, Ian J; Stevanovic, Marija; Nicholson, John W

2016-06-01

The purpose of this study was to compare the effects of professional tooth whitening agents containing highly concentrated hydrogen peroxide (with and without laser activation), on the enamel surface; and the potential of four different toothpastes to remineralize any alterations. The study was performed on 50 human molars, divided in two groups: treated with Opalescence(®) Boost and Mirawhite(®) Laser Bleaching. Furthermore, each group was divided into five subgroups, a control one and 4 subgroups remineralized with: Mirasensitive(®) hap+, Mirawhite(®) Gelleѐ, GC Tooth Mousse™ and Mirafluor(®) C. The samples were analysed by SEM/3D-SEM-micrographs, SEM/EDX-qualitative analysis and SEM/EDX-semiquantitative analysis. The microphotographs show that both types of bleaching cause alterations: emphasized perikymata, erosions, loss of interprizmatic substance; the laser treatment is more aggressive and loss of integrity of the enamel is determined by shearing off the enamel rods. In all samples undergoing remineralization deposits were observed, those of toothpastes based on calcium phosphate technologies seem to merge with each other and cover almost the entire surface of the enamel. Loss of integrity and minerals were detected only in the line-scans of the sample remineralized with GC Tooth Mousse™. The semiquantitative EDX analysis of individual elements in the surface layer of the enamel indicates that during tooth-bleaching with HP statistically significant loss of Na and Mg occurs, whereas the bleaching in combination with a laser leads to statistically significant loss of Ca and P. The results undoubtedly confirm that teeth whitening procedures lead to enamel alterations. In this context, it must be noted that laser bleaching is more aggressive for dental substances. However, these changes are reversible and can be repaired by application of remineralization toothpastes. © 2015 The Authors Journal of Microscopy © 2015 Royal Microscopical Society.

Fracture toughness of bleached enamel: Effect of applying three different nanobiomaterials by nanoindentation test.

PubMed

Khoroushi, Maryam; Mazaheri, Hamid; Saneie, Tahere; Samimi, Pouran

2016-01-01

Despite the absence of dispute about the efficacy of bleaching agents, a prime concern is about their compromising effect on the enamel structure. This in vitro study investigated whether the addition of three different biomaterials, including nano-bioactive glass (n-BG)/nano-hydroxy apetite (n-HA)/nano-amorphous calcium phosphate (n-ACP), to bleaching agents can affect the fracture toughness (FT) and vickers hardness number (VHN) of bovine enamel. The crowns of the newly extracted permanent bovine incisors teeth were separated from the root and sectioned along their central line; one half serving as the control specimen and the other half as the test specimen. After mounting and polishing procedure, all the control specimens (C) were subjected to nano-indentation test to obtain the baseline values of FT. Then, the control specimens were exposed to a 38% hydrogen peroxide for four times, each time for 10 min. The test specimens were divided into three groups and treated as follows, with the same protocol used for the control specimens: Group 1; ACP + hydrogen peroxide (HP) mixed gel; Group 2 BG + HP mixed gel; and Group 3 HA + HP mixed gel. FT measurements with nano-indentation were carried out subsequent to bleaching experiments. Data were analyzed using SPSS and Kruskal-Wallis test (α = 0.05). A significant difference in young's modulus (YM), VHN, and FT at baseline and subsequent to bleaching in control group was observed. However, no significant differences were found in YM, VHN, and FT between the test groups, compared to the respective baseline values. Under the limitations of the current study, it can be concluded that the n-HA, n-ACP, and n-BG could be potential biomaterials used to reduce the adverse effects of tooth bleaching.

Fracture toughness of bleached enamel: Effect of applying three different nanobiomaterials by nanoindentation test

PubMed Central

Khoroushi, Maryam; Mazaheri, Hamid; Saneie, Tahere; Samimi, Pouran

2016-01-01

Background: Despite the absence of dispute about the efficacy of bleaching agents, a prime concern is about their compromising effect on the enamel structure. This in vitro study investigated whether the addition of three different biomaterials, including nano-bioactive glass (n-BG)/nano-hydroxy apetite (n-HA)/nano-amorphous calcium phosphate (n-ACP), to bleaching agents can affect the fracture toughness (FT) and vickers hardness number (VHN) of bovine enamel. Materials and Methods: The crowns of the newly extracted permanent bovine incisors teeth were separated from the root and sectioned along their central line; one half serving as the control specimen and the other half as the test specimen. After mounting and polishing procedure, all the control specimens (C) were subjected to nano-indentation test to obtain the baseline values of FT. Then, the control specimens were exposed to a 38% hydrogen peroxide for four times, each time for 10 min. The test specimens were divided into three groups and treated as follows, with the same protocol used for the control specimens: Group 1; ACP + hydrogen peroxide (HP) mixed gel; Group 2 BG + HP mixed gel; and Group 3 HA + HP mixed gel. FT measurements with nano-indentation were carried out subsequent to bleaching experiments. Data were analyzed using SPSS and Kruskal–Wallis test (α = 0.05). Results: A significant difference in young's modulus (YM), VHN, and FT at baseline and subsequent to bleaching in control group was observed. However, no significant differences were found in YM, VHN, and FT between the test groups, compared to the respective baseline values. Conclusion: Under the limitations of the current study, it can be concluded that the n-HA, n-ACP, and n-BG could be potential biomaterials used to reduce the adverse effects of tooth bleaching. PMID:27307669

Removing polysaccharides-and saccharides-related coloring impurities in alkyl polyglycosides by bleaching with the H2O2/TAED/NaHCO3 system.

PubMed

Yanmei, Liu; Jinliang, Tao; Jiao, Sun; Wenyi, Chen

2014-11-04

The effect of H2O2/TAED/NaHCO3 system, namely NaHCO3 as alkaline agent with the (tetra acetyl ethylene diamine (TAED)) TAED-activated peroxide system, bleaching of alkyl polyglycosides solution was studied by spectrophotometry. The results showed that the optimal bleaching conditions about H2O2/TAED/NaHCO3 system bleaching of alkyl polyglycosides solution were as follows: molar ratio of TAED to H2O2 was 0.06, addition of H2O2 was 8.6%, addition of NaHCO3 was 3.2%, bleaching temperature of 50-65 °C, addition of MgO was 0.13%, and bleaching time was 8h. If too much amount of NaHCO3 was added to the system and maintained alkaline pH, the bleaching effect would be greatly reduced. Fixing molar ratio of TAED to H2O2 and increasing the amount of H2O2 were beneficial to improve the whiteness of alkyl polyglycosides, but adding too much amount of H2O2 would reduce the transparency. In the TAED-activated peroxide system, NaHCO3 as alkaline agent and buffer agent, could overcome the disadvantage of producing black precipitates when NaOH as alkaline agent. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of bleaching on sound enamel and with early artificial caries lesions using confocal laser microscopy.

PubMed

Berger, Sandrine Bittencourt; Pavan, Sabrina; Dos Santos, Paulo Henrique; Giannini, Marcelo; Bedran-Russo, Ana Karina B

2012-01-01

The aim of this study was to evaluate effect of bleaching agents on sound enamel (SE) and enamel with early artificial caries lesions (CL) using confocal laser scanning microscopy (CLSM). Eighty blocks (4 x 5 x 5 mm) of bovine enamel were used and half of them were submitted to a pH cycling model to induce CL. Eight experimental groups were obtained from the treatments and mineralization level of the enamel (SE or CL) (n=10). SE groups: G1 - unbleached (control); G2 - 4% hydrogen peroxide (4 HP); G3 - 4 HP containing 0.05% Ca (Ca); G4 - 7.5% hydrogen peroxide (7.5 HP) containing amorphous calcium phosphate (ACP). CL groups: G5 - unbleached; G6 - 4 HP; G7 - 4 HP containing Ca; G8 - 7.5 HP ACP. G2, G3, G6, G7 were treated with the bleaching agents for 8 h/day during 14 days, while G4 and G8 were exposed to the bleaching agents for 30 min twice a day during 14 days. The enamel blocks were stained with 0.1 mM rhodamine B solution and the demineralization was quantified using fluorescence intensity detected by CLSM. Data were analyzed using ANOVA and Fisher's tests (α=0.05). For the SE groups, the bleaching treatments increased significantly the demineralization area when compared with the unbleached group. In the CL groups, no statistically significant difference was observed (p>0.05).The addition of ACP or Ca in the composition of the whitening products did not overcome the effects caused by bleaching treatments on SE and neither was able to promote remineralization of CL.

Spectrophotometric Evaluation of the Pulpal Peroxide Levels in Intact and Restored Teeth - An Invitro Study.

PubMed

Patri, Gaurav; Acharya, Gourismita; Agrawal, Pratik; Panda, Vijeta

2016-08-01

Hydrogen peroxide (30%) is a commonly used "in office" bleaching agent. Deleterious effects of hydrogen peroxide on the pulp have been observed. The present study was conducted with the aim to evaluate the penetration of 30% hydrogen peroxide into the pulp chamber through intact teeth and through the surface of teeth, restored with either hybrid composite or Resin Modified Glass Ionomer Cement (RMGIC). Sixty extracted human maxillary central incisors were selected and divided into six groups. Two groups were restored with hybrid composite resin and two with RMGIC, while two groups were left intact. The teeth with acetate buffer solution in their pulp cavity were then immersed in either 30% hydrogen peroxide or distilled water depending upon the group, for 60 minutes at 37°C. Then horseradish peroxidase and leucocrystal violet were added to the acetate buffer solution present in the pulp chamber after it was transferred to a test tube and the optical density of the resultant blue solution obtained was measured spectrophotometrically. The data obtained were analyzed using one way ANOVA and Student's t-test. The data obtained established that hydrogen peroxide penetrated into the pulp from the bleaching agent used. Hydrogen peroxide (30%) showed the highest pulpal peroxide level in teeth restored with RMGIC followed by teeth restored with hybrid composite resin and the least amount of penetration was observed in intact teeth. The amount of peroxide penetration into the tooth is more through restored tooth than intact tooth and is also dependant on the type of restorative materials used.

In situ Effect of Nanohydroxyapatite Paste in Enamel Teeth Bleaching.

PubMed

Gomes, Yasmin Sb de Lima; Alexandrino, Larissa D; Alencar, Cristiane de M; Alves, Eliane B; Faial, Kelson Cf; Silva, Cecy M

2017-11-01

Evaluate in situ the effect of nanohydroxyapatite paste (nano-HAP) before bleaching with hydrogen peroxide 35% (HP35%) by ion chromatography (IC) Knoop hardness number (KHN) and tristimulus colorimetry (TC). A total of 60 fragments were obtained from third molars included (3 mm × 3 mm × 3 mm) and the specimens were divided into three groups (n = 20): Gas chromatography (CG) (negative control group) = no bleaching; HP35% (positive control group) = HP35% whitening (whiteness HP35%); nano-HAP = application for 10 minutes before bleaching treatment + HP35%. The specimens were fixed to the volunteers' molars. The KHN and TC were measured before and after bleaching. For IC, the dentin layer was removed, leaving the enamel that was crushed, and autoclaved for chemical quantification (calcium, fluorine, and phosphorus). The results of KHN and TC were analyzed statistically by analysis of variance (ANOVA) followed by Tukey test (p < 0.05). The HP35% group showed reduction of the Ca, F, and P ions. The initial and final KHN mean of the CG and nano-HAP did not differ statistically; however, the group of HP35% did differ statistically. The mean ΔE of the HP35% and nano-HAP groups did not differ statistically from each other. However, they differed from the CG. The nano-HAP paste preserved the KHN, promoted the lower loss of Ca and P ions and an increase of F ions when compared with the CG, but did not influence the effectiveness of the bleaching treatment. Nano-HA is a biomaterial that has shown positive results in the prevention of deleterious effects on the enamel by the action of the office bleaching treatment.

Influence of Bleaching Regimen and Time Elapsed on Microtensile Bond Strength of Resin Composite to Enamel

PubMed Central

Topcu, Fulya Toksoy; Erdemir, Ugur; Ozel, Emre; Tiryaki, Murat; Oktay, Elif Aybala; Yildiz, Esra

2017-01-01

Objectives: The aim of this study was to evaluate the effects of time elapsed since bleaching and different bleaching regimens on the microtensile bond strength of resin composite to enamel. Methodology: Forty flattened buccal enamel surfaces were divided into four groups: An unbleached (control) group and three bleaching groups. Control group specimens were not subjected to a bleaching regimen (Group 1), while those in the bleaching groups were bleached as follows: opalescence 10% (Group 2), whiteness perfect 16% (Group 3), and whiteness hydrogen peroxide 35% (Group 4). Thereafter, the bleached specimens were divided into three subgroups (n = 4 teeth each) for restoration according to predetermined posttreatment time intervals (immediately, 1 week, and 2 weeks). Bonded specimens were then sectioned and subjected to μTBS testing. The data were analyzed using Kruskal–Wallis and Mann–Whitney U-tests at α = 0.05. Results: There was a significant difference in the μTBS of the resin composite to enamel in groups that were bonded immediately after bleaching and in the control group (P < 0.05). Compared to the control group, the μTBS in Groups 2, 3, and 4 decreased significantly 1-week postbleaching (P < 0.05). No significant difference in μTBS was observed between the bleached and unbleached groups 2 weeks after treatment (P > 0.05). Conclusions: Adhesive restorative procedures could not be performed immediately or after 1 week irrespective of the type or concentration of bleaching system used. Composite restorations on bleached enamel surfaces should be performed after an interval of at least 2 weeks. PMID:29042734

Influence of Bleaching Regimen and Time Elapsed on Microtensile Bond Strength of Resin Composite to Enamel.

PubMed

Topcu, Fulya Toksoy; Erdemir, Ugur; Ozel, Emre; Tiryaki, Murat; Oktay, Elif Aybala; Yildiz, Esra

2017-01-01

The aim of this study was to evaluate the effects of time elapsed since bleaching and different bleaching regimens on the microtensile bond strength of resin composite to enamel. Forty flattened buccal enamel surfaces were divided into four groups: An unbleached (control) group and three bleaching groups. Control group specimens were not subjected to a bleaching regimen (Group 1), while those in the bleaching groups were bleached as follows: opalescence 10% (Group 2), whiteness perfect 16% (Group 3), and whiteness hydrogen peroxide 35% (Group 4). Thereafter, the bleached specimens were divided into three subgroups ( n = 4 teeth each) for restoration according to predetermined posttreatment time intervals (immediately, 1 week, and 2 weeks). Bonded specimens were then sectioned and subjected to μTBS testing. The data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests at α = 0.05. There was a significant difference in the μTBS of the resin composite to enamel in groups that were bonded immediately after bleaching and in the control group ( P < 0.05). Compared to the control group, the μTBS in Groups 2, 3, and 4 decreased significantly 1-week postbleaching ( P < 0.05). No significant difference in μTBS was observed between the bleached and unbleached groups 2 weeks after treatment ( P > 0.05). Adhesive restorative procedures could not be performed immediately or after 1 week irrespective of the type or concentration of bleaching system used. Composite restorations on bleached enamel surfaces should be performed after an interval of at least 2 weeks.

An in vivo study of the effect of a 38 percent hydrogen peroxide in-office whitening agent on enamel.

PubMed

Cadenaro, Milena; Navarra, Chiara Ottavia; Mazzoni, Annalisa; Nucci, Cesare; Matis, Bruce A; Di Lenarda, Roberto; Breschi, Lorenzo

2010-04-01

In an in vivo study, the authors tested the hypothesis that no difference in enamel surface roughness is detectable either during or after bleaching with a high-concentration in-office whitening agent. The authors performed profilometric and scanning electron microscopic (SEM) analyses of epoxy resin replicas of the upper right incisors of 20 participants at baseline (control) and after each bleaching treatment with a 38 percent hydrogen peroxide whitening agent, applied four times, at one-week intervals. The authors used analysis of variance for repeated measures to analyze the data statistically. The profilometric analysis of the enamel surface replicas after the in vivo bleaching protocol showed no significant difference in surface roughness parameters (P > .05) compared with those at baseline, irrespective of the time interval. Results of the correlated SEM analysis showed no relevant alteration on the enamel surface. Results of this in vivo study support the tested hypothesis that the application of a 38 percent hydrogen peroxide in-office whitening agent does not alter enamel surface roughness, even after multiple applications. The use of a 38 percent hydrogen peroxide in-office whitening agent induced no roughness alterations of the enamel surface, even after prolonged and repeated applications.

High levels of hydrogen peroxide in overnight tooth-whitening formulas: effects on enamel and pulp.

PubMed

Pugh, George; Zaidel, Lynette; Lin, Nora; Stranick, Michael; Bagley, Daniel

2005-01-01

Limited data are available to assess the safety of high levels of hydrogen peroxide in overnight tooth-whitening formulas. The purpose of this study was to assess the effects of hydrogen peroxide on enamel microhardness, pulp penetration, and enamel morphology. Colgate Platinum Professional Overnight Whitening System (Colgate Oral Pharmaceuticals, Inc., Canton, MA, USA) (10% carbamide peroxide, equivalent to 3.5% hydrogen peroxide) was compared with two prototype formulations containing either 7.0% or 12.0% hydrogen peroxide. In the pulp chamber studies, human extracted teeth were exposed to 3.5%, 7.0%, or 12.0% hydrogen peroxide for 30 minutes, 4 hours, or 7 hours. Microhardness, electron spectroscopy for chemical analysis, and atomic force microscopy evaluations were made from enamel blocks cut from human extracted molars. The enamel blocks were evaluated following 14 7-hour treatments (98 h total). At 7 hours' post-treatment, hydrogen peroxide penetrated the pulp chamber at 23.12 +/- 10.09, 24.58 +/- 6.90, and 26.39 +/- 5.43 microg for 3.5%, 7.0%, and 12.0% hydrogen peroxide, respectively. With regard to enamel morphology, pulp penetration, microhardness, and elemental composition, no statistically significant differences were observed between treatment groups following 98 hours of treatment. Hydrogen peroxide does not adversely affect enamel morphology or microhardness. The levels recovered in pulp indicate that hydrogen peroxide is not expected to inhibit pulpal enzymes. Overnight tray products containing levels of hydrogen peroxide of 3.5%, 7.0%, and 12.0% are not expected to adversely affect the enamel or pulpal enzymes. Additional safety studies are needed to assess the potential for tooth sensitivity and gingival irritation.

Microleakage comparison of glass-ionomer and white mineral trioxide aggregate used as a coronal barrier in nonvital bleaching.

PubMed

Vosoughhosseini, Sepideh; Lotfi, Mehrdad; Shahmoradi, Kaveh; Saghiri, Mohammad-Ali; Zand, Vahid; Mehdipour, Masoumeh; Ranjkesh, Bahram; Mokhtari, Hadi; Salemmilani, Amin; Doosti, Sirvan

2011-11-01

There is some evidence that the pH at the root surface is reduced by intracoronal placement of bleaching pastes, which is known to enhance osteoclastic activity. Therefore, it is recommended that a protective barrier be used over the canal filling to prevent leakage of bleaching agents. Glass-ionomer (GI) is commonly used as a coronal barrier before nonvital bleaching. Because mineral trioxide aggregate (MTA) creates high alkalinity after mixing with water, using MTA as a protective barrier over the canal filling may not only prevent leakage of bleaching agents and microorganisms, but may prevent cervical resorption. The aim of this study was to evaluate sealing ability of white mineral trioxide aggregate (WMTA) as a coronal barrier before nonvital bleaching. Root canals of one hundred thirty human maxillary incisors were instrumented and filled with gutta-percha without sealer. Gutta-percha was removed up to 3 mm below the cementoenamel junction (CEJ). The teeth were randomly divided into six experimental groups of 20 teeth each and two control groups of 5. In three experimental groups, WMTA was packed into the canal to the level of CEJ. In the remaining experimental groups, glass-ionomer (GI) was used as a coronal barrier. After a 24-hour incubation period, one of the following three bleaching agents was placed in the access cavity of each of the WMTA or GI groups. These three bleaching agents were 30% hydrogen peroxide, sodium perborate mixed with 30% hydrogen peroxide, and sodium perborate mixed with distilled water. The bleaching agents were replaced every 3 days for three times. In the positive controls, no coronal barrier was used. In the negative controls, all the tooth surfaces were covered by two layers of nail varnish. Microleakage was evaluated using protein leakage test. Statistical analyses were performed with the Kruskal-Wallis and Mann-Whitney tests. The experimental groups showed minimum leakage which was not significantly more than tha in the

Influence of skin cold sensation threshold in the occurrence of dental sensitivity during dental bleaching: a placebo controlled clinical trial.

PubMed

Rahal, Vanessa; Gallinari, Marjorie de Oliveira; Barbosa, Juliana Stuginski; Martins-Junior, Reynaldo Leite; Santos, Paulo Henrique Dos; Cintra, Luciano Tavares Angelo; Briso, André Luiz Fraga

2018-01-18

This study verified the occurrence of dental sensitivity in patients submitted to a 35% hydrogen peroxide based product (Whiteness HP Maxx 35% - FGM), skin cold sensation threshold (SCST) and its influence on dental sensitivity. Sixty volunteers were divided into 4 groups (n = 15), according to SCST (low: GI and GIII, and high: GII and IV) and bleaching treatment (hydrogen peroxide: GI and GII, and placebo: GIII and GIV). SCST was determined in the inner forearm for 6 different times using a neurosensory analyzer, the TSA II (Medoc Advanced Medical Systems, Ramat Yishai, Northern District, Israel). Dental sensitivity measurements were performed 10 different times using a thermal stimulus and an intraoral device attached to TSA II, positioned in the buccal surface of the upper right central incisor. Spontaneous dental sensitivity was also determined using the Visual Analogue Scale (VAS). Data were submitted to Student's t-test and Pearson's Correlation Test (α=0.05). SCST remained the same during bleaching treatment. Distinct responses of dental sensitivity were found in patients with low and high SCST during the first and third bleaching session (p≤0.05). The teeth submitted to the bleaching treatment became more sensitive to cold than those treated with placebo. Moreover, data obtained with TSA and VAS presented moderate correlation. Bleaching treatment increased dental sensitivity and skin cold sensation threshold might represent a determining factor in this occurrence, since low and high SCST patients had different responses to the thermal stimulus in the teeth.

Transenamel and transdentinal penetration of hydrogen peroxide applied to cracked or microabrasioned enamel.

PubMed

Briso, A L F; Lima, A P B; Gonçalves, R S; Gallinari, M O; dos Santos, P H

2014-01-01

The present study evaluated transenamel and transdentinal penetration of hydrogen peroxide during tooth whitening recognized in altered enamel by the presence of cracks or microabrasion. We used 72 experimental units (n=20) obtained from bovine incisors: GI-sound enamel; GII-teeth showing visible enamel cracks (4 mm to 5.7 mm in length); and GIII-microabrasioned enamel. The 12 remaining specimens were used to analyze the enamel surface morphology using scanning electron microscopy. The specimens were cylindrical and 5.7 mm in diameter and 3.5 mm thick. A product based on 35% hydrogen peroxide was used for bleaching, following the manufacturer's recommendations for use. To quantify the H2O2 penetration, the specimens were placed in artificial pulp chambers containing an acetate buffer solution. After bleaching, the solution was collected and adequately proportioned with leucocrystal violet, peroxidase enzyme, and deionized water. The resulting solution was evaluated using ultraviolet visible reflectance spectrophotometer equipment. The data were analyzed by analysis of variance (ANOVA) and Fisher's PLSD at a significance level of 0.05, and significant differences in the penetration of peroxide in different substrate conditions were observed (p<0.0001). The penetration of hydrogen peroxide was more intense in cracked teeth. The group in which the enamel was microabraded showed intermediate values when compared to the control group. Microabrasion and the presence of cracks in the enamel make this substrate more susceptible to penetration of hydrogen peroxide during in-office whitening.

Penetration of 35% hydrogen peroxide into the pulp chamber in bovine teeth after LED or Nd:YAG laser activation.

PubMed

Camargo, Samira Esteves Afonso; Cardoso, Paula Elaine; Valera, Marcia Carneiro; de Araújo, Maria Amélia Máximo; Kojima, Alberto Noriyuki

2009-01-01

This aim of the present study was to evaluate the pulp chamber penetration of 35% hydrogen peroxide activated by LED (light-emitting diode) or Nd:YAG laser in bovine teeth, after an in-office bleaching technique. Forty-eight bovine lateral incisors were divided into four groups, acetate buffer was placed into the pulp chamber and bleaching agent was applied as follows: for group A (n = 12), activation was performed by LED; for group B (n = 12), activation was performed by Nd:YAG laser (60 mJ, 20 Hz); group C (n = 12) received no light or laser activation; and the control group (n = 12) received no bleaching gel application or light or laser activation. The acetate buffer solution was transferred to a glass tube and Leuco Crystal Violet and horseradish peroxidase were added, producing a blue solution. The optical density of this solution was determined spectrophotometrically and converted into microgram equivalents of hydrogen peroxide. The results were analysed using ANOVA and Tukey's test (5%). It was verified that the effect of activation was significant, as groups activated by LED or laser presented greater hydrogen peroxide penetration into the pulp chamber (0.499 +/- 0.622 microg) compared with groups that were not (0.198 +/- 0.218 microg). There was no statistically significant difference in the penetration of hydrogen peroxide into the pulp chamber between the two types of activation (LED or laser). The results suggest that activation by laser or LED caused an increase in hydrogen peroxide penetration into the pulp chamber.

Coloring, bleaching, and perming: influence on EtG content in hair.

PubMed

Kerekes, Isabelle; Yegles, Michel

2013-08-01

Hair analysis of ethyl glucuronide (EtG) has become, beside fatty acid ethyl ester, a valuable marker for the detection of moderate and chronic excessive alcohol consumption. So far, only few studies exist about the influence of cosmetic treatment on EtG content in hair. The aim of this study was to evaluate the effect of coloring, bleaching, and perming on the concentration of this alcohol marker in hair. Studies were also performed to evaluate the chemical stability of EtG in the presence of hydrogen peroxide and ammonium thioglycolate. Six air samples were treated in vitro by the different commercial cosmetics following the suppliers' instructions. After washing, pulverization, incubation in ultrasonic bath, and solid phase extraction, EtG was determined by GC/MS-NICI after solid phase extraction and heptafluorobutyric anhydride derivatization. The results showed that samples (n = 10) treated with the coloring product did not show any important change in the EtG results. In the bleaching study (n = 23), a mean decrease of 73.5% was observed. After incubation of a solution of EtG with hydrogen peroxide (15%), a decrease of 45% was shown supporting the hypothesis of a chemical degradation of EtG and a leaching out effect from the hair matrix. In the perm treatment study (n = 23), a mean decrease of 95.7% of EtG was found. Incubation of a solution of EtG with ammonium thioglycolate (5%) showed a total decrease of EtG supporting the hypothesis of a chemical degradation. Coloring treatment did not importantly influence EtG content in hair. However, an important decrease of EtG in hair could be found after bleaching and permanent wave treatment. This decrease seems to be because of a chemical degradation of EtG, after bleaching, and a leaching out effect from the matrix. After perming, it seems to be more of a chemical degradation of EtG. These data have to be considered for the correct interpretation of EtG amounts in hair.

The effect of bleaching agents on the degradation of vitamins and carotenoids in spray-dried whey protein concentrate.

PubMed

Stout, M A; Park, C W; Drake, M A

2017-10-01

Previous research has shown that bleaching affects flavor and functionality of whey proteins. The role of different bleaching agents on vitamin and carotenoid degradation is unknown. The objective of this study was to determine the effects of bleaching whey with traditional annatto (norbixin) by hydrogen peroxide (HP), benzoyl peroxide (BP), or native lactoperoxidase (LP) on vitamin and carotenoid degradation in spray-dried whey protein concentrate 80% protein (WPC80). An alternative colorant was also evaluated. Cheddar whey colored with annatto (15 mL/454 L of milk) was manufactured, pasteurized, and fat separated and then assigned to bleaching treatments of 250 mg/kg HP, 50 mg/kg BP, or 20 mg/kg HP (LP system) at 50°C for 1 h. In addition to a control (whey with norbixin, whey from cheese milk with an alternative colorant (AltC) was evaluated. The control and AltC wheys were also heated to 50°C for 1 h. Wheys were concentrated to 80% protein by ultrafiltration and spray dried. The experiment was replicated in triplicate. Samples were taken after initial milk pasteurization, initial whey formation, after fat separation, after whey pasteurization, after bleaching, and after spray drying for vitamin and carotenoid analyses. Concentrations of retinol, a-tocopherol, water-soluble vitamins, norbixin, and other carotenoids were determined by HPLC, and volatile compounds were measured by gas chromatography-mass spectrometry. Sensory attributes of the rehydrated WPC80 were documented by a trained panel. After chemical or enzymatic bleaching, WPC80 displayed 7.0 to 33.3% reductions in retinol, β-carotene, ascorbic acid, thiamin, α-carotene, and α-tocopherol. The WPC80 bleached with BP contained significantly less of these compounds than the HP- or LP-bleached WPC80. Riboflavin, pantothenic acid, pyridoxine, nicotinic acid, and cobalamin concentrations in fluid whey were not affected by bleaching. Fat-soluble vitamins were reduced in all wheys by more than 90

Effect of high- or low-concentration bleaching agents containing calcium and/or fluoride on enamel microhardness.

PubMed

Furlan, Isabella Spinardi; Bridi, Enrico Coser; Amaral, Flávia Lucisano Botelho do; França, Fabiana Mantovani Gomes; Turssi, Cecilia Pedroso; Basting, Roberta Tarkany

2017-01-01

The aim of this in vitro study was to evaluate enamel microhardness following bleaching treatments using either high- or low-concentration hydrogen peroxide (HP) agents containing calcium and/or fluoride. Sixty enamel blocks were bleached with 1 of 6 different bleaching agents (n = 10). The high-concentration HP agents were Whiteness HP Maxx (35% HP), Whiteness HP Blue (35% HP, 2% calcium gluconate), Pola Office+ (37.5% HP, 5% potassium nitrate), and Opalescence Boost (38% HP, 1.1% fluoride ion, 3% potassium nitrate). The low-concentration HP agents evaluated were Pola Day (9.5% HP) and White Class (10% HP, potassium nitrate, calcium, fluoride). High-concentration agents were applied in 3 sessions, whereas low-concentration agents were applied for 14 days. Knoop microhardness measurements were taken on the surface of the enamel before bleaching, at various timepoints during bleaching, and 14 days after the final bleaching treatment. The 2-way analysis of variance test showed that microhardness values were significantly influenced by the bleaching agent (P < 0.001) and application time (P < 0.001). The Tukey test showed that enamel bleached with Whiteness HP Maxx or White Class presented lower microhardness values than did the enamel treated with the remaining products. There was a reduction in micro-hardness values up to the end of the treatment. The results showed that the composition, concentration, and application protocol for each bleaching agent influenced the enamel microhardness values in that the microhardness decreased over time, regardless of the agent used or the addition of calcium and/or fluoride.

Influences of Light-emitting Diode Illumination Bleaching Technique on Nanohardness of Computer-aided Design and Computer-aided Manufacturing Ceramic Restorative Materials.

PubMed

Juntavee, Niwut; Juntavee, Apa; Saensutthawijit, Phuwiwat

2018-02-01

This study evaluated the effect of light-emitting diode (LED) illumination bleaching technique on the surface nanohardness of various computer-aided design and computer-aided manufacturing (CAD/CAM) ceramic materials. Twenty disk-shaped samples (width, length, and thickness = 10, 15, and 2 mm) were prepared from each of the ceramic materials for CAD/CAM, including Lava™ Ultimate (L V ), Vita Enamic® (E n ) IPS e.max® CAD (M e ), inCoris® TZI (I C ), and Prettau® zirconia (P r ). The samples from each type of ceramic were randomly divided into two groups based on the different bleaching techniques to be used on them, using 35% hydrogen peroxide with and without LED illumination. The ceramic disk samples were bleached according to the manufacturer's instruction. Surface hardness test was performed before and after bleaching using nanohardness tester with a Berkovich diamond indenter. The respective Vickers hardness number upon no bleaching and bleaching without or with LED illumination [mean ± standard deviation (SD)] for each type of ceramic were as follows: 102.52 ± 2.09, 101.04 ± 1.18, and 98.17 ± 1.15 for L V groups; 274.96 ± 5.41, 271.29 ± 5.94, and 268.20 ± 7.02 for E n groups; 640.74 ± 31.02, 631.70 ± 22.38, and 582.32 ± 33.88 for M e groups; 1,442.09 ± 35.07, 1,431.32 ± 28.80, and 1,336.51 ± 34.03 for I C groups; and 1,383.82 ± 33.87, 1,343.51 ± 38.75, and 1,295.96 ± 31.29 for P r groups. The results indicated surface hardness reduction following the bleaching procedure of varying degrees for different ceramic materials. Analysis of variance (ANOVA) revealed a significant reduction in surface hardness due to the effect of bleaching technique, ceramic material, and the interaction between bleaching technique and ceramic material (p < 0.05). Bleaching resulted in a diminution of the surface hardness of dental ceramic for CAD/CAM. Using 35% hydrogen peroxide bleaching agent with LED illumination exhibited more reduction in surface hardness

Determination of nicotine content in teeth submitted to prophylaxis and in-office bleaching by gas chromatography-mass spectrometry (GC-MS).

PubMed

de Geus, Juliana L; Beltrame, Flávio L; Wang, Mei; Avula, Bharathi; Khan, Ikhlas A; Loguercio, Alessandro D; Kossatz, Stella; Reis, Alessandra

2018-02-21

The objective of this study was to evaluate the dental color exposed to acute cigarette smoke treatment and quantify the amount of nicotine in samples exposed to cigarette smoke, after dental prophylaxis and after in-office bleaching. Sixty-nine healthy human molars were subjected to cigarette smoke in a cigarette machine. The teeth were divided into three groups: positive control, prophylaxis, and bleaching. Forty cycles of smoke exposition with duration of 15 min each were performed using 10 cigarettes (positive control). Dental prophylaxis was performed with a rotating brush and prophylaxis paste; in-office bleaching was performed with 35% hydrogen peroxide, in two sessions of three 15-min applications, with a 1-week interval between sessions. The color was evaluated at the baseline, after exposure to cigarette smoke, after dental prophylaxis, and after in-office bleaching. Teeth from each group were powdered and analyzed by gas chromatography-mass spectrometry in order to measure the amount of nicotine present in each group. Data from quantification of nicotine and color change were analyzed by one-way ANOVA and Tukey's test (α = 0.05). Data for subjective and objective color evaluation, a perceptible dental darkening occurred in teeth after exposure to cigarette smoke. Dental prophylaxis was able to recover the original color of teeth however, only after bleaching teeth became whiter than at the baseline (p < 0.001). The amount of nicotine was significantly different and higher in positive control group (3.3 ± 1.3 μg/g of tooth), followed by the prophylaxis group (2.1 ± 1.4 μg/g) and the bleaching group (0.8 ± 0.3 μg/g) (p < 0.001). Cigarette smoke penetrates into the dental structure. Dental prophylaxis and bleaching with 35% hydrogen peroxide can partially remove the nicotine from tobacco smoke. However, when in-office bleaching was applied, a more significant nicotine removal was achieved. Dental prophylaxis could remove

Separate whitening effects on enamel and dentin after fourteen days.

PubMed

Kugel, Gerard; Petkevis, Jason; Gurgan, Sevil; Doherty, Eileen

2007-01-01

The purpose of this study was to investigate the mechanism of action of a bleaching agent, as it relates to enamel and dentin. Twenty-six extracted human molar teeth were sectioned at the cemento-enamel junction and were randomly assigned to two groups. L*a*b* readings were taken with a spectrophotometer: on buccal surfaces of the crown, at enamel and dentin. The teeth were exposed to carbamide peroxide or placebo gel and L*a*b* scores were again recorded to determine color changes. Treatments were compared using ancova test with baseline color as the covariate. Relative to placebo, buccal surfaces exhibited the greatest Deltab* and DeltaL* color change. On buccal surfaces, the adjusted mean (SE) treatment differences were -7.8 (1.00) for Deltab* and 5.7 (0.97) for DeltaL, with groups differing significantly (p < 0.0001). On enamel surfaces, treatment differences were -3.6 (0.61) for Deltab* and 4.6 (0.80) for DeltaL* (p < 0.0001). Dentin exhibited the least color improvement. Adjusted mean (SE) treatment differences were -1.9 (0.87) for Deltab* and 2.4 (1.10) for DeltaL*, with groups differing significantly (p < 0.02) on dentin color change. The majority of color change seen on the buccal surface of tooth crowns exposed to carbamide peroxide 15% was because of the color change in enamel. As compared to enamel, dentin was less affected after 14 days.

Effects of a bleaching agent with calcium on bovine enamel

PubMed Central

Alexandrino, Larissa; Gomes, Yasmin; Alves, Eliane; Costi, Hilton; Rogez, Hervé; Silva, Cecy

2014-01-01

Objective: This in vitro study analyzed the effects of a bleaching treatment containing 35% hydrogen peroxide (HP) with or without calcium on bovine enamel, using the Knoop hardness number (KHN), tristimulus colorimetry (TC), and scanning electron microscopy. Materials and Methods: Forty-five specimens were randomly divided into groups (n = 5), which included artificial saliva (negative control [NC]), 35% HP (positive control [PC]), and 35% HP Blue Calcium (HP Blue). The specimens were subjected to three bleaching sessions. During the sessions, the specimens were immersed in artificial saliva at 37°C. Before and after bleaching, KHN tests were conducted using a force of 25 gf for 5 s. TC was performed using the CIE-L*a*b* system and readouts were obtained at the following 4 time points: Before the bleaching treatment; after the first session, the second session, and the third session. The specimens were dehydrated and coated with gold, and the photomicrographs were analyzed in a double-blind manner with a LEO microscope. Results: Using one-way analysis of variance and Tukey's test (P < 0.05), a statistically significant difference was identified between the initial and final mean KHNs of the NC and PC groups, while the initial and final mean KHNs were not significantly different in the HP Blue group. The final mean values of ΔE, ΔL, and Δb of the PC and HP Blue groups were significantly higher than the initial values (P < 0.01 for both). The photomicrographs revealed no differences among the groups. Conclusions: Therefore, treatment with HP Blue prevented changes in the KHN without reducing the efficacy of bleaching. PMID:25202210

Simultaneous production of bio-ethanol and bleached pulp from red algae.

PubMed

Yoon, Min Ho; Lee, Yoon Woo; Lee, Chun Han; Seo, Yung Bum

2012-12-01

The red algae, Gelidium corneum, was used to produce bleached pulp for papermaking and ethanol. Aqueous extracts obtained at 100-140 °C were subjected to saccharification, purification, fermentation, and distillation to produce ethanol. The solid remnants were bleached with chlorine dioxide and peroxide to make pulp. In the extraction process, sulfuric acid and sodium thiosulfate were added to increase the extract yield and to improve de-polymerization of the extracts, as well as to generate high-quality pulp. An extraction process incorporating 5% sodium thiosulfate by dry weight of the algae provided optimal production conditions for the production of both strong pulp and a high ethanol yield. These results suggest that it might be possible to utilize algae instead of trees and starch for pulp and ethanol production, respectively. Copyright © 2012 Elsevier Ltd. All rights reserved.

A safety study in vitro for the effects of an in-office bleaching system on the integrity of enamel and dentine.

PubMed

Sulieman, M; Addy, M; Macdonald, E; Rees, J S

2004-09-01

The aim of this study was to investigate safety concerns with bleaching procedures by studying the effects of a high concentration hydrogen peroxide (HP) in-surgery bleaching product on enamel and dentine. Flat enamel and dentine samples embedded in epoxy resin were prepared from human third molar teeth. Erosion of enamel: groups of enamel samples were treated with 35% HP then citric acid (CA) or brushing with toothpaste or CA alone and water alone. Enamel Loss was measured using a profilometer. Abrasion/erosion of dentine: groups of dentine specimens were treated as follows: Group 1--brushed with water for 30 min. Group 2--brushed with 35% HP for 30 min. Group 3--power bleached for 30 min and then Group 4--brushed with toothpaste for 1 minute. Group 5--water soaked for 30 min followed by brushing with toothpaste for 1 min. Group 6--orange juice soaked for 30 min followed by brushing with toothpaste for 1 min. Treatment effects were measured using a profilometer. Hardness tests: enamel and dentine specimens were hardness tested using a Wallace indenter prior to and post bleaching. Scanning Electron Microscopy: enamel and dentine specimens were taped and the exposed tissue treated with 35% HP and then studied under scanning electronmicroscopy (SEM). Enamel erosion: bleaching enamel samples had no measurable effect on enamel. Pre-bleaching had no significant effect on subsequent CA erosion or brushing. Abrasion/erosion of dentine: no significant differences were found between treatments 1-5 with little change from baseline detected. Orange juice (Group 6) produced considerable and significantly more erosion than other treatments. Hardness tests: there were no significant changes in hardness values for enamel and dentine. SEM: there was no evidence of any topographical changes to either enamel or dentine. Using one of the highest concentrations of HP for tooth bleaching procedures and maximum likely peroxide exposure, there was no evidence of deleterious effects on

Comparison of different fungal enzymes for bleaching high-quality paper pulps.

PubMed

Sigoillot, Cécile; Camarero, Susana; Vidal, Teresa; Record, Eric; Asther, Michèle; Pérez-Boada, Marta; Martínez, María Jesús; Sigoillot, Jean-Claude; Asther, Marcel; Colom, José F; Martínez, Angel T

2005-02-23

Wild and recombinant hydrolases and oxidoreductases with a potential interest for environmentally sound bleaching of high-quality paper pulp (from flax) were incorporated into a totally chlorine free (TCF) sequence that also included a peroxide stage. The ability of feruloyl esterase (from Aspergillus niger) and Mn2+-oxidizing peroxidases (from Phanerochaete chrysosporium and Pleurotus eryngii) to decrease the final lignin content of flax pulp was shown. Laccase from Pycnoporus cinnabarinus (without mediator) also caused a slight improvement of pulp brightness that was increased in the presence of aryl-alcohol oxidase. However, the best results were obtained when the laccase treatment was performed in the presence of a mediator, 1-hydroxybenzotriazol (HBT), enabling strong delignification of pulps. The enzymatic removal of lignin resulted in high-final brightness values that are difficult to attain by chemical bleaching of this type of pulp. A partial inactivation of laccase by HBT was observed but this negative effect was strongly reduced in the presence of pulp. The good results obtained with the same laccase expressed in A. niger at bioreactor scale, revealed the feasibility of using recombinant laccase for bleaching high-quality non-wood pulps in the presence of a mediator.

ESR investigation of ROS generated by H2O2 bleaching with TiO2 coated HAp.

PubMed

Saita, Makiko; Kobayashi, Kyo; Kobatashi, Kyou; Yoshino, Fumihiko; Hase, Hiriko; Nonami, Toru; Kimoto, Katsuhiko; Lee, Masaichi-Chang-il

2012-01-01

It is well known that clinical bleaching can be achieved with a solution of 30% hydrogen peroxide (H2O2) or H2O2/titanium dioxide (TiO2) combination. This study examined the hypothesis that TiO2 coated with hydroxyapatite (HAp-TiO2) can generate reactive oxygen species (ROS). ROS are generated via photocatalysis using electron spin resonance (ESR). The bleaching properties of HAp-TiO2 in the presence of H2O2 can be measured using hematoporphyrin litmus paper and extracted teeth. We demonstrate that superoxides (O2(•-)) and hydroxyl radicals (HO(•)) can be generated through excitation of anatase TiO2, rutile TiO2, anatase HAp-TiO2, and rutile HAp-TiO2 in the presence of H2O2. The combination of R HAp-TiO2 with H2O2 produced the highest level of HO(•) generation and the most marked bleaching effects of all the samples. The superior bleaching effects exhibited by R HAp-TiO2 with H2O2 suggest that this combination may lead to novel methods for the clinical application of bleaching treatments.

Efficacy and cytotoxicity of a bleaching gel after short application times on dental enamel.

PubMed

Soares, Diana Gabriela; Ribeiro, Ana Paula Dias; da Silveira Vargas, Fernanda; Hebling, Josimeri; de Souza Costa, Carlos Alberto

2013-11-01

This study aimed to evaluate and correlate the efficacy and cytotoxicity of a 35 % hydrogen peroxide (HP) bleaching gel after different application times on dental enamel. Enamel/dentin disks in artificial pulp chambers were placed in wells containing culture medium. The following groups were formed: G1, control (no bleaching); G2 and G3, three or one 15-min bleaching applications, respectively; and G4 and G5, three or one 5-min bleaching applications, respectively. Extracts (culture medium with bleaching gel components) were applied for 60 min on cultured odontoblast-like MDPC-23 cells. Cell metabolism (methyl tetrazolium assay) (Kruskal-Wallis/Mann-Whitney; α = 5 %) and cell morphology (scanning electron microscopy) were analyzed immediately after the bleaching procedures and the trans-enamel and trans-dentinal HP diffusion quantified (one-way analysis of variance/Tukey's test; α = 5 %). The alkaline phosphatase (ALP) activity was evaluated 24 h after the contact time of the extracts with the cells (Kruskal-Wallis/Mann-Whitney; α = 5 %). Tooth color was analyzed before and 24 h after bleaching using a spectrophotometer according to the Commission Internationale de l'Eclairage L*a*b* system (Kruskal-Wallis/Mann-Whitney; α = 0.05). Significant difference (p < 0.05) in cell metabolism occurred only between G1 (control, 100 %) and G2 (60.6 %). A significant decrease (p < 0.05) in ALP activity was observed between G2, G3, and G4 in comparison with G1. Alterations on cell morphology were observed in all bleached groups. The highest values of HP diffusion and color alterations were observed for G2, with significant difference among all experimental groups (p < 0.05). G3 and G4 presented intermediate color change and HP diffusion values with no statistically significant differences between them (p > 0.05). The lowest amount of HP diffusion was observed in G5 (p < 0.05), which also exhibited no significant color alteration compared to the control group (p > 0.05). HP

Effects of the Ratio between Pigment and Bleaching Gel on the Fracture Resistance and Dentin Microhardness of endodontically treated Teeth.

PubMed

Galloza, Marina Og; Jordão-Basso, Keren Cf; Bandeca, Matheus C; Costa, Samuel O; Borges, Alvaro H; Tonetto, Mateus R; Tirintan, Fabio C; Keine, Kátia C; Kuga, Milton C

2017-11-01

The aim of this study was to evaluate the effects of bleaching gel using 35% hydrogen peroxide (HP), associated with red carmine pigment (RC), in the 3:1 or 1:1 ratio, on fracture resistance and dentin microhardness of endodontically treated teeth. A total of 40 lower incisors were endodontically treated and divided into four groups (n = 10), according to the bleaching protocol: G1 (HP3), 35% HP + RC (3:1); G2 (HP1), 35% HP + RC (1:1); G3 (positive), 38% HP; and G4 (negative), unbleached. Four dental bleaching sessions were performed. The dental crowns were restored after the last session and submitted to the fracture resistance test. Totally, 60 specimens from the endodontically treated lower incisor crowns were prepared to evaluate the effects on dentin microhardness. The analysis was measured (in Knoop) prior to and after the last dental bleaching session using similar bleaching protocols. G2 presented the lowest fracture resistance (p < 0.05). The other groups were similar to each other (p > 0.05). No difference was observed in the reduction of dentin microhardness among the groups (p > 0.05). A 1:1 ratio (bleaching gel:pigment) caused a significant fracture resistance reduction in relation to the other protocols. No effect on the dentin microhardness reduction was observed. The pigment addition to the bleaching agent accelerates the bleaching chemical reaction. However, no studies have evaluated the ideal proportion to optimize tooth bleaching.

Efficacy of cold light bleaching using different bleaching times and their effects on human enamel.

PubMed

Wang, Wei; Zhu, Yuhe; Li, Jiajia; Liao, Susan; Ai, Hongjun

2013-01-01

This study investigated the efficacy of cold light bleaching using different bleaching times and the effects thereof on tooth enamel. Before and after bleaching, stained tooth specimens were subjected to visual and instrumental colorimetric assessments using Vita Shade Guide and spectrophotometric shade matching. Enamel surface alterations were examined using scanning electron microscopy (SEM) to analyze surface morphology, surface microhardness (SMH) measurement to determine changes in mechanical properties, and X-ray diffraction (XRD) to characterize post-bleaching enamel composition. Cold light bleaching successfully improved tooth color, with optimal efficacy when bleaching time was beyond 10 min. Significant differences in surface morphology were observed among the different bleaching times, but no significant differences were observed for enamel composition and surface microhardness among the different bleaching times. Results of this study revealed an association between the bleaching time of cold light bleaching and its whitening efficacy. Together with the results on enamel surface changes, this study provided positive evidence to support cold light bleaching as an in-office bleaching treatment.

The influence of chemical surface modification of kenaf fiber using hydrogen peroxide on the mechanical properties of biodegradable kenaf fiber/poly(lactic acid) composites.

PubMed

Razak, Nur Inani Abdul; Ibrahim, Nor Azowa; Zainuddin, Norhazlin; Rayung, Marwah; Saad, Wan Zuhainis

2014-03-07

Bleaching treatment of kenaf fiber was performed in alkaline medium containing hydrogen peroxide solution maintained at pH 11 and 80 °C for 60 min. The bleached kenaf fiber was analyzed using Fourier Transform Infrared (FTIR) and X-ray Diffraction (XRD) analysis. The bleached kenaf fiber was then compounded with poly-(lactic acid) (PLA) via a melt blending method. The mechanical (tensile, flexural and impact) performance of the product was tested. The fiber treatment improved the mechanical properties of PLA/bleached kenaf fiber composites. Scanning electron micrograph (SEM) morphological analysis showed improvement of the interfacial adhesion between the fiber surface and polymer matrix.

Impact of toothbrushing with a dentifrice containing calcium peroxide on enamel color and roughness.

PubMed

Feitosa, Diala Aretha de Sousa; Borges, Boniek Castillo Dutra; Pinheiro, Fabio Henrique de Sa Leitao; Duarte, Rosangela Marques; Araujo, Renato Evangelista de; Braz, Rodivan; Santos, Maria Carmo Moreira da Silva; Montes, Marcos Antonio Japiassu Resende

2015-01-01

This in vitro study sought to evaluate both the bleaching potential and changes to average surface roughness (Ra) of enamel after brushing with a dentifrice. Fifty-four enamel specimens (4 x 4 x 2 mm) were divided into 3 groups (n = 18) and treated with 1 of 3 dentifrices: 1 with calcium peroxide, and 2 without. The samples were submitted to 20,000 brushing cycles. Color and Ra were measured before and after brushing. Although the Ra increased in all groups after brushing, only the dentifrice containing calcium peroxide resulted in an increase in reflectance.

Time of Application of Sodium Ascorbate on Bonding to Bleached Dentin.

PubMed

Jung, Kyoung-Hwa; Seon, Eun-Mi; Choi, An-Na; Kwon, Yong-Hoon; Son, Sung-Ae; Park, Jeong-Kil

2017-01-01

This study examined the effects of different application times of sodium ascorbate (SA) on the bond strength of composite resin to bleached dentin. Specimens with an exposed dentin surface were divided into 3 groups according to the type of bleaching agent used: Group A, mixture of sodium perborate (SP) and distilled water (DW); Group B, mixture of SP and hydrogen peroxide (HP); control group, no bleaching. Each group was classified into 10 subgroups. Subgroups IB and DB underwent immediate bonding and delayed bonding, respectively. 10% SA was applied to 3, 5, 10, and 30 minutes and 1, 24, 48, and 72 hours, respectively. Microtensile bond strength ( μ TBS) was measured after restoration, and the data was analyzed by one-way ANOVA and Scheffé's test. Before restoration, the dentin surfaces were examined by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). SEM showed that most dentin surfaces were filled with crystals when SA was applied to more than 24 hours. EDS revealed peaks of calcium, carbon, oxygen, and sodium. The application of SA for 5 minutes to 48 hours or for 30 minutes to 24 hours is suggested when a mixture of SP and DW or HP is used, respectively.

High-performance supercapacitors using flexible and freestanding MnOx/carbamide carbon nanofibers

NASA Astrophysics Data System (ADS)

Samuel, Edmund; Jo, Hong Seok; Joshi, Bhavana; Park, Hyun Goo; Kim, Yong Il; An, Seongpil; Swihart, Mark T.; Yun, Je Moon; Kim, Kwang Ho; Yoon, Sam S.

2017-11-01

We demonstrate the fabrication of a MnOx/carbamide carbon nanofiber (CCNF) composite consisting of MnO particles embedded in CCNFs as a highly flexible and freestanding electrode material for supercapacitors. A sacrificial polymer component, polymethylmethacrylate, included in the precursor solution, pyrolyzes during heating, resulting in pores in the fibers, some of which are filled by the MnO nanocrystals. Carbamide is added to control the size of the MnOx particles as well as to increase the carbon content of the composite and hence its conductivity. The X-ray diffraction and Raman spectra of the composite show that the MnO particles formed have low crystallinity. Transmission electron microscopy confirms that the MnO particles are distributed very uniformly over the CCNFs. Symmetric supercapacitors constructed using electrodes of this composite exhibit specific capacitances of 498 F•g-1 at a scan rate of 10 mV•s-1 and 271 F•g-1 at a current density of 1 A•g-1. They also exhibit excellent long-term cycling performance, retaining 93% of their initial capacity after 5000 cycles of galvanostatic charging/discharging.

Effect of Toothpaste Application Prior to Dental Bleaching on Whitening Effectiveness and Enamel Properties.

PubMed

Vieira-Junior, W F; Lima, D A N L; Tabchoury, C P M; Ambrosano, G M B; Aguiar, F H B; Lovadino, J R

2016-01-01

The purpose of this study was to investigate the effects on the enamel properties and effectiveness of bleaching using 35% hydrogen peroxide (HP) when applying toothpastes with different active agents prior to dental bleaching. Seventy enamel blocks (4 × 4 × 2 mm) were submitted to in vitro treatment protocols in a tooth-brushing machine (n=10): with distilled water and exposure to placebo gel (negative control [NC]) or HP bleaching (positive control [PC]); and brushing with differing toothpastes prior to HP bleaching, including potassium nitrate toothpaste (PN) containing NaF, conventional sodium monofluorophosphate toothpaste (FT), arginine-based toothpastes (PA and SAN), or a toothpaste containing bioactive glass (NM). Color changes were determined using the CIE L*a*b* system (ΔE, ΔL, Δa, and Δb), and a roughness (Ra) analysis was performed before and after treatments. Surface microhardness (SMH) and cross-sectional microhardness (CSMH) were analyzed after treatment. Data were analyzed with repeated measures ANOVA for Ra, one-way ANOVA (SMH, ΔE, ΔL, Δa, and Δb), split-plot ANOVA (CSMH), and Tukey post hoc test (α<0.05). The relationship between the physical surface properties and color properties was evaluated using a multivariate Canonical correlation analysis. Color changes were statistically similar in the bleached groups. After treatments, SMH and CSMH decreased in PC. SMH increased significantly in the toothpaste groups vs the negative and positive control (NM > PA = SAN > all other groups) or decreased HP effects (CSMH). Ra increased in all bleached groups, with the exception of NM, which did not differ from the NC. The variation in the color variables (ΔL, Δa, and Δb) explained 21% of the variation in the physical surface variables (Ra and SMH). The application of toothpaste prior to dental bleaching did not interfere with the effectiveness of treatment. The bioactive glass based toothpaste protected the enamel against the deleterious

Efficacy of quercetin flavonoid in recovering the postbleaching bond strength of orthodontic brackets: A preliminary study.

PubMed

Shamsedin, Mana; Arash, Valiollah; Jahromi, Masoud Babaei; Moghadamnia, Ali Akbar; Kamel, Manouchehr Rahmati; Ezoji, Fariba; Bijani, Ali; Kavoli, Samira; Ghasemi, Tania; Ramezani, Gholamhossein

2017-01-01

To evaluate comparatively the effect of quercetin on postbleaching shear bond strength (SBS) and adhesive remnant index (ARI). Intact maxillary premolars were divided randomly into 12 groups of 10 each: (1) bonding the bracket immediately after bleaching, (2) bonding 1 week after bleaching, (3-8) application of three experimental concentrations of quercetin (0.1%, 0.5%, and 1%) at two time durations (5 and 10 min), (9-10) application of the solvent of quercetin at two time periods (5 and 10 min), (11) application of 10% sodium ascorbate for 10 min, and (12) bonding the brackets on nonbleached teeth. Bleaching was performed using 15% carbamide peroxide gel for 5 days (6 h daily). After incubation and thermocycling, the SBS of brackets was measured. The ARI too was recorded at ×20. The data were analyzed statistically (α =0.05). Bleaching reduced the SBS below 10 Megapascal (MPa) level ( P < 0.05) while all the postbleaching treatments (except the application of the solvent of quercetin) recovered the SBS back to values greater than 10 MPa ( P < 0.05) and also back to nonbleached SBS levels ( P > 0.01). All eight postbleaching treatments had rather similar efficacies ( P = 0.1396). The concentration of quercetin (beta = 0.259, P = 0.042) but not its duration (beta = 0.213, P = 0.093) significantly improved its efficacy. Bleaching can weaken the bond strength of orthodontic brackets below acceptable levels. The application of quercetin or Vitamin C or delaying the bracket bonding improved the postbleaching SBS.

Evaluation of the Effect of Different Laser Activated Bleaching Methods on Enamel Susceptibility to Caries; An In Vitro Mode.

PubMed

Ashnagar, Sajjad; Monzavi, Abbas; Abbasi, Mehdi; Aghajani, Mahdi; Chiniforush, Nasim

2017-01-01

Introduction: Today, bleaching is a routine noninvasive alternative for treatment of discolored teeth. The aim of this study was to determine whether conventional or laser activated bleaching predispose teeth to develop caries or not. Methods: Sixty human molars were mounted on acrylic cylinders and their Knoop microhardness (KHN) as well as DIAGNOdent (DD) values were recorded. They were divided into 4 experimental groups; G1) conventional bleaching with 40% hydrogen peroxide gel, G2) Diode laser assisted bleaching with same gel, G3) Nd:YAG laser assisted bleaching with the same gel, G4) control group. After bleaching, all samples were subjected to a three day pH cycling regimen and then, KHN and DD values were measured. Results: All groups had significant reduction in KHN values. It seems that there is no statistically meaningful difference between changes in enamel microhardness of the sample groups and all groups have changed in a similar amount. Reduction of DD scores were significant in Diode laser and conventional groups, however changes in Nd:YAG laser and control groups were not significant. Changes in DD values have followed a similar pattern among groups, except in G1- G4 and G2-G4 couples. Conventional and diode laser groups had a meaningful difference in reduction of DD values in comparison with the control group. Conclusion: It can be concluded that bleaching whether conventional or laser activated, does not make teeth vulnerable to develop carious lesions.

Effect of 10% Strontium Chloride and 5% Potassium Nitrate with Fluoride on Bleached Bovine Enamel.

PubMed

Alencar, Cristiane de Melo; Pedrinha, Victor Feliz; Araújo, Jesuína Lamartine Nogueira; Esteves, Renata Antunes; Silva da Silveira, Ana Daniela; Silva, Cecy Martins

2017-01-01

Dental whitening has been increasingly sought out to improve dental aesthetics, but may cause chemical and morphological changes in dental enamel surfaces. This study evaluated in vitro the effect of 10% strontium chloride and 5% potassium nitrate with fluoride on bovine enamel, through tristimulus colorimetry, Knoop microhardness (KHN), and roughness after bleaching with 35% hydrogen peroxide (HP). The specimens were divided into three groups (n=15): GControl received bleaching treatment with 35% HP; GNitrate received bleaching with 35% HP followed by the application of 5% potassium nitrate with 2% sodium fluoride; and GStrontium received bleaching with 35% HP followed by the application of 10% strontium chloride on the enamel. Next, five specimens of each experimental group were subjected to KHN and tristimulus colorimetry tests, and 10 specimens were subjected to surface roughness (SR) tests. The values obtained for the different groups were compared through analysis of variance (ANOVA) followed by a post-hoc Tukey-Kramer test in addition to Student's T-test for paired data. In the intergroup comparison, KHN final differed statistically ( p <0.05). The mean SR final of the experimental groups differed statistically from the GControl group ( p <0.05). In addition, the groups did not differ in color variation ( p >0.05). 10% strontium chloride and 5% potassium nitrate combined with 2% fluoride downplayed morphological changes to the enamel, without interfering with the effectiveness of the bleaching process.

Effect of 10% Strontium Chloride and 5% Potassium Nitrate with Fluoride on Bleached Bovine Enamel

PubMed Central

Alencar, Cristiane de Melo; Pedrinha, Victor Feliz; Araújo, Jesuína Lamartine Nogueira; Esteves, Renata Antunes; Silva da Silveira, Ana Daniela; Silva, Cecy Martins

2017-01-01

Background: Dental whitening has been increasingly sought out to improve dental aesthetics, but may cause chemical and morphological changes in dental enamel surfaces. Objective: This study evaluated in vitro the effect of 10% strontium chloride and 5% potassium nitrate with fluoride on bovine enamel, through tristimulus colorimetry, Knoop microhardness (KHN), and roughness after bleaching with 35% hydrogen peroxide (HP). Methods: The specimens were divided into three groups (n=15): GControl received bleaching treatment with 35% HP; GNitrate received bleaching with 35% HP followed by the application of 5% potassium nitrate with 2% sodium fluoride; and GStrontium received bleaching with 35% HP followed by the application of 10% strontium chloride on the enamel. Next, five specimens of each experimental group were subjected to KHN and tristimulus colorimetry tests, and 10 specimens were subjected to surface roughness (SR) tests. The values obtained for the different groups were compared through analysis of variance (ANOVA) followed by a post-hoc Tukey-Kramer test in addition to Student’s T-test for paired data. Results: In the intergroup comparison, KHN final differed statistically (p<0.05). The mean SR final of the experimental groups differed statistically from the GControl group (p<0.05). In addition, the groups did not differ in color variation (p>0.05). Conclusion: 10% strontium chloride and 5% potassium nitrate combined with 2% fluoride downplayed morphological changes to the enamel, without interfering with the effectiveness of the bleaching process. PMID:28979576

Structure of complexes of uranyl succinate with carbamide and dimethylurea

NASA Astrophysics Data System (ADS)

Serezhkina, L. B.; Grigor'ev, M. S.; Seliverstova, N. V.; Serezhkin, V. N.

2017-09-01

Three new succinate-containing complexes of uranyl with carbamide ( Urea) and N,N'-dimethylurea ( s-Dmur) are synthesized and studied by IR spectroscopy and X-ray diffraction. Structures of the same type, [UO2( Urea)4(H2O)][(UO2)2(C4H4O4)3] · 3H2O and [UO2( Urea)4(H2O)][(UO2)2(C4H4O4)3] · 2 Urea contain two sorts of uranium-containing complex groups, namely, mononuclear [UO2( Urea)4(H2O)]2+ cations and two-dimensional [(UO2)2(C4H4O4)3]2- anions described by crystal-chemical formulas AM 5 1 and A 2 Q 3 02, respectively ( A = UO2 2+, M 1 = Urea or H2O, Q 02 = C4H4O4 2-), and differ only in the nature of noncoordinated molecules—water and carbamide. The main structural groups of the [(UO2)2(C4H4O4)2( s-Dmur)3] crystals are [(UO2)2(C4H4O4)2( s-Dmur)3] chains belonging to the A 2 Q 2 02 M 3 1 ( A = UO2 2+, Q 02 = C4H4O4 2-, M 1 = s-Dmur) crystal-chemical group. Specific features of intermolecular interactions in the crystal structures are revealed using the Voronoi-Dirichlet method of molecular polyhedra.

Preemptive Use of Naproxen on Tooth Sensitivity Caused by In-Office Bleaching: A Triple-Blind, Crossover, Randomized Clinical Trial.

PubMed

Fernandes, M T; Vaez, S C; Lima, C M; Nahsan, F P; Loguércio, A D; Faria-E-Silva, A L

A triple-blind, randomized, crossover clinical trial evaluated prior use of nonsteroidal anti-inflammatory naproxen on sensitivity reported by patients undergoing in-office tooth bleaching. Fifty patients were subjected to two sessions of in-office tooth bleaching with 35% hydrogen peroxide in a single application of 40 minutes for two sessions, with an interval of seven days between applications. One hour prior to the procedure, each patient randomly received a single dose of naproxen (500 mg) or placebo. The patient's sensitivity level was evaluated during and immediately after the bleaching using two scales (verbal and visual analog); the verbal scale only was repeated after 24 hours. The effectiveness of the bleaching procedures was evaluated with the Bleachedguide scale. Relative risk to sensitivity was calculated and adjusted by session, while comparison of overall risk was performed by the McNemar test. Data on the sensitivity level for both scales and shade were subjected to the Friedman, Wilcoxon, and Mann-Whitney tests (α=0.05). The use of naproxen only decreased the absolute risk and intensity of tooth sensitivity reported immediately after the second session. On the other hand, no measurable effect was observed during or 24 hours after either session. The sequence of drug administration did not affect the bleaching effectiveness. Preemptive use of naproxen only reduced tooth sensitivity reported by patients immediately after the second session of bleaching.

Micro-CT and FE-SEM enamel analyses of calcium-based agent application after bleaching.

PubMed

Gomes, Mauricio Neves; Rodrigues, Flávia Pires; Silikas, Nick; Francci, Carlos Eduardo

2018-03-01

The objective of the present study is to evaluate the effects of casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) on bleached enamel. A bleaching agent (35% hydrogen peroxide) was applied, 4 × 8 min on premolar teeth (n = 8). A CPP-ACP paste was applied for 7 days. Prior and post-treatment, microtomography images were obtained and 3D regions of interest (ROIs) were selected, from outer enamel, extending to 110.2-μm depth. CT parameters of structure: thickness (St.Th), separation (St.Sp), and fragmentation index (Fr.I.) were calculated for each (ROI). Data was submitted to paired t tests at a 95% confidence level. The samples were evaluated at 3000 to 100,000 magnification. Quantitative analysis of enamel mineral content was also determined by SEM EDX. There was a significant increase in structure thickness and calcium content. The phosphorus content increased after bleaching. There was also a decreased separation and fragmentation index on the outer enamel to a depth of 56.2 μm (p < 0.05). There were no changes at 110.2-μm depth for the bleaching CPP-ACP association. A covering layer and decreased spaces between the hydroxyapatite crystals appeared around the enamel prisms, 7 days after the CPP-ACP application. The application of a CPP-ACP provides a compact structure on the enamel's outer surface, for 7 days, due to calcium deposition. CT parameters seem to be a useful tool for mineralizing and remineralizing future studies. CPP-ACP neutralizes any adverse effects on enamel surface when applied during a week after bleaching and minimizes any side effects of the bleaching treatment due to a more compact structure.

A novel approach for in-office tooth bleaching with 6% H2O2/TiO_N and LED/laser system-a controlled, triple-blinded, randomized clinical trial.

PubMed

Bortolatto, Janaina Freitas; Trevisan, Tamara Carolina; Bernardi, Priscila Sadalla Ismael; Fernandez, Eduardo; Dovigo, Livia Nordi; Loguercio, Alessandro Dourado; Batista de Oliveira Junior, Osmir; Pretel, Hermes

2016-04-01

The purpose of this randomized, parallel, triple-blinded clinical trial was to compare efficacy and tooth sensitivity (TS) after use of an in-office bleaching agent of 6% hydrogen peroxide containing nanoparticles of nitrogen-doped titanium oxide (HP6) vs. 35% hydrogen peroxide (HP35). Forty-eight volunteers were randomly divided either a HP6 or HP35. Two clinical sessions were performed with an interval of 7 days between them for each group. In each session, two consecutive applications of each bleaching agent were performed and activated by a hybrid LED/laser light. Efficacy was determined by color alteration (ΔE), recorded with reflectance spectroscopy. It was assessed at baseline and after the first and second bleaching session. TS was characterized according to occurrence, intensity, duration, and type. Efficacy was analyzed by repeated measures analysis of variance (ANOVA) and post hoc Bonferroni test, and TS was analyzed by means of chi(2) test (α = 0.05). For HP35, highest and significant values of ΔE were found after bleaching when compared to HP6 (p = 0.002). However, HP35 showed a significantly higher occurrence of TS than HP6 (p = 0.008). Also, intensity and duration were higher in HP35. The majority of volunteers classified the type experienced in their sensitivity in the form of a "shock." The use of HP6 despite reducing efficacy when compared to an in-office bleaching in higher concentration (35%) produced less tooth sensitivity. In terms of tooth sensitivity, the use of lower concentrations of in-office bleaching should be the first choice, suggesting greater biocompatibility and safety compared to a conventional HP35.

Evaluation of biocompatibility of sodium perborate and 30% hydrogen peroxide using the analysis of the adherence capacity and morphology of macrophages.

PubMed

Asfora, Kattyenne Kabbaz; Santos, Maria do Carmo Moreira da Silva; Montes, Marcos Antonio Japiassú Resende; de Castro, Célia Maria Machado Barbosa

2005-02-01

The purpose of this study was to evaluate the biocompatibility of the most used bleaching materials for pulpless teeth, sodium perborate and 30% hydrogen peroxide, in an experimental model of macrophages, through analysis of the adherence index and the cellular morphology. Inflammatory macrophages were obtained from peritoneal washed of Wistar rats. The evaluation of the adherence capacity of these cells to the plastic surface was conducted in Eppendorf tubes containing RPMI, after treatment with the bleaching agents diluted in 1:10, 1:100 and 1:1000 for 15 and 30 min, and incubation at 37 degrees C and humidified atmosphere of 5% CO(2) in air. The cellular morphology was verified after incubation of the cells treated with the bleaching agents in culture plaques and compared with normal cells in culture medium. Results showed that sodium perborate neither increased the adherence index, nor altered the cellular morphology when compared to the control group. The distribution, cellular morphology, cytoplasmatic and nuclear characteristics, reproduced the aspects observed in normal macrophages. However, the treatment with 30% hydrogen peroxide presented an increase in adherence index when compared to the control group (RPMI), in all dilutions, according to Mann-Whitney test (n=08 and p=0.001 for dilutions 1:10 and 1:100, and n=08 and p=0.004 for dilution 1:1000). The morphology of the cells treated with this product presented structural alterations proportionally greater, depending on the dilution of this bleaching agent, and even in the highest dilution (1:1000) the cells presented very evident alterations. This irreversible cellular damage as well as the elevation of the adherence index, characterizes the aggressive potential of 30% hydrogen peroxide, regardless of its dilution. Sodium perborate, on the other hand, showed biocompatibitity, since, no morphological nor functional alteration was observed in macrophages.

Application of taguchi method for selection parameter bleaching treatments against mechanical and physical properties of agave cantala fiber

NASA Astrophysics Data System (ADS)

Yudhanto, F.; Jamasri; Rochardjo, Heru S. B.

2018-05-01

The characterized agave cantala fiber in this research came from Sumenep, Madura, Indonesia was chemically processed using sodium hydroxide (NaOH) and hydrogen peroxide (H2O2) solution. The treatment with both solutions is called bleaching process. Tensile strength test of single fiber was used to get mechanical properties from selecting process of the various parameter are temperature, PH and concentration of H2O2 with an L9 orthogonal array by Taguchi method. The results indicate that PH is most significant parameter influencing the tensile strength followed by temperature and concentration H2O2. The influence of bleaching treatment on tensile strength showed increasing of crystallinity index of fiber by 21%. It showed by lost of hemicellulose and lignin layers of fiber can be seen from waveforms changes of 1735 (C=O), 1627 (OH), 1319 (CH2), 1250 (C-O) by FTIR graph. The photo SEM showed that the bleaching of fibers causes the fibers more roughly and clearly than untreated fibers.

IN VITRO STUDY OF THE PULP CHAMBER TEMPERATURE RISE DURING LIGHT-ACTIVATED BLEACHING

PubMed Central

Carrasco, Thaise Graciele; Carrasco-Guerisoli, Laise Daniela; Fröner, Izabel Cristina

2008-01-01

This study evaluated in vitro the pulp chamber temperature rise induced by the light-activated dental bleaching technique using different light sources. The root portions of 78 extracted sound human mandibular incisors were sectioned approximately 2 mm below the cementoenamel junction. The root cavities of the crowns were enlarged to facilitate the correct placing of the sensor into the pulp chamber. Half of specimens (n=39) was assigned to receive a 35% hydrogen peroxide gel on the buccal surface and the other halt (n=39) not to receive the bleaching agent. Three groups (n=13) were formed for each condition (bleach or no bleach) according to the use of 3 light sources recommended for dental bleaching: a light-emitting diode (LED)-laser system, a LED unit and a conventional halogen light. The light sources were positioned perpendicular to the buccal surface at a distance of 5 mm and activated during 30 s. The differences between the initial and the highest temperature readings for each specimen were obtained, and, from the temperature changes, the means for each specimen and each group were calculated. The values of temperature rise were compared using Kruskal-Wallis test at 1% significance level. Temperature rise varied significantly depending on the light-curing unit, with statistically significant differences (p<0.01) among the groups. When the bleaching agent was not applied, the halogen light induced the highest temperature rise (2.38±0.66°C). The LED unit produced the lowest temperature increase (0.29±0.13°C); but there was no significant difference between LED unit and LED-laser system (0.35±0.15°C) (p>0.01). When the bleaching agent was applied, there were significant differences among groups (p<0.01): halogen light induced the highest temperature rise (1.41±0.64°C), and LED-laser system the lowest (0.33±0.12°C); however, there was no difference between LED-laser system and LED unit (0.44±0.11°C). LED and LED-laser system did not differ

Evaluation of bleaching efficacy of 37.5% hydrogen peroxide on human teeth using different modes of activations: An in vitro study

PubMed Central

Bhutani, Neha; Venigalla, Bhuvan Shome; Patil, Jaya Prakash; Singh, Thakur Veerandar; Jyotsna, Sistla Venkata; Jain, Abhilasha

2016-01-01

Introduction: The aim of this in vitro study is to evaluate the role of light and laser sources in the bleaching ability of 37.5% H2 O2 on extracted human teeth. Materials and Methods: About 30 caries-free single-rooted maxillary central incisors were used for the study. Specimens were prepared by sectioning the crown portion of teeth mesiodistally, and labial surface was used for the study. Specimens were then immersed in coffee solution for staining. Color of each tooth was analyzed using Shadestar, a digital shademeter. Specimens were then divided into three groups of 10 each and were subjected to bleaching with 37.5% H2 O2, 37.5% H2 O2 + light activation, and 37.5% H2 O2 + laser activation, respectively. Postbleaching, the color was analyzed for all the specimens immediately and then after 1, 2, and 3 weeks intervals, respectively. Results: All the statistical analyses were done using SPSS version 17. Intra- and inter-group comparisons were done with Friedman test and Kruskal–Wallis ANOVA, respectively. Statistical analysis concluded with a significant improvement in their shade values from baseline in all the three groups. Halogen light activation and laser-activated groups showed comparatively enhanced bleaching results over no-activation group, though the difference was not statistically significant. Conclusion: The results of the present study show that bleaching assisted with halogen light and laser showed increased lightness than nonlight activated group. Durability of bleaching results obtained postbleaching was maintained throughout the experimental trail period of 3 weeks for both halogen light and laser activation group, whereas no-light activation group presented with shade rebound after 2 weeks postbleaching. PMID:27217641

Effect of low-level laser therapy on tooth sensitivity induced by in-office bleaching.

PubMed

Moosavi, Horieh; Arjmand, Nooshin; Ahrari, Farzaneh; Zakeri, Majid; Maleknejad, Fatemeh

2016-05-01

This study aimed to investigate the effect of low-level laser therapy (LLLT) on tooth sensitivity induced by in-office bleaching. Sixty-six patients enrolled in this randomized clinical trial. Following the in-office procedure with 40% hydrogen peroxide, the participants were randomly divided into three groups. The patients in group 1 received irradiation from a low-level red laser (LLRL; 660 nm, 200 mW, 15 s, 12 J/cm(2)), whereas participants in group 2 were subjected to a low-level infrared laser (LLIL; 810 nm) under similar conditions as in group 1. In group 3 (placebo), the laser treatment was the same as that in groups 1 and 2, but without energy output. The degree of tooth sensitivity was recorded at 1, 24, and 48 h after bleaching using a visual analog scale (VAS). The change in tooth shade was measured 30 days after tooth whitening. The intensity of tooth sensitivity was not significantly different between groups at 1 h after bleaching (p > 0.05). At 24 h after therapy, pain level was significantly lower in the LLIL group compared to the LLRL and placebo groups (p < 0.05). At 48 h after bleaching, VAS scores in the LLIL and LLRL groups were comparable to each other (p > 0.05) and both were significantly lower than that of the placebo group (p < 0.05). There was no significant difference in the efficacy of tooth whitening among groups (p > 0.05). LLLT with an infrared diode laser could be recommended as a suitable strategy to reduce the intensity of tooth sensitivity after in-office bleaching.

Body image disturbance and skin bleaching.

PubMed

Charles, Christopher A D; McLean, Shua-Kym

2017-11-01

This study looks at body image disturbance among Jamaicans who bleach their skin. The hypothesis states that there is a positive relationship between skin bleaching and body image disturbance. The study used a convenience sample of 160 participants with a skin bleaching group (n = 80) and a non-bleaching comparison group (n = 80). The instrument included demographic questions, the body image disturbance questionnaire (BIDQ), and questions about skin bleaching. The results of a t-test revealed that the skin bleaching group (M = 1.5255, SD = 0.42169) was not significantly different from the non-bleaching group (M = 1.4938, SD = 0.74217) in terms of body image disturbance, t(158) = 0.333, p = .740. The participants who bleached did not suffer from body image disturbance. Self-reports revealed that they bleached to acquire beauty, attract a partner, elude the police, and market skin bleaching products. The practice was fashionable and popular and it made some participants feel good, while others were fans of a popular musical artiste who bleached his skin. The majority of participants bleached because of the perceived personal, social, and entrepreneurial benefits of the practice and not because they suffered emotional distress, anxiety, and functional impairment because of their skin colour. However, there was some level of BID among the minority of participants who argued that they bleached because they wanted to be pretty so they were emotionally distressed about there body image and experienced functional impairment. © 2017 The British Psychological Society.

The effects of fractional CO2 laser, Nano-hydroxyapatite and MI paste on mechanical properties of bovine enamel after bleaching

PubMed Central

Moosavi, Horieh

2017-01-01

Background This study investigated the effect of post bleaching treatments to the change of enamel elastic modulus and microhardness after dental bleaching in- vitro. Material and Methods Fifty bovine incisor slab were randomly assigned into five groups (n=10). The samples were bleached for three times; 20 minutes each time, by 40% hydrogen peroxide. Next it was applied fractional CO2 laser for two minutes, Nano- hydroxy apatite (N-HA) and MI-paste for 7 days and 2 minutes per day. The sound enamel and bleached teeth without post treatment remained as control groups. The elastic modulus and microhardness were measured at three times; 24 hours, 1 and 2 months. Data were statistically analyzed by two-way analysis of variance with 95% confidence level. Results Different methods of enamel treatment caused a significant increase in elastic modulus compared to bleached group (P<0.05). Modulus was significantly increased in 1 and 2 months (P<0/001: bleach, P= 0/015: laser, P= 0/008: NHA, P=0/010: MI paste) but there were no significantly difference between 1 and 2 months (P>0.05). There was any significance difference for hardness among treated and control groups, but hardness increased significantly by increasing storage time (P<0.05). Conclusions The use of the protective tested agents can be useful in clinical practice to reduce negative changes of enamel surface after whitening procedures. Key words:Bleaching enamel, CO2 laser, MI pastes, Nano-hydroxy apatite, Microhardness, Elastic modulus. PMID:29410753

Bleach vs. Bacteria

MedlinePlus

... Inside Life Science > Bleach vs. Bacteria Inside Life Science View All Articles | Inside Life Science Home Page Bleach vs. Bacteria By Sharon Reynolds ... For Proteins, Form Shapes Function This Inside Life Science article also appears on LiveScience . Learn about related ...

Bleaching of cotton fabric with tetraacetylhydrazine as bleach activator for H2O2.

PubMed

Liu, Kai; Zhang, Xuan; Yan, Kelu

2018-05-15

Tetraacetylhydrazine (TH) as bleach activator for H 2 O 2 cotton bleaching was synthesized and characterized by 1 H NMR, 13 C NMR and MS spectra. TH has better solubility than that of TAED. The CIE whiteness index (WI), H 2 O 2 decomposition rate and bursting strength were employed to investigate the performance of H 2 O 2 /TH bleaching system. By addition of TH, WI and H 2 O 2 decomposition rate increased significantly at 70 °C. Bleaching temperature, NaHCO 3 concentration and bleaching time were also discussed in detail and the loss of bursting strength is not clear. By using benzenepentacarboxylic acid (BA) as a fluorescent probe for hydroxyl radical detection, the bleaching process of H 2 O 2 /TH system was investigated. Acetylhydrazine and diacetylhydrazine were also utilized to further confirm the process. In addition, bimolecular decomposition was investigated by using 9,10-dimethylanthracene (DMA) as fluorescent probe of 1 O 2 . Based on these experimental results, the bleaching mechanism of H 2 O 2 /TH system was proposed. Copyright © 2018 Elsevier Ltd. All rights reserved.

Changes in Bleaching Susceptibility among Corals Subject to Ocean Warming and Recurrent Bleaching in Moorea, French Polynesia

PubMed Central

Pratchett, Morgan S.; McCowan, Dominique; Maynard, Jeffrey A.; Heron, Scott F.

2013-01-01

Background Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. Methodology/Principal Findings This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites), during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98%) than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. Conclusions/Significance Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species) is producing a coral assemblage that is more resistant to

Changes in bleaching susceptibility among corals subject to ocean warming and recurrent bleaching in Moorea, French Polynesia.

PubMed

Pratchett, Morgan S; McCowan, Dominique; Maynard, Jeffrey A; Heron, Scott F

2013-01-01

Climate-induced coral bleaching poses a major threat to coral reef ecosystems, mostly because of the sensitivities of key habitat-forming corals to increasing temperature. However, susceptibility to bleaching varies greatly among coral genera and there are likely to be major changes in the relative abundance of different corals, even if the wholesale loss of corals does not occur for several decades. Here we document variation in bleaching susceptibility among key genera of reef-building corals in Moorea, French Polynesia, and compare bleaching incidence during mass-bleaching events documented in 1991, 1994, 2002 and 2007. This study compared the proportion of colonies that bleached for four major genera of reef-building corals (Acropora, Montipora, Pocillopora and Porites), during each of four well-documented bleaching events from 1991 to 2007. Acropora and Montipora consistently bleached in far greater proportions (up to 98%) than Pocillopora and Porites. However, there was an apparent and sustained decline in the proportion of colonies that bleached during successive bleaching events, especially for Acropora and Montipora. In 2007, only 77% of Acropora colonies bleached compared with 98% in 1991. Temporal variation in the proportion of coral colonies bleached may be attributable to differences in environmental conditions among years. Alternately, the sustained declines in bleaching incidence among highly susceptible corals may be indicative of acclimation or adaptation. Coral genera that are highly susceptible to coral bleaching, and especially Acropora and Montipora, exhibit temporal declines in their susceptibility to thermal anomalies at Moorea, French Polynesia. One possible explanation for these findings is that gradual removal of highly susceptible genotypes (through selective mortality of individuals, populations, and/or species) is producing a coral assemblage that is more resistant to sustained and ongoing ocean warming.

Effect of acidity of in-office bleaching gels on tooth sensitivity and whitening: a two-center double-blind randomized clinical trial.

PubMed

Loguercio, A D; Servat, F; Stanislawczuk, R; Mena-Serrano, A; Rezende, M; Prieto, M V; Cereño, V; Rojas, M F; Ortega, K; Fernandez, E; Reis, A

2017-12-01

The study aimed to compare the tooth sensitivity (TS) and bleaching efficacy of two hydrogen peroxide gels with different pHs (acid pH [Pola Office, SDI] and the neutral pH [Pola Office+, SDI]) used for in-office bleaching. Fifty-four patients from Brazil and Chile, with right superior incisor darker than A2, were selected for this double-blind, split-mouth randomized trial. Teeth were bleached in two sessions, with 1-week interval. Each session had three applications of 8 min each, according to the manufacturer's instructions. The color changes were evaluated by subjective (Vita Classical and Vita Bleachedguide) and objective (Easy shade spectrophotometer) methods. Participants recorded TS with 0-10 visual analog scale. Color change in shade guide units (SGU) and ΔE was analyzed by Student's t test (α = 0.05). The absolute risk and intensity of TS were evaluated by McNemar's test and Wilcoxon-paired test, respectively (α = 0.05). All groups achieved the same level of whitening after 30 days of clinical evaluation. The use of a neutral in-office bleaching gel significantly decreases the absolute risk of TS (28%, 95% CI 18-41) and intensity of TS when compared to the acid bleaching gel (absolute risk of 50%, 95% CI 37-63). The use of a neutral in-office bleaching agent gel produced the same whitening degree than an acid bleaching gel but with reduced risk and intensity of tooth sensitivity. Clinicians should opt to use in-office bleaching with a neutral gel than an acid product because the former causes a significant lower risk and intensity of tooth sensitivity.

Effect of Er:YAG laser pulse duration on the shear bond strength of bleached dentin

NASA Astrophysics Data System (ADS)

Yu, Ping; Yu, Dandan; Zhao, Peng; Xu, Zhou; Gao, Shanshan

2017-11-01

The influence of different Er:YAG laser pulse durations on the shear bond strength (SBS) of bleached dentin was investigated in this study. In total, 176 crowns of extracted human premolars were cut horizontally, embedded and ground to expose the sound dentin. Of these, 132 specimens were bleached with 12% hydrogen peroxide (HP) and divided into three groups, irradiated by an Er:YAG laser with different pulse lengths of 50 µs super short pulse (SSP), 100 µs moderate short pulse (MSP) and 300 µs short pulse (SP), respectively. The energy density of the three groups was the same at about 15.73 J cm-2 for each. Then, each group was further divided into two subgroups according to whether it had been etched with 37% phosphoric acid or not. The control group (N  =  22) was bleached and etched with acid while the blank group (N  =  22) was just etched with acid. The surface morphology of the dentin was observed using scanning electron microscopy (SEM). The SBS of the composite resin to the conditioned dentin was tested with a universal testing machine. It was found that the SBS of the dentin significantly decreased after bleaching treatment, while it was possible to restore it using Er:YAG laser irradiation. Lasers with various pulse durations led to different surface morphologies but had no effect on the SBS. The SSP laser was more suitable on account of it resulting in less thermal damage, and additional acid etching was not necessary for the irradiated bleached dentin in the clinic because it could not further improve the SBS value.

The effect of dental bleaching on pulpal tissue response in a diabetic animal model.

PubMed

Cintra, L T A; Ferreira, L L; Benetti, F; Gastélum, A A; Gomes-Filho, J E; Ervolino, E; Briso, A L F

2017-08-01

To evaluate pulpal tissue response after dental bleaching in normal and alloxan-induced diabetic rats. Twenty-eight rats were divided into two groups of normoglycaemic and diabetic rats (n = 14). Diabetes mellitus (DM) was induced with alloxan. After DM confirmation, all rats were anaesthetized and dental bleaching was performed with 35% hydrogen peroxide (H 2 O 2 ) on the right maxillary molars for 30 min. Left molars were used as controls. Bleaching resulted in four hemimaxillae groups: normoglycaemic (N), N-bleached (NBle), diabetic (D) and D-bleached (DBle). After 2 or 30 days, the animals were euthanized and the hemimaxillae were removed, processed for histopathological analysis and stained with haematoxylin-eosin (HE), Masson's trichrome (MT) and picrosirius red (PSR). Results obtained within animals (normoglycaemic or diabetic rats) were submitted to Wilcoxon or paired t-tests, and between animal (normoglycaemic and diabetic rats), to Mann-Whitney test or t-tests. At 2 days, the NBle group had a mild inflammatory infiltration in the pulpal tissue, whilst the DBle had severe inflammation or necrosis (P < 0.05). At 30 days, no inflammation was present. However, a significant difference in pulp chamber area reduction by reactionary dentine deposition was found between the NBle and DBle groups (P < 0.05). At 2 days, fewer immature collagen fibres and more mature collagen fibres were noted in the NBle, D and DBle groups; this was significantly different when compared to the N group (P < 0.05). At 30 days, significantly fewer immature collagen fibres and more mature collagen fibres were noted in NBle compared with DBle group (P < 0.05). The inflammatory tissue response in rats' teeth after dental bleaching was greater in diabetic rats. Additionally, the increase in reactionary dentine deposition and mature collagen fibres observed in diabetic rats needs further evaluation to confirm the present results. © 2016 International Endodontic Journal

Bleach boosting effect of xylanase A from Bacillus halodurans C-125 in ECF bleaching of wheat straw pulp.

PubMed

Lin, Xiao-qiong; Han, Shuang-yan; Zhang, Na; Hu, Hui; Zheng, Sui-ping; Ye, Yan-rui; Lin, Ying

2013-02-05

Past studies have revealed major difficulties in applications of xylanase in the pulp and paper industry as enzymes isolated from many different species could not tolerate high temperatures or highly alkaline conditions. The thermostable xylanase A from Bacillus halodurans C-125 (C-125 xylanase A) was successfully cloned and expressed in Pichia pastoris with a yield as high as 3361 U/mL in a 2 L reactor. Its thermophilic and basophilic properties (optimal activity at 70 °C and pH 9.0), together with the fact it is cellulase-free, render this enzyme attractive for compatible applications in the pulp and paper industry. The pretreatment of wheat straw pulp with C-125 xylanase A at pH 9.0 and 70 °C for 90 min induced the release of both chromophores (Ab(237), Ab(254), Ab(280)) and hydrophobic compounds (Ab(465)) into the filtrate as well as sugar degradation. Moreover, the addition of 10 U xylanase to 1 g wheat straw pulp (dry weight) as pretreatment improved brightness by 5.2% ISO and decreased the kappa number by 5.0% when followed by hydrogen peroxide bleaching. In addition, compared with two commercial enzymes, Pulpzyme HC and AU-PE89, which are normally incorporated in ECF bleaching of wheat straw pulp, C-125 xylanase A proved to be more effective in enhancing brightness as well as preserving paper strength properties. When evaluating the physical properties of pulp samples, such as tensile index, tearing index, bursting index, and post-color (PC) number, the enzymes involved in pretreating pulps exhibited better or the same performances as chemical treatment. Compared with chemical bleaching, chlorine consumption can be significantly reduced by 10% for xylanase-pretreated wheat straw pulp while maintaining the brightness together with the kappa number at the same level. Scanning electron microscopy revealed significant surface modification of enzyme-pretreated pulp fibers with no marked fiber disruptions. Copyright © 2012 Elsevier Inc. All rights reserved.

The effect of bleaching gel and (940 nm and 980 nm) diode lasers photoactivation on intrapulpal temperature and teeth whitening efficiency.

PubMed

Al-Karadaghi, Tamara S; Al-Saedi, Asmaa A; Al-Maliky, Mohammed A; Mahmood, Ali S

2016-12-01

This in vitro study aimed to investigate the whitening efficacy of 940 nm and 980 nm diode laser photoactivation in tooth bleaching by analysing pulp chamber temperature, as well as the change in tooth colour. Root canals of thirty extracted human lower premolars were prepared. Laserwhite* 20 bleaching agent containing 38% of hydrogen peroxide was photoactivated with 7 W output power of 940 nm and 980 nm diode lasers for 120 s. Bleaching gel reduced 27-29% of the temperature from reaching the pulp chamber. For shade assessment, only the groups photoactivated using diode lasers showed statistically significant differences from control group P < 0.001. Within the studied parameters, both 940 nm and 980 nm diode lasers produced a safe pulp temperature increase. Diode laser photoactivation of bleaching gel resulted in more efficient teeth whitening. Photoactivation with 940 nm diode laser yielded the highest change in colour with only minor increase in pulp chamber temperature. © 2016 Australian Society of Endodontology Inc.

The efficacy of laser-assisted in-office bleaching and home bleaching on sound and demineralized enamel

PubMed Central

Akbari, Majid; Mohammadpour, Sakineh

2015-01-01

Aims: This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel. Materials and Methods: The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups. Results: There were significant differences in the color change between T2 and T3 (ΔE T2–T3) and T2 and T4 (ΔE T2–T4) stages among the study groups (p<0.05). Pairwise comparison by Duncan test revealed that both ΔET2–T3 and ΔET2–T4 were significantly greater in demineralized teeth submitted to laser-assisted in-office bleaching (group 1) as compared to the other groups (P< 0.05). Conclusion: Laser-assisted in-office bleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth. PMID:26877590

The efficacy of laser-assisted in-office bleaching and home bleaching on sound and demineralized enamel.

PubMed

Ahrari, Farzaneh; Akbari, Majid; Mohammadpour, Sakineh; Forghani, Maryam

2015-12-30

This study investigated the effectiveness of laser-assisted in-office bleaching and home-bleaching in sound and demineralized enamel. The sample consisted of 120 freshly-extracted bovine incisors. Half of the specimens were stored in a demineralizing solution to induce white spot lesions. Following exposure to a tea solution for 7.5 days, the specimens were randomly assigned to 4 groups of 30 according to the type of enamel and the bleaching procedure employed. Groups 1 and 2 consisted of demineralized teeth subjected to in-office bleaching and home bleaching, whereas in groups 3 and 4, sound teeth were subjected to in-office and home bleaching, respectively. A diode laser (810 nm, 2 W, continuous wave, four times for 15 seconds each) was employed for assisting the in-office process. The color of the specimens was measured before (T1) and after (T2) staining and during (T3) and after (T4) the bleaching procedures using a spectrophotometer. The color change (ΔE) between different treatments stages was compared among the groups. There were significant differences in the color change between T2 and T3 (ΔE T2-T3) and T2 and T4 (ΔE T2-T4) stages among the study groups (p<0.05). Pairwise comparison by Duncan test revealed that both ΔET2-T3 and ΔET2-T4 were significantly greater in demineralized teeth submitted to laser-assisted in-office bleaching (group 1) as compared to the other groups (P< 0.05). Laser-assisted in-office bleaching could provide faster and greater whitening effect than home bleaching on stained demineralized enamel, but both procedures produced comparable results on sound teeth.

Augmented reality experimentation on oxygen gas generation from hydrogen peroxide and bleach reaction.

PubMed

Gan, Hong Seng; Tee, Nicholas Yee Kwang; Bin Mamtaz, Mohammad Raziun; Xiao, Kevin; Cheong, Brandon Huey-Ping; Liew, Oi Wah; Ng, Tuck Wah

2018-05-01

The appreciation and understanding of gas generation through processes is vital in biochemical education. In this work, an augmented reality tool is reported to depict the redox reaction between hydrogen peroxide and sodium hypochlorite solutions, two ubiquitous oxidizing agents, to create oxygen, a combustible gas. As it operates out of smartphones or tablets, students are able to conduct the exercise collaboratively, respond in a manner similar to an actual physical experiment, and able to depict the oxygen volume changes in relation to the volume of hydrogen peroxide of different concentrations used. The tool offers to help students acquire bench skills by limiting handing risks and to mitigate possible student anxiety on handling chemical materials and implements in the laboratory. The feedback received from Year 11 and 12 high school student participants in an outreach exercise indicate the overall effectiveness of this tool. © 2018 by The International Union of Biochemistry and Molecular Biology, 46(3):245-252, 2018. © 2018 The International Union of Biochemistry and Molecular Biology.

Preventive Use of a Resin-based Desensitizer Containing Glutaraldehyde on Tooth Sensitivity Caused by In-office Bleaching: A Randomized, Single-blind Clinical Trial.

PubMed

Diniz, Acs; Lima, Snl; Tavarez, RRdJ; Borges, A H; Pinto, Scs; Tonetto, M R; Loguercio, A D; Bandéca, M C

2018-03-23

To evaluate the risk and intensity of bleaching-induced tooth sensitivity (TS) after in-office bleaching following topical application of a resin-based glutaraldehyde desensitizer. Thirty-three patients were randomly assigned to the experimental (Gluma Desensitizer Liquid, Heraeus Kulzer, Hanau, Germany) and placebo groups. The placebo or Gluma Desensitizer Liquid was applied for one minute prior to application of an in-office bleaching gel. Bleaching was performed with 35% hydrogen peroxide gel (three applications × 15 minutes each) over two sessions, one week apart. The color of the anterior teeth was evaluated before and 21 days after treatment using the VITA Classical shade guide, Bleachedguide 3D, and Easyshade spectrophotometer. TS during and after the bleaching was recorded according to the visual analog (VAS) and numerical rating (NRS) scales. All data were submitted to statistical analysis (α=0.05). There was no significant difference in absolute risk or intensity of TS between the two groups (risk and VAS, p=0.93 and 0.31, respectively; NRS, p≥0.45). At the end of the bleaching protocol, tooth whitening was observed in both groups, as evident from color change in shade guide units (ΔSGU, 4.1-7.1; both guides) and overall color change (ΔE, 7.4-9.3 units); however, there were no significant differences in whitening between the two groups ( p>0.11). Gluma Desensitizer Liquid was not able to reduce the risk or intensity of TS. Bleaching efficacy was not affected by application of the desensitizer.

Influence of adhesive restorations on diffusion of H2O2 released from a bleaching agent and its toxic effects on pulp cells.

PubMed

Soares, Diana Gabriela; Pastana, Júlia Vieira; de Oliveira Duque, Carla Caroline; Dias Ribeiro, Ana Paula; Basso, Fernanda Gonçalves; Hebling, Josimeri; de Souza Costa, Carlos Alberto

2014-04-01

To assess the influence of adhesive restorations on hydrogen peroxide (H2O2) diffusion through enamel and dentin and its cytotoxicity to pulp (MDPC-23) cells. Sound and resin-restored enamel/dentin disks were stored in water for 24 h or 6 months and adapted to artificial pulp chambers. Bleaching gels with 20% or 35% H2O2 were applied to the enamel surface for 45 min, and a culture medium in direct contact with the dentin surface (extract) was applied for 1 h to the MDPC-23 cells. Cell metabolism (MTT assay) and cell morphology (SEM) were assessed. The amount of H2O2 in the extracts was also quantified (peroxidase/leuco-crystal violet reaction). A significant reduction in cell metabolism was observed between the group bleached with the 35% gel and the control group (sound, nonbleached) (p < 0.05). The H2O2 diffusion was directly related to its concentration in the bleaching gel. The variables "presence of restoration" and "time of water storage" did not significantly influence H2O2 diffusion or cell metabolism for either of the bleaching gels (p > 0.05). All bleached groups presented alterations in cell morphology related to the concentration of H2O2 in the bleaching gel. The reduction in cell metabolism and the changes in cell morphology were H2O2-concentration dependent, having no relationship with the presence of either new or aged adhesive restorations on teeth subjected to bleaching therapies.

Study of the temporal evolution of Whitening Teeth immersed in Peroxide of hydrogen (H2O2) Using Digital Image Processing

NASA Astrophysics Data System (ADS)

Díaz, L.; Morales, Y.; Torres, C.

2015-01-01

The esthetic dentistry reference in our society is determined by several factors, including one that produces more dissatisfaction is abnormal tooth color or that does not meet the patient's expectations. For this reason it has been designed and implemented an algorithm in MATLAB that captures, digitizes, pre-processing and analyzed dental imaging by allowing to evaluate the degree of bleaching caused by the use of peroxide of hidrogen. The samples analyzed were human teeth extracted, which were subjected to different concentrations of peroxide of hidrogen and see if they can teeth whitening when using these products, was used different concentrations and intervals of time to analysis or study of the whitening of the teeth with the hydrogen peroxide.

Effect of topical application of dipyrone on dental sensitivity reduction after in-office dental bleaching: A randomized, triple-blind multicenter clinical trial.

PubMed

Rezende, Márcia; Chemin, Kaprice; Vaez, Savil Costa; Peixoto, Aline Carvalho; Rabelo, Jéssica de Freitas; Braga, Stella Sueli Lourenço; Faria-E-Silva, André Luis; Silva, Gisele Rodrigues da; Soares, Carlos José; Loguercio, Alessandro D; Reis, Alessandra

2018-05-01

Tooth sensitivity commonly occurs during and immediately after dental bleaching. The authors conducted a trial to compare tooth sensitivity after in-office bleaching after the use of either a topical dipyrone or placebo gel. A split-mouth, triple-blind, randomized, multicenter clinical trial was conducted among 120 healthy adults having teeth that were shade A2 or darker. The facial tooth surfaces of the right or left sides of the maxillary arch of each patient were randomly assigned to receive either topical dipyrone or placebo gel before 2 in-office bleaching sessions (35% hydrogen peroxide) separated by 2 weeks. Visual analog and numerical rating scales were used to record tooth sensitivity during and up to 48 hours after bleaching. Tooth color change from baseline to 1 month after bleaching was measured with shade guide and spectrophotometer measures. The primary outcome variable was absolute risk of tooth sensitivity. An intention-to-treat analysis was used to analyze data from all patients who were randomly assigned to receive the dipyrone and placebo gels. No statically significant difference was found in the absolute risk of tooth sensitivity between the dipyrone and placebo gels (83% and 90%, respectively, P = .09; relative risk, 0.92; 95% confidence interval, 0.8 to 1.0). A whitening effect was observed in both groups with no statistically significant difference (P > .05) between them. No adverse effects were observed. Topical use of dipyrone gel before tooth bleaching, at the levels used in this study, did not reduce the risk or intensity of bleaching-induced tooth sensitivity. Topical application of dipyrone gel does not reduce bleaching-induced tooth sensitivity. Copyright © 2018 American Dental Association. Published by Elsevier Inc. All rights reserved.

In vitro assessment of pulp chamber temperature of different teeth submitted to dental bleaching associated with LED/laser and halogen lamp appliances.

PubMed

Torres, Carlos Rocha Gomes; Caneppele, Taciana Marco Ferraz; Arcas, Felipe Carlos Dias; Borges, Alessandra Buhler

2008-01-01

This study sought to assess the pulp chamber temperature in different groups of human teeth that had been bleached using hydrogen peroxide gel activated with halogen lamps or hybrid LED/laser appliances. Four groups of ten teeth (maxillary central incisors, mandibular incisors, mandibular canines, and maxillary canines) were used. A digital thermometer with a K-type thermocouple was placed inside pulp chambers that had been filled with thermal paste. A 35% hydrogen peroxide-based red bleaching gel was applied to all teeth and photocured for a total of three minutes and 20 seconds (five activations of 40 seconds each), using light from an LED/laser device and a halogen lamp. The temperatures were gauged every 40 seconds and the data were analyzed by three-way ANOVA, followed by Tukey's test. Regardless of the light source, statistically significant differences were observed between the groups of teeth. The mean temperature values (+/- SD) were highest for maxillary central incisors and lowest for mandibular canines. The halogen lamp appliance produced more pulp chamber heating than the LED/laser appliance. The increase in irradiation time led to a significant increase in temperature.

Coral bleaching independent of photosynthetic activity.

PubMed

Tolleter, Dimitri; Seneca, François O; DeNofrio, Jan C; Krediet, Cory J; Palumbi, Stephen R; Pringle, John R; Grossman, Arthur R

2013-09-23

The global decline of reef-building corals is due in part to the loss of algal symbionts, or "bleaching," during the increasingly frequent periods of high seawater temperatures. During bleaching, endosymbiotic dinoflagellate algae (Symbiodinium spp.) either are lost from the animal tissue or lose their photosynthetic pigments, resulting in host mortality if the Symbiodinium populations fail to recover. The >1,000 studies of the causes of heat-induced bleaching have focused overwhelmingly on the consequences of damage to algal photosynthetic processes, and the prevailing model for bleaching invokes a light-dependent generation of toxic reactive oxygen species (ROS) by heat-damaged chloroplasts as the primary trigger. However, the precise mechanisms of bleaching remain unknown, and there is evidence for involvement of multiple cellular processes. In this study, we asked the simple question of whether bleaching can be triggered by heat in the dark, in the absence of photosynthetically derived ROS. We used both the sea anemone model system Aiptasia and several species of reef-building corals to demonstrate that symbiont loss can occur rapidly during heat stress in complete darkness. Furthermore, we observed damage to the photosynthetic apparatus under these conditions in both Aiptasia endosymbionts and cultured Symbiodinium. These results do not directly contradict the view that light-stimulated ROS production is important in bleaching, but they do show that there must be another pathway leading to bleaching. Elucidation of this pathway should help to clarify bleaching mechanisms under the more usual conditions of heat stress in the light. Copyright © 2013 Elsevier Ltd. All rights reserved.

Reef corals bleach to resist stress.

PubMed

Obura, David O

2009-02-01

A rationale is presented here for a primary role of bleaching in regulation of the coral-zooxanthellae symbiosis under conditions of stress. Corals and zooxanthellae have fundamentally different metabolic rates, requiring active homeostasis to limit zooxanthellae production and manage translocated products to maintain the symbiosis. The control processes for homeostasis are compromised by environmental stress, resulting in metabolic imbalance between the symbionts. For the coral-zooxanthella symbiosis the most direct way to minimize metabolic imbalance under stress is to reduce photosynthetic production by zooxanthellae. Two mechanisms have been demonstrated that do this: reduction of the chlorophyll concentration in individual zooxanthellae and reduction of the relative biomass of zooxanthellae. Both mechanisms result in visual whitening of the coral, termed bleaching. Arguments are presented here that bleaching provides the final control to minimize physiological damage from stress as an adversity response to metabolic imbalance. As such, bleaching meets the requirements of a stress response syndrome/general adaptive mechanism that is sensitive to internal states rather than external parameters. Variation in bleaching responses among holobionts reflects genotypic and phenotypic differentiation, allowing evolutionary change by natural selection. Thus, reef corals bleach to resist stress, and thereby have some capacity to adapt to and survive change. The extreme thermal anomalies causing mass coral bleaching worldwide lie outside the reaction norms for most coral-zooxanthellae holobionts, revealing the limitations of bleaching as a control mechanism.

Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide

PubMed Central

Deng, Meng; Wen, Hai-Lin; Dong, Xiao-Li; Li, Feng; Xu, Xin; Li, Hong; Li, Ji-Yao; Zhou, Xue-Dong

2013-01-01

Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass (BG) before, after, and during 35% hydrogen peroxide (HP) bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups: distilled deionized water (DDW), BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order: group HP>BG before HP, BG after HP>BG during HP>DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents. PMID:23743618

Effects of 45S5 bioglass on surface properties of dental enamel subjected to 35% hydrogen peroxide.

PubMed

Deng, Meng; Wen, Hai-Lin; Dong, Xiao-Li; Li, Feng; Xu, Xin; Li, Hong; Li, Ji-Yao; Zhou, Xue-Dong

2013-06-01

Tooth bleaching agents may weaken the tooth structure. Therefore, it is important to minimize any risks of tooth hard tissue damage caused by bleaching agents. The aim of this study was to evaluate the effects of applying 45S5 bioglass (BG) before, after, and during 35% hydrogen peroxide (HP) bleaching on whitening efficacy, physicochemical properties and microstructures of bovine enamel. Seventy-two bovine enamel blocks were prepared and randomly divided into six groups: distilled deionized water (DDW), BG, HP, BG before HP, BG after HP and BG during HP. Colorimetric and microhardness tests were performed before and after the treatment procedure. Representative specimens from each group were selected for morphology investigation after the final tests. A significant color change was observed in group HP, BG before HP, BG after HP and BG during HP. The microhardness loss was in the following order: group HP>BG before HP, BG after HP>BG during HP>DDW, BG. The most obvious morphological alteration of was observed on enamel surfaces in group HP, and a slight morphological alteration was also detected in group BG before HP and BG after HP. Our findings suggest that the combination use of BG and HP could not impede the tooth whitening efficacy. Using BG during HP brought better protective effect than pre/post-bleaching use of BG, as it could more effectively reduce the mineral loss as well as retain the surface integrity of enamel. BG may serve as a promising biomimetic adjunct for bleaching therapy to prevent/restore the enamel damage induced by bleaching agents.

Immune defenses of healthy, bleached and diseased Montastraea faveolata during a natural bleaching event.

PubMed

Mydlarz, Laura D; Couch, Courtney S; Weil, Ernesto; Smith, Garriet; Harvell, C Drew

2009-11-16

One prominent hypothesis regarding climate change and scleractinian corals is that thermal stress compromises immune competence. To test this hypothesis we tracked how the immune defenses of bleached, apparently healthy and yellow band disease (YBD) diseased Montastraea faveolata colonies varied with natural thermal stress in southwestern Puerto Rico. Colonies were monitored for 21 mo from the peak of the bleaching event in October 2005 to August 2007. Since sea surface temperature was significantly higher in summer and fall 2005 than 2006, year of collection was used as a proxy for temperature stress, and colony fragments collected in 2005 were compared with those collected in 2006. Mortality rate was high (43% overall) and all colonies (except one) either died or became infected with YBD by August 2007. YBD-infected tissue did not bleach (i.e. expel zooxanthellae) during the 2005 bleaching event, even when healthy tissue of these colonies bleached. Immune activity was assayed by measuring prophenoloxidase (PPO), peroxidase (POX), lysozyme-like (LYS) and antibacterial (AB) activity. Immune activity was variable between all coral samples, but there was a significant elevation of PPO activity in bleached colonies collected in 2005 relative to apparently healthy and YBD-diseased corals in 2006. In YBD-diseased colonies, LYS and AB activity were elevated in both healthy and infected tissue, indicating a systemic response; activity levels in these colonies were higher compared to those that appeared healthy. In both these immune parameters, there was a trend for suppression of activity in corals that were bleached in 2005. These data, while complicated by between-genet variability, illustrate the complex interaction between disease and temperature stress on immune function.

21 CFR 582.1975 - Bleached beeswax.

Code of Federal Regulations, 2010 CFR

2010-04-01

... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Bleached beeswax. 582.1975 Section 582.1975 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL... Additives § 582.1975 Bleached beeswax. (a) Product. Bleached beeswax (white wax). (b) Conditions of use...

Influence of enamel/dentin thickness on the toxic and esthetic effects of experimental in-office bleaching protocols.

PubMed

de Oliveira Duque, C C; Soares, D G; Basso, F G; Hebling, J; de Souza Costa, C A

2017-11-01

This paper aims to assess the whitening effectiveness and toxicity of tooth-bleaching protocols applied to enamel/dentin disks simulating mandibular incisors (ICs) and premolars (PMs). A 10% hydrogen peroxide (H 2 O 2 ) gel was applied for 3 × 15, 1 × 15, or 1 × 5 min to enamel/dentin disks simulating mandibular ICs and PMs, and the trans-enamel and trans-dentinal diffusion products were applied to human dental pulp cells (1 h). Professional therapy (35% H 2 O 2 -3 × 15 min) was used as positive control, and non-bleached samples were used as negative control. Cell viability and morphology, oxidative stress generation, and odontoblastic marker expression were assessed. The H 2 O 2 diffusion and enamel color change (ΔE) were also analyzed. The 10% H 2 O 2 gel induced significant cell viability reduction only when applied 3 × 15 min, with the intensity of oxidative stress and down-regulation of odontoblastic markers being higher in the IC group. The other experimental bleaching protocols caused slight alterations regarding the cell parameters evaluated, with intensity being related to enamel/dentin thickness. These effects were also correlated with higher H 2 O 2 diffusion in the IC group. ΔE values similar as positive control were found for the 10% 3 × 15 and 1 × 15 protocols on IC group, after 4 and 6 sessions. Application of a 10% H 2 O 2 bleaching gel for 15 or 45 min to thin dental substrate significantly minimizes cell toxicity in comparison with highly concentrated gels associated with similar esthetic outcomes by increasing the number of bleaching sessions. Bleaching gels with 10% H 2 O 2 applied in small teeth for short periods may be an interesting alternative to obtain whitening effectiveness without causing toxicity to pulp cells, which may be able to reduce the tooth hypersensitivity claimed by patients.

Effects of staining and bleaching on a nanohybrid composite with or without surface sealant

PubMed Central

Halacoglu, Derya Merve; Yamanel, Kıvanc; Basaran, Saffet; Tuncer, Duygu; Celik, Cigdem

2016-01-01

Objective: The effect of different staining solutions and a bleaching procedure on color stability and surface roughness of a nanohybrid resin composite were evaluated with or without liquid resin polishing (RP). Materials and Methods: Ninety-six disc-shaped resin composite specimens (A1 Shade, Z550 Filtek 3M ESPE, St. Paul, MN, USA) were prepared and divided randomly into two groups (n = 48). Liquid RP (BisCover LV, Bisco Inc., Schaumburg, IL, USA) was applied in one group (RP) and not in the other (P). Specimen color and surface roughness were determined using a colorimeter and profilometer, respectively. After baseline measurements, each group was divided into four subgroups (n = 12) for immersion in a control (distilled water) or three different staining solutions (ice tea, red wine, and cola) for 1 week. Color and surface roughness were then reevaluated. After measurements, all specimens were bleached using a 35% hydrogen peroxide gel. The color and surface roughness of the specimens were reevaluated. Statistical Analysis: Data were subjected to an analysis of variance for repeated measurements among the groups (P < 0.05). Results: Staining and bleaching did not change the surface roughness of the RP and P groups (P > 0.05). Discoloration in the red wine group was higher than for the other staining solutions for the RP (P < 0.001) and P groups (P = 0.018). Conclusion: Application of liquid RP did not enhance the color stability and surface roughness of the composite resin restoration. PMID:27403054

Effects of combination of ultraviolet light and hydrogen peroxide on inactivation of Escherichia coli O157:H7, native microbial loads, and quality of button mushrooms

USDA-ARS?s Scientific Manuscript database

Mushrooms are prone to microbial spoilage and browning during growing and processing. Ultraviolet light (UV-C) has been used as an alternative technology to chemical sanitizers for food products. Hydrogen peroxide is classified as generally recognized as safe for use in foods as a bleaching and ant...

Hsp33 confers bleach resistance by protecting elongation factor Tu against oxidative degradation in Vibrio cholerae

PubMed Central

Wholey, Wei-Yun; Jakob, Ursula

2012-01-01

Summary The redox-regulated chaperone Hsp33 protects bacteria specifically against stress conditions that cause oxidative protein unfolding, such as treatment with bleach or exposure to peroxide at elevated temperatures. To gain insight into the mechanism by which expression of Hsp33 confers resistance to oxidative protein unfolding conditions, we made use of V. cholerae strain O395 lacking the Hsp33 gene hslO. We found that this strain, which is exquisitely bleach-sensitive, displays a temperature-sensitive (ts) phenotype during aerobic growth, implying that V. cholerae suffers from oxidative heat stress when cultivated at 43°C. We utilized this phenotype to select for E. coli genes that rescue the ts phenotype of V. cholerae ΔhslO when overexpressed. We discovered that expression of a single protein, the elongation factor EF-Tu, was sufficient to rescue both the ts and bleach-sensitive phenotypes of V. cholerae ΔhslO. In vivo studies revealed that V. cholerae EF-Tu is highly sensitive to oxidative protein degradation in the absence of Hsp33, indicating that EF-Tu is a vital chaperone substrate of Hsp33 in V. cholerae. These results suggest an “essential client protein” model for Hsp33’s chaperone action in Vibrio in which stabilization of a single oxidative stress-sensitive protein is sufficient to enhance the oxidative stress resistance of the whole organism. PMID:22296329

Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching.

PubMed

Swain, Timothy D; Vega-Perkins, Jesse B; Oestreich, William K; Triebold, Conrad; DuBois, Emily; Henss, Jillian; Baird, Andrew; Siple, Margaret; Backman, Vadim; Marcelino, Luisa

2016-07-01

As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982-2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ±SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel

Coral bleaching response index: a new tool to standardize and compare susceptibility to thermal bleaching

PubMed Central

SWAIN, TIMOTHY D.; VEGA-PERKINS, JESSE B.; OESTREICH, WILLIAM K.; TRIEBOLD, CONRAD; DUBOIS, EMILY; HENSS, JILLIAN; BAIRD, ANDREW; SIPLE, MARGARET; BACKMAN, VADIM; MARCELINO, LUISA

2017-01-01

As coral bleaching events become more frequent and intense, our ability to predict and mitigate future events depends upon our capacity to interpret patterns within previous episodes. Responses to thermal stress vary among coral species; however the diversity of coral assemblages, environmental conditions, assessment protocols, and severity criteria applied in the global effort to document bleaching patterns creates challenges for the development of a systemic metric of taxon-specific response. Here, we describe and validate a novel framework to standardize bleaching response records and estimate their measurement uncertainties. Taxon-specific bleaching and mortality records (2036) of 374 coral taxa (during 1982–2006) at 316 sites were standardized to average percent tissue area affected and a taxon-specific bleaching response index (taxon-BRI) was calculated by averaging taxon-specific response over all sites where a taxon was present. Differential bleaching among corals was widely variable (mean taxon-BRI = 25.06 ± 18.44%, ± SE). Coral response may differ because holobionts are biologically different (intrinsic factors), they were exposed to different environmental conditions (extrinsic factors), or inconsistencies in reporting (measurement uncertainty). We found that both extrinsic and intrinsic factors have comparable influence within a given site and event (60% and 40% of bleaching response variance of all records explained, respectively). However, when responses of individual taxa are averaged across sites to obtain taxon-BRI, differential response was primarily driven by intrinsic differences among taxa (65% of taxon-BRI variance explained), not conditions across sites (6% explained), nor measurement uncertainty (29% explained). Thus, taxon-BRI is a robust metric of intrinsic susceptibility of coral taxa. Taxon-BRI provides a broadly applicable framework for standardization and error estimation for disparate historical records and collection of novel

Warm waters, bleached corals

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roberts, L.

1990-10-12

Two researchers, Tom Goreau of the Discovery Laboratory in Jamaica and Raymond Hayes of Howard University, claim that they have evidence that nearly clinches the temperature connection to the bleached corals in the Caribbean and that the coral bleaching is an indication of Greenhouse warming. The incidents of scattered bleaching of corals, which have been reported for decades, are increasing in both intensity and frequency. The researchers based their theory on increased temperature of the seas measured by satellites. However, some other scientists feel that the satellites measure the temperature of only the top few millimeters of the water andmore » that since corals lie on reefs perhaps 60 to 100 feet below the ocean surface, the elevated temperatures are not significant.« less

Reef fishes can recognize bleached habitat during settlement: sea anemone bleaching alters anemonefish host selection

PubMed Central

Scott, Anna; Dixson, Danielle L.

2016-01-01

Understanding how bleaching impacts the settlement of symbiotic habitat specialists and whether there is flexibility in settlement choices with regard to habitat quality is essential given our changing climate. We used five anemonefishes (Amphiprion clarkii, Amphiprion latezonatus, Amphiprion ocellaris, Amphiprion percula and Premnas biaculeatus) and three host sea anemones (Entacmaea quadricolor, Heteractis crispa and Heteractis magnifica) in paired-choice flume experiments to determine whether habitat naive juveniles have the olfactory capabilities to distinguish between unbleached and bleached hosts, and how this may affect settlement decisions. All anemonefishes were able to distinguish between bleached and unbleached hosts, and responded only to chemical cues from species-specific host anemones irrespective of health status, indicating a lack of flexibility in host use. While bleached hosts were selected as habitat, this occurred only when unbleached options were unavailable, with the exception of A. latezonatus, which showed strong preferences for H. crispa regardless of health. This study highlights the potential deleterious indirect impacts of declining habitat quality during larval settlement in habitat specialists, which could be important in the field, given that bleaching events are becoming increasingly common. PMID:27226472

Reef fishes can recognize bleached habitat during settlement: sea anemone bleaching alters anemonefish host selection.

PubMed

Scott, Anna; Dixson, Danielle L

2016-05-25

Understanding how bleaching impacts the settlement of symbiotic habitat specialists and whether there is flexibility in settlement choices with regard to habitat quality is essential given our changing climate. We used five anemonefishes (Amphiprion clarkii, Amphiprion latezonatus, Amphiprion ocellaris, Amphiprion percula and Premnas biaculeatus) and three host sea anemones (Entacmaea quadricolor, Heteractis crispa and Heteractis magnifica) in paired-choice flume experiments to determine whether habitat naive juveniles have the olfactory capabilities to distinguish between unbleached and bleached hosts, and how this may affect settlement decisions. All anemonefishes were able to distinguish between bleached and unbleached hosts, and responded only to chemical cues from species-specific host anemones irrespective of health status, indicating a lack of flexibility in host use. While bleached hosts were selected as habitat, this occurred only when unbleached options were unavailable, with the exception of A. latezonatus, which showed strong preferences for H. crispa regardless of health. This study highlights the potential deleterious indirect impacts of declining habitat quality during larval settlement in habitat specialists, which could be important in the field, given that bleaching events are becoming increasingly common. © 2016 The Author(s).

Pre-operative use of dexamethasone does not reduce incidence or intensity of bleaching-induced tooth sensitivity. A triple-blind, parallel-design, randomized clinical trial.

PubMed

da Costa Poubel, Luiz Augusto; de Gouvea, Cresus Vinicius Deppes; Calazans, Fernanda Signorelli; Dip, Etyene Castro; Alves, Wesley Veltri; Marins, Stella Soares; Barcelos, Roberta; Barceleiro, Marcos Oliveira

2018-04-25

This study evaluated the effect of the administration of pre-operative dexamethasone on tooth sensitivity stemming from in-office bleaching. A triple-blind, parallel-design, randomized clinical trial was conducted on 70 volunteers who received dexamethasone or placebo capsules. The drugs were administered in a protocol of three daily 8-mg doses of the drug, starting 48 h before the in-office bleaching treatment. Two bleaching sessions with 37.5% hydrogen peroxide gel were performed with a 1-week interval. Tooth sensitivity (TS) was recorded on visual analog scales (VAS) and numeric rating scales (NRS) in different periods up to 48 h after bleaching. The color evaluations were also performed. The absolute risk of TS and its intensity were evaluated by using Fisher's exact test. Comparisons of the TS intensity (NRS and VAS data) were performed by using the Mann-Whitney U test and a two-way repeated measures ANOVA and Tukey's test, respectively. In both groups, a high risk of TS (Dexa 80% x Placebo 94%) was detected. No significant difference was observed in terms of TS intensity. A whitening of approximately 3 shade guide units of the VITA Classical was detected in both groups, which were statistically similar. It was concluded that the administration pre-operatively of dexamethasone, in the proposed protocol, does not reduce the incidence or intensity of bleaching-induced tooth sensitivity. The use of dexamethasone drug before in-office bleaching treatment does not reduce incidence or intensity of tooth sensitivity. NCT02956070.

Coral bleaching at Little Cayman, Cayman Islands 2009

NASA Astrophysics Data System (ADS)

van Hooidonk, Ruben J.; Manzello, Derek P.; Moye, Jessica; Brandt, Marilyn E.; Hendee, James C.; McCoy, Croy; Manfrino, Carrie

2012-06-01

The global rise in sea temperature through anthropogenic climate change is affecting coral reef ecosystems through a phenomenon known as coral bleaching; that is, the whitening of corals due to the loss of the symbiotic zooxanthellae which impart corals with their characteristic vivid coloration. We describe aspects of the most prevalent episode of coral bleaching ever recorded at Little Cayman, Cayman Islands, during the fall of 2009. The most susceptible corals were found to be, in order, Siderastrea siderea, Montastraea annularis, and Montastraea faveolata, while Diplora strigosa and Agaricia spp. were less so, yet still showed considerable bleaching prevalence and severity. Those found to be least susceptible were Porites porites, Porites astreoides, and Montastraea cavernosa. These observations and other reported observations of coral bleaching, together with 29 years (1982-2010) of satellite-derived sea surface temperatures, were used to optimize bleaching predictions at this location. To do this a Degree Heating Weeks (DHW) and Peirce Skill Score (PSS) analysis was employed to calculate a local bleaching threshold above which bleaching was expected to occur. A threshold of 4.2 DHW had the highest skill, with a PSS of 0.70. The method outlined here could be applied to other regions to find the optimal bleaching threshold and improve bleaching predictions.

Improvement in rice straw pulp bleaching effluent quality by incorporating oxygen delignification stage prior to elemental chlorine-free bleaching.

PubMed

Kaur, Daljeet; Bhardwaj, Nishi K; Lohchab, Rajesh Kumar

2017-10-01

Environmental degradation by industrial and other developmental activities is alarming for imperative environmental management by process advancements of production. Pulp and paper mills are now focusing on using nonwood-based raw materials to protect forest resources. In present study, rice straw was utilized for pulp production as it is easily and abundantly available as well as rich in carbohydrates (cellulose and hemicelluloses). Soda-anthraquinone method was used for pulp production as it is widely accepted for agro residues. Bleaching process during paper production is the chief source of wastewater generation. The chlorophenolic compounds generated during bleaching are highly toxic, mutagenic, and bioaccumulative in nature. The objectives of study were to use oxygen delignification (ODL) stage prior to elemental chlorine-free (ECF) bleaching to reduce wastewater load and to study its impact on bleached pulp characteristics. ODL stage prior to ECF bleaching improved the optical properties of pulp in comparison to only ECF bleaching. When ODL stage was incorporated prior to bleaching, the tensile index and folding endurance of the pulp were found to be 56.6 ± 1.5 Nm/g and 140, respectively, very high in comparison to ECF alone. A potential reduction of 51, 57, 43, and 53% in BOD 3 , COD, color, and AOX, respectively was observed on adding the ODL stage compared to ECF only. Generation of chlorophenolic compounds was reduced significantly. Incorporation of ODL stage prior to bleaching was found to be highly promising for reducing the toxicity of bleaching effluents and may lead to better management of nearby water resources. Graphical abstract ᅟ.

Mass coral bleaching in 2010 in the southern Caribbean.

PubMed

Alemu I, Jahson Berhane; Clement, Ysharda

2014-01-01

Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision making process to cope with mass bleaching events. The bleaching signal (length of exposure to high ocean temperatures) varied widely between the Atlantic and Caribbean reefs, but regardless of this variation most taxa bleached. Colpophyllia natans, Montastraea faveolata and Siderastrea siderea were considered the most bleaching vulnerable taxa. Interestingly, reefs with the highest coral cover showed the greatest decline reef building taxa, and conversely, reefs with the lowest coral cover showed the most bleaching but lowest change in coral cover with little algal overgrowth post-bleaching.

Mass Coral Bleaching in 2010 in the Southern Caribbean

PubMed Central

Alemu I, Jahson Berhane; Clement, Ysharda

2014-01-01

Ocean temperatures are increasing globally and the Caribbean is no exception. An extreme ocean warming event in 2010 placed Tobago's coral reefs under severe stress resulting in widespread coral bleaching and threatening the livelihoods that rely on them. The bleaching response of four reef building taxa was monitored over a six month period across three major reefs systems in Tobago. By identifying taxa resilient to bleaching we propose to assist local coral reef managers in the decision making process to cope with mass bleaching events. The bleaching signal (length of exposure to high ocean temperatures) varied widely between the Atlantic and Caribbean reefs, but regardless of this variation most taxa bleached. Colpophyllia natans, Montastraea faveolata and Siderastrea siderea were considered the most bleaching vulnerable taxa. Interestingly, reefs with the highest coral cover showed the greatest decline reef building taxa, and conversely, reefs with the lowest coral cover showed the most bleaching but lowest change in coral cover with little algal overgrowth post-bleaching. PMID:24400078

Is personality relevant in the choice of bleaching?

PubMed

Herrera, A; Martín, J; Pérez, F; Bonafé, E; Reis, A; Dourado, A Loguercio; Fernández, E

2016-11-01

The purpose was to administer the NEO-FFI personality test to patients who did and did not want to have their teeth bleached and before and after bleaching to the participants who accepted the treatment. The research question is to correlate styles and personality factors with bleaching. There were 128 patients eligible for bleaching; 58 accepted (AB) while 70 refused (RB). The test was administered to both groups (AB-RB). The group AB was administered before and 1 week after the end of the bleaching. For each personality domain comparison, the Mann-Whitney test was used. For the group AB, the results for each domain before and after bleaching were compared using the Wilcoxon test. There was a significant difference between the groups (AB-RB) in the extraversion factor (p = 0.01). There was no significant difference between any of the personality items before and after bleaching (p > 0.1). The comparison between groups by sex revealed significant differences in extraversion and neuroticism factors. Males who AB scored higher in extraversion than males who RB (p < 0.05). Females scored higher in neuroticism than males who AB (p < 0.05). There were personality differences between people who decided to bleach compared with those who did not want the bleaching, which was mainly in the extroversion factor. This stereotypes the patients, who could be described as more sociable, extroverted, and concerned about esthetics and cleanliness. The bleaching protocol, however, cannot modify any of the personality factors. It is important to understand a patient's behavior to meet their needs and to determine the type of patients who would like to have their teeth bleached.

Global warming and recurrent mass bleaching of corals

NASA Astrophysics Data System (ADS)

Hughes, Terry P.; Kerry, James T.; Álvarez-Noriega, Mariana; Álvarez-Romero, Jorge G.; Anderson, Kristen D.; Baird, Andrew H.; Babcock, Russell C.; Beger, Maria; Bellwood, David R.; Berkelmans, Ray; Bridge, Tom C.; Butler, Ian R.; Byrne, Maria; Cantin, Neal E.; Comeau, Steeve; Connolly, Sean R.; Cumming, Graeme S.; Dalton, Steven J.; Diaz-Pulido, Guillermo; Eakin, C. Mark; Figueira, Will F.; Gilmour, James P.; Harrison, Hugo B.; Heron, Scott F.; Hoey, Andrew S.; Hobbs, Jean-Paul A.; Hoogenboom, Mia O.; Kennedy, Emma V.; Kuo, Chao-Yang; Lough, Janice M.; Lowe, Ryan J.; Liu, Gang; McCulloch, Malcolm T.; Malcolm, Hamish A.; McWilliam, Michael J.; Pandolfi, John M.; Pears, Rachel J.; Pratchett, Morgan S.; Schoepf, Verena; Simpson, Tristan; Skirving, William J.; Sommer, Brigitte; Torda, Gergely; Wachenfeld, David R.; Willis, Bette L.; Wilson, Shaun K.

2017-03-01

During 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

Bleaching and recovery of a phototrophic bioeroding sponge

NASA Astrophysics Data System (ADS)

Marlow, Joseph; Davy, Simon K.; Shaffer, Megan; Haris, Abdul; Bell, James J.

2018-06-01

In the Wakatobi region of Indonesia, a prolonged period of elevated water temperature in 2016 caused extensive coral bleaching and mortality. Unusually, bleaching was also observed in the bioeroding sponge Cliona aff. viridis, with affected sponges expelling 99% of their Symbiodinium. Bleaching surveys of C. aff. viridis were conducted 6 weeks apart, coinciding with a 0.8 °C drop in water temperature. Over this period, bleaching prevalence dropped from 73.9% (± 9.9 SE) to 25.7% (± 5.8 SE), and bleaching severity dropped from 25.95% (± 4.5 SE) to 11.54% (± 1.9 SE) of sponge tissue. Over the same period, monitored bleached sponges showed an 81% drop in bleaching severity, but also a 13% reduction in overall sponge size. Our results show that while the clionaid- Symbiodinium relationship is susceptible to break down under thermal stress, rapid recovery can occur, although incurring some partial host mortality.

Global warming and recurrent mass bleaching of corals.

PubMed

Hughes, Terry P; Kerry, James T; Álvarez-Noriega, Mariana; Álvarez-Romero, Jorge G; Anderson, Kristen D; Baird, Andrew H; Babcock, Russell C; Beger, Maria; Bellwood, David R; Berkelmans, Ray; Bridge, Tom C; Butler, Ian R; Byrne, Maria; Cantin, Neal E; Comeau, Steeve; Connolly, Sean R; Cumming, Graeme S; Dalton, Steven J; Diaz-Pulido, Guillermo; Eakin, C Mark; Figueira, Will F; Gilmour, James P; Harrison, Hugo B; Heron, Scott F; Hoey, Andrew S; Hobbs, Jean-Paul A; Hoogenboom, Mia O; Kennedy, Emma V; Kuo, Chao-Yang; Lough, Janice M; Lowe, Ryan J; Liu, Gang; McCulloch, Malcolm T; Malcolm, Hamish A; McWilliam, Michael J; Pandolfi, John M; Pears, Rachel J; Pratchett, Morgan S; Schoepf, Verena; Simpson, Tristan; Skirving, William J; Sommer, Brigitte; Torda, Gergely; Wachenfeld, David R; Willis, Bette L; Wilson, Shaun K

2017-03-15

During 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching, the third global-scale event since mass bleaching was first documented in the 1980s. Here we examine how and why the severity of recurrent major bleaching events has varied at multiple scales, using aerial and underwater surveys of Australian reefs combined with satellite-derived sea surface temperatures. The distinctive geographic footprints of recurrent bleaching on the Great Barrier Reef in 1998, 2002 and 2016 were determined by the spatial pattern of sea temperatures in each year. Water quality and fishing pressure had minimal effect on the unprecedented bleaching in 2016, suggesting that local protection of reefs affords little or no resistance to extreme heat. Similarly, past exposure to bleaching in 1998 and 2002 did not lessen the severity of bleaching in 2016. Consequently, immediate global action to curb future warming is essential to secure a future for coral reefs.

[Assessment of tooth bleaching efficacy with spectrophotometer].

PubMed

Zhu, Wenhao; Liu, Chang; Pan, Jie

2014-06-01

To analyze the changes in CIE L*, a*, and b* at cervical, body, and incisal sites after tooth bleaching by using a spectrophotometer. Sixty-seven intact and healthy maxillary central incisors were in-vestigated. These incisors were darker than A3 according to the Vita Classical shade guide. The CIE tooth shade parameters L*, a*, and b* were simultaneously recorded at three tooth areas (cervical, body, and incisal) with a spectrophotometer before and after tooth bleaching (35%H2O2 coordinating with Beyond whitening accelerator irradiating). The shade dif-ferential (DeltaE) was calculated. ANOVA, paired t-test, and Pearson correlation analysis were used for data analysis. The efficacy rates of tooth bleaching were satisfactory, with 86.6%, 86.6%, and 85.1% in the cervical, body, and incisal sites, respectively. The average values of DeltaE were 5.09, 4.44, and 4.40 in the cervical, body, and incisal sites. Tooth bleaching significantly increased L* and significantly decreased a* and b* in all tooth areas (P < 0.01). The decreasing range of Deltab* was more than the increasing range of DeltaL* at the cervical site; opposite results were observed at the incisal site. A positive correlation was detected between baseline b* and DeltaE. The spectrophotometer could objectively evaluate the whitening effect of tooth bleaching at the different tooth sites. The tooth bleaching system (35%H202 coordinating with Beyond whitening accelerator irradiating) exerts powerful bleaching actions in most of the tooth areas investigated. The order of tooth bleaching effectiveness is cervicalbody>incisal. Yellow coloration is decreased mainly at the cervical site, and brightness was increased mostly at theincisal site. The effectiveness of tooth bleaching increases as the baseline b* value increases.

The effect of hydrogen peroxide concentration on metal ion release from dental casting alloys.

PubMed

Al-Salehi, S K; Hatton, P V; Johnson, A; Cox, A G; McLeod, C

2008-04-01

There are concerns that tooth bleaching agents may adversely affect dental materials. The aim of this study was to test the hypothesis that increasing concentrations of hydrogen peroxide (HP) are more effective than water at increasing metal ion release from two typical dental casting alloys during bleaching. Discs (n = 28 for each alloy) were prepared by casting and heat treated to simulate a typical porcelain-firing cycle. Discs (n = 7) of each alloy were immersed in either 0%, 3%, 10% or 30% (w/v) HP solutions for 24 h at 37 degrees C. Samples were taken for metal ion release determination using inductively coupled plasma-mass spectrometry and the data analysed using a two-way anova followed by a one-way anova. The surface roughness of each disc was measured using a Talysurf contact profilometer before and after bleaching and the data analysed using a paired t-test. With the exception of gold, the differences in metal ion concentration after treatment with 0% (control) and each of 3%, 10% and 30% HP (w/v) were statistically significant (P < 0.05). Metal ion release from the two alloys increased with increasing HP concentrations (over 3000% increase in Ni and 1400% increase in Pd ions were recorded when HP concentration increased from 0% to 30%). Surface roughness values of the samples before and after bleaching were not significantly different (P > 0.05) Exposure of the two dental casting alloys to HP solutions increased metal ion release of all the elements except gold.

Incorporating adaptive responses into future projections of coral bleaching.

PubMed

Logan, Cheryl A; Dunne, John P; Eakin, C Mark; Donner, Simon D

2014-01-01

Climate warming threatens to increase mass coral bleaching events, and several studies have projected the demise of tropical coral reefs this century. However, recent evidence indicates corals may be able to respond to thermal stress though adaptive processes (e.g., genetic adaptation, acclimatization, and symbiont shuffling). How these mechanisms might influence warming-induced bleaching remains largely unknown. This study compared how different adaptive processes could affect coral bleaching projections. We used the latest bias-corrected global sea surface temperature (SST) output from the NOAA/GFDL Earth System Model 2 (ESM2M) for the preindustrial period through 2100 to project coral bleaching trajectories. Initial results showed that, in the absence of adaptive processes, application of a preindustrial climatology to the NOAA Coral Reef Watch bleaching prediction method overpredicts the present-day bleaching frequency. This suggests that corals may have already responded adaptively to some warming over the industrial period. We then modified the prediction method so that the bleaching threshold either permanently increased in response to thermal history (e.g., simulating directional genetic selection) or temporarily increased for 2-10 years in response to a bleaching event (e.g., simulating symbiont shuffling). A bleaching threshold that changes relative to the preceding 60 years of thermal history reduced the frequency of mass bleaching events by 20-80% compared with the 'no adaptive response' prediction model by 2100, depending on the emissions scenario. When both types of adaptive responses were applied, up to 14% more reef cells avoided high-frequency bleaching by 2100. However, temporary increases in bleaching thresholds alone only delayed the occurrence of high-frequency bleaching by ca. 10 years in all but the lowest emissions scenario. Future research should test the rate and limit of different adaptive responses for coral species across latitudes and

Comparison of laser and power bleaching techniques in tooth color change.

PubMed

Fekrazad, Reza; Alimazandarani, Shervin; Kalhori, Katayoun Am; Assadian, Hadi; Mirmohammadi, Seyed-Mahdi

2017-04-01

Laser-assisted bleaching uses laser beam to accelerate release of free radicals within the bleaching gel to decrease time of whitening procedure. The aim of this study was to compare the efficacy of power bleaching using Opalescence Xtra Boost® and laser bleaching technique using LaserSmile gel and diode laser as an activator in their tooth whitening capacity. Student t test showed that the laser bleaching group significantly outperformed the power bleaching group in changing ∆E ( p =0.977). Similarly, while comparing the groups in changing ∆L, the laser bleaching group indicated significantly superior results ( p =0.953). Statistical data from student t test while comparing the groups in changing the parameter of yellowness indicated that samples in laser bleaching group underwent a more significant reduction than power-bleached samples ( p =0.85). Correspondingly, changes in whiteness were statistically tested through student t test, showing that laser bleaching technique increased whiteness of the samples significantly more than those treated by power bleaching ( p =0.965). The digital color evaluation data was in accordance with spectrophotometry and showed that laser bleaching outperformed power bleaching technique. Both techniques were able to increase whiteness and decrease yellowness ratio of the samples. ΔE decrease for laser bleaching and power bleaching groups were 3.05 and 1.67, respectively. Tooth color change in laser bleaching group was 1.88 times more than that of power bleaching group ( p <0.001). It could be concluded that under the conditions of this study, both laser-assisted and power bleaching techniques were capable of altering tooth color change, but laser bleaching was deemed a more efficient technique in this regard. Key words: Laser, power bleaching, tooth color introduction.

40 CFR 63.445 - Standards for the bleaching system.

Code of Federal Regulations, 2010 CFR

2010-07-01

... process using secondary or non-wood fibers, that use chlorine dioxide. (b) The equipment at each bleaching... system. (a) Each bleaching system that does not use any chlorine or chlorinated compounds for bleaching... systems shall meet all the provisions of this section: (1) Bleaching systems that use chlorine; (2...

40 CFR 63.445 - Standards for the bleaching system.

Code of Federal Regulations, 2011 CFR

2011-07-01

... process using secondary or non-wood fibers, that use chlorine dioxide. (b) The equipment at each bleaching... system. (a) Each bleaching system that does not use any chlorine or chlorinated compounds for bleaching... systems shall meet all the provisions of this section: (1) Bleaching systems that use chlorine; (2...

Effect of laser activated bleaching on the chemical stability and morphology of intracoronal dentin.

PubMed

Lopes, Fabiane Carneiro; Roperto, Renato; Akkus, Anna; Akkus, Ozan; Palma-Dibb, Regina Guenka; de Sousa-Neto, Manoel Damião

2018-02-01

To evaluate the effect of the bleaching with 35% hydrogen peroxide either activated or not by a 970nm diode laser on the chemical stability and dentin surface morphology of intracoronary dentin. Twenty-seven slabs of intracoronary dentin specimens (3×3mm) were distributed into three groups (n=9), according to surface treatment: HP - 35% hydrogen peroxide (1×4'), DL - 970nm diode laser (1×30"/0,8W/10Hz), HP+DL - 35% HP activated with 970nm diode laser (1×30"/0,8W/10Hz leaving the gel in contact to the surface for 4' after activation). Three Raman spectra from each fragment were obtained to calculate the mean intensity of peaks of inorganic component (a.u.), organic collagen content (a.u.), and the ratio of inorganic/organic content, before and after treatment. Analyses of the samples by confocal laser microscopy were performed to evaluate the surface roughness, percentage of tubules, perimeter and area percentage of tubules, before and after treatment. Data were analyzed by Kruskal-Wallis, Dunn's, and Wilcoxon test (P<0.05). Data analysis showed that HP+DL did not change the inorganic content peaks 8.31 [29.78] or the inorganic/organic ratio 3.37 [14.67] (P>0.05). Similarly, DL did not affect the chemical stability of the dentin surface (P>0.05). However, HP significantly increased inorganic content peaks 10.87 [22.62], as well as the inorganic/organic ratio 6.25 [27.78] (P<0.05). Regarding the morphological alterations, all surface treatments increase tubules exposure; HP treatment significantly increases perimeter and area percentage; and HP+DL increases surface roughness. Bleaching HP combined with DL offers an improvement in terms of intracoronal dentin surface protection, yielding better maintenance of dentin chemical stability and morphology. Copyright © 2017 Elsevier Ltd. All rights reserved.

Large-scale bleaching of corals on the Great Barrier Reef.

PubMed

Hughes, T P; Kerry, J T; Simpson, T

2018-02-01

In 2015-2016, record temperatures triggered a pan-tropical episode of coral bleaching. In the southern hemisphere summer of March-April 2016, we used aerial surveys to measure the level of bleaching on 1,156 individual reefs throughout the 2,300 km length of the Great Barrier Reef, the world's largest coral reef system. The accuracy of the aerial scores was ground-truthed with detailed underwater surveys of bleaching at 260 sites (104 reefs), allowing us to compare aerial and underwater bleaching data with satellite-derived temperatures and with associated model predictions of bleaching. The severity of bleaching on individual reefs in 2016 was tightly correlated with the level of local heat exposure: the southernmost region of the Great Barrier Reef escaped with only minor bleaching because summer temperatures there were close to average. Gradients in nutrients and turbidity from inshore to offshore across the Great Barrier Reef had minimal effect on the severity of bleaching. Similarly, bleaching was equally severe on reefs that are open or closed to fishing, once the level of satellite-derived heat exposure was accounted for. The level of post-bleaching mortality, measured underwater after 7-8 months, was tightly correlated with the aerial scores measured at the peak of bleaching. Similarly, reefs with a high aerial bleaching score also experienced major shifts in species composition due to extensive mortality of heat-sensitive species. Reefs with low bleaching scores did not change in composition, and some showed minor increases in coral cover. Two earlier mass bleaching events occurred on the Great Barrier Reef in 1998 and 2002, that were less severe than 2016. In 2016, <9% of scored reefs had no bleaching, compared to 42% in 2002 and 44% in 1998. Conversely, the proportion of reefs that were severely bleached (>60% of corals affected) was four times higher in 2016. The geographic footprint of each of the three events is distinctive, and matches satellite

Spatial consequences of bleaching adaptation in cat retinal ganglion cells.

PubMed Central

Bonds, A B; Enroth-Cugell, C

1981-01-01

1. Experiments were conducted to study the effects of localized bleaching on the centre responses of rod-driven cat retinal ganglion cells. 2. Stimulation as far as 2 degrees from the bleaching site yielded responses which were reduced nearly as much as those generated at the bleaching site. Bleaching in the receptive field middle reduced responsiveness at a site 1 degrees peripheral more than bleaching at that peripheral site itself. 3. The effectiveness of a bleach in reducing centre responsiveness is related to the sensitivity of the region in which the bleach is applied. 4. Response reduction after a 0.2 degree bleach followed the same temporal pattern for concentric test spots of from 0.2 to 1.8 degrees in diameter, implying a substantially uniform spread of adaptation within these bounds. 5. A linear trade-off between fraction of rhodopsin and area bleached over a range of 8:1 yields the same pattern of response reduction, implying that the non-linear nature of bleaching adaptation is a property of the adaptation pool rather than independent photoreceptors. PMID:7320894

Study of melanin bleaching after immunohistochemistry of melanin-containing tissues.

PubMed

Shen, Hongwu; Wu, Wenqiao

2015-04-01

Melanin may interfere with immunohistochemical staining. The goal of this study was to investigate the effects of trichloroisocyanuric acid (TCCA) bleaching, potassium permanganate bleaching, and potassium dichromate bleaching on melanin, tissue antigen, and 3,3'-diaminobenzidine (DAB) using melanin-containing and melanin-free tissue samples. Our results demonstrated that all 3 bleaching methods efficiently bleached melanin and partially destroyed tissue antigen. In addition, potassium permanganate bleaching and potassium dichromate bleaching clearly destroyed DAB, whereas TCCA bleaching had no significant effect on DAB. Therefore, neither potassium permanganate nor potassium dichromate is an ideal solution, whereas TCCA might be an ideal solution for melanin bleaching after the immunohistochemical staining of melanin-containing tissues. After immunostaining followed by TCCA bleaching, the melanin could be completely removed in all 120 malignant melanoma tissue sections. Compared with the control, the DAB intensity was clear, and the tissue structure and cellular nuclei were well maintained. It is worth noting that TCCA should be freshly prepared before each experiment, and used within 2 hours of its preparation. In addition, sections should not be incubated with TCCA for over 30 minutes.

Concentrations of and application protocols for hydrogen peroxide bleaching gels: effects on pulp cell viability and whitening efficacy.

PubMed

Soares, Diana Gabriela; Basso, Fernanda Gonçalves; Hebling, Josimeri; de Souza Costa, Carlos Alberto

2014-02-01

To assess the whitening effectiveness and the trans-enamel/trans-dentinal toxicity of experimental tooth-bleaching protocols on pulp cells. Enamel/dentine discs individually adapted to trans-well devices were placed on cultured odontoblast-like cells (MDPC-23) or human dental pulp cells (HDPCs). The following groups were formed: G1 - no treatment (control); G2 to G4 - 35% H2O2, 3 × 15, 1 × 15, and 1 × 5 min, respectively; and G5 to G7 - 17.5% H2O2, 3 × 15, 1 × 15, and 1 × 5 min, respectively. Cell viability and morphology were evaluated immediately after bleaching (T1) and 72 h thereafter (T2). Oxidative stress and cell membrane damage were also assessed (T1). The amount of H2O2 in culture medium was quantified (Mann-Whitney; α=5%) and colour change (ΔE) of enamel was analysed after 3 sessions (Tukey's test; α=5%). Cell viability reduction, H2O2 diffusion, cell morphology alteration, oxidative stress, and cell membrane damage occurred in a concentration-/time-dependent fashion. The cell viability reduction was significant in all groups for HDPCs and only for G2, G3, and G5 in MDPC-23 cells compared with G1. Significant cell viability and morphology recovery were observed in all groups at T2, except for G2 in HDPCs. The highest ΔE value was found in G2. However, all groups presented significant ΔE increases compared with G1. Shortening the contact time of a 35%-H2O2 gel for 5 min, or reducing its concentration to 17.5% and applying it for 45, 15, or 5 min produce gradual tooth colour change associated with reduced trans-enamel and trans-dentinal cytotoxicity to pulp cells. The experimental protocols tested in the present study provided significant tooth-bleaching improvement associated with decreased toxicity to pulp cells, which may be an interesting alternative to be tested in clinical situations intended to reduce tooth sensitivity and pulp damage. Copyright © 2013 Elsevier Ltd. All rights reserved.

Release of hydrogen peroxide and antioxidants by the coral Stylophora pistillata to its external milieu

NASA Astrophysics Data System (ADS)

Armoza-Zvuloni, R.; Shaked, Y.

2014-09-01

Hydrogen peroxide (H2O2), a common reactive oxygen species, plays multiple roles in coral health and disease. Elevated H2O2 production by the symbiotic algae during stress may result in symbiosis breakdown and bleaching of the coral. We have recently reported that various Red Sea corals release H2O2 and antioxidants to their external milieu, and can influence the H2O2 dynamics in the reef. Here, we present a laboratory characterization of H2O2 and antioxidant activity release kinetics by intact, non-stressed Stylophora pistillata. Experimenting with bleached and non-bleached corals and different stirring speeds, we explored the sources and modes of H2O2 and antioxidant release. Since H2O2 is produced and degraded simultaneously, we developed a methodology for resolving the actual H2O2 concentrations released by the corals. H2O2 and antioxidant activity steadily increased in the water surrounding the coral over short periods of 1-2 h. Over longer periods of 5-7 h, the antioxidant activity kept increasing with time, while H2O2 concentrations were stabilized at ~ 1 μM by 1-3 h, and then gradually declined. Solving for H2O2 release, corals were found to release H2O2 at increasing rates over 2-4 h, and then to slow down and stop by 5-7 h. Stirring was shown to induce the release of H2O2, possibly since the flow reduces the thickness of the diffusive boundary layer of the coral, and thus increases H2O2 mass flux. Antioxidant activity was released at similar rates by bleached and non-bleached corals, suggesting that the antioxidants did not originate from the symbiotic algae. H2O2, however, was not released from bleached corals, implying that the symbiotic algae are the source of the released H2O2. The observed flow-induced H2O2 release may aid corals in removing some of the internal H2O2 produced by their symbiotic algae, and may possibly assist in preventing coral bleaching under conditions of elevated temperature and irradiance.

[Evaluation of pH variation and cervical dentin permeability in teeth submitted to bleaching treatment].

PubMed

Dezotti, Mariela S G; Souza, Mário Honorato Silva e; Nishiyama, Celso Kenji

2002-01-01

External cervical root resorption is one of the disadvantages of the bleaching procedure. There are several mechanisms that may be responsible for causing resorption, such as the chemical and physical action of the utilized materials and the morphology of the cementoenamel junction. The purpose of this study was to investigate the presence of a communication between the pulp chamber and the external root surface. The investigation was carried out by means of pH tests and measurement of dye infiltration into cervical dentin after the bleaching procedure. Thirty-four human permanent incisors were submitted to endodontic treatment. The teeth were assigned to three experimental groups, according to the level at which the filling was cut, and to the sealing of the root canal entrance with glass ionomer cement. Sodium perborate and 30% hydrogen peroxide were utilized for bleaching. pH readings were carried out after 30 minutes, 24 h, 48 h and 72 h from the beginning of the procedure. The teeth were immersed in 0.5% basic fuchsin for 24 h in order to determine possible differences in the permeability of cervical dentin. The results revealed that pH tended to change when the root filling was cut at the entrance of the canal, when 2 mm of the filling were removed, and when the canal entrance was sealed with glass ionomer. Dentinal permeability increased in the three experimental groups, in comparison with the control group. These slight differences may suggest a communication between the pulp chamber and the external root surface.

Spectrophotometric and computerized evaluation of tooth bleaching employing 10 different home-bleaching procedures: In-vitro study

PubMed Central

Peskersoy, Cem; Tetik, Ayhan; Ozturk, Veli Ozgen; Gokay, Necmi

2014-01-01

Objective: The aim of this in-vitro study was to evaluate the efficacy of bleaching products, determine the applicability and validation of the measurement methods. Materials and Methods: Freshly extracted 110 human incisor teeth were stained with whole blood and hemolysate solution prior to the application of 10 different home-bleaching products. Spectrophotometric measurements of the tooth shades were performed for each specimen before and after bleaching at the 1st, 3rd, 7th, and 14 days. Differences in lightness (Δl), chroma (Δc), hue (Δh) values and shade changes were measured to evaluate process. Computerized digital imaging analyses to determine the color changes were performed with Photoshop CS4 software (Adobe, San Jose, CA, USA). Statistical analyses were performed with analysis of variance, Scheffe and Tukey tests. Results: In all of the test groups regardless of the material used, a significant increase in lightness and hue, and decrease of chroma were observed, as compared to the control group. After recommended bleaching applications, Δl and Δh values respectively increased in group Zaris White and Brite (ZWB) and group Pola Night and Δc values showed significant decrease in groups ZWB and Rembrandt REM3 (P < 0.05). At the end of the procedure both spectrophotometric and digital imaging analysis showed ZWB was the most effective product among the others while Yotuel and Happy Smile were the least (P < 0.05). Conclusions: Home-bleaching systems showed slower but almost permanent bleaching effect likewise office-based methods. Both software and spectrophotometric analyses have advantages such as evaluating the results objectively and numerically, also treatment outcomes could be preserved. PMID:25512738

Coral bleaching--capacity for acclimatization and adaptation.

PubMed

Coles, S L; Brown, Barbara E

2003-01-01

Coral bleaching, i.e., loss of most of the symbiotic zooxanthellae normally found within coral tissue, has occurred with increasing frequency on coral reefs throughout the world in the last 20 years, mostly during periods of El Nino Southern Oscillation (ENSO). Experiments and observations indicate that coral bleaching results primarily from elevated seawater temperatures under high light conditions, which increases rates of biochemical reactions associated with zooxanthellar photosynthesis, producing toxic forms of oxygen that interfere with cellular processes. Published projections of a baseline of increasing ocean temperature resulting from global warming have suggested that annual temperature maxima within 30 years may be at levels that will cause frequent coral bleaching and widespread mortality leading to decline of corals as dominant organisms on reefs. However, these projections have not considered the high variability in bleaching response that occurs among corals both within and among species. There is information that corals and their symbionts may be capable of acclimatization and selective adaptation to elevated temperatures that have already resulted in bleaching resistant coral populations, both locally and regionally, in various areas of the world. There are possible mechanisms that might provide resistance and protection to increased temperature and light. These include inducible heat shock proteins that act in refolding denatured cellular and structural proteins, production of oxidative enzymes that inactivate harmful oxygen radicals, fluorescent coral pigments that both reflect and dissipate light energy, and phenotypic adaptations of zooxanthellae and adaptive shifts in their populations at higher temperatures. Such mechanisms, when considered in conjunction with experimental and observational evidence for coral recovery in areas that have undergone coral bleaching, suggest an as yet undefined capacity in corals and zooxanthellae to adapt to

A new, high-resolution global mass coral bleaching database

PubMed Central

Rickbeil, Gregory J. M.; Heron, Scott F.

2017-01-01

Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50%) or likely (>66%) probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures. PMID:28445534

A new, high-resolution global mass coral bleaching database.

PubMed

Donner, Simon D; Rickbeil, Gregory J M; Heron, Scott F

2017-01-01

Episodes of mass coral bleaching have been reported in recent decades and have raised concerns about the future of coral reefs on a warming planet. Despite the efforts to enhance and coordinate coral reef monitoring within and across countries, our knowledge of the geographic extent of mass coral bleaching over the past few decades is incomplete. Existing databases, like ReefBase, are limited by the voluntary nature of contributions, geographical biases in data collection, and the variations in the spatial scale of bleaching reports. In this study, we have developed the first-ever gridded, global-scale historical coral bleaching database. First, we conducted a targeted search for bleaching reports not included in ReefBase by personally contacting scientists and divers conducting monitoring in under-reported locations and by extracting data from the literature. This search increased the number of observed bleaching reports by 79%, from 4146 to 7429. Second, we employed spatial interpolation techniques to develop annual 0.04° × 0.04° latitude-longitude global maps of the probability that bleaching occurred for 1985 through 2010. Initial results indicate that the area of coral reefs with a more likely than not (>50%) or likely (>66%) probability of bleaching was eight times higher in the second half of the assessed time period, after the 1997/1998 El Niño. The results also indicate that annual maximum Degree Heating Weeks, a measure of thermal stress, for coral reefs with a high probability of bleaching increased over time. The database will help the scientific community more accurately assess the change in the frequency of mass coral bleaching events, validate methods of predicting mass coral bleaching, and test whether coral reefs are adjusting to rising ocean temperatures.

NemR Is a Bleach-sensing Transcription Factor*

PubMed Central

Gray, Michael J.; Wholey, Wei-Yun; Parker, Benjamin W.; Kim, Minwook; Jakob, Ursula

2013-01-01

Hypochlorous acid (HOCl), the active component of household bleach, also functions as a powerful antimicrobial during the innate immune response. Despite its widespread use, surprisingly little is known about how cells sense or respond to HOCl. We now demonstrate that Escherichia coli NemR is a redox-regulated transcriptional repressor, which uses the oxidation status of HOCl-sensitive cysteine residues to respond to bleach and related reactive chlorine species. NemR controls bleach-mediated expression of two enzymes required for detoxification of reactive electrophiles: glyoxalase I and N-ethylmaleimide reductase. Both enzymes contribute to bacterial bleach survival. These results provide evidence that bleach resistance relies on the capacity of organisms to specifically sense reactive chlorine species and respond with the up-regulation of enzymes dedicated to detoxification of methylglyoxal and other reactive electrophiles. PMID:23536188

Changes in coral-associated microbial communities during a bleaching event.

PubMed

Bourne, David; Iida, Yuki; Uthicke, Sven; Smith-Keune, Carolyn

2008-04-01

Environmental stressors such as increased sea surface temperatures are well-known for contributing to coral bleaching; however, the effect of increased temperatures and subsequent bleaching on coral-associated microbial communities is poorly understood. Colonies of the hard coral Acropora millepora were tagged on a reef flat off Magnetic Island (Great Barrier Reef) and surveyed over 2.5 years, which included a severe bleaching event in January/February 2002. Daily average water temperatures exceeded the previous 10-year average by more than 1 degrees C for extended periods with field-based visual surveys recording all tagged colonies displaying signs of bleaching. During the bleaching period, direct counts of coral zooxanthellae densities decreased by approximately 64%, before recovery to pre-bleaching levels after the thermal stress event. A subset of three tagged coral colonies were sampled through the bleaching event and changes in the microbial community elucidated. Denaturing gradient gel electrophoresis (DGGE) analysis demonstrated conserved bacterial banding profiles between the three coral colonies, confirming previous studies highlighting specific microbial associations. As coral colonies bleached, the microbial community shifted and redundancy analysis (RDA) of DGGE banding patterns revealed a correlation of increasing temperature with the appearance of Vibrio-affiliated sequences. Interestingly, this shift to a Vibrio-dominated community commenced prior to visual signs of bleaching. Clone libraries hybridized with Vibrio-specific oligonucleotide probes confirmed an increase in the fraction of Vibrio-affiliated clones during the bleaching period. Post bleaching, the coral microbial associations again shifted, returning to a profile similar to the fingerprints prior to bleaching. This provided further evidence for corals selecting and shaping their microbial partners. For non-bleached samples, a close association with Spongiobacter-related sequences were

Coral community response to bleaching on a highly disturbed reef

PubMed Central

Guest, J. R.; Low, J.; Tun, K.; Wilson, B.; Ng, C.; Raingeard, D.; Ulstrup, K. E.; Tanzil, J. T. I.; Todd, P. A.; Toh, T. C.; McDougald, D.; Chou, L. M.; Steinberg, P. D.

2016-01-01

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress. PMID:26876092

Coral community response to bleaching on a highly disturbed reef.

PubMed

Guest, J R; Low, J; Tun, K; Wilson, B; Ng, C; Raingeard, D; Ulstrup, K E; Tanzil, J T I; Todd, P A; Toh, T C; McDougald, D; Chou, L M; Steinberg, P D

2016-02-15

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

Coral community response to bleaching on a highly disturbed reef

NASA Astrophysics Data System (ADS)

Guest, J. R.; Low, J.; Tun, K.; Wilson, B.; Ng, C.; Raingeard, D.; Ulstrup, K. E.; Tanzil, J. T. I.; Todd, P. A.; Toh, T. C.; McDougald, D.; Chou, L. M.; Steinberg, P. D.

2016-02-01

While many studies of coral bleaching report on broad, regional scale responses, fewer examine variation in susceptibility among coral taxa and changes in community structure, before, during and after bleaching on individual reefs. Here we report in detail on the response to bleaching by a coral community on a highly disturbed reef site south of mainland Singapore before, during and after a major thermal anomaly in 2010. To estimate the capacity for resistance to thermal stress, we report on: a) overall bleaching severity during and after the event, b) differences in bleaching susceptibility among taxa during the event, and c) changes in coral community structure one year before and after bleaching. Approximately two thirds of colonies bleached, however, post-bleaching recovery was quite rapid and, importantly, coral taxa that are usually highly susceptible were relatively unaffected. Although total coral cover declined, there was no significant change in coral taxonomic community structure before and after bleaching. Several factors may have contributed to the overall high resistance of corals at this site including Symbiodinium affiliation, turbidity and heterotrophy. Our results suggest that, despite experiencing chronic anthropogenic disturbances, turbid shallow reef communities may be remarkably resilient to acute thermal stress.

Comparative clinical evaluation of two professional tooth-whitening products.

PubMed

Kowitz, G M; Nathoo, S A; Wong, R

1994-01-01

A 2-week study was conducted to compare the tooth-whitening efficacy of two 10% carbamide peroxide products: Colgate Platinum Professional Toothwhitening System and Rembrandt Lighten Bleaching Gel. Fifty subjects were divided into two groups and assigned a product to use for 2 weeks. Change in tooth color was measured by reflectance spectroscopy at the initiation of study, at 1 week, and at 2 weeks into the study. Color change was calculated using the color-difference equation established by the Commission International de L'Eclairage. Results showed that Colgate Platinum was 62% more effective at tooth whitening after 1 week and 83% more effective after 2 weeks of treatment vs Rembrandt. At the termination of the study, the mean color difference (deltaE) for Colgate Platinum was 4.29 and 2.34 for Rembrandt. Statistical analysis demonstrated that the Colgate product is significantly superior at increasing tooth whiteness, increasing tooth lightness, reducing redness, and reducing yellowness. In this study, no adverse reactions were noted on clinical examination and none were reported by panelists with normal healthy dentition.

Flotation of Toxocara canis Eggs in Commercial Bleach and Effects of Bleach Treatment Times on Larval Development in These Eggs.

PubMed

von Dohlen, Alexa Rosypal; Houk-Miles, Alice E; Zajac, Anne M; Lindsay, David S

2017-04-01

Toxocara canis is a common intestinal nematode of young dogs. Puppies contaminate the environment with large numbers of eggs that can embryonate and become infective in less than a month. Embryonated eggs are infectious for humans and other paratenic hosts. Most T. canis infections in humans are asymptomatic; however, migration of T. canis larvae in the eye and in the central nervous system can result in vision loss, blindness, and even death. The eggs of T. canis are highly resistant to harsh environmental conditions and routinely used chemical disinfectants. The objective of this study was to evaluate the effects of full-strength commercial bleach (5.25% sodium hypochlorite solution) treatment on development of T. canis eggs and to report our serendipitous finding that T. canis eggs in dog feces can float in passive fecal flotation tests using bleach. We also demonstrated that T. canis eggs could be identified using the McMaster's fecal eggs counting test using 100% bleach. Toxocara canis eggs collected from the feces of naturally infected 4-8 wk old puppies were treated with full-strength bleach (5.25% sodium hypochlorite solution) for 15 min, 30 min, 60 min, and 120 min; washed free of bleach smell by centrifugation; and resuspended in 0.1 N sulfuric acid solution to undergo larval development at room temperature for 18 days after exposure to bleach. Motile larvae were observed in T. canis eggs in all groups treated for 15-120 min and eggs continuously exposed to bleach for 18 days. Our results indicate that bleach may not be an appropriate disinfectant for dog kennels, cages, or laboratory utensils and work surfaces. Toxocara canis eggs are resistant to bleach treatment and continue to pose a risk for canine and human infections. Further study is needed to find the most appropriate methods for disinfection and removal of eggs to reduce the risk of transmission of this parasite.

In situ observations of coral bleaching in the central Saudi Arabian Red Sea during the 2015/2016 global coral bleaching event.

PubMed

Monroe, Alison A; Ziegler, Maren; Roik, Anna; Röthig, Till; Hardenstine, Royale S; Emms, Madeleine A; Jensen, Thor; Voolstra, Christian R; Berumen, Michael L

2018-01-01

Coral bleaching continues to be one of the most devastating and immediate impacts of climate change on coral reef ecosystems worldwide. In 2015, a major bleaching event was declared as the "3rd global coral bleaching event" by the United States National Oceanic and Atmospheric Administration, impacting a large number of reefs in every major ocean. The Red Sea was no exception, and we present herein in situ observations of the status of coral reefs in the central Saudi Arabian Red Sea from September 2015, following extended periods of high temperatures reaching upwards of 32.5°C in our study area. We examined eleven reefs using line-intercept transects at three different depths, including all reefs that were surveyed during a previous bleaching event in 2010. Bleaching was most prevalent on inshore reefs (55.6% ± 14.6% of live coral cover exhibited bleaching) and on shallower transects (41% ± 10.2% of live corals surveyed at 5m depth) within reefs. Similar taxonomic groups (e.g., Agariciidae) were affected in 2015 and in 2010. Most interestingly, Acropora and Porites had similar bleaching rates (~30% each) and similar relative coral cover (~7% each) across all reefs in 2015. Coral genera with the highest levels of bleaching (>60%) were also among the rarest (<1% of coral cover) in 2015. While this bodes well for the relative retention of coral cover, it may ultimately lead to decreased species richness, often considered an important component of a healthy coral reef. The resultant long-term changes in these coral reef communities remain to be seen.

Fixation-free rehalogenating bleached reflection holograms recorded on BB-640 plates