The Effect of a 10% Carbamide Peroxide

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THE EFFECT OF A 10% CARBAMIDE PEROXIDE BLEACHING AGENT ON MICROHARDNESS OF FOUR TYPES OF DIRECT RESIN BASED RESTORATIVE MATERIALS

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Author- MQ AlQahtani Operative dentistry,2013,38-3, 316-323

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No of slides- 53 No of illustrations- 9 Time taken for presentation-30min

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References

Attin et al Effect of bleaching on restorative materials and restorations—a systematic review Dental Materials (2004) 20, 852–861

Yu, H., Li, Q., Cheng, H., & Wang, Y. (2011). The effects of temperature and bleaching gels on the properties of tooth-colored restorative materials. Journal of Prosthetic Dentistry, 105(2), 100-107.

Gabriel Rodrigues Hatanaka . Effect of Carbamide Peroxide Bleaching Gel on Composite Resin Flexural Strength and Microhardness Brazilian Dental Journal (2013) 24(3): 263-266

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AUJ Yap Wattanapayungkul .Effects of In-Office Tooth Whiteners on Hardness of Tooth-Colored Restoratives. Operative Dentistry, 2002, 27, 137-14

Effect of bleaching agents on the microhardness of tooth-colored restorative materials. Journal of Prosthetic Dentistry Volume 95, Issue 4 , Pages 286-289, April 2006.

Taher NM. The effect of bleaching agents on the surface hardness of tooth colored restorative materials. J Contemp Dent Pract. 2005;6(2):18-26.

Effects of different concentrations of bleaching agent on the micro hardness and shear bond strength of restorative materials – An in vitro study Journal of Dentistry and Oral Hygiene Vol. 2(1), pp. 7-14, June 2010

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Effects of External Bleaching on Restorative Materials: A ReviewJ Can Dent Assoc 2011;71:b59

Jefferson KL, Zena RB, Giammara B. Effects of carbamideperoxide on dental luting agents. J Endod 1992;18:128—32.

Turker SB, Biskin T. Effect of three bleaching agents on the surface properties of three different esthetic restorative materials. J Prosthet Den2003;89:466—73.

Turker SB, Biskin T. The effect of bleaching agents on the microhardness of dental aesthetic restorative materials. J Oral Rehabil 2002;29:657—61.

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CONTENTS

Introduction Reason for selection of the article Aim of the study Materials and methods Results Discussion Conclusion Critical analysis Clinical significance

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Introduction

Esthetics - (Arens, 1989).

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Esthetics procedures – to alter smile, alterations in form, texture, position and color of teeth.

Bleaching- most conservative non invasive

Most common – 10% carbamide peroxide.

Patients seeking bleaching agents may have metal or resin based restorations.

Clinical durability of restorations might be affected by bleaching

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Reason for selection of article ?

The influence of bleaching agents on these restorative materials should be known to render proper treatment.

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Aim of the study

To evaluate the effect of a 10% carbamide peroxide bleaching agent on the microhardness of four types of direct resin based restorative materials.

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Materials and methods

Specimen fabricationFiltek Z250 microhybrid resin compositeMatrix- Bis-GMA, UDMA, Bis –EMAFiller- Zr/Si (0.01-3.5 µm)Filler by volume- 60%

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Filtek Z 350 Nanofilled resin composite Matrix BIS GMA,UDMA, TEGDMA, and BIS

–EMA Filler- combination of aggregated

zirconia/silica cluster filler(0.6-1.4µm) and non aggregated 20 nm silica filler.

Filler volume : 59.5%

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Filtek P90 lowshrink resin composite Matrix- new ring opening silorane Filler- epoxy functional silane treated

silica and ytterbium fluoride (0.1 -2 µm) Filler volume 55%

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Valux plus hybrid composite Matrix : Bis GMA ,TEGDMA Filler : single filler 100 % Zr/Si (0.001-

3.5µm) Filler volume: 66%

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OpalescencePF 10 % carbamide peroxide , potassium

nitrate, carbopol, glycerine, 0.11% fluoride ion

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Method

30 DISK SHAPED specimens 10mm diameter × 2 mm depth.

A3 shade. Cylindrical rubber molds were positioned on

a transparent plastic matrix strip lying on a glass plate.

2 mm increments Every specimen light polymerized -40 sec

halogen light 480-520 mW/cm2

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Polished with medium, fine, super fine polishing discs

This polished flattened surface was essential to prevent distorted indentation for hardness measurement on any material (Anusavice, 2003)

Final thickness measured with micrometer

Ultrasonic cleaning with distilled water for 2 min

stored in distilled water at 37°c for 24 hrs.

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Groups

3 groups . (10 / group) Control group : immersed for 14 days in

artificial saliva, with no bleaching treatment .

Group A : Treated with 10 % CP for 14 days

Group B: Treated with 10 % CP for 14 days and then immersed in artificial saliva for 14 days.

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CONTROL GROUP

Stored in artificial saliva for 14 days at 37 C No bleaching Immersion in distilled water for 24 hrs. Saliva replaced daily. CompositionNaCl 0.4 gKCl 0.4gCaCl2.H2O 0.795 gSodium Dihydrogen phosphate 0.69 gSodium sulphide 0.005 gDistilled water 1000 mL

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Bleaching procedure

On top of specimens in groups A, B At-home bleaching material (Opalescence

PF 10% Carbamide Peroxide ) 1mm thickness. At the end of every bleaching application,

treated specimens were first washed in distilled water and in ultrasonic cleaner.

Placed in artificial saliva for 16hrs at 37 C Saliva replaced daily.

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Group ABleaching agent applied for 8 hrs daily 14

days at 37C

Stored in distilled water for 24 hrs at 37C

Microhardness test

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Group BBleaching agent applied for 8 hrs daily 14

days at 37C

Stored in artificial saliva for 14days at 37 C

Immersed in distilled water for 24 hrs at 37C

Microhardness test

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Vickers Hardness test

After the specimens were dried,VHN

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Statistical Analysis

Data were subjected to one way analysis of variance and Tukeys HSD multiple comparisions test

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Results

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Graph

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DISCUSSION

HARDNESS Strength, ductility, elastic stiffnes ,

plasticity, strain, toughness, viscoelasticity, and viscosity.

The ability of a material to abrade or to be abraded by opposing dental structures, materials,or any chemical softening has implications for the clinical durability of dental restorations.

Temperature is fixed at 37 C for both bleached and unbleached samples in this study.

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Effect of temperature

Yu et al had evaluated the effect of bleaching agents with 2 different temperatures on 4 composites, compomer, GIC and ceramic.

CP had greater effect on microhardness of resin based composite and GIC at 37 C than 25 C

Reasons Due to release of more free radicals at higher

temperature. Enhanced penetration ability of CP at a higher

environmental temperature. Release of hydroxyl radicals from peroxide can be

accelerated by heatingYu, H., Li, Q., Cheng, H., & Wang, Y. (2011). The effects of temperature and

bleaching gels on the properties of tooth-colored restorative materials. Journal of Prosthetic Dentistry, 105(2), 100-107.

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10 % Carbamide peroxide one third hydrogen peroxide two- thirds urea. Hydrogen peroxide

breaks down into free radicals oxidative cleavage of polymer chains

chemical softening of dental materials.

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The free radicals eventually combine to form molecular oxygen and water.

Some aspect of this chemical process might accelerate the hydrolytic degradation of composites described by Söderholm &others (1984)

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Artificial saliva - accelerator in degradation of CP Mimic oral environment Minimize adverse effects of bleaching Salivary remineralization due to calcium

and phosphates. In contrast, findings of this study showed

no benefit using artificial saliva Reduction of microhardness , not inhibited

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Microhardness reduction percentages Filtek –z250- 0.97% Filtek –z 350 - 12.59% Filtek P-90- 18.39% Valux plus- 12.08%

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Order of Microhardness reduction Silorane based low shrink Nanofilled Z350 Hybrid resin composites Microhybrid composite. - Minimal

reduction

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Higher amount of TEGDMA in Z350 (nanofilled) and valux plus( hybrid)

Absence of TEGDMA in Z250( microfilled) TEGDMA diluent monomers in resin matrix make

it less resistant to bleaching agents and may increase softening of resin matrix.

In contrast, reduction in microhardness of z 350 ( 12.59%) was higher than that of valux plus (12.08%)

High molecular weight of resin matrix and low filler content in z 350 compared with valux plus.

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Siloranes (p 90) showed more reduction in microhardness compared with other tested materials.

This is due to ring opening mechanism in resin matrix and lowfiller content .

This resin matrix is softer than other resin matrices (Bis-GMA, UDMA, Bis-EMA) and easily soluble by bleaching agents.

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Silorane composite

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Effect of bleaching on different restorative materials

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STUDY 1:Gabriel et al. investigated the effect of 16% carbamide peroxide on microhardness of the hybrid, nanofill, and two micro-hybrid composites.

Hybrid presented the highest microhardness value, followed by nanofill and finally by microhybrid.

Reasons: Higher filler content (71%) of hybrid composite Better behaviour of nanofill is due to effect of

composition and degree of conversion of the polymer matrix on hardness, as well as the resin matrix greater mechanical strength.

Higher resistance of the aggregated zirconia/silica cluster filler to the Vickers indenter.

Gabriel Rodrigues Hatanaka . Effect of Carbamide Peroxide Bleaching Gel on Composite Resin Flexural Strength and Microhardness Brazilian Dental Journal (2013) 24(3): 263-266

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Softening effect ↓ MICROHYBRID COMPOSITE ↓ Breakdown of CP ↓ Free radicals ↓ Oxidative cleavage of polymer chains .

This was not observed for hybrid and nanofilled because of different composition of monomer resins, which are not susceptible to the oxidative reaction.

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STUDY 2: Prabhakar et al (2010) 10 and 22% CP composites and compomers Result: composites – similar reduction

compomer- no significant reductionREASON: Chemical softening of the restorative

materials might occur if the bleaching products have solubility parameters similar to that of the resin matrix.

Effects of different concentrations of bleaching agent on the micro hardness and shear bond strength of restorative materials – An in vitro study Journal of Dentistry and Oral Hygiene Vol. 2(1), pp. 7-14, June 2010

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The Bisphenol A-glycidyl methacrylate (BisGMA) and urethane dimethacrylate (UDMA) resin polymers used in composites can be softened by chemicals with solubility parameters in the range of 1.82 x 104 to 2.97 x 104 (J/m3) 1/2 (Wu & McKinney, 1982)

This shows that the effect of carbamide peroxide gels may be material dependent.

Yap & Wattanapayungkul: Effects of In-Office Tooth Whiteners on Hardness of Tooth-Colored RestorativesOperative Dentistry, 2002, 27, 137-141

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STUDY 3: Yap et al (2002) investigated the effects of35% CP and 35% HP on the hardness of hybrid , polyacid-modified ,PRG composites and a resin-modified glass ionomer cement ..

No significant difference in hardness was observed between treatment groups for polyacid and PRG composites .

For and Hybrid and glass ionomer , specimens treated with 35 % CP were significantly harder than those treated with 35% HP.

Reason: Active ingredient for both bleaching gels is the same Presence of carotene in opalesent xtra ( 35% HP)

AUJ Yap Wattanapayungkul .Effects of In-Office Tooth Whiteners on Hardness of Tooth-Colored Restoratives. Operative Dentistry, 2002, 27, 137-14

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Study 4: Mujdeci et al (2006) evaluated the effect of a 10 % CP and 14% HP on the microhardness of nanohybrid composite resin ,a polyacid-modified composite resin , glass-ionomer cement .

The bleaching products used in this study did not adversely affect the microhardness of the restorative materials.

REASONS: changes in structure or composition of restorative materials have

provied more resistant surfaces against bleaching treatments. The frequency with which the bleaching agents were changed

may also contribute to the disparity between the results of the studies.

The application times of the bleaching agents might have affected this result

Effect of bleaching agents on the microhardness of tooth-colored restorative materials. Journal of Prosthetic Dentistry Volume 95, Issue 4 , Pages 286-289, April 2006

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The influence of different bleaching gels depends on the oxidation process that occurs in the organic matrix, which can facilitate water absorption and lead to loss of particles, reducing superficial integrity and microhardness.

Attin et al Effect of bleaching on restorative materialsand restorations—a systematic reviewDental Materials (2004) 20, 852–861

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Bleaching can also alter the optical propertiesof composite resins, which depend on the

compositionof materials as well as on the bleaching agent. The inorganic content of resin composites

however, offers resistance to bleaching. Form, amount and distribution of fillers are all

aspects that determine the clinical performance of these restorative materials.

Attin et al Effect of bleaching on restorative materialsand restorations—a systematic reviewDental Materials (2004) 20, 852–861

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To summarize

The effects of in-office tooth whiteners on hardness were material dependent.

Filler matrix interactions have great effect on increasing the resistance of composite resin.

The discrepancies between these studies may be explained by the differences in experimental methodologies, bleaching agents applied, and restorative materials used. 

Some tooth colored restorative materials may be more susceptible to alterations

Some bleaching agents are more likely to cause such alterations( Swift &Peridagao 1983)

Also attributed to different ph of bleaching agents .

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High concentration carbamide peroxide bleaching gel, used as intended by the manufacturers, poses minimal risk to composite restorations.

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Glass ionomer cement

Jefferson et al. examined alterations of atomic weight percentages in glass ionomer cement after contact with 10% carbamide peroxidewith pH 4.5.

He reported that the matrix of the specimens showed surface wash-off and corrosion with the cores of the silica more exposed and a decrease of surface aluminum content.

Jefferson KL, Zena RB, Giammara B. Effects of carbamideperoxide on dental luting agents. J Endod 1992;18:128—32.

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GIC

Turker and biskin found increased microhadrness of GIC after bleaching

REASON: The increase is due to silica core localized at

surface after erosion of glass ionomer cement.

Turker SB, Biskin T. The effect of bleaching agents on themicrohardness of dental aesthetic restorative materials.J Oral Rehabil 2002;29:657—61

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CERAMICS

Turker and Biskin found 10–16% carbamide peroxide gels (applied for 8 h per day for 30 days) were able to significantly decrease surface hardness of the porcelain material tested.

REASON:

Degradation in ceramics due to the interaction between free radicals released from the bleaching gels and the ceramic glass network, which leads to the loss of alkali metal ions from the glass surface

Turker SB, Biskin T. Effect of three bleaching agents on the surface properties of three different esthetic restorative materials. J Prosthet Den2003;89:466—73.

Turker SB, Biskin T. The effect of bleaching agents on themicrohardness of dental aesthetic restorative materials.J Oral Rehabil 2002;29:657—61.

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Conclusions

10 % CP bleaching agent had an adverse effect on microhardness of nano filled, silorane –based low shrink, hybrid types of resin-based composite materials compared with micro hybrid type.

The microhardness reduction in different resin based composite materials after bleaching was not inhibited by the use of artificial saliva storage media during and after bleaching procedure.

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Critical appraisal

Merits: Used different types of composites

Demerits Did not evaluate different concentrations. Did not compare different temperatures. Did not evaluate the other associated effects

of bleaching on restorations such as the surface roughness, microleakage and color changes in tooth colored restorative materials .

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Clinical relevance

Bleaching agents should not be used indiscriminately in the patients mouth.

Teeth that have extensive tooth-colored restorations should not be exposed to bleaching agents or at least protected.

Patients should be informed that the physical properties of tooth colored restorations might be affected by bleaching procedure and the restorations might be softened.

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This could potentially predispose to increased adherence of cariogenic bacteria ,surface wear rate, stain absorption and potential marginal strengths of these restorations and that they may need to be replaced.

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Thank you

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