Cobalt-chromium Alloys in Dentistry2

8/17/2019 Cobalt-chromium Alloys in Dentistry2

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CONTENTS

•

Introduction•Material and methods

•Results

•Discussion

•Conclusions


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Greig DGM. Contact dermatitis reaction to a metal buckle on cervical hea

Br Dent J 1983;155:61-2.


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Purpose

•

The purpose of this in vitro study was to evaluatethe ion release of chromium, cobalt, and ironfrom the Co-Cr alloys used for traditionally castand computer-aided design/computer-aidedmanufacturing dental devices after interaction

with oral bacteria and different pH conditions.


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MATERIAL AND METHODS

•Three different types of dental metal alloys were selec(all nominal compositions were provided by themanufacturer Ivoclar Vivadent):

1.CASTING ALLOY

2.MILLING ALLOY

3.LASER-SINTERING ALLOY

All alloys were free of nickel, beryllium, and cadmium

according to DIN EN ISO standard 22674:2011.41


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•Each dental alloy was shaped into 10 disks, each15 mm in diameter and 1mm thick.

• All specimens were polished with silicon carbidepaper with a grinder polisher machine.

•The specimens were than cleaned in ethanol and

deionized water in an ultrasonic cleaner for 5minutes to remove contaminants and finallyautoclave-sterilized.


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•Three solutions were prepared in order toevaluate chemical corrosion following the study

byMutlu-Sagesen et al.and according to ISOstandard 1027143

•NaCl saline solution

•artificial saliva solution

•lactic acid

Mutlu-Sagesen L, Ergun G, Karabulut E. Ion release from metal-ceramic

in three different media. Dent Mater J 2011;30:598-610.


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•Three solutions were prepared to evaluate bio-corrosi

•a solution of 50% artificial saliva (pH 7.1), 45% trypti

broth (TSB; Oxoid) and 5% defibrinated horse blood(SS+B; Oxoid).

•a solution of 50% artificial saliva buffered with H3POpH 5.5, 45% TSB (Sigma-Aldrich) and 5% defibrinatehorse blood (SS+AB; Oxoid).

•a solution of 50% artificial saliva (pH 7.1), 45% TSB(Oxoid), and 5% defibrinated horse blood (Oxoid) addewith 5 × 106 cells/mL E. corrodens (SS+BB).

•One sample of artificial saliva/TSB blood was adopted

blank reference.


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•Each metal ceramic alloy was immersed in thesolutions in polypropylene test tubes and

incubated at 37 C to simulate the oraltemperature.

•The solutions were analyzed after 15 and 30 daysin the chemical corrosion test and 30 days in thebiocorrosion test to detect ions released in

different solutions.

•The biocorrosion test was conducted in acontrolled atmosphere with 5% CO2concentration.


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Results

CASTING

ALLOY


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MILLING

ALLOY


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LASER-

SINTERING

ALLOY


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DISCUSSION

•

The oral microflora plays a relevant role becausethe presence of specific bacteria, pathogens, orhealthy commensal organisms can triggerbiocorrosion mechanisms on dental alloys.

Shiozu I, Shiozu J, Takazoe I, Okuda K. Corroding characteristics of Eike

corrodens. Bull Tokyo Dent Coll 1992;33:1-6.


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•Porcelain firing process phases may alter themetallurgical state, surface oxides, and corrosionproperties of the alloy depending on its chemicalcomposition.

• Autoclaving, in contrast, has no effect on thesurface characteristics or chemical property of analloy because of the low temperature reached (120

C-160 C) in steam sterilization compared with themelting temperature of base dental alloys (1000C-1400 C).


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Can G, Akpinar G, Aydin A. The release of eleme

from dental casting alloy into cell-culture mediu

and artificial saliva. Eur J Dent 2007;1:86-90

•Can et al emphasized that the release of metalions from dental cast alloys has correlated withthe surrounding environmental conditions and

the surface of dental alloy.

AlJbb iYSK t kiTB dkiXZi li


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Al Jabbari YS, Koutsoukis T, Barmpagadaki X, ZineliMetallurgical and interfacial characterization of PFMCr dental alloys fabricated via casting, milling or selelaser melting. Dent Mater 2014;30:79-88.

• Al Jabari et al found gross porosity only in dental allfabricated by means of conventional casting (LW).

•The interdendritic porosity due to shrinkage during alloy solidification weakens the structure of the pros

•Grains of microstructure are not well defined and conof few large crystals with each crystal forming a simpdendrite.

• No porosity was detected in milling (M) or laser sint(LS) alloys.


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•E. corrodens can play a role in specificaggregation with certain gram-positive andgram-negative bacteria present in humanperiodontal pockets but probably cannot producea stable biofilm without interaction with othermicroflora components.

.Taylor R, Maryan C, Verran J. Retention of oral microorganisms on cobalt-chr

alloy and dental acrylic resin with different surface finishes.

J Prosthet Dent 1998;80:592-7.


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CONCLUSION

• Co-Cr alloys processed with different fabrication techniqu(casting, milling, and laser sintering) show a release of lowamounts of ions in all tested conditions.

• No difference was noted when the specimens were exposedenriched bacteria environment.

• It was concluded that all the alloys are adequately corrosiresistant and well suited for dental usage, although the LWalloy shows the greatest risk of corrosion under acidicconditions.


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References• .Taylor R, Maryan C, Verran J. Retention of oral microorganisms on cobchromium alloy and dental acrylic resin with different surface finishes.JDent 1998;80:592-7.

• Al Jabbari YS, Koutsoukis T, Barmpagadaki X, Zinelis S. Metalluinterfacial characterization of PFM Co-Cr dental alloys fabricatcasting, milling or selective laser melting. Dent Mater 2014;30:79

• Can G, Akpinar G, Aydin A. The release of elements from dental castingcell-culture medium and artificial saliva. Eur J Dent 2007;1:86-90.

• Shiozu I, Shiozu J, Takazoe I, Okuda K. Corroding characteristics of Eik

corrodens. Bull Tokyo Dent Coll 1992;33:1-6.

• Mutlu-Sagesen L, Ergun G, Karabulut E. Ion release from metal-alloys in three different media. Dent Mater J 2011;30:598-610.

• International Standards Organization. ISO 10271. Dentistry corrmethods for metallic materials. Geneva: ISO.Accessed July 3, 201

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Cobalt-chromium Alloys in Dentistry2