Evaluation of enamel wear caused by various ceramic materials and gold
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Evaluation of Enamel Wear caused By Various Ceramic Materials and Gold. Asmaa Elmaria DDS, MS Gary R. Goldstein, DDS T.V. Vijayaraghavan, PhD Raquel Z. Legeros, Ph.D NYU Kriser Dental Center. Enamel Wear. Occlusal contact - wear Enamel against enamel – 25-40 µm per/year*

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Evaluation of Enamel Wear caused By Various Ceramic Materials and Gold

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Evaluation of Enamel Wear caused By Various Ceramic Materials and Gold

Asmaa Elmaria DDS, MS

Gary R. Goldstein, DDS

T.V. Vijayaraghavan, PhD

Raquel Z. Legeros, Ph.D

NYU Kriser Dental Center


Enamel Wear

  • Occlusal contact - wear

    • Enamel against enamel – 25-40 µm per/year*

    • Enamel against Restorative materials

      • Ceramic > Composite > Gold

  • Restorative material wear

    • Gold > composites > Glazed ceramics

      • *Lambrecht P, Braem M, Vuylsteke- wauters M, Vanherle G. Quantitative in vivo wear of human enamel. J Dent. Res. 1989; 68:1752-54.


Enamel Wear -Factors

Smoother surface  wears less

  • Rougher surface  greater wear

  • Harder surface  greater wear

    Bite and Chewing forces

  • Para-functional habits

  • pH, enamel character & morphology


Jacobi & Shillinburg, Monasky and Taylor, Hudson et al.

abrasive nature of porcelain

Krejci et al. –

rate of enamel wear function; surface finish,& hardness

Krejci et al.

Polishing of pressed glass ceramic led to less wear than glazing.

Klausner et al.

Ra values same for polished/glazed

Raimondo et al.

auto-glazed better vs. polished

Prior studies


Clinical factors

  • Occlusal adjustments a norm!

    • Requires re-glazing

    • Time, cost & Inconvenience

  • Alternative?

    • Polishing


Polishing as an alternative

  • Avoid repeated firing

    • Avoid devitrification  loss of translucency

    • Less time consuming

    • Convenient


Objective:

  • The purpose of this study was to evaluate enamel wear caused by a gold alloy and three ceramic substrates in the glazed and polished conditions.


Null hypotheses to be tested:

  • Enamel wear caused by a glazed substrate is similar to that caused by a glazed surface that has been adjusted and polished.

  • Enamel wear caused by glazed or polished surface (after adjustment) is not dependent on the type of ceramic.

  • Enamel wear caused by a gold substrate is similar to any of the ceramic substrates in both surface conditions.


Materials and Methods

  • Natural Enamel cusps, Ceramics, Gold

  • 10 samples/condition/material

    • Linear wear excursions (10,000 cycles)

      • Track length = 6 mm

  • Surface roughness (Ra)- Before and after


Materials

Fusion Temp.

Glazing Temp.

Manufacturer

Type III Gold

75% Au, 11.5% Ag, 10% Cu, 3%

Jeneric/Pentron, Wellingford, CT

Composition/

IPS-Empress

1100 °C

1100 °C

63 SiO2, 17.7 Al2O3, 11.2 K2O, 4.2 Na2O, 1.6 CaO, 0.7BaO, 0.6 B2O3, 0.4 CeO2, 0.2 TiO2

(40-50%)

Williams/Ivoclar, Amherst, NY

(Leucite content, %)

Procera All-Ceram

900 °C

920 °C

Na2O, K2O, Al2O3, SiO2, CaO, SnO2, Y2O3, CeO2

(15-20%)

Procera/Sandvic AB, Stockholm, Sweden

Finesse Porcelain

750 °C

760 °C

Na2O, K2O, Al2O3, SiO2

(8-10%)

Ceramco Inc. Burlington N.J.

Restorative Materials


Materials and Methods


Materials and Methods

  • Measurement of enamel wear

    • From trace of enamel cusp profile

    • Qualitative wear (SEM)


Materials and Methods


Results

  • t-Test, pooled variance, 2 tail; p<0.05

  • One-way ANOVA,followed by Scheffe test; p=0.05

  • SE Micrographs


Material and Condition

N

Subset for alpha = .05

1

2

3

Gold

10

.11296

Finesse, Pol

10

.63694

.63694

All-Ceram, Pol

10

.76460

.76460

All-Ceram, Glz

10

.97508

.97508

IPS-Empress Pol

10

1.05224

1.05224

Finesse, Glz

10

1.15380

1.15380

IPS-Empress Glz

10

1.51756

Sig.

.060

.249

.197

Multiple comparisonsEnamel height loss


Material

Before wear

After wear

P Value

Gold

0.090.025

0.290.25

0.03

Glazed Finesse

0.720.19

0.800.26

0.4

Polished Finesse

0.370.14

0.440.13

0.09

Glazed All-Ceram

0.170.05*

0.440.15

0.001

Polished All-Ceram

0.230.11*

0.450.21

0.01

Glazed IPS Empress

0.460.19

0.640.41

0.3

Polished IPS Empress

0.150.05

0.280.09

0.002

Surface roughness, Ra (mm)Before and after wear

(N=10 per group), Student's t-Test, significant differences based on p = 0.05


Gold Alloy

Left: low magnification (35X),the track created by the enamel cusp at 10,000 cycles.

Right: higher magnification(350X) showing polishing lines and smoother track region.

Ra: 0.09- 0.29 µm-before & after wear)


Finesse- polished condition

(35X). The track region has been outlined (continuous line) and reveals continuous grooves.

The background reveals a pitted appearance with dark isolated regions indicated by arrows

(background), suggesting removal of some micro-structural constituent .

(Ra: 0.37-0.44 µm - -before & after wear)


IPS-Empress- polished condition

The track region is visible and reveals a smoother surface than the surrounding background. Polishing marks can be seen in the background region. Debris is visible as bright white discontinuous regions. (35 X) (Ra: 0.15-0.28 µm -before & after wear)


IPS-Empress- glazed condition

Left: low magnification (35X)

Right: Higher magnification (500X)

(Ra: 0.46-0.64µm - -before & after wear)


Discussion

  • Polishing produced a smoother surface only in two materials

    • Grit size- polishing material

    • Grain or crystal size, phases & hardness –substrate, glazing Pressure and Temperature,

    • Leucite content increased hardness*

  • IPS-Empress and Finesse

  • Smoothness and roughness

    • (polishing and wear)

      *Kingery WD: Introduction to Ceramics, John Wiley and Sons, Inc., 1960, 597-599.


  • Discussion

    • Adjustment & Polishing

      • Gross & minor wear

        • Removal of glaze

    • Traditional porcelain – would require re-glazing unglazed porc.- significant  modulus of rupture

    • Newer generation porcelain –greater than normal adjustment may be possible- then polishing

      • Density, processing mode, homogeneity, leucite crystalline additions


    Mean Roughness Value

    • Roughness and polishing

      • Ra value in this study was below 1µm

    • Roughness and wear

      • Smooth - higher wear !

      • Rough – lower wear !


    Conclusion

    Ranking of enamel cusp height loss

    • Gold < PFIN <PALC <GALC <PEMP <GFIN <GEMP

  • Ranking of mean Ra values

    • Gold < PEMP<GALC<PALC<PFIN<GEMP<GFIN


  • Conclusions

    • Gold caused significantly less enamel wear than ceramic substrates

    • Glazed surfaces exhibited significantly more enamel wear than polished surfaces

    • Finesse caused the least enamel wear among all the ceramic materials, and was not significantly different than Gold

    • Empress caused the greatest wear


    Thank you


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