Track 6. Technological innovations in biomedical training and practice Authors: Alessandro Ruggiero, Roberto D'Amato, Ludovico Sbordone, Fernando Blaya and Antonio Lanza

1. “On the Dental BioTribology: Comparison of Zirconia/Zirconia and
Zirconia/Natural Tooth Friction Coefficients by Using a Reciprocating
Tribometer”
Salamanca (ES) October22-26, 2018
Alessandro Ruggiero, Roberto D'Amato, Ludovico Sbordone, Fernando Blaya Haro, Antonio Lanza
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1. REASONS FOR THE RESEARCH
• Wear of natural or artificial teeth is unavoidable and can leads to
a lack of perfect teeth contact and to a reduction of the efficiency
of the masticatory system.
• Choice of materials for dental restorations by taking in account:
corrosion behavior, cost, availability, biocompatibility and
aesthetic values
• To Test the tribological performances of ceramic restorations
made of a single material
• To simulate with exact tribological conditions present in the oral
cavity the tribological behavior of the dental restorations

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2. METHODOLOGY
Two different tribo-couples were examined:
zirconianatural tooth vs. zirconia vs. zirconia

4. TR_Bio 282 pin-on-flat reciprocatory DUCOM tribometer
The assembly of the pin and flat in the tribometer
Schematic view of the tribometer
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3. METHODOLOGY

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4. TESTS SET UP
• The stroke length was 2 mm, according to the range of displacement used in the
scientific literature.
• Normal force: 20 N
• The time test was of 60 minutes
• Oscillation frequency: 5 Hz (harmonic alternative motion).
• Room temperature (20±1 ºC), in laboratory air at controlled levels of relative
humidity (55±5 %).
• All the tests were carried out with the interposition of artificial saliva between
the sliding surfaces
• Three tests were performed for both the tribological couplings under study
• With this set-up, the total sliding distancewas equal to 72 m.

6. • The teeth were fixed in the holders by acrylic
resin
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5. TESTS SET UP: NATURAL TOOTH VS. ZIRCONIA
• Five wisdom teeth without caries were placed
in a solution of chlorhexidine 0,2%
• The Teeth were cut perpendicularly in four
parts by using a diamond saw.
• The result were 20 pins of teeth

7. • The composition is: high purity zirconium
dioxidestabilized with 5% mole of yttrium.
25 mm
25 mm
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• Four specimens of composite zirconia
were realized.
• The four specimens were obtained
through sintering at 1500 ºC using 3M ™
Lava ™ EstheticZirconia discs.
• This type of material possesses a strength
of 800 MPa and a high translucency
optimized for crowns and aesthetic
bridges with full profile
6. TESTS SET UP: NATURAL TOOTH VS. ZIRCONIA

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25 mm
25 mm
Zirconia ball with 10 mm in diameter
7. TESTS SET UP: ZIRCONIA VS. ZIRCONIA
artificial saliva
Ceramic ball
Ceramic specimen
Schematic assembly view

9. Teeth vs. Zirconia Zirconia vs. Zirconia
8. RESULTS: FRICTION COEFFICIENT EVOLUTION
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9. RESULTS

11. Real tooth vs. zirconia tests
10. PLOT OF FRICTION FORCE VS. TIME (POINTS) VS. DISPLACEMENT
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12. 11. PLOT OF FRICTION FORCE VS. TIME (POINTS) VS. DISPLACEMENT
Zirconia vs. zirconia tests
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13. 12. 2D AND 3D TOPOGRAPHIES OF THE TOOTH WORN SURFACES ACQUIRED BY
CONFOCAL INSTRUMENTATION
Tooth- Zirconia
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14. 13. 2D AND 3D TOPOGRAPHIES OF THE CERAMIC WORN SURFACES ACQUIRED BY
CONFOCAL INSTRUMENTATION
Zirconia-Zirconia contact
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14. CONCLUSIONS
• The results in terms of COF are similar in the case of Zirconia vs. Zirconia tribo-
couple, corresponding to 0.49±0.03 and the case of natural Tooth-Zirconia couple
this value is 0.52 ±0.03.
• The used apparatus (reciprocating tribometer) represents a good didactic and
research tool for in vitro simulation of the complex phenomena that occur in the
dental contacts
• The results on the wear mass loss show a very low wear rate of Zirconia both
coupled with Zirconia, both with natural tooth; while a mean value of 0.5 mg was
found on natural tooth coupled with Zirconia.
• This paper represents a first step toward an extensive tribological
characterization of new artificial dental materials in order to fully understand
differences in tribological behavior principally against natural teeth

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15. FUTURE RESEARCH
• Extend the methodology used for the characterization of other materials
• To individuate a bio-compatible coating (for artificial teeth) in order to reduce
natural teeth wear phenomena (bruxism)
• To simulate the presence of food (acting as third body)
• To propose a standardized methodology for the in-vitro dental tribological
investigations

17. THANKS FOR YOUR ATTENTION
Salamanca (ES) October22-26, 2018 17