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O
ABSTRACT
www.fob.usp.br/jaos or www.scielo.br/jaos
J Appl Oral Sci. 2009;17(5):451-6
ABRASION WEAR RESISTANCE OF DIFFERENT
ARTIFICIAL TEETH OPPOSED TO METAL AND
COMPOSITE ANTAGONISTS
Pâmela Carbone MELLO1, Abílio Ricciardi COPPEDÊ1, Ana Paula MACEDO2, Maria da Gloria Chiarello de MATTOS3,
Renata Cristina Silveira RODRIGUES4, Ricardo Faria RIBEIRO3
1- DDS, MSc, Graduate student, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo,
Ribeirão Preto, SP, Brazil.
2- Laboratory technician (Electrical engineer), Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of
São Paulo, Ribeirão Preto, SP, Brazil.
3- DDS, MSc, PhD, Full Professor, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São Paulo,
Ribeirão Preto, SP, Brazil.
4- DDS, MSc, PhD, Assistant Professor, Department of Dental Materials and Prosthodontics, Dental School of Ribeirão Preto, University of São
Paulo, Ribeirão Preto, SP, Brazil.
Corresponding address: Ricardo Faria Ribeiro - Departamento de Materiais Dentários e Prótese, Faculdade de Odontologia de Ribeirão Preto,
Universidade de São Paulo. Av. do Café, s/n, 14040-904 - Ribeirão Preto, SP - Brasil. - Phone: +55-16-3602-4046 / Fax: +55-16-3633-0999 - e-mail:
rribeiro@forp.usp.br
Received: July 30, 2008 - Modification: November 09, 2008 - Accepted: May 18, 2009
ne of the most important properties of artificial teeth is the abrasion wear resistance, which is determinant in the maintenance
of the rehabilitation’s occlusal pattern. Objectives: This in vitro study aims to evaluate the abrasion wear resistance of 7 brands of
artificial teeth opposed to two types of antagonists. Material and methods: Seven groups were prepared with 12 specimens each
(BIOLUX – BL, TRILUX – TR, BLUE DENT – BD, BIOCLER – BC, POSTARIS – PO, ORTHOSIT – OR, GNATHOSTAR –
GN), opposed to metallic (M – nickel-chromium alloy), and to composite antagonists (C – Solidex indirect composite). A mechanical
loading device was used (240 cycles/min, 4 Hz speed, 10 mm antagonist course). Initial and final contours of each specimen were
registered with aid of a profile projector (20x magnification). The linear difference between the two profiles was measured and the
registered values were subjected to ANOVA and Tukey’s test. Results: Regarding the antagonists, only OR (M = 10.45 ± 1.42 m
and C = 2.77 ± 0.69 m) and BC (M = 6.70 ± 1.37 m and C = 4.48 ± 0.80 m) presented statistically significant differences (p <
0.05). Best results were obtained with PO (C = 2.33 ± 0.91 m and M = 1.78 ± 0.42 m), followed by BL (C = 3.70 ± 1.32 m and
M = 3.70 ± 0.61 m), statistically similar for both antagonists (p>0.05). Greater result variance was obtained with OR, which
presented the worse results opposed to Ni-Cr (10.45 ± 1.42 m), and results similar to the best ones against composite (2.77 ± 0.69
m). Conclusions: Within the limitations of this study, it may be concluded that the antagonist material is a factor of major importance
to be considered in the choice of the artificial teeth to be used in the prosthesis.
Key words: Tooth, artificial. Comparative study. Tooth abrasion.
INTRODUCTION
The abrasion wear of artificial teeth used in prosthetic
rehabilitation treatments is of great clinical interest. Worn
teeth alter the vertical dimension of occlusion, which may
lead to craniofacial disorders, reduce chewing efficiency,
cause fatigue of masticatory muscles, increase patient
discomfort and impair the esthetics4,12,13,19. In order to
maintain adequate function and stable occlusion, more
attention should be given to the choice of the artificial teeth,
which should be made considering the material of the
antagonist teeth2,6.
There are three options of materials for posterior artificial
teeth: porcelain, acrylic resin and metal. In removable
prostheses, acrylic resin teeth are used more frequently than
porcelain teeth5,7. Acrylic resin teeth present some
advantages over porcelain teeth, such as: less brittleness,
better connection to the denture base material, easier occlusal
adjustments and repolishing, more natural appearance and
less chewing noises15,18.
The low resistance to abrasion wear of the acrylic resin
teeth consists in a limitation of these teeth. They do not resist
parafunctional habits, and many times it is hard to maintain
the vertical dimension. In order to improve abrasion wear
resistance, acrylic artificial teeth with better mechanical
properties have been developed, such as the interpenetrated
451
polymer network (IPN) resin teeth, with polymer double-
crossed links (DCL), and resin teeth with addition of
inorganic agents in their composition15-17. However, a recent
study reported that these teeth, when compared to
conventional ones, have worse adhesion to the denture base
resin11.
The objective of this study was to evaluate the in vitro
abrasion wear resistance of 7 commercial brands of artificial
denture teeth (BIOLUX, TRILUX, BLUE DENT,
BIOCLER, POSTARIS, ORTHOSIT, GNATHOSTAR),
opposed to metallic antagonists (M – nickel-chromium alloy)
and composite antagonists (C – Solidex indirect composite).
Although some of these artificial teeth are commercially
available only in the Brazilian market, all of them have
formulations found worldwide and can therefore indicate
the expected results when used in dental prostheses.
MATERIAL AND METHODS
Figure 1 shows the artificial denture teeth evaluated in
this study. Seven groups of 12 specimens each were prepared
and divided in two subgroups: one group was tested opposed
to metallic antagonists (M – Ni-Cr alloy [Vera Bond II, Aalba
Dent. Inc., Cordelia, CA, USA]), and another group was
tested opposed to composite antagonists (C – indirect
composite, (Solidex [Shofu Inc., Tokyo, Japan]). Six
maxillary first premolars of each brand were used (N = 84).
The Ni-Cr alloy was selected because it is extensively used
in oclusal surfaces of fixed partial dentures, as clinically
observed in partially edentulous patients.
The 84 specimens were included in 1-inch PVC rings
with self-curing acrylic resin, using a custom-made
parallelometer (Ribeirão Preto Dental School, University
of São Paulo), with a griping tip that stabilized the specimen
FIGURE 1- Groups of artificial teeth
*Based on manufacturers’ informations
Groups
BD
BL
BC
TR
PO
GN
OR
N
12
12
12
12
12
12
12
Composition*
High-density
polymethylmethacrylate, cross-
linked
Polymethylmethacrylate;
Polymerized Ethyleneglycol
Dimethacrylate (EDMA);
Fluorescent; Biocompatible
Pigments
Polymethylmethacrylate, cross-
linked; Fluorescent
Polymethylmethacrylate;
Polymerized Ethyleneglycol
Dimethacrylate (EDMA);
Fluorescent; Biocompatible
Pigments
Synthetic polymer based on
Polymethylmethacrylate;
double cross linked
Synthetic polymer based on
Polymethylmethacrylate
Microfilled resin composite
(Isosit+Inorganic fillers)
(urethane dimethacrylate –
UDMA)
Commercial Brand
BLUE DENT
BIOLUX
BIOCLER GII
TRILUX
SR POSTARIS DCL
GNATHOSTAR
SR ORTHOSIT PE
Manufacturer
Blue Dent Dental, Pirassununga,
Brazil
VIPI Indústria, Comércio,
Exportação e Importação de
Produtos Odontológicos Ltda,
Pirassununga, Brazil
DentBras Indústria, Comércio,
Importação e Exportação de
Produtos Odontológicos Ltda,
Pirassununga, Brazil
VIPI Indústria, Comércio,
Exportação e Importação de
Produtos Odontológicos Ltda,
Pirassununga, Brazil
Ivoclar Vivadent AG.Schaan,
Liechtenstein
Ivoclar Vivadent AG.Schaan,
Liechtenstein
Ivoclar Vivadent AG.Schaan,
Liechtenstein
ABRASION WEAR RESISTANCE OF DIFFERENT ARTIFICIAL TEETH OPPOSED TO METAL AND COMPOSITE ANTAGONISTS
452
during the inclusion.
For preparation of the antagonist tablets, a 20-mm-
diameter polytetrafluoroethylene matrix was manufactured
in the Department of Dental Materials and Prosthodontics
of Ribeirão Preto Dental School, University of São Paulo
(DDMP), with 2- and 3-mm-thick spacers. Using 2-mm-
thick spacers and Picodip wax (Renfert GmbH, Hilzingen,
Germany) liquefied in a wax dipping pot (Hotty Led, Renfert,
Hilzingen, Germany), patterns were obtained, and were
included with phosphate-based investment (Termocast,
Polidental Ind. Bras. Ltda, São Paulo, Brazil), and cast with
Ni-Cr alloy in the Discovery Plasma casting machine (EDG
Equipments and Controls Ltda, São Carlos, SP, Brazil),
under vacuum and inert argon atmosphere. The castings
obtained were sandblasted with 100-m aluminum oxide
stream, under 80 psi (5.62 kgf/cm2) pressure. Using the same
matrix, but with the 3-mm-thick spacer, 12 other tablets were
obtained with the Solidex composite. Each tablet was
obtained using an incremental technique, according to which
2 composite increments were built, each one subjected to a
90-s curing cycle in a light-curing unit (UniXS, Heraeus
Kulzer GmbH, Hanau, Germany). The polymerized
specimen was retrieved from the matrix and subjected to
more 90-s of light curing.
According to the DIN method stated by the ISO/TS
14569-2 standard, the surface of the antagonist tablet must
have a surface roughness of 0.75 m. Thus, all antagonist
tablets were prepared with 300-, 600- and 1200-grit silicon
carbide paper in a decreasing sequence of abrasiveness, and
their surface roughness was read in a surface roughness meter
(SPJ-2, Mitutoyo, Tokyo, Japan).
Before abrasion wear tests, the specimens were taken to
a profile projector (Nikon 6C, Tokyo, Japan) with a 20x
magnification and were individually placed in a positioning
platform that allows further placement of the specimen in
the same position for the post-test measurements. A vegetable
graph paper was used to obtain each specimen’s profile.
The original profile of the specimens was traced for posterior
analysis of contour changes.
The abrasion wear tests were performed in the
mechanical loading device developed at the DDMP. In this
device, an electrical motor moves a lever arm with a 265
cycles/min speed. An acrylic recipient is attached to the
device´s lever arm, and performs a 10-mm course, resulting
in a linear speed of 88 mm/s. The test assembly was installed
inside the acrylic recipient.
Specimens were placed in a pole with vertical
adjustment, allowing it to be positioned over the antagonist.
Once the pole was completely released, a load of 5 N,
corresponding to the whole weight of the assembly, was
applied to the specimens. This mechanical loading device
was designed according to the ISO/TS 14569-2 standard
(Dental Materials – Guidance on testing of wear – Part 2:
Wear by two – and/or three-body contact, 2001) under the
Freiburg Method. The tests completed 40,000 cycles,
simulating approximately 120 days of normal oral function4
(150 min, 4 Hz), with specimens and antagonists completely
immerse in deionized water (Figure 2).
Specimens and composite antagonists were stored in
distilled water at 37o ± 1oC during 7 days before the tests. In
the test machine, the antagonist tablet was placed into a
recipient with deionized water. Immediately after removal
of the water storage, the specimens were dried with absorbent
paper and a gentle air stream, and had their final contour
traced in the profile projector (Nikon 6C, Tokyo, Japan),
over the initial profile traced. The measure of the abrasion
wear was determined by the linear difference between the
two profiles, utilizing a digital paquimeter (Mitutoyo CD –
15C, Japan, Tokyo) accurate to the nearest 0.01 mm (Figure
3).
The wear values (m) of all tested specimens, grouped
by antagonist, were subjected to one-way ANOVA and
Tukey’s test. The paired t-test was used for comparisons
within each specimen group, among different antagonists,
All statistics were performed using the SPSS statistical
package (SPSS Inc., Chicago, IL, USA).
RESULTS
The results obtained in the abrasion wear resistance tests
by the artificial teeth are shown in Figure 4.
There were statistically significant differences (p=0.001)
for comparisons among the different artificial teeth against
FIGURE 2- Wear abrasion test device
MELLO P C, COPPEDÊ A R, MACEDO A P, MATTOS M da G C de, RODRIGUES R C S, RIBEIRO R F
453
composite antagonist. PO (2.33 ± 0.91 m) and OR (2.77 ±
0.69 m), which had the lowest wear mean values, were
significantly different from groups BC (4.48 ± 0.80 m)
and GN (4.50 ± 0.73 m), which had the highest wear mean
values.
Statistically significant differences (p=0.000) were found
when the groups were compared against metallic antagonist.
OR (10.45 ± 1.42 m) presented the highest wear mean
value, and differed significantly from all other groups
(p<0.001). There were significant differences (p<0.05)
between BC (6.70 ± 1.37 m) and TRI (4.30 ± 0.43 m),
BL (3.70 ± 0.61 m) and PO (1.78 ± 0.42 m). Significant
differences (p<0.05) were also found when BD (5.37 ± 1.65
m) and TRI (4.30 ± 0.43 m) were compared to PO (1.78
± 0.42 m), which had the lowest wear mean values (Figure
3).
In order to compare the wear for each group caused by
the two types of antagonists, a paired-sample t-test were
performed. Significant differences were observed for BC
(p=0.007), which presented mean wear of 4.48 ± 0.80 m
against composite and 6.70 ± 1.37 m against metal, and
for OR (p=0.000), which presented mean wear of 2.77 ±
0.69 m against composite and 10.45 ± 1.42m against
metal. All other groups had no statistically significant
differences from each other (p>0.05).
No wear was observed in the antagonists.
DISCUSSION
This study excluded clinical variables, such as
neuromuscular forces and movements, saliva pH and
lubrication, oral hygiene habits and diet, because according
to previous studies, those factors are very difficult to control,
FIGURE 3- Measure of abrasion wear determined by the linear difference between the initial and final profiles
FIGURE 4- Original values, mean values and standard deviations of all specimens opposed to the antagonists (metallic, NiCr,
and composite, Solidex) after the abrasion wear resistance tests (in µm) - please refer to text in order to follow statistically
significant differences
ABRASION WEAR RESISTANCE OF DIFFERENT ARTIFICIAL TEETH OPPOSED TO METAL AND COMPOSITE ANTAGONISTS
454
and are costly and time consuming10,15.
Prosthetic rehabilitation success depends on adopting
correct procedures in order to obtain comfort, function and
esthetics. The choice of the materials that will replace
missing dental structures is a critical clinical issue for both
the professional and the patient. The dentist has to have
knowledge and discernment to adjust the patient’s
expectations to the characteristics of the materials indicated
for the case. Also, the dentist must be familiar with the
properties of the various artificial teeth available in the
market and must be aware of patient’s characteristics, such
as diet and presence of parafunctional habits, in order to
obtain the best possible treatment prognosis1,7.
Stober, et al.15 (2006) has stated that natural enamel is
an unsuitable antagonist material for standardized wear tests
because the composition, shape and wear properties of
biological substances are highly variable. Based on this
information, human enamel was not used in this study.
However, it should be considered that the interaction with
the enamel provide important data for the evaluation of
artificial teeth.
In the two-body wear test used in the present study, there
is direct contact between the tested material and its respective
antagonist, with no intermediate material, but running water.
Other studies, however, used an intermediate material to
simulate the food bolus. Kadokawa, et al.9 (2006) evaluated
the abrasion wear and other abrasive properties of porcelain,
gold alloy, composite resin and human enamel using 2-body
and 3-body conditions (PMMA slurry). The authors
concluded that the wear values in 3-body wear were
significantly smaller.
According to Whitman, et al.17 (1987) and Hirano, et
al.7 (1998), artificial teeth made of improved acrylic resin
(IPN, DCL), or polymers with addition of inorganic agents
are more resistant than conventional polymethylmetacrylate
(PMMA) teeth. In a recent abrasion wear resistance test,
cross-linked teeth or teeth with addition of an inorganic layer
presented greater abrasion wear resistance than conventional
PMMA teeth16. Other clinical studies, however, did not find
significant differences among the wear presented by
conventional PMMA teeth and improved acrylic teeth (DCL,
IPN)5,8,10,12.
Based on the findings of Ghazal, et al.5 (2008), the test
performed in this study correspond to an approach of two-
body wear with direct contact between the artificial teeth
tested and the antagonist, which produces a mixed wear of
adhesion, attrition and fatigue. Some authors have stated
that this condition is especially important when considering
complete dentures with a bilaterally balanced occlusion6,15.
Additionally, in a 2-body wear test only direct interactions
between surfaces of sample and antagonist cause a substance
loss15.
In the present study, the group PO (double cross-linking
[DCL] polymethylmetacrylate) presented the smallest wear
mean values, for both metallic and composite antagonists.
The group OR (polymer with inorganic filling) presented
the highest wear mean values against metallic antagonists
among all other groups tested. However, it presented small
wear mean values against composite antagonists, similar to
the best results obtained by the other groups, which suggests
a different type of interaction, possibly justified by the fact
that both types of artificial teeth are based on the same
polymer type. Brigagão, et al.2 (2005) obtained smaller
values of weight and height loss for PO teeth. However,
these authors did not obtain enough wear on the tested
specimens, and no significant differences were observed
among the groups, using 200,000 cycles, which
corresponded to 1 year of clinical function14, with 400 g
load.
Possibly due to the load used in this study, which was
low (5 N), no wear was measured in the antagonists. Because
the rough surface characteristics (75 m, accordingly to the
DIN method of the ISO/TS 14569-2 standard) just a mark
was visible. The vertical substance loss measured in this
study, as a consequence of the sliding contact of a buccal
cusp of artificial teeth and the antagonist tablets, represents
the abraded area of the teeth. Each artificial teeth used in
this study has a particular cusp shape, and the contact area
increased as the abrasion test was performed. In order to
avoid higher influence of this increased contact area, the
tests performed were limited to simulate a 120-day use of
the teeth. In addition, the cusp shape in this study was in
accordance with the sample dimensions described in the ISO/
TS 14569-2 standard (Dental Materials – Guidance on
testing of wear – Part 2: Wear by two – and/or three-body
contact, 2001) under the Freiburg Method. However, this is
a limitation of the method used3. Other evaluations, with
higher loads, must be performed to determine the effects on
both the artificial teeth and antagonist materials. Reis, et
al.13 (2008) used a canine tooth to test the in vitro wear
resistance for three types of PMMA artificial teeth in a
similar way, and observed that tested PMMA denture teeth
have significantly different wear resistance against abraded
ceramic. The highest values were found for high-strength
PMMA teeth than conventional PMMA teeth.
The findings of present in vitro study are important for
the comparison of the abrasion wear resistance of different
commercially available artificial teeth against different types
of antagonists. However, clinical trials with these materials
for longer periods are still necessary. In addition, new studies
should be accomplished to establish the wear resistance of
artificial teeth when they are used opposing materials with
the same wear characteristics.
CONCLUSIONS
Based on the methodology applied to this study,
considering the inherent limitations and the obtained results,
it may be concluded that the antagonist material present on
(or planed for) a clinical rehabilitation is a factor of major
importance to be considered for the choice of the artificial
teeth to be used in the prosthesis. OR was the group that
presented the greatest result variance regarding the abrasion
wear resistance; it also presented the worst result opposed
to metallic antagonist (10.45 ± 1.42 m), and a result similar
MELLO P C, COPPEDÊ A R, MACEDO A P, MATTOS M da G C de, RODRIGUES R C S, RIBEIRO R F
455
to the best ones opposed to composite antagonists (2.77 ±
0.69 m). The group PO presented the smallest wear mean
values, both for metallic (1.70 ± 0.42 m) and composite
(2.30 ± 0.91 m) antagonists. In the light of the obtained
results, dentist’s decision to indicate any of the artificial teeth
tested in this study can be made based on the analysis of
important characteristics in determining its functionality and
esthetics, allied to the cost of the material.
ACKNOWLEDGMENTS
The authors thank to Mr. Luiz Sérgio Soares and Mr.
Paulo Donato Frighetto for their technical assistance, as well
as the manufacturers for donation of artificial teeth.
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