Article_6_2_1-1
DENTAL MATERIALS
IN VITRO WEAR OF TEN UNIVERSAL COMPOSITES
Original Articles
Jean-François-Roulet1a* , Hind Hussein1b, Nader Abdulhameed1c , Chiayi Shen1d
Department of Restorative Dental Science, Center of Dental Biomaterials College of Dentistry
1
University of Florida, Gainesville, FL32610, USA
a
Dr. med.dent, Dr. hc, Professor
b
DDS
c
DDS
d
DMD, PhD
ABSTRACT DOI: https://doi.org/10.25241/stomaeduj.2019.6(2).art.1
Objectives: To test wear of 10 universal composites and the antagonist. Null hypothesis:
OPEN ACCESS This is
there are no differences in the composite and antagonist wear. an Open Access article under
Materials and Methods: Flat samples, light cured as of manufacturer’s instructions and the CC BY-NC 4.0 license.
polished were made from Admira Fusion (AF), Filtek Supreme Ultra (FS), G-aenial Sculpt Peer-Reviewed
(GS), Harmonize (HR), Herculite Ultra (HU), Tetric Evoceram (TE), TPH Spectra (SP) and three Article
Ultradent experimental materials (UPI Exp 1-3) (n = 8), and stored in water for 3 weeks. Citation: Roulet J-F, Hussein H,
Abdulhameed N, Shen C. In vitro
They were subjected to wear in a chewing simulator (1.2 x 105 cycles, 49 N, 0.7 mm lateral wear of ten universal composites.
movement, 1 Hz, steatite antagonists (Ø 6 mm), simultaneously thermocycled (5/55°C) Stoma Edu J. 2019;6(2):91-99
every 90 s). The volumetric wear of the composite was measured with a 3D laser scanner) Received: June 10, 2019
Revised: June 21, 2019
after 5,000, 10,000 then every 10,000, up to 120,000 cycles. The wear of antagonists was Accepted: June 27, 2019
measured after 120,000 cycles. Published: June 28, 2019
Results: From 5,000 – 120,000 load cycles wear was linear. The total volumetric wear of Corresponding author:
Professor Jean-François Roulet, DDS,
composites was: GS 0.428 ± 0.083 mm3, UPI Exp 3 0.51 ± 0.042 mm3, HU 0.576 ± 0.072 PhD, Prof hc, Director of Center for
mm3, SP 0.609 ± 0.088 mm3, FS 0.635 ± 0.077 mm3, HR 0.658 ± 0.116 mm3, TE 0.714 ± 0.097 Dental Biomaterials, Department
of Restorative Dental Sciences,
mm3, Ultradent UPI Exp2 0.725 ± 0.132 mm3, UPI Exp 1 0.894 ± 0.278 mm3 and AF 1.578 ± College of Dentistry, University of
Florida, 1395 Center Drive, Room
0.37 mm3. The wear of AF was significantly the largrest (p < 0.0001). GS showed the lowest D9-6, PO Box 100415, Gainesville,
wear, but shared this position with UPI Exp 3, HU, SP, FS and HR. The total wear of UPI Exp3 FL-32610-0415, USA, Tel / Fax:
(352) 273-5850, e-mail: JRoulet@
was the lowest. dental.ufl.edue
Conclusion: The null hypothesis was rejected. Copyright: © 2019 the Editorial
Clinical Relevance: Except for AF, wear should be within acceptable limits. Council for the Stomatology Edu
Journal.
Keywords: Dental materials; In vitro; Wear; Composite; Thermocycling.
1. Introduction recognized that optimal "intelligent" filler particle
Since their invention in the 1950s [1-3], composites size distribution reduced the resin content, which
have been continuously improved, however had a positive effect on polymerization shrinkage
without abandoning their basic concepts. Over the [8]. Using flame spray pyrolysis [10] silica based
years it became very obvious that the fillers used nanoparticles over a wide range of size could be
had the greatest influence on their physical and produced. Furthermore, it was possible to create
mechanical properties [4]. The fillers determine spherical mixed oxide (ytterbium oxide and silica)
the mechanical properties, they reduce the nanoparticles that matched the refractive index
polymerization shrinkage, the filler selection may of the resin mix (1.53) resulting in radiopaque
optimize wear behavior, they influence the optical composites with high translucency [11]. Finally,
properties (translucency) and may enhance the composites based solely on nanoparticle technology
radiopacity. Furthermore, the surface characteristics were introduced. However, the true single particle
and thus the polishability depend on the fillers, nanofillers are dispersed in a matrix, which is filled
with consequences for the handling properties and with so-called nanoclusters, with dimensions far
finally the aesthetic appearance of a composite away from the nano range [12]. Being aggregated
restoration [5]. Historically quartz was first replaced nanoparticles, the clusters lost many advantages of
by a variety of different glasses, followed by so- the nanotechnology. The changes outlined above are
called microfillers (Aerosil, fumed silica), which reflected in a multitude of composite classifications
were first introduced into a resin matrix, which was based on their fillers [4,6,7,13-17].
polymerized and ground into powder. This filler Clinical Studies of early composites placed in
was also referred to as prepolymerized particles [6- posterior teeth have revealed substantial wear
8] which were incorporated into a matrix filled with [18]. With the improvement of the filler technology
fumed silica. Optimal X-ray contrast was achieved as described above, the longevity of posterior
by ytterbium trifluoride filler [9]. In parallel with the composite restorations can be excellent. The survival
improvement in glass milling technology, it was also behavior of restorations is shown best with Kaplan-
Stomatology Edu Journal 91
IN VITRO WEAR OF TEN UNIVERSAL COMPOSITES
Original Articles Table 1. Materials used incl. filler composition.
Name Color Type Filler Manufacturer Batch #
Universal
Admira Fusion 84% w/w inorganic fillers: SiO2 glass and Voco GmbH,
A2 Nanohybrid- 1638273
(AF) nanoparticles Cuxhaven, Germany
Ormocer
Agglomerated zirconia/silica cluster,
average cluster size 0.6 – 20 µm. Non
Filtek Supreme A2 3M Espe St. Paul, MN,
Ultra Universal agglomerated/non aggregated silica N808359
Ultra (FS) Enamel USA
filler 20 nm, and zirconia filler 4 – 11 nm.
Total filler 72.5 % w/w
Universal
G-aenial Adult Uniform nano-filler dispersion GC Corp, Tokyo,
Nanohybrid 1506111
Sculpt (GS) Enamel technology Barium glass 300 nm Japan
Compactable
Barium glass 400 nm, Silica and zirconia
Harmonize A2 E Nanohybrid Kerr Co., Orange, CA,
nanoparticles > 5nm. Average particle 6173894
(HR) Enamel Universal USA
size 50 nm Total filler 81 % w/w
Ba-glass filler 0.4µm, Prepolymerized
Herculite Ultra A2
Nanohybrid Filler, Silica nanofiller, 20 – 50 nm Total Kerr Co., Orange, CA 6037221
(HU) Enamel
filler 78 % w/w
Ba-Al-Silicate glass 0.4 and 0.7 µm,
Tetric A2 Universal Yterbuimfluoride, Mixed Oxyde 160 nm, Ivoclar Vivadent,
V27337
EvoCeram (TE) Enamel Composite Isofiller (Prepolymerized Filler), SiO2 40 Schaan Liechtenstein
nm
TPH Spectra Universal Ba-Al-borosilicate glass, Ba-B-F-al- Dentsply Caulk,
A2 HV 160401
(SP) Composite silicate glass, SiO2. Total filler 77.2% w/w Milford, DE, USA
Total filler: 68% v/v Ultradent Products
Ultradent UPI A2 Universal RT00E00A
zirconia-silica glass ceramic and 20 Inc., South Jordan,
Exp 1 Dentin Composite
nanometer silica UT, USA
Total filler: 56% v/v Ultradent Products
Ultradent UPI Universal SW20E15B
Enamel zirconia-silica glass ceramic and 20 Inc., South Jordan,
Exp 2 Composite
nanometer silica UT, USA
Total filler: 80.9% w/w Ultradent Products
Ultradent UPI Nano-hybrid 20E15B
Enamel barium borosilicate glass filler. Average Inc., South Jordan,
Exp 3 Composite
particle size is 0.89 micrometers UT, USA
Meier survival statistics. However, with those the factors influencing longevity of restorations were
comparison of different studies is difficult. Therefore, the patient, the dentist and the material. In an
most authors report the % survival of restorations extensive review about the longevity of restorations
after a given time (e.g. 5 or 10 years). For direct Manhart et al [25] found that over time composites
comparisons these can be converted into %-annual have significantly improved. For direct restorations
failure rates (AFR). On the one side, clinical long-term they found in publications before 1990 an AFR of 4.2,
studies show annual failure rates (AFR) between while in papers published after 1990 the AFR was 2.0.
0.1% and 0.67% after 10 years [19], 1.1% after 30 In the past, composites were specifically developed
years [20], and 1.5/2.2% after 22 years [21]. On the for a specific indication (anterior or posterior
other hand, higher AFRs have been reported. In a restorations), based on their aesthetic or wear
systematic review Opdam et al [22] reported AFRs behavior. Contemporary composite materials
of 1.8% (5 years) and 2.4% (10 years). However, that have reached a high degree of maturity, are
when discriminating between high caries risk and complex constructs [26], and well accepted by
low caries risk, the respective numbers were 3.2% the profession. They are designed as universal
and 4.6% for high caries risk and 1.2% and 1.6% for composites suitable for the application in the
low caries risk respectively. A significant material anterior and posterior segment. Furthermore, with
effect could be found as well. In another review the improved knowledge of application techniques
article, Demarco et al [23] reported AFRs between composites are used for larger restorations as in the
0% and 8.6%, which may allow the question that past, which brings back the question if composites
the dentist may be a significant cofactor. Hickel and are sufficiently wear resistant to carry occlusal load.
Manhart [24] found similar results. They reported Composite restorations should have similar wear to
AFRs between 0% and 9%. Only 3 out of 24 studies enamel so restorations behave similarly to teeth.
reported wear. The authors concluded that the This is important, especially when the indication of
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IN VITRO WEAR OF TEN UNIVERSAL COMPOSITES
Original Articles
Table 2. Light curing parameters according to manufacturers' Table 3. Settings of Chewing Simulator.
instructions for use.
Load 5 kg
Curing Exitance Radiant
Material time irradiation exposure Upstroke 2 mm
(s) (mW/cm2) (J/cm2)
Downstroke 1 mm
Admira Fusion 20 1170 23.40 Horizontal
0.7 mm
movement
Filtek Supreme
10 1170 11.70 Upward speed 60 mm/s
Ultra
G-aenial Sculpt 10 1170 11.70 Downward speed 60 mm/s
Horizontal speed 40 mm/s
Harmonize 10 1170 11.70
Frequency 1 Hz
Herculite Ultra 10 1170 11.70
5°C-55°C 30 s holding time,
Thermocycling
Tetric EvoCeram 10 1170 11.70 transfer time 15 s, total cycle 90 s
Direction Back and forth
TPH Spectra 10 1170 11.70
UPI Exp 1 20 1170 23.40
holders with composite were used as antagonists. One
antagonist per sample (n = 64) was used and discarded
UPI EXP 2 20 1170 23.40 after finishing all cycles.
The chewing simulator was run according to the
UPI EXP 3 20 1170 23.40 parameters listed in Table 3. The specimens were
simultaneously thermocycled (5/55°C) every 90 s. This
resulted in 120,000 mechanical cycles and 1333 thermal
direct composite restorations includes the buildup cycles as a total. After 5,000, 10,000, 20,000, 40,000,
of missing cusps. Then the occlusion cannot be 60,000, 80,000, 100,000, and 120,000 load cycles,
supported by natural tooth structure (enamel). Polyvinylsiloxane impressions (Virtual Extra light body,
Therefore, the aim of this study was to test the Fast set Wash material, Ivoclar Vivadent, Liechtenstein)
wear characteristics of three experimental universal using small cylindrical PVC trays were taken from the
composites as compared to seven commercially samples. From the antagonists, impressions were
available contemporary composites with different taken before the experiment and after 120,000 cycles
filler-compositions. The null hypothesis was that (end point of the experiment). All impressions were
there are no differences in the composite wear as cast using a dental stone (Micro stone, Whip Mix Co,
well as in the wear of the antagonists. Louisville, KY, USA).
The stone models were then scanned with a 3D laser
scanner, Laserscanner LAS-20 (SD Mechatronik GmbH,
2. Materials and Methods Feldkirchen-Westerham, Germany). By using geometric
The Universal composite materials used are software Geomagic control 2014 (3D Systems, Inc,
described in Table 1. USA), the scanned data were used to measure the wear
Eighty aluminum sample holders (inner Ø 8 mm of the samples after each round. The flat surface of the
depth 1.5 mm) were modified to have mechanical sample was used as a reference plain and the wear was
retention, then one coat of universal bond (Monobond calculated as the volume of the wear facet relative to
Plus, Ivoclar Vivadent, Liechtenstein) was added and the reference plane. The wear of the steatite antagonists
left for 60 s, followed by air blasting to evaporate the was measured as well in volume loss comparing the
solvent. Then one coat of adhesive (Optibond FL 2, initial with the final model. Data were analyzed using
Kerr, CA, USA) was applied and light cured according ANOVA, linear regression and the Tukey test.
to the manufacturers’ instructions using a Valo Grand From every group selected samples were dried in
(Ultradent Products, South Jordan, UT, USA) at standard ambient air, sputtered with AuPd, and SEM, MIRA3
mode delivering 1170 mW/cm2, measured with a (TESCAN, PA, USA) pictures at magnifications up to
Bluephase Meter II (Ivoclar Vivadent, Liechtenstein). 3200 were taken from the worn surfaces (composite
The composites were filled into the sample holders and antagonist) in order to see the wear patterns and
in one increment, then the top surface was flattened possible breakdowns in the surfaces.
with a Mylar® matrix band and the composites were
light cured with a Valo Grand in contact with the matrix
band according to the composites manufacturers’ 3. Results
instructions (Table 2). As expected, from 10,000 – 120,000 load cycles we
The composite surfaces where finished and polished found a statistically significant linear correlation of
by using (Sof-Lex Disks, 3M, MN, USA), light orange wear with chewing cycle (Fig. 1) The ANOVA showed
disc for finishing and yellow disc for polishing for 10- significant differences (p < 0.0001). After 120,000
15 s, and the final gloss was obtained with Astropl cycles, the total wear of composite in volume varied
silicon polishers (Ivoclar Vivadent, Liechtenstein). All from 0.428 mm3 to 1.578 mm3.
samples were stored in distilled water for 3 weeks at The volumetric wear for every material after 120,000
37⁰C. Steatite balls (Ø 6 mm) mounted into aluminum
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IN VITRO WEAR OF TEN UNIVERSAL COMPOSITES
Original Articles Table 4. Wear of composites in mm3 after 120K cycles. Same letter =
same statistical group (p < 0.05).
Statistical
Material Mean ± SD
group
Admira Fusion 1.578 ± 0.369 mm3 A
UPI Exp 1 0.894 ± 0.278 mm3 B
UPI Exp 2 0.725 ± 0.132 mm 3
BC
Tetric EvoCeram 0.714 ± 0.097 mm3 BC
Harmonize 0.658 ± 0.116 mm 3
BCD
Filtek Supreme Ultra 0.635 ± 0.077 mm3 BCD
TPH Spectra 0.609 ± 0.088 mm 3
CD
Herculite Ultra 0.576 ± 0.072 mm3 CD
UPI Exp 3 0.510 ± 0.042 mm 3
CD Figure 1. Cumulative wear of ten composites up to 120,000 load cycles.
G-aenial Sculpt 0.428 ± 0.083 mm3 D (p < 0.0001).
Table 5. Wear of antagonists in mm3 generated by the different
composites tested after 120K cycles. Same letter = same statistical
group (p < 0.05).
Statistical
Material mean ± SD
group
G-aenial Sculpt 0.290 ± 0.023 mm3 A
Herculite Ultra 0.231 ± 0.024 mm3 B
UPI Exp 2 0.210 ± 0.024 mm3 BC
Harmonize 0.206 ± 0.025 mm3 BC
TPH Spectra 0.175 ± 0.018 mm3 C
UPI Exp 3 0.130 ± 0.037 mm3 D
Figure 2. Wear volume of ten composites and the corresponding antag-
Tetric EvoCeram 0.129 ± 0.028 mm3 D onists after 120,000 load cycles. Blue letters show same statistical group
for composites, red letter for antagonists (p < 0.05). AF = Admira Fusion, FS
UPI Exp 1 0.121 ± 0.026 mm3 D = Filtek Supreme, GS = G-aenial Sculpt, HR = Harmonize, HU = Herculite
Ultra, TE = Tetric Evoceram, SP = TPH Spectra, UPI Exp 1-3 = Ultradent
Filtek Supreme Ultra 0.113 ± 0.017 mm3 D experimental composites.
Admira Fusion 0.100 ± 0.017 mm3 D
load cycles is shown in Table 4. The different
composites created significantly different wear of
the steatite antagonists (p < 0.05) (Table 5 and Fig. 2).
Note that AF had significantly more wear than all
other materials tested. GS showed the least wear;
however, it shared this position with UPI Exp3, HU, SP,
FS and HR. Since most composites wear in a similar
way, there is a lot of overlap between 0.6 mm3 and
0.9 mm3 volume loss.
In general, the antagonist wear was a fraction of
the composite wear and as a trend, materials which Figure 3. Total wear (∑ of composite + antagonist wear) in mm3..
were worn a lot, produced the least antagonist wear,
as seen with AF. On the other side, the material that scratches. Furthermore, pores were visible as well
showed the least wear (GS), was the most aggressive (Figs. 10 and 11).
against the antagonist. When looking at wear as
a system, then the total wear (∑composite wear
+ antagonist wear) is of interest Fig. 3). Here the 4. Discussion
ranking was similar to the one of composite wear. The seven commercial universal composites
However, UPI Exp 3 due to its very low antagonist represent a selection of widely used materials. The
wear ended up having the least total wear. three experimental materials were formulations
Some selected SEMs are shown in Figs 5-11. The of composites to be placed in the same market
composites mostly revealed the filler structure at segment. All composites were light cured according
high magnification (Figs 4–9), while the antagonists to manufacturer’s recommendations which reflects
were either smooth or showed various degrees of the condition of their clinical use. As can be seen in
Table 2 the radiant exposure was
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IN VITRO WEAR OF TEN UNIVERSAL COMPOSITES
Original Articles
Figure 4. Cumulative wear of composites vs cumulative wear of
Antagonists. AF = Admira Fusion, FS = Filtek Supreme, GS = G-aenial
Sculpt, HR = Harmonize, HU = Herculite Ultra, TE = Tetric Evoceram, SP = Figure 8. Worn surface of UPI Exp2. Note the larger particles as
TPH Spectra, UPI Exp 1-3 = Ultradent experimental composites. compared to the ones in Fig 6 (M006).
Figure 5. Worn surface of AF. Note the sharp filler particles and the Figure 9. Worn surface of UPI Exp 3. Note the densly packed spherical
fracture line. SEM 3200 (AF1 011). particles of various sizes. (Mu2-15).
Figure 6. Worn surface of GS. Note the fine granular surface. SEM 3200x Figure 10. Antagonist worn by AF. Note the smooth surface and the
(GS2-016). pores SEM 400x. (Af Ant 004).
Figure 7 Worn surface of UPI Exp 1 Note the filler particles that are well Figure 11. Antagonist surface worn by GS. Note the pores and the
integrated SEM 3200x (MO1-014). scratches. (GS 2 Ant 004).
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IN VITRO WEAR OF TEN UNIVERSAL COMPOSITES
between 11.7 and 23.4 J/cm2, which is within the
Original Articles Table 6. Wear rate in x 10-6 mm3/cycle of the tested materials.
recommendations found in the literature to cure 2 Same letter = means same statistical group (p < 0.05).
mm depth of composite [27,28].
Statistical
Wear is a complex process. Therefore, there is Material mean ± SD
group
no specific standard for testing wear of dental
restorative materials. Especially in vitro, it is difficult Admira Fusion 13.33 ± 3.24 A
to completely mimic the clinical situation. The UPI Exp 1 6.77 ± 1.83 B
various in vitro wear simulating machines use UPI Exp 2 6.11 ± 1.15 BC
different approaches; recently, however, two-
body wear machines with a sliding component Tetric EvoCeram 6.09 ± 0.95 BC
and preferably computer-controlled forces and Harmonize 5.40 ±1.00 BCD
movements have been preferred [29]. Since every Filtek Supreme Ultra 5.1 ± 0.72 BCD
wear tester uses a different theoretical model [29],
different antagonists are used in terms of material, TPH Spectra 5.04 ± 0.74 CD
shape and dimensions [30-35]. In the present work, Herculite Ultra 5.40 ± 0.54 CD
spherical steatite antagonists (ø 6 mm) were used UPI Exp 3 4.26 ± 0.49 CD
because of their hardness, reproducibility, the
G-aenial Sculpt 3.26 ± 0.73 D
standard shape similar to a molar cusp, and the
easy availability. It was deliberately decided not we had two evaluators who outlined the wear facets
to use enamel as antagonists, due to variability and measured the volume as an expression of wear
in mechanical properties and shape. Attempts to based on the LAS 20 scans, which obtained identical
grind natural cusp tips into a standard shape have data. All in all, this resulted in small standard
revealed additional defects which would contribute deviations so that we could differentiate the material
to the variability of the expected results. In addition, wear of the different materials at an early stage.
most Mechatronics chewing simulator users use As in earlier experiments [36,37], the wear behavior
steatite antagonists, allowing comparisons with was inconsistent in the first 5,000 - 10,000 cycles
other studies. For the operation of the chewing and had a higher variability. This is a well-known
simulator standard parameters as recommended effect called "running in". Therefore, the analysis of
by the manufacturer were used [36]. Therefore, our the data began at 10,000 cycles. From this point on
data are comparable to those of the Ivoclar Vivadent the wear development was linear with an excellent
group in Schaan [26]. The Ivoclar protocol uses correlation with the number of cycles (R2 > 0.98, see
standardized Empress (leucite ceramics) antagonists Fig. 2), reflecting the results of Heintze et al. [31,39],
that are in the shape of a molar cusp, while in the Wang et al. [41] and Matias et al [37].
present experiment spherical steatite antagonists When comparing the wear volume, the tested
were used, which may explain the slightly different composites had approximately the same values as
findings. Tetric N Ceram Bulkfil, as tested in an earlier study
The wear values obtained with similar composite [36], where at 120,000 load cycles, Tetric Ceram
materials in a previous experiment [37] were Bulkfil showed 0.66 ± 0.27 mm3 whereas in the
approximately twice that of those in the present present study Tetric Ceram had 0.714 ± 0.097 mm3
study using the same chewing simulator. This wear. The wear data of the present study are also
difference can be explained by the different chewing comparable to those presented by Lendenmann
force [37]. In the present experiment, a load of 49 and Wanner [26] for a large group of composites. The
N was used, while in the previous experiment the slight differences can be explained by the fact that
load was 59 N, which seems to be too much since different antagonists were used. In the present work,
fractures of the same samples had occurred. It is steatite spheres with a diameter of 6 mm were used,
difficult to determine the actual chewing force in while the Ivoclar-Vivadent method used Empress
vivo under function. Literature data show a large antagonists in the shape of a molar cusp [26].
variation (20-120 N). The decision to use 49 N was The linear wear development over time confirms the
based on a publication by Gibbs et al. [38], where 49 results of previous studies and allows formulating
N were found to be the average chewing force under a wear rate for each material (Table 6). Considering
normal function. that there are 4 statistical groups for the wear and
A laser scanner was used to measure wear facets. the wear rate of the composites (Table 4 and 6, Fig.
Heintze et al. [39] have shown that there is no 2) the null hypothesis is rejected. The same is true for
significant difference between a mechanical or the antagonist wear (Table 5, Fig. 2).
optical profilometer and a laser scanner. To better understand the wear behavior of the
For the present study, almost the same method was tested composites, a plot of wear of composite
used as in previous studies [36,37]. The difference vs wear of antagonists was created (Fig. 4). Some
was that in the Matias study, the composite samples trends became visible. On the one side there is GS
and the antagonists were directly scanned, while which forms a quite well-defined cluster with low
in the present study we chose to use hard plaster wear and high antagonist wear. On the other side,
replicas. The reason for this was that when we namely the other extreme, it seems that AF forms
scanned directly facets in polished, flat composite its own group with very low antagonist wear but
or ceramic surfaces and analyzed them with the high composite wear. There we notice as well that
Geomagic software, we found distortions in the flat for the composite wear there is a wide spread of the
surface at the transition to the facet [40]. In addition, data points especially towards high wear. All other
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composites, with the exception of UPI Exp1 that the present study. The other two are predecessors
Original Articles
has two “outlieres” they all form a big cluster which with a less developed technology as the comparable
explains the overlap with statistical groups. Using ones in the present study. For Tetric EvoCeram
the SEM pictures one can speculate about different they report 0.33 ± 0.052 mm3, while in the present
wear mechanisms. AF (Fig. 5) seems to contain sharp study the same material showed 0.714 ± 0.097 mm3
edged filler particles up to 3 µm, which seem to be volumetric wear. This is substantially higher. The
dislocating from the surface. In Fig. 4 even a fracture comparison between Filtek Suprem XTE and Filtec
line is visible. These may explain the high wear of the Supreme Ultra is about the same (0.374 ± 0.05 mm3
material. Furthermore, AF is the only material under vs 0.635 ± 0.077 mm3) with the incertitude about the
test that contains an ormocere as matrix, which may slight material difference. The discrepancy can be
as well be the reason for the higher wear. On the explained with a slight difference in the methods.
other side, GS showed itself a scratch pattern, but Lazaridou et al were loading the samples in water
“grooves” and “mountains” showed the same very at 37°C, while in the present study the samples were
small granular structure (Fig. 6). It seems that very thermocycled, which represents an additional stress.
small and hard filler particles, which are well retained On the other hand, the difference between G-aenial
to the matrix are responsible for the high wear of Posterior and GS (0.342 ± 0.07 mm3 vs 0.427 ± 0.083
the antagonists as well as for the low wear of the mm3) is only minimal, which leads to the assumption
material itself. that this material has been significantly improved
The UPI Exp1 and UPI Exp2 are the “Dentin” and the over the years.
“Enamel” version of the same material. Regarding In the present study the wear of TE was determined
wear, they are in the same statistical group, which to be 0.7 mm3. Heintze et al [39] have used almost the
they share with TE, HR and FS. However, their same approach as used in this study and measured
structure as seen in Figs. 7 and 8 is slightly different. for Tetric Ceram, approx. 0.6 mm3; Tetric N Ceram’s
Both have spheroid/spherical fillers which seem to wear was determined with the same method
be perfectly integrated into the matrix. However, being approximately 0.5 mm3 and the one of Tetric
the size seems to vary slightly. The “dentin” version EvoCeram was approximately 0.4 mm3 [42]. These
(UPI Exp 1) contains particles which have sizes below data compare well with the values of D’Arcangelo
4 µm, while the “enamel” version has not only filler et al. [30] which reported mean wear values for
particles of about the same dimension, but there different direct composites between 0.529 ± 0.139
are also definitely larger particles (8-10 µm and mm3 and 1.425 ± 0.245 mm3. This is almost the same
larger).This makes sense, since the light is scattered range as was found in the present study despite the
at the resin filler interface, which means that with fact that they used a different antagonist (3 mm ø
larger filler particle less scattering and thus more zirkonium oxide).
translucency may be expected. UPI EXP3 (Fig. 9) Early composites showed definitely more wear than
seems to be based on a different approach. Most of enamel [18], but during the continuous improvement
the particles seem to be spherical, but there is a wide of composite resins, the materials characteristics,
range of sizes. Thus, they may have been produced especially the physical and mechanical data got
with spray flame pyrolysis [10] and the manufacturer improved much [5] and the wear characteristics
has attempted to reach a maximum filler load by improved as well. With this fact, other characteristics
using different ranges of particle distributions have become more important for the clinicians in
[8]. This may be an explanation for its good wear the selection process for the favorite material to use.
behavior. Aesthetic considerations (shade, chameleon effect),
The different scratch patterns seen on the antagonists ease of application (bulk fil, thixotropy, low stickiness)
should correlate to the measured wear. This was or good short-term outcome (no postoperative pain)
only partly conclusive. The antagonists of AF seem got more into the focus in the last years. Never the
polished (Fig. 10) while the antagonists of UPI EXP3 less wear of the tested composites is still higher
seem almost untouched. On the other side severe than the wear of enamel [36]. Therefore, the wear
scratches could be observed on the antagonists of behavior should, among other parameters, still be
GS (Fig. 11) and SP. The other materials have more part of the evaluation process of resin composites.
or less similar scratch patterns of median expression.
Basically, one could expect that fillers with lower
hardness would produce less scratches. 5. Conclusions
Every known wear testing device has a different The majority of the tested composites showed a
approach on how to simulate wear [31]. Therefore, similar wear behavior with slight differences of
direct comparisons of numeric values, e.g. the measured volumetric wear. Some materials
volumetric or vertical wear are impossible. Thus, were either positioned on the high side (AF with
only studies done with Willitec/Mechatronik wear significantly higher wear) and GS with the lowest
testing machines can be used to perform direct wear. If one considers total wear, then UPI EXP 3
comparisons with the present study. However, this showed the most favorable outcome with low wear
is difficult as well, since there are only a few studies and the lowest antagonist wear.
available which have tested the same composite Since these results were produced with an in vitro
materials. Lazaridou et al [33] have tested among wear simulation, the transposition of the outcome
others G-aenial Posterior, Tetric Evo Ceram and Filtek into the clinical situation should be done with much
Supreme XTE. From these 3 materials only Tetric caution.
EvoCeram is the same material as the one tested in
Stomatology Edu Journal 97
IN VITRO WEAR OF TEN UNIVERSAL COMPOSITES
on a resin or Class II restorations: three year
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Jean-François ROULET
DDS, DMD, PhD, Dr hc, Prof hc, Professor
Department of Restorative Dental Sciences, Center for Dental Biomaterials
College of Dentistry, University of Florida
Gainesville, FL, USA
CV
Jean-François Roulet, DDS, Dr med dent, PhD, is the former chair and current professor of the Department of Restorative Dental
Sciences at the University of Florida. Professor Roulet is author/coauthor of more than 210 papers, edited/contributed to 27
textbooks and mentored more than 150 theses. He is a renowned international lecturer with over 920 appearances to date.
Dr. Roulet is a member of many professional organizations, has won numerous awards, and holds four patents. He is editor
of Stomatology Edu Journal. His areas of interest include minimally invasive dentistry, dental materials (ie, composites and
ceramics), adhesive dentistry, esthetic dentistry, and application concepts in preventive dentistry.
Questions
1. An universal composite is:
qa. A composite with a universal, standard filler;
qb. A composite which allows restorations with all cavity classes;
qc. A composite for high esthetic indications;
qd. A composite with high wear resistance.
2. The materials were stressed as follows:
qa. Mechanical stress static 100 N for 50 h;
qb. Thermocycling for 1333 cycles from 5°C to 55°C;
qc. 120,000 mechanical cycles with 50 N maximum force and lateral movement under load;
qd. 120,000 mechanical cycles with 50 N maximum force and lateral movement under load and thermocycling
for 1333 cycles from 5°C to 55°C.
3. Composite wear results:
qa. There were significant differences between the materials with G-aenial Sculpt having the least wear and UPI
Exp1 and 2, Tetric EvoCeram, Filtec Supreme Ultra, and Admira Fusion being in the group with the highest wear;
qb. There were no statistical differences in the wear rate of the different composites tested;
qc. The measured wear varied between 0.05 mm3 and 0.4 mm3;
qd. The standard deviation was more than 50%.
4. The antagonist wear was:
qa. Larger than the composite wear;
qb. Equal to the composite wear;
qc. Strongly correlated to the composite wear;
qd. Much smaller than the composite wear with the exception of G-aenial Sculpt.
Stomatology Edu Journal 99