INLUENCE OF DIET IN THE MICROHARDNESS OF DENTAL
COMPOSITES
Rosemarie R. Rezende 1, Cynthia S. B. Castro2, Hermes S. Costa1, Ezequiel S.
Costa Jr.1
1Departmet
of Materials, Federal Center of Technological Education of Minas Gerais, Belo Horizonte
(MG), Brazil
2Fundation Technological Center of Minas Gerais, Belo Horizonte (MG), Brazil
Summary. The composites used in aesthetic dental restorations need to have good physical and
mechanical properties to withstand the harsh conditions of the oral environment. The objective of this
study was to evaluate the change in hardness of two composites nanohybrids (Composite A-and
Composite B) caused by alcoholic and nonalcoholic media present in the diet. Eighteen specimens of
each composite were prepared using a metal matrix with dimensions of 24 x 4 x 0.4 mm. the
specimens were divided into six groups including a control group (1) kept dry at 37° C. The other
groups were immersed in water (2), liquor (3), beer (4), condenser (5) and wine (6) for 7 days. The
Vickers hardness measurement of the irradiated surface was evaluated using a microhardness testing
machine (FM-700, Future Tech, 50 g/10 s). For statistical analysis was used the MINITAB14 program,
with 95% confidence index. The results showed that after immersing of composite into the media the
samples presented hardness values lower than the values observed in the samples before immersion
tests. The average hardness value was 58.1VH before immersion and 49.7VH after immersion. Also
was observed a more evident decrease in the hardness for immersion of samples into the cachaça.
The reduction observed was more evident after being soaked in cachaça that was reduced by 27.5%.
Keywords: Composite resin, Degradation, Diet
1- INTRODUCTION
Among the challenges faced by dentistry highlights the quest for a dental
restorative material to restore the function of the tooth, and that present good optical
characteristics as well physical properties similar to those of dental tissues
(DRUMMOND, 2008; ZIMMERLI et al., 2010). The focus of aesthetic materials in
Odontology has considered the need of alternative materials for metal in restoration
of teeth, when esthetic and functional restorations are required. Currently are used
as aesthetic restorative materials a composite made with organic matrix, inorganic
particles and bonding agent (BARATIERI et al., 1992; PEUTZFELDT, 1997; RAWLS
& ESQUIVEL-UPSHAW, 2005; ZIMMERLI et al., 2010).
Around the year 2003, were introduced in dentistry market the composites with
nanoparticles (MITRA et al., 2003). Since then, manufacturers launch new
composites with these particles, to promote improvements in various physical and
mechanical properties without scientific evidence that confirm such information
(BRITO et al., 2007). Furthermore, it is necessary to understand the clinical behavior
of the resin so that the use is appropriate (CONSANI et al., 2002; FARES et al.,
2005). The hardness of the composite is influenced by the shape, type and amount
of inorganic particles (CONSANI et al., 2002; NEVES et al., 2002). Whereas the
media that the composites are subjected, such as ethanol, penetrating the resin
matrix causing changes in its physical and mechanical properties due to aging and
degradation (DRUMMOND, 2008; PFEIFER et al., 2009) the objective of this study
was to evaluate the influence of drink, present in the diet, in the microhardness of two
nanohybrids composite.
2. MATERIALS AND METHODS
For this study, we chose two commercial composite: A (Urethane Bis-GMA modified,
Bis-EMA and TEGDMA) and B (Bis-GMA and TEGDMA), which have around 76% of
inorganic particles in the nanometric scale, not presented in others composites, and
without studies in the literature for the use of these trademarks. As immersion
medium were used alcohol media (cachaça, beer and wine) and nonalcoholic media
(water and soft drink).
For the tests 18 rectangular specimens of each composite were made with
dimensions of 24mm x 4mm x 0.4 mm submitted by curing light using the Blue Star 2
(Microdont) for 20s each quarter of the specimen. The specimens were divided into
six groups for each composite (A and B). The control groups (1A and 1B) were kept
dry in a stove at 37 °C while the other groups were immersed for seven days in one
of the following media: water (2A and 2B), cachaça (3A and 3B), beer (4A and 4B),
soft drink (5A and 5B) and wine (6A and 6B). The liquids media were removed and
replaced by fresh media every 24 hours. The Vickers microhardness was recorded
by the equipment FM 700 (Future Tech Corp., Tokyo, Japan), with a load of 50g for
15s. Three indentations were carried out on the irradiated surface (face facing the
light source) in each of the 36 specimen, totaling 108 measures. After each
indentation, the diagonals of the base of the pyramid printed in the material were
measured and converted into values of Vickers hardness (VH) directly by the
equipment.
The results were subjected to analysis of variance with an index of 95% of the
program MINITAB14.
3. RESULTS AND DISCUSSION
Figure 1 presents the average results for each group. The results shown for
samples soaked, the composite B obtained mean Vickers hardness (52.4VH) higher
in comparison with the composite A (49.7VH), except for the samples soaked in beer.
The Vickers hardness values of the composites subjected to immersion media
(49.7VH) were lower if compared to composites before immersion into the media
(58.1VH), independent of the material tested.
Vickers Microhardness
70
60
50
VH
40
A
30
B
20
10
0
1
2
3
Media
4
5
6
Graph 1 - Average values of Vickers microhardness (VH)
Analysis of variance showed that the composite used is statistically significant
(p = 0.027) like the media (p = 0.00).
These results are in agreement with studies of Asmussen and Peutzfeldt
(2003) and Luis (2007) that is a modification of hardness in the composite after
immersion. Table 1 shows the percentage reduction of the hardness in the composite
provided by media used, if compared to the composite hardness observed before
immersion process.
In 1998, Ferracane et al. observed that the water storage causes limited
degradation of the composite, but other solvents can be more aggressive, as
demonstrated by Aguiar et al. (2005), where the immersion in ethanol promoted a
greater reduction in hardness than water. This study also was observed that the
alcoholic media promotes further reduction in hardness (15.55%) for no alcoholic
media (8.69%). Wongkhantee et al. (2006) demonstrated that acid media, such as
cola soft drinks, reduced the hardness of resin composite restorations. Although the
soft drink can promotes reduction in hardness (8.64%), the results are similar to
water (8.74%).
Moreover was observed that the cachaça and beer providing a greater
reduction in hardness of the composite B which may be caused by the greater
amount of Bis-GMA, which is in accordance with the study of Asmussem (1984),
while other media affect more the composite A.
Table 1 - Reduction of the hardness in relation to the composite non-immersed (%)
Water Soft drink Cachaça Beer Wine Alcoholic media Non alcoholic
A
10
9
26
9
19
18
10
B
6
7
28
16
9
12
7
SD - A
5,65
3,77
5,10
3,53
4,31
5,69
4,67
SD - B
4,38
4,86
2,42
2,78
5,62
6,19
4,49
SD – standard deviation
Importantly, the indentations performed on samples of composite B were more
irregular than those presented by composite A. This may indicate that the residual
elastic tension of the composite B was higher than that of A, and therefore may
influence the results.
The differences in the results between both composites can be related to the
chemical difference in composition (CONSANI et al., 2002) and not to the amount of
inorganic particles (PEUTZFELDT, 1997; FARES et al., 2005; ROCHA, 2006; PIRES
et al., 2007; SOUZA et al., 2009), because the composites exhibit similar percentage
of inorganic particles.
CONCLUSIONS
It was concluded that immersion of dental composites in some media present
in diet, is capable to promote changes in mechanical properties, such as hardness,
where such modifications dependent by the media that these materials are exposed.
ACKNOWLEDGMENTS
To Cetec-Senai in the person of Dr. Margareth Spangler Andrade, coordinator
of the laboratory of metallurgy, by enabling the laboratory to perform microhardness
tests.
The authors gratefully acknowledge CAPES, CNPq, FAPEMIG and
CEFET/MG.
REFERENCES
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
AGUIAR, F.H.B. et al. Hardness and diametral tensile strength of a hybrid composite resin
polymerized with different modes and immersed in ethanol or distilled water media. Dent.
Mater., [S.l.], v. 21, n. 12, p. 1098-1103, dec. 2005.
ASMUSSEN, E. Softening of BISGMA-based polymers by ethanol and by organic acids of
plaque. Scand. J. Dent. Res., [S.l.], v. 92, n. 3, p. 257-261, 1984.
ASMUSSEN, E; PEUTZFELDT, A. Polymer structure of a light-cured resin composite in relation
to distance from the surface. Eur J Oral Sci. [S.l.], v. 111, p. 277-279, 2003.
BARATIERI, L.N. et al. Restaurações com resina composta. In: ______. Dentística:
procedimentos preventivos e restauradores. 2. ed. São Paulo: Santos, 1992, cap. 7.
BRITO, A.C.R. et al. Avaliação comparativa da resistência à compressão entre uma resina
composta direta e duas resinas laboratoriais. Pesq. Bras. Odontoped. Clin. Integr., João
Pessoa, v. 7, n. 2, p. 145-148, maio/ago. 2007.
CONSANI, S. et al. Efeito dos métodos de fotoativação e de inserção sobre a dureza de
resinas compostas. Pesq. Odontol. Bras., São Paulo, v. 16, n. 4, p. 355-360, dez. 2002.
DRUMMOND, J.L. Degradation, Fatigue, and Failure of Resin Dental Composite Materials. J.
Dent. Res., v.87, n. 8, p.710-719, 2008.
FARES, N.H. et al. Resistência flexural e módulo de elasticidade da resina composta. Rev. de
Clín. Pesq. Odontol., Curitiba, v. 2, n. 1, p. 53-55, jul./set. 2005
FERRACANE, J.L. et al. In vitro aging of dental composites in water - Effect of degree of
conversion, filler volume, and filler/ matrix coupling. J. Biomed. Mater. Res., [S.l.], v. 42, n. 3,
p. 465-472, dec. 1998.
LUIZ, B.K.M. Resinas compostas fotoativadas: propriedades micro e macroscópicas após
cura e armazenadas em meios que simulam dieta. 2007. 100f. Tese (Doutorado em Ciência e
Engenharia de Materiais) - Universidade Federal de Santa Catarina. Florianópolis.
MITRA, S.B. et al. An application of nanotechnology in advanced dental materials. J. Am. Dent.
Assoc., Chicago, v. 134, n. 10, p. 1382-1390, oct. 2003.
12.
13.
14.
15.
16.
17.
18.
19.
20.
NEVES, A.D. et al. Correlação entre grau de conversão, microdureza e conteúdo inorgânico
em compósitos. Pesq. Odontol. Bras., São Paulo, v. 16, n. 4, p. 349-354, 2002.
PEUTZFELDT, A. Resin composites in dentistry: the monomer systems. Eur. J. Oral. Sci.
[S.l.], v. 105, n. 2, p. 97-116, apr. 1997.
PFEIFER, C.S. et al. Bis-GMA co-polymerizations: influence on conversion, flexural properties,
fracture toughness and susceptibility to ethanol degradation of experimental composites. Dent.
Mater., [S.l.], v. 25, n. 9, 1136-1141, sep. 2009.
PIRES, H.C. et al. Avaliação da dureza Vickers de 29 resinas compostas. Revista
Odontológica de Araçatuba, v. 28, n. 3, p. 16-23, set./dez. 2007.
RAWLS, H.R.; ESQUIVEL-UPSHAW, J. Resinas restauradoras. In: ANUSAVICE, Kenneth J.
Phillips materiais dentários. Trad. de Alessandro Dourado et al. 11. ed. Rio de Janeiro:
Elsevier, 2005. cap. 15, p. 375-417.
ROCHA, R.S.F. Estudo de propriedades físico-químicas de resinas odontológicas: grau
de conversão, dureza e expansão térmica. 2006. 73f. Dissertação (Mestrado em Ciência dos
Materiais) - Universidade Estadual Paulista. Faculdade de Engenharia de Ilha Solteira. São
Paulo.
SOUZA, R.O.A. et al. Avaliação da dureza Vickers de resinas compostas de uso direto e
indireto. Cienc. Odontol. Bras., São José dos Campos, v. 12, n. 1, p. 23-30, jan./mar. 2009.
WONGKHANTEE, S. et al. Effect of acidic food and drinks on surface hardness of enamel,
dentine, and tooth-coloured filling materials. Journal of Dentistry, [S.l], v. 34, n. 3, p. 214-220,
mar. 2006.
ZIMMERLI, B. et al. Composite materials: Composition, properties and clinical applications. A
Literature Review. Schweiz Monatsschr Zahnmed. [S.l.], v. 120, n. 11, p. 972-986, 2010.