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Braz Dent Sci 2024 Apr/June;27 (2): e4357
Silva ESR et al.
Impact of plasticization temperature on the mechanical pr operties of sports mouthguards
Silva ESR et al. Impact of plasticization temperature on the mechanical
properties of sports mouthguards
The comparative analysis of plasticization
temperatures showed that the groups subjected to
the highest temperatures, corresponding to 128°C
in Group B2 and 121°C in Group F2, had their
energy absorption capacity reduced. This nding
reafrms the study by Yamada and Maeda [13]
since both temperatures are higher than the ideal
EVA plasticization range (> 120°C) and present a
lower performance of the material. Groups B1 and
F1, plasticized within the ideal range between
80°C and 120°C, showed better energy absorption.
The physical and mechanical properties of
the sheets vary with the chemical composition
of the material, and even commercial brands
made of the same material can also vary in terms
of these properties [13,21]. Likewise, when
comparing Groups B1 and F1, composed of EVA
and plasticized within the ideal temperature
range, the last one showed that it reached the
plasticization point at a lower temperature and
also presented a better capacity to absorb energy.
The modulus of elasticity refers to a fundamen-
tal mechanical property of the material that can be
measured through the slope coefcient of a straight
line and a stress-strain graph obtained in the elastic
regime. In the elastic regime, when removing the
force causing deformation, all absorbed energy
must be fully returned. Flexible materials undergo
greater deformation within their elasticity range,
while rigid materials do not ex and, when absorb-
ing energy, can reach their fracture limit. Therefore,
the modulus of elasticity is higher in rigid materials
and lower in exible materials such as EVA [22].
The graphs referring to the modulus of
elasticity show that Group F1 plasticized at the
lowest temperature and with the highest absorp-
tion capacity, presented the lowest modulus of
elasticity among the others. At rst, considering
the plasticized groups within the ideal temperature
range, Brand F proved to be superior to Brand B
in terms of energy absorption capacity. However,
with the increase in temperature, the performance
of the Brand F test specimens became similar to
that presented by Brand B, which can be possibly
attributed to the change in the microstructure of
the Brand F material and, consequently, its change
in elastic modulus. As a result, it is possible to
establish as a preliminary result that, depend-
ing on the commercial brand, the plasticization
temperature can in fact inuence the modulus of
elasticity of the material and, consequently, its
ability to absorb energy.
Furthermore, Group F1, which was plasti-
cized at the lowest temperature, showed greater
absorption capacity, and lower modulus of elastic-
ity, in addition to less variation in its dimensions.
As a result, it proved to be the most effective
in protection and with the greatest durability.
However, in Brand B, the different plasticization
temperatures showed little interference in the
change in the elastic modulus, expressing a toler-
able difference. Furthermore, Group B2 exhibited
the lowest standard deviation during compression
tests, which may be an indication that this is a
more reliable material for experiments since it had
a lower failure rate.
Finally, the present study highlighted the
possibility of measuring the temperature of a
vacuum laminator using a culinary thermometer,
an accessible tool in terms of value and availability
on the market. Thus, the dentist can check and
control the plasticization temperature in his own
ofce in order to promote better properties for
the sports mouthguard.
CONCLUSION
The plasticization temperature of EVA sheets
signicantly inuences the absorption capacity
of mouthguards. An increase in temperature led
to a reduction in this property, especially when
higher than 120°C. However, the inuence of
the plasticization temperature on the process
of manufacturing a mouthguard may vary
depending on the commercial brand used.
The culinary thermometer can be easily
used to check the plasticization temperature by
the dentist in his ofce in order to provide better
properties to the mouthguard.
Author’s Contributions
ESRS: Conceptualization, Methodology,
Investigation, Resources, Data Curation,
Writing – Original Draft Preparation. TRMG:
Conceptualization, Methodology, Resources,
Writing – Review & Editing, Visualization,
Supervision. SSIO: Validation, Formal Analysis,
Writing – Review & Editing, Visualization,
Supervision. KMW: Validation, Formal Analysis,
Visualization, Supervision. LGM: Validation,
Formal Analysis, Visualization. JNSMDM:
Validation, Formal Analysis, Visualization.