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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.