[Shock absorption of mouthguard materials--influence of temperature conditions and shore hardness on shock absorption].
OBJECTIVE
To consider changes in the physical properties of mouthguard materials with the change of temperature, shock-absorbing examination and Shore hardness measurement of existing MG materials and other elastic materials were carried out.


METHODS
Both examinations were done under two temperature conditions: at room temperature (25 degrees C) and simulated intraoral temperature (37 degrees C). In addition, a comparative study of the relation between Shore hardness and shock absorption of the materials was made. A self-made drop impact machine was used for the shock-absorbing examination. The thickness of a sample was assumed to be 3 mm. The loading was applied by dropping 3 kinds of steel ball, phi 10 mm (4.0 g), phi 15 mm (13.7 g), and phi 20 mm (32.6 g) from a height of 60 cm. The shock absorption of all materials was compared by the maximum impact force. Shore hardness was measured based on the JIS standard.


RESULTS
The shock absorption of each material showed a different tendency depending on the loading condition. Furthermore, the shock absorption of the same material showed different results depending on the temperature condition. Shore hardness measurements tended to show low values with the condition of 37 degrees C for all materials.


CONCLUSIONS
From the relation between shock absorption and Shore hardness, it was confirmed that there is a correlation between hardness and the maximum impact force in the materials that showed shock absorption by elastic deformation. Some materials showed high shock absorption compared with existing MG materials.
Tomita
Takashi
T
Department of Removable Partial Denture Prosthodontics, Nihon University School of Dentistry. tomita-t@dent.nihon-u.ac.jp
Tsukimura
Naoki
N
Ohno
Shigeru
S
Umekawa
Yoshitada
Y
Sawano
Muneyuki
M
Fujimoto
Toshiki
T
Takamura
Masaaki
M
Majima
Aiko
A
Katakura
Yuusuke
Y
Kurata
Akemi
A
Ohyama
Tetsuo
T
Ishigami
Tomohiko
T
D006244:Hardness; D009064:Mouth Protectors; D013314:Stress, Mechanical; D013696:Temperature