Nihon Hotetsu Shika Gakkai Zasshi

A method whereby various materials used to make interocclusal records may be tested, was established and the accuracy and variance of: seven practical materials, that is, Xanthano, Super bite, Tosicon (silicone-body), Bite compound, Ramitec, Bite wax, Sapphire myo-print, were studied. The obtained results were as follows:
1. Xanthano and Super bite were the least variable and most reliable of all materials investigated.
2. Tosicon raevealed almost the same accuracy to Xanthano and Super bite, however with large variance for mounting procedure.
3. Bite compound, Ramitec, Bite wax and Sapphire myo-print were not reliable because of lower accuracy and large variances. And any of these four materials showed statistically significant mounting discrepancies amoung three operators.
4. Super bite and Sapphire myo-print resulted in statistically significant mounting descrepancies due to storage time of 2, 24 and 48 hours after making registrations.

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Viscoelastic properties of silicone material (code-named MDX-4-4210) and 4 commercial soft liners and related materials (Kurepate, Neo-Snugger, Super-Soft and Viscogel) were examined using a stress relaxation testing instrument. All measurements were preformed in water at a temperature of 37±0.5°C.
In the case of other 4 materials, except Visco-gel, the decreasing rates of relative stress {f(t)/f(0)} with time were relatively small. Furthermore, the decreases of stress relaxation modulus {Er(t)} of these materials with period soaked in water at 37°C were also very small, with exception of Visco-gel. Code-named MDX-4-4210 showed the most superior elastic properties in materials used. The relative stress in Visco-gel diminished markedly with time.
These results indicate that all materials, excluding Visco-gel, have possessed the favourable properties as soft liners and related materials since it is necessary for these materials to remain in oral cavity for long period of month.

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Recently, silicone has been widely used for soft liners and related materials. The purpose of this investigation was to examine the adhesive strength of a silicone material (MDX-4-4210) to acrylic resins and to discussed the possibility to clinical application (especically, for the case of soft palate substance defects). The materials tested were code-named MDX-4-4210 and four commercial materials (Kurepate, Neo-Snugger, Super-Soft and Viscogel). The adhesive strength of each material was investigated using Instron testing machine.
The mean adhesive strengths under tension to acrylic resins were 16.2kg/cm² for MDX-4-4210, 83.6kg/cm² for Kurepate, 11.6kg/cm² for Neo-Snugger, 28.8kg/cm² for Super-Soft and 3.0kg/cm² for Visco-gel. Furthermore, the mean adhesive strengths under shear were 6.5kg/cm² for MDX-4-4210, 100.4kg/cm² for Kurepate, 7.4kg/cm² for Neo-Snugger, 22.4 kg/cm² for Super-Soft and 1.8kg/cm² for Visco-gel.
From these results, it can be seen that the adhesive strength of MDX-4-4210 to acrylic resin is retatively small, However, the deformation of MDX-4-4210 obtained when debonding from acrylic resin occured was the highest of the materials used in this investigation and attained its maximum value of 15mm.
It can be seen that this property of MDX-4-4210 is clinically favourable since it is considered that the movement of denture and the displacement of soft tissue are relatively marked, during masticating.

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