[Mechanical behavior of the cement layer of a cast crown--effect of the mechanical properties of casting alloy].
Experimental crowns with uniform thickness at their axial surfaces were made of dental casting gold-silver-palladium alloy (12% gold) and dental casting gold alloy (Type IV). They were cemented on model teeth for abutment and their deformations under applied loads were measured with strain gages. The effect of axial metal thickness on the crown's rigidity and the cement fracture strength were examined. Among the structures of cemented crowns and abutment teeth, that of the axial metal thickness of 0.3 mm had cement failure at the smallest loads. As the metal thickness was increased, the crown's deformation decreased and the cement failure load increased. For a thickness greater than 0.7 mm, however, the increase in failure load was not obvious. The difference of the casting alloy had no significant effect on the cement fracture. Accordingly, the rigidity of dental prostheses should be one of the most important design factors for preventing failure under occlusal load, and it is recommended that the thickness of the axial surface should be more than 0.7 mm.
Sugita
T
T
Biomechanics, Graduate School of Dentistry, Tokyo Medical and Dental University.
Takakuda
K
K
Miyairi
H
H
D003722:Dental Alloys; D003738:Dental Cements; D006047:Gold Alloys; D013314:Stress, Mechanical
D003722:Dental Alloys; D003738:Dental Cements; D006047:Gold Alloys