Flexural strength of the joint between glass-infiltrated alumina frames and the alumina-magnesia modifier.
OBJECTIVE
The purpose of the present study was to evaluate the flexural strength of the joint between glass-infiltrated alumina frames and the experimental adjusting agent (MA modifier) that contains alumina and magnesia.


METHODS
A commercially available adjusting agent (Optimizer), a slurry of alumina powder (Alumina modifier), and a bulk specimen (joint-free alumina) were used as controls. Beam-shaped alumina specimens were machined from an alumina block. The ends of two alumina beams were positioned at an interval of 1.0 mm and joined with each adjusting agent. The joined specimens were subjected to sintering, glass infiltration firing, glass control firing, and then a three-point bending test was carried out to evaluate the flexural strength.


RESULTS
The maximum flexural strength was observed in the joint-free alumina, followed by MA modifier, Optimizer and Alumina modifier. With the exception for joint-free alumina, the failure modes after three-point bending test tended to shift from adhesive failure at substrate material-adjusting agent interface to cohesive failure within adjusting agent as the flexural strength increased.


CONCLUSIONS
The use of MA modifier significantly improved the flexural strength of joined glass-infiltrated alumina frame. The MA modifier could be applied for adjusting the margin as an alternative to Optimizer when fabricating crown and bridge substructures with In-Ceram Alumina system.
Taira
Yohsuke
Y
Applied Prosthodontics, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1, Sakamoto, Nagasaki 852-8588, Japan. yohsuke@nagasaki-u.ac.jp
Fukui
Junichi
J
Odatsu
Tetsuro
T
Kamada
Kohji
K
Sawase
Takashi
T
D000537:Aluminum Oxide; D003764:Dental Materials; D005898:Glass; D008277:Magnesium Oxide; D008422:Materials Testing; D018583:Pliability
D003764:Dental Materials; D008277:Magnesium Oxide; D000537:Aluminum Oxide