[Experimental study of the effect on marginal seating of the castings by different investing methods].
OBJECTIVE
The purpose of this study was to observe the effect on marginal seating of the castings with and without ring investments.


METHODS
Standarded as-cast specimens and round capsules simulated post tooth crowns were made. 12 wax pattern were prepared on the as-cast specimens. The 12 specimens were divided into two groups with 6 wax pattern in each group. Two different investing methods with the same investing material were tested. The marginal seating of the castings was measured under travelling microscope.


RESULTS
The marginal seating of the casting without ring investment had significant difference compared with the castings with ring investment (P<0.05).


CONCLUSIONS
Casting without ring can improve the marginal seating of the castings.
School of Dentistry, Shandong University, Jinan 250012, China.
Wei-shan
WS
Ding
Ai-ling
AL
Huang
Yan-ying
YY
Zhang
Yi-jun
YJ
Hu
Jin-mei
JM
Hou